EyeLink Clinical and Oculomotor Eye-Tracking Publications
All EyeLink clinical and oculomotor research publications up until 2019 (with some early 2020s) are listed below by year. You can search the publications using keywords such as Saccadic Adaptation, Schizophrenia, Nystagmus, etc. You can also search for individual author names, and limit searches by year (choose the year then click the search button). If we missed any EyeLink clinical or oculomotor article, please email us!
All clinical and oculomotor publications are also available for download / import into reference management software as a single Bibtex (.bib) file.
2020 |
Valerie M Beck; Timothy J Vickery Oculomotor capture reveals trial-by-trial neural correlates of attentional guidance by contents of visual working memory Journal Article Cortex, 122 , pp. 159–169, 2020. @article{Beck2020, title = {Oculomotor capture reveals trial-by-trial neural correlates of attentional guidance by contents of visual working memory}, author = {Valerie M Beck and Timothy J Vickery}, doi = {10.1016/j.cortex.2018.09.017}, year = {2020}, date = {2020-01-01}, journal = {Cortex}, volume = {122}, pages = {159--169}, publisher = {Elsevier Ltd}, abstract = {Evidence from attentional and oculomotor capture, contingent capture, and other paradigms suggests that mechanisms supporting human visual working memory (VWM) and visual attention are intertwined. Features held in VWM bias guidance toward matching items even when those features are task irrelevant. However, the neural basis of this interaction is underspecified. Prior examinations using fMRI have primarily relied on coarse comparisons across experimental conditions that produce varying amounts of capture. To examine the neural dynamics of attentional capture on a trial-by-trial basis, we applied an oculomotor paradigm that produced discrete measures of capture. On each trial, subjects were shown a memory item, followed by a blank retention interval, then a saccade target that appeared to the left or right. On some trials, an irrelevant distractor appeared above or below fixation. Once the saccade target was fixated, subjects completed a forced-choice memory test. Critically, either the target or distractor could match the feature held in VWM. Although task irrelevant, this manipulation produced differences in behavior: participants were more likely to saccade first to an irrelevant VWM-matching distractor compared with a non-matching distractor – providing a discrete measure of capture. We replicated this finding while recording eye movements and scanning participants' brains using fMRI. To examine the neural basis of oculomotor capture, we separately modeled the retention interval for capture and non-capture trials within the distractor-match condition. We found that frontal activity, including anterior cingulate cortex and superior frontal gyrus regions, differentially predicted subsequent oculomotor capture by a memory-matching distractor. Other regions previously implicated as involved in attentional capture by VWM-matching items showed no differential activity across capture and non-capture trials, even at a liberal threshold. Our findings demonstrate the power of trial-by-trial analyses of oculomotor capture as a means to examine the underlying relationship between VWM and attentional guidance systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Evidence from attentional and oculomotor capture, contingent capture, and other paradigms suggests that mechanisms supporting human visual working memory (VWM) and visual attention are intertwined. Features held in VWM bias guidance toward matching items even when those features are task irrelevant. However, the neural basis of this interaction is underspecified. Prior examinations using fMRI have primarily relied on coarse comparisons across experimental conditions that produce varying amounts of capture. To examine the neural dynamics of attentional capture on a trial-by-trial basis, we applied an oculomotor paradigm that produced discrete measures of capture. On each trial, subjects were shown a memory item, followed by a blank retention interval, then a saccade target that appeared to the left or right. On some trials, an irrelevant distractor appeared above or below fixation. Once the saccade target was fixated, subjects completed a forced-choice memory test. Critically, either the target or distractor could match the feature held in VWM. Although task irrelevant, this manipulation produced differences in behavior: participants were more likely to saccade first to an irrelevant VWM-matching distractor compared with a non-matching distractor – providing a discrete measure of capture. We replicated this finding while recording eye movements and scanning participants' brains using fMRI. To examine the neural basis of oculomotor capture, we separately modeled the retention interval for capture and non-capture trials within the distractor-match condition. We found that frontal activity, including anterior cingulate cortex and superior frontal gyrus regions, differentially predicted subsequent oculomotor capture by a memory-matching distractor. Other regions previously implicated as involved in attentional capture by VWM-matching items showed no differential activity across capture and non-capture trials, even at a liberal threshold. Our findings demonstrate the power of trial-by-trial analyses of oculomotor capture as a means to examine the underlying relationship between VWM and attentional guidance systems. |
Soazig Casteau; Daniel T Smith On the link between attentional search and the oculomotor system: Is preattentive search restricted to the range of eye movements? Journal Article Attention, Perception, & Psychophysics, pp. 1–15, 2020. @article{Casteau2020, title = {On the link between attentional search and the oculomotor system: Is preattentive search restricted to the range of eye movements?}, author = {Soazig Casteau and Daniel T Smith}, year = {2020}, date = {2020-01-01}, journal = {Attention, Perception, & Psychophysics}, pages = {1--15}, publisher = {Attention, Perception, & Psychophysics}, abstract = {It has been proposed that covert visual search can be fast, efficient, and stimulus driven, particularly when the target is defined by a salient single feature, or slow, inefficient, and effortful when the target is defined by a nonsalient conjunction offeatures. This distinction between fast, stimulus-driven orienting and slow, effortful orienting can be related to the distinction between exog- enous spatial attention and endogenous spatial attention. Several studies have shown that exogenous, covert orienting is limited to the range of saccadic eye movements, whereas covert endogenous orienting is independent of the range of saccadic eye movements. The current study examined whether covert visual search is affected in a similar way. Experiment 1 showed that covert visual search for feature singletons was impaired when stimuli were presented beyond the range of saccadic eye move- ments, whereas conjunction search was unaffected by array position. Experiment 2 replicated and extended this effect by measuring search times at 6 eccentricities. The impairment in covert feature search emerged only when stimuli crossed the effective oculomotor range and remained stable for locations further into the periphery, ruling out the possibility that the results of Experiment 1 were due to a failure to fully compensate for the effects of cortical magnification. The findings are interpreted in terms ofbiased competition and oculomotor theories ofspatial attention. It is concluded that, as with covert exogenous orienting, biological constraints on overt orienting in the oculomotor system constrain covert, preattentive search. Keywords}, keywords = {}, pubstate = {published}, tppubtype = {article} } It has been proposed that covert visual search can be fast, efficient, and stimulus driven, particularly when the target is defined by a salient single feature, or slow, inefficient, and effortful when the target is defined by a nonsalient conjunction offeatures. This distinction between fast, stimulus-driven orienting and slow, effortful orienting can be related to the distinction between exog- enous spatial attention and endogenous spatial attention. Several studies have shown that exogenous, covert orienting is limited to the range of saccadic eye movements, whereas covert endogenous orienting is independent of the range of saccadic eye movements. The current study examined whether covert visual search is affected in a similar way. Experiment 1 showed that covert visual search for feature singletons was impaired when stimuli were presented beyond the range of saccadic eye move- ments, whereas conjunction search was unaffected by array position. Experiment 2 replicated and extended this effect by measuring search times at 6 eccentricities. The impairment in covert feature search emerged only when stimuli crossed the effective oculomotor range and remained stable for locations further into the periphery, ruling out the possibility that the results of Experiment 1 were due to a failure to fully compensate for the effects of cortical magnification. The findings are interpreted in terms ofbiased competition and oculomotor theories ofspatial attention. It is concluded that, as with covert exogenous orienting, biological constraints on overt orienting in the oculomotor system constrain covert, preattentive search. Keywords |
Ziad M Hafed; Laurent Goffart Gaze direction as equilibrium: More evidence from spatial and temporal aspects of small-saccade triggering in the rhesus macaque monkey Journal Article Journal of Neurophysiology, 123 (1), pp. 308–322, 2020. @article{Hafed2020, title = {Gaze direction as equilibrium: More evidence from spatial and temporal aspects of small-saccade triggering in the rhesus macaque monkey}, author = {Ziad M Hafed and Laurent Goffart}, doi = {10.1152/jn.00588.2019}, year = {2020}, date = {2020-01-01}, journal = {Journal of Neurophysiology}, volume = {123}, number = {1}, pages = {308--322}, abstract = {Rigorous behavioral studies made in human subjects have shown that small-eccentricity target displacements are associated with increased saccadic reaction times, but the reasons for this remain unclear. Before characterizing the neurophysiological foundations underlying this relationship between the spatial and temporal aspects of saccades, we tested the triggering of small saccades in the male rhesus macaque monkey. We also compared our results to those obtained in human subjects, both from the existing literature and through our own additional measurements. Using a variety of behavioral tasks exercising visual and nonvisual guidance of small saccades, we found that small saccades consistently require more time than larger saccades to be triggered in the nonhuman primate, even in the absence of any visual guidance and when valid advance information about the saccade landing position is available. We also found a strong asymmetry in the reaction times of small upper versus lower visual field visually guided saccades, a phenomenon that has not been described before for small saccades, even in humans. Following the suggestion that an eye movement is not initiated as long as the visuo-oculomotor system is within a state of balance, in which opposing commands counterbalance each other, we propose that the longer reaction times are a signature of enhanced times needed to create the symmetry-breaking condition that puts downstream premotor neurons into a push-pull regime necessary for rotating the eyeballs. Our results provide an important catalog of nonhuman primate oculomotor capabilities on the miniature scale, allowing concrete predictions on underlying neurophysiological mechanisms.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Rigorous behavioral studies made in human subjects have shown that small-eccentricity target displacements are associated with increased saccadic reaction times, but the reasons for this remain unclear. Before characterizing the neurophysiological foundations underlying this relationship between the spatial and temporal aspects of saccades, we tested the triggering of small saccades in the male rhesus macaque monkey. We also compared our results to those obtained in human subjects, both from the existing literature and through our own additional measurements. Using a variety of behavioral tasks exercising visual and nonvisual guidance of small saccades, we found that small saccades consistently require more time than larger saccades to be triggered in the nonhuman primate, even in the absence of any visual guidance and when valid advance information about the saccade landing position is available. We also found a strong asymmetry in the reaction times of small upper versus lower visual field visually guided saccades, a phenomenon that has not been described before for small saccades, even in humans. Following the suggestion that an eye movement is not initiated as long as the visuo-oculomotor system is within a state of balance, in which opposing commands counterbalance each other, we propose that the longer reaction times are a signature of enhanced times needed to create the symmetry-breaking condition that puts downstream premotor neurons into a push-pull regime necessary for rotating the eyeballs. Our results provide an important catalog of nonhuman primate oculomotor capabilities on the miniature scale, allowing concrete predictions on underlying neurophysiological mechanisms. |
Raymond M Klein; Maryam Kavyani; Alireza Farsi; Michael A Lawrence Using the locus of slack logic to determine whether the output form of inhibition of return affects an early or late stage of processing Journal Article Cortex, 122 , pp. 123–130, 2020. @article{Klein2020, title = {Using the locus of slack logic to determine whether the output form of inhibition of return affects an early or late stage of processing}, author = {Raymond M Klein and Maryam Kavyani and Alireza Farsi and Michael A Lawrence}, doi = {10.1016/j.cortex.2018.10.023}, year = {2020}, date = {2020-01-01}, journal = {Cortex}, volume = {122}, pages = {123--130}, publisher = {Elsevier Ltd}, abstract = {Slower reaction times to targets presented at a previously cued or attended location are often attributed to inhibition of return (IOR). It has been suggested that IOR affects a process at the output end of processing continuum when it is generated while the oculomotor system is activated. Following the path set by Kavyani, Farsi, Abdoli, and Klein (2017) we used the locus of slack logic embedded in the psychological refractory period (PRP) paradigm to test this idea. We generated what we expected would be the output form of IOR by beginning each with participants making a target directed saccade which was followed by two tasks. Task 1, was a 2-choice auditory discrimination task and Task 2 was a 2-choice visual localization task. We varied the interval between the onsets of the two targets associated with these two tasks (using TTOAs of 200, 400, or 800 msec). As expected the visual task suffered from a robust PRP effect (substantially delayed RTs at the shorter TTOAs). There was also a robust IOR effect with RTs to localize visual targets being slower when the targets were presented at a previously fixated location. Importantly, and in striking to our previous results wherein we generated the input form of IOR, in the present study there was an additive effect between IOR and TTOA on RT2. As implied by the locus of slack logic, we therefore conclude that the form of IOR generated when the oculomotor system is activated affects a late stage of processing. Converging evidence for this conclusion, from a variety of neuroscientific methods, is presented and the dearth of such evidence about the input form of IOR is noted.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Slower reaction times to targets presented at a previously cued or attended location are often attributed to inhibition of return (IOR). It has been suggested that IOR affects a process at the output end of processing continuum when it is generated while the oculomotor system is activated. Following the path set by Kavyani, Farsi, Abdoli, and Klein (2017) we used the locus of slack logic embedded in the psychological refractory period (PRP) paradigm to test this idea. We generated what we expected would be the output form of IOR by beginning each with participants making a target directed saccade which was followed by two tasks. Task 1, was a 2-choice auditory discrimination task and Task 2 was a 2-choice visual localization task. We varied the interval between the onsets of the two targets associated with these two tasks (using TTOAs of 200, 400, or 800 msec). As expected the visual task suffered from a robust PRP effect (substantially delayed RTs at the shorter TTOAs). There was also a robust IOR effect with RTs to localize visual targets being slower when the targets were presented at a previously fixated location. Importantly, and in striking to our previous results wherein we generated the input form of IOR, in the present study there was an additive effect between IOR and TTOA on RT2. As implied by the locus of slack logic, we therefore conclude that the form of IOR generated when the oculomotor system is activated affects a late stage of processing. Converging evidence for this conclusion, from a variety of neuroscientific methods, is presented and the dearth of such evidence about the input form of IOR is noted. |
Kinan Muhammed; Edwin Dalmaijer; Sanjay Manohar; Masud Husain Voluntary modulation of saccadic peak velocity associated with individual differences in motivation Journal Article Cortex, 122 , pp. 198–212, 2020. @article{Muhammed2020, title = {Voluntary modulation of saccadic peak velocity associated with individual differences in motivation}, author = {Kinan Muhammed and Edwin Dalmaijer and Sanjay Manohar and Masud Husain}, doi = {10.1016/j.cortex.2018.12.001}, year = {2020}, date = {2020-01-01}, journal = {Cortex}, volume = {122}, pages = {198--212}, publisher = {Elsevier Ltd}, abstract = {Saccadic peak velocity increases in a stereotyped manner with the amplitude of eye movements. This relationship, known as the main sequence, has classically been considered to be fixed, although several recent studies have demonstrated that velocity can be modulated to some extent by external incentives. However, the ability to voluntarily control saccadic velocity and its association with motivation has yet to be investigated. Here, in three separate experimental paradigms, we measured the effects of incentivisation on saccadic velocity, reaction time and preparatory pupillary changes in 53 young healthy participants. In addition, the ability to voluntarily modulate saccadic velocity with and without incentivisation was assessed. Participants varied in their ability to increase and decrease the velocity of their saccades when instructed to do so. This effect correlated with motivation level across participants, and was further modulated by addition of monetary reward and avoidance of loss. The findings show that a degree of voluntary control of saccadic velocity is possible in some individuals, and that the ability to modulate peak velocity is associated with intrinsic levels of motivation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccadic peak velocity increases in a stereotyped manner with the amplitude of eye movements. This relationship, known as the main sequence, has classically been considered to be fixed, although several recent studies have demonstrated that velocity can be modulated to some extent by external incentives. However, the ability to voluntarily control saccadic velocity and its association with motivation has yet to be investigated. Here, in three separate experimental paradigms, we measured the effects of incentivisation on saccadic velocity, reaction time and preparatory pupillary changes in 53 young healthy participants. In addition, the ability to voluntarily modulate saccadic velocity with and without incentivisation was assessed. Participants varied in their ability to increase and decrease the velocity of their saccades when instructed to do so. This effect correlated with motivation level across participants, and was further modulated by addition of monetary reward and avoidance of loss. The findings show that a degree of voluntary control of saccadic velocity is possible in some individuals, and that the ability to modulate peak velocity is associated with intrinsic levels of motivation. |
A Pressigout; K Dore-Mazars How does number magnitude influence temporal and spatial parameters of eye movements? Journal Article Experimental Brain Research, 238 , pp. 101–109, 2020. @article{Pressigout2020, title = {How does number magnitude influence temporal and spatial parameters of eye movements?}, author = {A Pressigout and K Dore-Mazars}, doi = {10.1007/s00221-019-05701-0}, year = {2020}, date = {2020-01-01}, journal = {Experimental Brain Research}, volume = {238}, pages = {101--109}, publisher = {Springer Berlin Heidelberg}, abstract = {The influence of numerical processing on individuals' behavior is now well documented. The spatial representation of numbers on a left-to-right mental line (i.e., SNARC effect) has been shown to have sensorimotor consequences, the majority of studies being mainly concerned with its impact on the response times. Its impact on the motor programming stage remains less documented, although swiping movement amplitudes have recently been shown to be modulated by number magnitude. Regarding saccadic eye movements, the few available studies have not provided clear-cut conclusions. They showed that spatial–numerical associations modulated ocular drifts, but not the amplitude of memory-guided saccades. Because these studies held saccadic coordinates constant, which might have masked potential numerical effects, we examined whether spontaneous saccadic eye movements (with no saccadic target) could reflect numerical effects. Participants were asked to look either to the left or to the right side of an empty screen to estimate the magnitude (textless or textgreater 5) of a centrally presented digit. Latency data confirmed the presence of the classical SNARC and distance effects. More critically, saccade amplitude reflected a numerical effect: participants' saccades were longer for digits far from the standard (1 and 9) and were shorter for digits close to it (4 and 6). Our results suggest that beyond response times, kinematic parameters also offer valuable information for the understanding of the link between numerical cognition and motor programming.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The influence of numerical processing on individuals' behavior is now well documented. The spatial representation of numbers on a left-to-right mental line (i.e., SNARC effect) has been shown to have sensorimotor consequences, the majority of studies being mainly concerned with its impact on the response times. Its impact on the motor programming stage remains less documented, although swiping movement amplitudes have recently been shown to be modulated by number magnitude. Regarding saccadic eye movements, the few available studies have not provided clear-cut conclusions. They showed that spatial–numerical associations modulated ocular drifts, but not the amplitude of memory-guided saccades. Because these studies held saccadic coordinates constant, which might have masked potential numerical effects, we examined whether spontaneous saccadic eye movements (with no saccadic target) could reflect numerical effects. Participants were asked to look either to the left or to the right side of an empty screen to estimate the magnitude (textless or textgreater 5) of a centrally presented digit. Latency data confirmed the presence of the classical SNARC and distance effects. More critically, saccade amplitude reflected a numerical effect: participants' saccades were longer for digits far from the standard (1 and 9) and were shorter for digits close to it (4 and 6). Our results suggest that beyond response times, kinematic parameters also offer valuable information for the understanding of the link between numerical cognition and motor programming. |
Li Zhang; Guoli Yan; Li Zhou; Zebo Lan; Valerie Benson Journal of Autism and Developmental Disorders, 50 , pp. 500–512, 2020. @article{Zhang2020, title = {The influence of irrelevant visual distractors on eye movement control in Chinese children with autism spectrum disorder: Evidence from the remote distractor paradigm}, author = {Li Zhang and Guoli Yan and Li Zhou and Zebo Lan and Valerie Benson}, doi = {10.1007/s10803-019-04271-y}, year = {2020}, date = {2020-01-01}, journal = {Journal of Autism and Developmental Disorders}, volume = {50}, pages = {500--512}, publisher = {Springer US}, abstract = {The current study examined eye movement control in autistic (ASD) children. Simple targets were presented in isolation, or with central, parafoveal, or peripheral distractors synchronously. Sixteen children with ASD (47–81 months) and nineteen age and IQ matched typically developing children were instructed to look to the target as accurately and quickly as possible. Both groups showed high proportions (40%) of saccadic errors towards parafoveal and peripheral distractors. For correctly executed eye movements to the targets, centrally presented distractors produced the longest latencies (time taken to initiate eye movements), followed by parafoveal and peripheral distractor conditions. Central distractors had a greater effect in the ASD group, indicating evidence for potential atypical voluntary attentional control in ASD children.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The current study examined eye movement control in autistic (ASD) children. Simple targets were presented in isolation, or with central, parafoveal, or peripheral distractors synchronously. Sixteen children with ASD (47–81 months) and nineteen age and IQ matched typically developing children were instructed to look to the target as accurately and quickly as possible. Both groups showed high proportions (40%) of saccadic errors towards parafoveal and peripheral distractors. For correctly executed eye movements to the targets, centrally presented distractors produced the longest latencies (time taken to initiate eye movements), followed by parafoveal and peripheral distractor conditions. Central distractors had a greater effect in the ASD group, indicating evidence for potential atypical voluntary attentional control in ASD children. |
Judith Bek; Ellen Poliakoff; Karen Lander Measuring emotion recognition by people with Parkinson's disease using eye-tracking with dynamic facial expressions Journal Article Journal of Neuroscience Methods, 331 , pp. 1–7, 2020. @article{Bek2020, title = {Measuring emotion recognition by people with Parkinson's disease using eye-tracking with dynamic facial expressions}, author = {Judith Bek and Ellen Poliakoff and Karen Lander}, doi = {10.1016/j.jneumeth.2019.108524}, year = {2020}, date = {2020-01-01}, journal = {Journal of Neuroscience Methods}, volume = {331}, pages = {1--7}, abstract = {Background: Motion is an important cue to emotion recognition, and it has been suggested that we recognize emotions via internal simulation of others' expressions. There is a reduction of facial expression in Parkinson's disease (PD), which may influence the ability to use motion to recognise emotions in others. However, the majority of previous work in PD has used only static expressions. Moreover, few studies have used eye-tracking to explore emotion processing in PD. New method: We measured accuracy and eye movements in people with PD and healthy controls when identifying emotions from both static and dynamic facial expressions. Results: The groups did not differ overall in emotion recognition accuracy, but motion significantly increased recognition only in the control group. Participants made fewer and longer fixations when viewing dynamic expressions, and interest area analysis revealed increased gaze to the mouth region and decreased gaze to the eyes for dynamic stimuli, although the latter was specific to the control group. Comparison with existing methods: Ours is the first study to directly compare recognition of static and dynamic emotional expressions in PD using eye-tracking, revealing subtle differences between groups that may otherwise be undetected. Conclusions: It is feasible and informative to use eye-tracking with dynamic expressions to investigate emotion recognition in PD. Our findings suggest that people with PD may differ from healthy older adults in how they utilise motion during facial emotion recognition. Nonetheless, gaze patterns indicate some effects of motion on emotional processing, highlighting the need for further investigation in this area.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: Motion is an important cue to emotion recognition, and it has been suggested that we recognize emotions via internal simulation of others' expressions. There is a reduction of facial expression in Parkinson's disease (PD), which may influence the ability to use motion to recognise emotions in others. However, the majority of previous work in PD has used only static expressions. Moreover, few studies have used eye-tracking to explore emotion processing in PD. New method: We measured accuracy and eye movements in people with PD and healthy controls when identifying emotions from both static and dynamic facial expressions. Results: The groups did not differ overall in emotion recognition accuracy, but motion significantly increased recognition only in the control group. Participants made fewer and longer fixations when viewing dynamic expressions, and interest area analysis revealed increased gaze to the mouth region and decreased gaze to the eyes for dynamic stimuli, although the latter was specific to the control group. Comparison with existing methods: Ours is the first study to directly compare recognition of static and dynamic emotional expressions in PD using eye-tracking, revealing subtle differences between groups that may otherwise be undetected. Conclusions: It is feasible and informative to use eye-tracking with dynamic expressions to investigate emotion recognition in PD. Our findings suggest that people with PD may differ from healthy older adults in how they utilise motion during facial emotion recognition. Nonetheless, gaze patterns indicate some effects of motion on emotional processing, highlighting the need for further investigation in this area. |
Leanne Nagels; Roelien Bastiaanse; Deniz Başkent; Anita Wagnera Individual differences in lexical access among cochlear implant users Journal Article Journal of Speech, Language, and Hearing Research, 63 , pp. 286–304, 2020. @article{Nagels2020, title = {Individual differences in lexical access among cochlear implant users}, author = {Leanne Nagels and Roelien Bastiaanse and Deniz Başkent and Anita Wagnera}, year = {2020}, date = {2020-01-01}, journal = {Journal of Speech, Language, and Hearing Research}, volume = {63}, pages = {286--304}, abstract = {Purpose: The current study investigates how individual differences in cochlear implant (CI) users' sensitivity to word–nonword differences, reflecting lexical uncertainty, relate to their reliance on sentential context for lexical access in processing continuous speech. Method: Fifteen CI users and 14 normal-hearing (NH) controls participated in an auditory lexical decision task (Experiment 1) and a visual-world paradigm task (Experiment 2). Experiment 1 tested participants' reliance on lexical statistics, and Experiment 2 studied how sentential context affects the time course and patterns of lexical competition leading to lexical access. Results: In Experiment 1, CI users had lower accuracy scores and longer reaction times than NH listeners, particularly for nonwords. In Experiment 2, CI users' lexical competition patterns were, on average, similar to those of NH listeners, but the patterns of individual CI users varied greatly. Individual CI users' word–nonword sensitivity (Experiment 1) explained differences in the reliance on sentential context to resolve lexical competition, whereas clinical speech perception scores explained competition with phonologically related words. Conclusions: The general analysis of CI users' lexical competition patterns showed merely quantitative differences with NH listeners in the time course of lexical competition, but our additional analysis revealed more qualitative differences in CI users' strategies to process speech. Individuals' word–nonword sensitivity explained different parts of individual variability than clinical speech perception scores. These results stress, particularly for heterogeneous clinical populations such as CI users, the importance of investigating individual differences in addition to group averages, as they can be informative for clinical rehabilitation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Purpose: The current study investigates how individual differences in cochlear implant (CI) users' sensitivity to word–nonword differences, reflecting lexical uncertainty, relate to their reliance on sentential context for lexical access in processing continuous speech. Method: Fifteen CI users and 14 normal-hearing (NH) controls participated in an auditory lexical decision task (Experiment 1) and a visual-world paradigm task (Experiment 2). Experiment 1 tested participants' reliance on lexical statistics, and Experiment 2 studied how sentential context affects the time course and patterns of lexical competition leading to lexical access. Results: In Experiment 1, CI users had lower accuracy scores and longer reaction times than NH listeners, particularly for nonwords. In Experiment 2, CI users' lexical competition patterns were, on average, similar to those of NH listeners, but the patterns of individual CI users varied greatly. Individual CI users' word–nonword sensitivity (Experiment 1) explained differences in the reliance on sentential context to resolve lexical competition, whereas clinical speech perception scores explained competition with phonologically related words. Conclusions: The general analysis of CI users' lexical competition patterns showed merely quantitative differences with NH listeners in the time course of lexical competition, but our additional analysis revealed more qualitative differences in CI users' strategies to process speech. Individuals' word–nonword sensitivity explained different parts of individual variability than clinical speech perception scores. These results stress, particularly for heterogeneous clinical populations such as CI users, the importance of investigating individual differences in addition to group averages, as they can be informative for clinical rehabilitation. |
William Rosengren; Marcus Nyström; Björn Hammar; Martin Stridh A robust method for calibration of eye tracking data recorded during nystagmus Journal Article Behavior Research Methods, 52 , pp. 36–50, 2020. @article{Rosengren2020, title = {A robust method for calibration of eye tracking data recorded during nystagmus}, author = {William Rosengren and Marcus Nyström and Björn Hammar and Martin Stridh}, doi = {10.3758/s13428-019-01199-0}, year = {2020}, date = {2020-01-01}, journal = {Behavior Research Methods}, volume = {52}, pages = {36--50}, abstract = {Eye tracking is a useful tool when studying the oscillatory eye movements associated with nystagmus. However, this oscillatory nature of nystagmus is problematic during calibration since it introduces uncertainty about where the person is actually looking. This renders comparisons between separate recordings unreliable. Still, the influence of the calibration protocol on eye movement data from people with nystagmus has not been thoroughly investigated. In this work, we propose a calibration method using Procrustes analysis in combination with an outlier correction algorithm, which is based on a model of the calibration data and on the geometry of the experimental setup. The proposed method is compared to previously used calibration polynomials in terms of accuracy, calibration plane distortion and waveform robustness. Six recordings of calibration data, validation data and optokinetic nystagmus data from people with nystagmus and seven recordings from a control group were included in the study. Fixation errors during the recording of calibration data from the healthy participants were introduced, simulating fixation errors caused by the oscillatory movements found in nystagmus data. The outlier correction algorithm improved the accuracy for all tested calibration methods. The accuracy and calibration plane distortion performance of the Procrustes analysis calibration method were similar to the top performing mapping functions for the simulated fixation errors. The performance in terms of waveform robustness was superior for the Procrustes analysis calibration compared to the other calibration methods. The overall performance of the Procrustes calibration methods was best for the datasets containing errors during the calibration.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Eye tracking is a useful tool when studying the oscillatory eye movements associated with nystagmus. However, this oscillatory nature of nystagmus is problematic during calibration since it introduces uncertainty about where the person is actually looking. This renders comparisons between separate recordings unreliable. Still, the influence of the calibration protocol on eye movement data from people with nystagmus has not been thoroughly investigated. In this work, we propose a calibration method using Procrustes analysis in combination with an outlier correction algorithm, which is based on a model of the calibration data and on the geometry of the experimental setup. The proposed method is compared to previously used calibration polynomials in terms of accuracy, calibration plane distortion and waveform robustness. Six recordings of calibration data, validation data and optokinetic nystagmus data from people with nystagmus and seven recordings from a control group were included in the study. Fixation errors during the recording of calibration data from the healthy participants were introduced, simulating fixation errors caused by the oscillatory movements found in nystagmus data. The outlier correction algorithm improved the accuracy for all tested calibration methods. The accuracy and calibration plane distortion performance of the Procrustes analysis calibration method were similar to the top performing mapping functions for the simulated fixation errors. The performance in terms of waveform robustness was superior for the Procrustes analysis calibration compared to the other calibration methods. The overall performance of the Procrustes calibration methods was best for the datasets containing errors during the calibration. |
Anke Weidmann; Laura Richert; Maximilian Bernecker; Miriam Knauss; Kathlen Priebe; Benedikt Reuter; Martin Bohus; Meike Müller-Engelmann; Thomas Fydrich Dwelling on verbal but not pictorial threat cues: An eye-tracking study with adult survivors of childhood interpersonal violence Journal Article Psychological Trauma: Theory, Research, Practice, and Policy, 12 (1), pp. 46–54, 2020. @article{Weidmann2020, title = {Dwelling on verbal but not pictorial threat cues: An eye-tracking study with adult survivors of childhood interpersonal violence}, author = {Anke Weidmann and Laura Richert and Maximilian Bernecker and Miriam Knauss and Kathlen Priebe and Benedikt Reuter and Martin Bohus and Meike Müller-Engelmann and Thomas Fydrich}, doi = {10.1037/tra0000424}, year = {2020}, date = {2020-01-01}, journal = {Psychological Trauma: Theory, Research, Practice, and Policy}, volume = {12}, number = {1}, pages = {46--54}, abstract = {Objective: Previous studies have found evidence of an attentional bias for trauma-related stimuli in posttraumatic stress disorder (PTSD) using eye-tracking (ET) technlogy. However, it is unclear whether findings for PTSD after traumatic events in adulthood can be transferred to PTSD after interpersonal trauma in childhood. The latter is often accompanied by more complex symptom features, including, for example, affective dysregulation and has not yet been studied using ET. The aim of this study was to explore which components of attention are biased in adult victims of childhood trauma with PTSD compared to those without PTSD. Method: Female participants with (n = 27) or without (n = 27) PTSD who had experienced interpersonal violence in childhood or adolescence watched different traumarelated stimuli (Experiment 1: words, Experiment 2: facial expressions). We analyzed whether traumarelated stimuli were primarily detected (vigilance bias) and/or dwelled on longer (maintenance bias) compared to stimuli of other emotional qualities. Results: For trauma-related words, there was evidence of a maintenance bias but not of a vigilance bias. For trauma-related facial expressions, there was no evidence of any bias. Conclusions: At present, an attentional bias to trauma-related stimuli cannot be considered as robust in PTSD following trauma in childhood compared to that of PTSD following trauma in adulthood. The findings are discussed with respect to difficulties attributing effects specifically to PTSD in this highly comorbid though understudied population.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Objective: Previous studies have found evidence of an attentional bias for trauma-related stimuli in posttraumatic stress disorder (PTSD) using eye-tracking (ET) technlogy. However, it is unclear whether findings for PTSD after traumatic events in adulthood can be transferred to PTSD after interpersonal trauma in childhood. The latter is often accompanied by more complex symptom features, including, for example, affective dysregulation and has not yet been studied using ET. The aim of this study was to explore which components of attention are biased in adult victims of childhood trauma with PTSD compared to those without PTSD. Method: Female participants with (n = 27) or without (n = 27) PTSD who had experienced interpersonal violence in childhood or adolescence watched different traumarelated stimuli (Experiment 1: words, Experiment 2: facial expressions). We analyzed whether traumarelated stimuli were primarily detected (vigilance bias) and/or dwelled on longer (maintenance bias) compared to stimuli of other emotional qualities. Results: For trauma-related words, there was evidence of a maintenance bias but not of a vigilance bias. For trauma-related facial expressions, there was no evidence of any bias. Conclusions: At present, an attentional bias to trauma-related stimuli cannot be considered as robust in PTSD following trauma in childhood compared to that of PTSD following trauma in adulthood. The findings are discussed with respect to difficulties attributing effects specifically to PTSD in this highly comorbid though understudied population. |
2019 |
Louise Kauffmann; Carole Peyrin; Alan Chauvin; Léa Entzmann; Camille Breuil; Nathalie Guyader Face perception influences the programming of eye movements Journal Article Scientific Reports, 9 , pp. 1–14, 2019. @article{Kauffmann2019, title = {Face perception influences the programming of eye movements}, author = {Louise Kauffmann and Carole Peyrin and Alan Chauvin and Léa Entzmann and Camille Breuil and Nathalie Guyader}, doi = {10.1038/s41598-018-36510-0}, year = {2019}, date = {2019-12-01}, journal = {Scientific Reports}, volume = {9}, pages = {1--14}, publisher = {Nature Publishing Group}, abstract = {Previous studies have shown that face stimuli elicit extremely fast and involuntary saccadic responses toward them, relative to other categories of visual stimuli. In the present study, we further investigated to what extent face stimuli influence the programming and execution of saccades examining their amplitude. We performed two experiments using a saccadic choice task: two images (one with a face, one with a vehicle) were simultaneously displayed in the left and right visual fields of participants who had to initiate a saccade toward the image (Experiment 1) or toward a cross in the image (Experiment 2) containing a target stimulus (a face or a vehicle). Results revealed shorter saccades toward vehicle than face targets, even if participants were explicitly asked to perform their saccades toward a specific location (Experiment 2). Furthermore, error saccades had smaller amplitude than correct saccades. Further analyses showed that error saccades were interrupted in mid-flight to initiate a concurrently-programmed corrective saccade. Overall, these data suggest that the content of visual stimuli can influence the programming of saccade amplitude, and that efficient online correction of saccades can be performed during the saccadic choice task.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Previous studies have shown that face stimuli elicit extremely fast and involuntary saccadic responses toward them, relative to other categories of visual stimuli. In the present study, we further investigated to what extent face stimuli influence the programming and execution of saccades examining their amplitude. We performed two experiments using a saccadic choice task: two images (one with a face, one with a vehicle) were simultaneously displayed in the left and right visual fields of participants who had to initiate a saccade toward the image (Experiment 1) or toward a cross in the image (Experiment 2) containing a target stimulus (a face or a vehicle). Results revealed shorter saccades toward vehicle than face targets, even if participants were explicitly asked to perform their saccades toward a specific location (Experiment 2). Furthermore, error saccades had smaller amplitude than correct saccades. Further analyses showed that error saccades were interrupted in mid-flight to initiate a concurrently-programmed corrective saccade. Overall, these data suggest that the content of visual stimuli can influence the programming of saccade amplitude, and that efficient online correction of saccades can be performed during the saccadic choice task. |
Mohsen Rakhshan; Vivian Lee; Emily Chu; Lauren Harris; Lillian Laiks; Peyman Khorsand; Alireza Soltani Influence of expected reward on temporal order judgment Journal Article Journal of Cognitive Neuroscience, pp. 1–17, 2019. @article{Rakhshan2019, title = {Influence of expected reward on temporal order judgment}, author = {Mohsen Rakhshan and Vivian Lee and Emily Chu and Lauren Harris and Lillian Laiks and Peyman Khorsand and Alireza Soltani}, doi = {10.1162/jocn_a_01516}, year = {2019}, date = {2019-12-01}, journal = {Journal of Cognitive Neuroscience}, pages = {1--17}, publisher = {MIT Press - Journals}, abstract = {Perceptual decision-making has been shown to be influenced by reward expected from alternative options or actions, but the underlying neural mechanisms are currently unknown. More specifically, it is debated whether reward effects are mediated through changes in sensory processing, later stages of decision-making, or both. To address this question, we conducted two experiments in which human participants made saccades to what they perceived to be either the first or second of two visually identical but asynchronously presented targets while we manipulated expected reward from correct and incorrect responses on each trial. By comparing reward-induced bias in target selection (i.e., reward bias) during the two experiments, we determined whether reward caused changes in sensory or decision-making processes. We found similar reward biases in the two experiments indicating that reward information mainly influenced later stages of decision-making [R1.1]. Moreover, the observed reward biases were independent of the individual's sensitivity to sensory signals. This suggests that reward effects were determined heuristically via modulation of decision-making processes instead of sensory processing. To further explain our findings and uncover plausible neural mechanisms, we simulated our experiments with a cortical network model and tested alternative mechanisms for how reward could exert its influence. We found that our experimental observations are more compatible with reward-dependent input to the output layer of the decision circuit. Together, our results suggest that, during a temporal judgment task, reward exerts its influence via changing later stages of decision-making (i.e., response bias) rather than early sensory processing (i.e., perceptual bias).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Perceptual decision-making has been shown to be influenced by reward expected from alternative options or actions, but the underlying neural mechanisms are currently unknown. More specifically, it is debated whether reward effects are mediated through changes in sensory processing, later stages of decision-making, or both. To address this question, we conducted two experiments in which human participants made saccades to what they perceived to be either the first or second of two visually identical but asynchronously presented targets while we manipulated expected reward from correct and incorrect responses on each trial. By comparing reward-induced bias in target selection (i.e., reward bias) during the two experiments, we determined whether reward caused changes in sensory or decision-making processes. We found similar reward biases in the two experiments indicating that reward information mainly influenced later stages of decision-making [R1.1]. Moreover, the observed reward biases were independent of the individual's sensitivity to sensory signals. This suggests that reward effects were determined heuristically via modulation of decision-making processes instead of sensory processing. To further explain our findings and uncover plausible neural mechanisms, we simulated our experiments with a cortical network model and tested alternative mechanisms for how reward could exert its influence. We found that our experimental observations are more compatible with reward-dependent input to the output layer of the decision circuit. Together, our results suggest that, during a temporal judgment task, reward exerts its influence via changing later stages of decision-making (i.e., response bias) rather than early sensory processing (i.e., perceptual bias). |
Felicity Deamer; Ellen Palmer; Quoc C Vuong; Nicol Ferrier; Andreas Finkelmeyer; Wolfram Hinzen; Stuart Watson Non-literal understanding and psychosis: Metaphor comprehension in individuals with a diagnosis of schizophrenia Journal Article Schizophrenia Research: Cognition, 18 , pp. 1–8, 2019. @article{Deamer2019, title = {Non-literal understanding and psychosis: Metaphor comprehension in individuals with a diagnosis of schizophrenia}, author = {Felicity Deamer and Ellen Palmer and Quoc C Vuong and Nicol Ferrier and Andreas Finkelmeyer and Wolfram Hinzen and Stuart Watson}, doi = {10.1016/J.SCOG.2019.100159}, year = {2019}, date = {2019-12-01}, journal = {Schizophrenia Research: Cognition}, volume = {18}, pages = {1--8}, publisher = {Elsevier}, abstract = {Previous studies suggest that understanding of non-literal expressions, and in particular metaphors, can be impaired in people with schizophrenia; although it is not clear why. We explored metaphor comprehension capacity using a novel picture selection paradigm; we compared task performance between people with schizophrenia and healthy comparator subjects and we further examined the relationships between the ability to interpret figurative expressions non-literally and performance on a number of other cognitive tasks. Eye-tracking was used to examine task strategy. We showed that even when IQ, years of education, and capacities for theory of mind and associative learning are factored in as covariates, patients are significantly more likely to interpret metaphorical expressions literally, despite eye-tracking findings suggesting that patients are following the same interpretation strategy as healthy controls. Inhibitory control deficits are likely to be one of multiple factors contributing to the poorer performance of our schizophrenia group on the metaphor trials of the picture selection task.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Previous studies suggest that understanding of non-literal expressions, and in particular metaphors, can be impaired in people with schizophrenia; although it is not clear why. We explored metaphor comprehension capacity using a novel picture selection paradigm; we compared task performance between people with schizophrenia and healthy comparator subjects and we further examined the relationships between the ability to interpret figurative expressions non-literally and performance on a number of other cognitive tasks. Eye-tracking was used to examine task strategy. We showed that even when IQ, years of education, and capacities for theory of mind and associative learning are factored in as covariates, patients are significantly more likely to interpret metaphorical expressions literally, despite eye-tracking findings suggesting that patients are following the same interpretation strategy as healthy controls. Inhibitory control deficits are likely to be one of multiple factors contributing to the poorer performance of our schizophrenia group on the metaphor trials of the picture selection task. |
Luke O'Gorman; Chelsea S Norman; Luke Michaels; Tutte Newall; Andrew H Crosby; Christopher Mattocks; Angela J Cree; Andrew J Lotery; Emma L Baple; Arjuna J Ratnayaka; Diana Baralle; Helena Lee; Daniel Osborne; Fatima Shawkat; Jane Gibson; Sarah Ennis; Jay E Self A small gene sequencing panel realises a high diagnostic rate in patients with congenital nystagmus following basic phenotyping Journal Article Scientific Reports, 9 , pp. 1–8, 2019. @article{OGorman2019, title = {A small gene sequencing panel realises a high diagnostic rate in patients with congenital nystagmus following basic phenotyping}, author = {Luke O'Gorman and Chelsea S Norman and Luke Michaels and Tutte Newall and Andrew H Crosby and Christopher Mattocks and Angela J Cree and Andrew J Lotery and Emma L Baple and Arjuna J Ratnayaka and Diana Baralle and Helena Lee and Daniel Osborne and Fatima Shawkat and Jane Gibson and Sarah Ennis and Jay E Self}, doi = {10.1038/s41598-019-49368-7}, year = {2019}, date = {2019-12-01}, journal = {Scientific Reports}, volume = {9}, pages = {1--8}, publisher = {Nature Publishing Group}, abstract = {Nystagmus is a disorder of uncontrolled eye movement and can occur as an isolated trait (idiopathic INS, IINS) or as part of multisystem disorders such as albinism, significant visual disorders or neurological disease. Eighty-one unrelated patients with nystagmus underwent routine ocular phenotyping using commonly available phenotyping methods and were grouped into four sub-cohorts according to the level of phenotyping information gained and their findings. DNA was extracted and sequenced using a broad utility next generation sequencing (NGS) gene panel. A clinical subpanel of genes for nystagmus/albinism was utilised and likely causal variants were prioritised according to methods currently employed by clinical diagnostic laboratories. We determine the likely underlying genetic cause for 43.2% of participants with similar yields regardless of prior phenotyping. This study demonstrates that a diagnostic workflow combining basic ocular phenotyping and a clinically available targeted NGS panel, can provide a high diagnostic yield for patients with infantile nystagmus, enabling access to disease specific management at a young age and reducing the need for multiple costly, often invasive tests. By describing diagnostic yield for groups of patients with incomplete phenotyping data, it also permits the subsequent design of ‘real-world' diagnostic workflows and illustrates the changing role of genetic testing in modern diagnostic workflows for heterogeneous ophthalmic disorders.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nystagmus is a disorder of uncontrolled eye movement and can occur as an isolated trait (idiopathic INS, IINS) or as part of multisystem disorders such as albinism, significant visual disorders or neurological disease. Eighty-one unrelated patients with nystagmus underwent routine ocular phenotyping using commonly available phenotyping methods and were grouped into four sub-cohorts according to the level of phenotyping information gained and their findings. DNA was extracted and sequenced using a broad utility next generation sequencing (NGS) gene panel. A clinical subpanel of genes for nystagmus/albinism was utilised and likely causal variants were prioritised according to methods currently employed by clinical diagnostic laboratories. We determine the likely underlying genetic cause for 43.2% of participants with similar yields regardless of prior phenotyping. This study demonstrates that a diagnostic workflow combining basic ocular phenotyping and a clinically available targeted NGS panel, can provide a high diagnostic yield for patients with infantile nystagmus, enabling access to disease specific management at a young age and reducing the need for multiple costly, often invasive tests. By describing diagnostic yield for groups of patients with incomplete phenotyping data, it also permits the subsequent design of ‘real-world' diagnostic workflows and illustrates the changing role of genetic testing in modern diagnostic workflows for heterogeneous ophthalmic disorders. |
Michele Scaltritti; Aliaksei Miniukovich; Paola Venuti; Remo Job; Antonella De Angeli; Simone Sulpizio Investigating effects of typographic variables on webpage reading through eye movements Journal Article Scientific Reports, 9 , pp. 1–12, 2019. @article{Scaltritti2019, title = {Investigating effects of typographic variables on webpage reading through eye movements}, author = {Michele Scaltritti and Aliaksei Miniukovich and Paola Venuti and Remo Job and Antonella {De Angeli} and Simone Sulpizio}, doi = {10.1038/s41598-019-49051-x}, year = {2019}, date = {2019-12-01}, journal = {Scientific Reports}, volume = {9}, pages = {1--12}, publisher = {Nature Publishing Group}, abstract = {Webpage reading is ubiquitous in daily life. As Web technologies allow for a large variety of layouts and visual styles, the many formatting options may lead to poor design choices, including low readability. This research capitalizes on the existing readability guidelines for webpage design to outline several visuo-typographic variables and explore their effect on eye movements during webpage reading. Participants included children and adults, and for both groups typical readers and readers with dyslexia were considered. Actual webpages, rather than artificial ones, served as stimuli. This allowed to test multiple typographic variables in combination and in their typical ranges rather than in possibly unrealistic configurations. Several typographic variables displayed a significant effect on eye movements and reading performance. The effect was mostly homogeneous across the four groups, with a few exceptions. Beside supporting the notion that a few empirically-driven adjustments to the texts' visual appearance can facilitate reading across different populations, the results also highlight the challenge of making digital texts accessible to readers with dyslexia. Theoretically, the results highlight the importance of low-level visual factors, corroborating the emphasis of recent psychological models on visual attention and crowding in reading.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Webpage reading is ubiquitous in daily life. As Web technologies allow for a large variety of layouts and visual styles, the many formatting options may lead to poor design choices, including low readability. This research capitalizes on the existing readability guidelines for webpage design to outline several visuo-typographic variables and explore their effect on eye movements during webpage reading. Participants included children and adults, and for both groups typical readers and readers with dyslexia were considered. Actual webpages, rather than artificial ones, served as stimuli. This allowed to test multiple typographic variables in combination and in their typical ranges rather than in possibly unrealistic configurations. Several typographic variables displayed a significant effect on eye movements and reading performance. The effect was mostly homogeneous across the four groups, with a few exceptions. Beside supporting the notion that a few empirically-driven adjustments to the texts' visual appearance can facilitate reading across different populations, the results also highlight the challenge of making digital texts accessible to readers with dyslexia. Theoretically, the results highlight the importance of low-level visual factors, corroborating the emphasis of recent psychological models on visual attention and crowding in reading. |
Isabel M Vanegas; Annabelle Blangero; James E Galvin; Alessandro Di Rocco; Angelo Quartarone; Felice M Ghilardi; Simon P Kelly Altered dynamics of visual contextual interactions in Parkinson's disease Journal Article npj Parkinson's Disease, 5 , pp. 1–8, 2019. @article{Vanegas2019, title = {Altered dynamics of visual contextual interactions in Parkinson's disease}, author = {Isabel M Vanegas and Annabelle Blangero and James E Galvin and Alessandro {Di Rocco} and Angelo Quartarone and Felice M Ghilardi and Simon P Kelly}, doi = {10.1038/s41531-019-0085-5}, year = {2019}, date = {2019-12-01}, journal = {npj Parkinson's Disease}, volume = {5}, pages = {1--8}, publisher = {Nature Publishing Group}, abstract = {Over the last decades, psychophysical and electrophysiological studies in patients and animal models of Parkinson's disease (PD), have consistently revealed a number of visual abnormalities. In particular, specific alterations of contrast sensitivity curves, electroretinogram (ERG), and visual-evoked potentials (VEP), have been attributed to dopaminergic retinal depletion. However, fundamental mechanisms of cortical visual processing, such as normalization or “gain control” computations, have not yet been examined in PD patients. Here, we measured electrophysiological indices of gain control in both space (surround suppression) and time (sensory adaptation) in PD patients based on steady-state VEP (ssVEP). Compared with controls, patients exhibited a significantly higher initial ssVEP amplitude that quickly decayed over time, and greater relative suppression of ssVEP amplitude as a function of surrounding stimulus contrast. Meanwhile, EEG frequency spectra were broadly elevated in patients relative to controls. Thus, contrary to what might be expected given the reduced contrast sensitivity often reported in PD, visual neural responses are not weaker; rather, they are initially larger but undergo an exaggerated degree of spatial and temporal gain control and are embedded within a greater background noise level. These differences may reflect cortical mechanisms that compensate for dysfunctional center-surround interactions at the retinal level.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Over the last decades, psychophysical and electrophysiological studies in patients and animal models of Parkinson's disease (PD), have consistently revealed a number of visual abnormalities. In particular, specific alterations of contrast sensitivity curves, electroretinogram (ERG), and visual-evoked potentials (VEP), have been attributed to dopaminergic retinal depletion. However, fundamental mechanisms of cortical visual processing, such as normalization or “gain control” computations, have not yet been examined in PD patients. Here, we measured electrophysiological indices of gain control in both space (surround suppression) and time (sensory adaptation) in PD patients based on steady-state VEP (ssVEP). Compared with controls, patients exhibited a significantly higher initial ssVEP amplitude that quickly decayed over time, and greater relative suppression of ssVEP amplitude as a function of surrounding stimulus contrast. Meanwhile, EEG frequency spectra were broadly elevated in patients relative to controls. Thus, contrary to what might be expected given the reduced contrast sensitivity often reported in PD, visual neural responses are not weaker; rather, they are initially larger but undergo an exaggerated degree of spatial and temporal gain control and are embedded within a greater background noise level. These differences may reflect cortical mechanisms that compensate for dysfunctional center-surround interactions at the retinal level. |
Antonia F Ten Brink; Jasper H Fabius; Nick A Weaver; Tanja C W Nijboer; Stefan Van der Stigchel Trans-saccadic memory after right parietal brain damage Journal Article Cortex, 120 , pp. 284–297, 2019. @article{TenBrink2019a, title = {Trans-saccadic memory after right parietal brain damage}, author = {Antonia F {Ten Brink} and Jasper H Fabius and Nick A Weaver and Tanja C W Nijboer and Stefan {Van der Stigchel}}, doi = {10.1016/j.cortex.2019.06.006}, year = {2019}, date = {2019-11-01}, journal = {Cortex}, volume = {120}, pages = {284--297}, publisher = {Elsevier BV}, abstract = {INTRODUCTION: Spatial remapping, the process of updating information across eye movements, is an important mechanism for trans-saccadic perception. The right posterior parietal cortex (PPC) is a region that has been associated most strongly with spatial remapping. The aim of the project was to investigate the effect of damage to the right PPC on direction specific trans-saccadic memory. We compared trans-saccadic memory performance for central items that had to be remembered while making a left- versus rightward eye movement, or for items that were remapped within the left versus right visual field. METHODS: We included 9 stroke patients with unilateral right PPC lesions and 31 healthy control subjects. Participants memorized the location of a briefly presented item, had to make one saccade (either towards the left or right, or upward or downward), and subsequently had to decide in what direction the probe had shifted. We used a staircase to adjust task difficulty (i.e., the distance between the memory item and probe). Bayesian repeated measures ANOVAs were used to compare left versus right eye movements and items in the left versus right visual field. RESULTS: In both conditions, patients with right PPC damage showed worse trans-saccadic memory performance compared to healthy control subjects (for the condition with left- and rightward gaze shifts}, keywords = {}, pubstate = {published}, tppubtype = {article} } INTRODUCTION: Spatial remapping, the process of updating information across eye movements, is an important mechanism for trans-saccadic perception. The right posterior parietal cortex (PPC) is a region that has been associated most strongly with spatial remapping. The aim of the project was to investigate the effect of damage to the right PPC on direction specific trans-saccadic memory. We compared trans-saccadic memory performance for central items that had to be remembered while making a left- versus rightward eye movement, or for items that were remapped within the left versus right visual field. METHODS: We included 9 stroke patients with unilateral right PPC lesions and 31 healthy control subjects. Participants memorized the location of a briefly presented item, had to make one saccade (either towards the left or right, or upward or downward), and subsequently had to decide in what direction the probe had shifted. We used a staircase to adjust task difficulty (i.e., the distance between the memory item and probe). Bayesian repeated measures ANOVAs were used to compare left versus right eye movements and items in the left versus right visual field. RESULTS: In both conditions, patients with right PPC damage showed worse trans-saccadic memory performance compared to healthy control subjects (for the condition with left- and rightward gaze shifts |
Christoph Huber-Huber; Antimo Buonocore; Olaf Dimigen; Clayton Hickey; David Melcher NeuroImage, 200 , pp. 344–362, 2019. @article{Huber-Huber2019, title = {The peripheral preview effect with faces: Combined EEG and eye-tracking suggests multiple stages of trans-saccadic predictive and non-predictive processing}, author = {Christoph Huber-Huber and Antimo Buonocore and Olaf Dimigen and Clayton Hickey and David Melcher}, doi = {10.1016/j.neuroimage.2019.06.059}, year = {2019}, date = {2019-10-01}, journal = {NeuroImage}, volume = {200}, pages = {344--362}, publisher = {Academic Press Inc.}, abstract = {The world appears stable despite saccadic eye-movements. One possible explanation for this phenomenon is that the visual system predicts upcoming input across saccadic eye-movements based on peripheral preview of the saccadic target. We tested this idea using concurrent electroencephalography (EEG) and eye-tracking. Participants made cued saccades to peripheral upright or inverted face stimuli that changed orientation (invalid preview) or maintained orientation (valid preview) while the saccade was completed. Experiment 1 demonstrated better discrimination performance and a reduced fixation-locked N170 component (fN170) with valid than with invalid preview, demonstrating integration of pre- and post-saccadic information. Moreover, the early fixation-related potentials (FRP) showed a preview face inversion effect suggesting that some pre-saccadic input was represented in the brain until around 170 ms post fixation-onset. Experiment 2 replicated Experiment 1 and manipulated the proportion of valid and invalid trials to test whether the preview effect reflects context-based prediction across trials. A whole-scalp Bayes factor analysis showed that this manipulation did not alter the fN170 preview effect but did influence the face inversion effect before the saccade. The pre-saccadic inversion effect declined earlier in the mostly invalid block than in the mostly valid block, which is consistent with the notion of pre-saccadic expectations. In addition, in both studies, we found strong evidence for an interaction between the pre-saccadic preview stimulus and the post-saccadic target as early as 50 ms (Experiment 2) or 90 ms (Experiment 1) into the new fixation. These findings suggest that visual stability may involve three temporal stages: prediction about the saccadic target, integration of pre-saccadic and post-saccadic information at around 50-90 ms post fixation onset, and post-saccadic facilitation of rapid categorization.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The world appears stable despite saccadic eye-movements. One possible explanation for this phenomenon is that the visual system predicts upcoming input across saccadic eye-movements based on peripheral preview of the saccadic target. We tested this idea using concurrent electroencephalography (EEG) and eye-tracking. Participants made cued saccades to peripheral upright or inverted face stimuli that changed orientation (invalid preview) or maintained orientation (valid preview) while the saccade was completed. Experiment 1 demonstrated better discrimination performance and a reduced fixation-locked N170 component (fN170) with valid than with invalid preview, demonstrating integration of pre- and post-saccadic information. Moreover, the early fixation-related potentials (FRP) showed a preview face inversion effect suggesting that some pre-saccadic input was represented in the brain until around 170 ms post fixation-onset. Experiment 2 replicated Experiment 1 and manipulated the proportion of valid and invalid trials to test whether the preview effect reflects context-based prediction across trials. A whole-scalp Bayes factor analysis showed that this manipulation did not alter the fN170 preview effect but did influence the face inversion effect before the saccade. The pre-saccadic inversion effect declined earlier in the mostly invalid block than in the mostly valid block, which is consistent with the notion of pre-saccadic expectations. In addition, in both studies, we found strong evidence for an interaction between the pre-saccadic preview stimulus and the post-saccadic target as early as 50 ms (Experiment 2) or 90 ms (Experiment 1) into the new fixation. These findings suggest that visual stability may involve three temporal stages: prediction about the saccadic target, integration of pre-saccadic and post-saccadic information at around 50-90 ms post fixation onset, and post-saccadic facilitation of rapid categorization. |
Teresa Fasshauer; Andreas Sprenger; Karen Silling; Johanna Elisa Silberg; Anne Vosseler; Seiko Minoshita; Shinji Satoh; Michael Dorr; Katja Koelkebeck; Rebekka Lencer Visual exploration of emotional faces in schizophrenia using masks from the Japanese Noh theatre Journal Article Neuropsychologia, 133 , pp. 1–10, 2019. @article{Fasshauer2019, title = {Visual exploration of emotional faces in schizophrenia using masks from the Japanese Noh theatre}, author = {Teresa Fasshauer and Andreas Sprenger and Karen Silling and Johanna Elisa Silberg and Anne Vosseler and Seiko Minoshita and Shinji Satoh and Michael Dorr and Katja Koelkebeck and Rebekka Lencer}, doi = {10.1016/j.neuropsychologia.2019.107193}, year = {2019}, date = {2019-10-01}, journal = {Neuropsychologia}, volume = {133}, pages = {1--10}, abstract = {Studying eye movements during visual exploration is widely used to investigate visual information processing in schizophrenia. Here, we used masks from the Japanese Noh theatre to study visual exploration behavior during an emotional face recognition task and a brightness evaluation control task using the same stimuli. Eye movements were recorded in 25 patients with schizophrenia and 25 age-matched healthy controls while participants explored seven photos of Japanese Noh masks tilted to seven different angles. Additionally, parti- cipants were assessed on seven upright binary black and white pictures of these Noh masks (Mooney-like pictures), seven Upside-down pictures (180° upside-down turned Mooneys), and seven Neutral pictures. Participants either had to indicate whether they had recognized a face and its emotional expression, or they had to evaluate the brightness of the picture (total N=56 trials). We observed a clear effect of inclination angle of Noh masks on emotional ratings (ptextless0.001) and visual exploration behavior in both groups. Controls made larger saccades than patients when not being able to recognize a face in upside-down Mooney pictures (ptextless0.01). Patients also made smaller saccades when exploring pictures for brightness (ptextless0.05). Exploration behavior in patients was related to depressive symptom expression during emotional face recognition but not during brightness evaluation. Our findings suggest that visual exploration behavior in patients with schizophrenia is less flexible than in controls depending on the specific task requirements, specifically when exploring physical aspects of the environment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Studying eye movements during visual exploration is widely used to investigate visual information processing in schizophrenia. Here, we used masks from the Japanese Noh theatre to study visual exploration behavior during an emotional face recognition task and a brightness evaluation control task using the same stimuli. Eye movements were recorded in 25 patients with schizophrenia and 25 age-matched healthy controls while participants explored seven photos of Japanese Noh masks tilted to seven different angles. Additionally, parti- cipants were assessed on seven upright binary black and white pictures of these Noh masks (Mooney-like pictures), seven Upside-down pictures (180° upside-down turned Mooneys), and seven Neutral pictures. Participants either had to indicate whether they had recognized a face and its emotional expression, or they had to evaluate the brightness of the picture (total N=56 trials). We observed a clear effect of inclination angle of Noh masks on emotional ratings (ptextless0.001) and visual exploration behavior in both groups. Controls made larger saccades than patients when not being able to recognize a face in upside-down Mooney pictures (ptextless0.01). Patients also made smaller saccades when exploring pictures for brightness (ptextless0.05). Exploration behavior in patients was related to depressive symptom expression during emotional face recognition but not during brightness evaluation. Our findings suggest that visual exploration behavior in patients with schizophrenia is less flexible than in controls depending on the specific task requirements, specifically when exploring physical aspects of the environment. |
Bob McMurray; Jamie Klein-Packarda; Bruce J Tomblinb A real-time mechanism underlying lexical deficits in developmental language disorder: Between-word inhibition Journal Article Cognition, 191 , pp. 1–13, 2019. @article{McMurray2019a, title = {A real-time mechanism underlying lexical deficits in developmental language disorder: Between-word inhibition}, author = {Bob McMurray and Jamie Klein-Packarda and Bruce J Tomblinb}, doi = {10.1016/J.COGNITION.2019.06.012}, year = {2019}, date = {2019-10-01}, journal = {Cognition}, volume = {191}, pages = {1--13}, publisher = {Elsevier}, abstract = {Eight to 11% of children have a clinical disorder in oral language (Developmental Language Disorder, DLD). Language deficits in DLD can affect all levels of language and persist through adulthood. Word-level processing may be critical as words link phonology, orthography, syntax and semantics. Thus, a lexical deficit could cascade throughout language. Cognitively, word recognition is a competition process: as the input (e.g., lizard) unfolds, multiple candidates (liver, wizard) compete for recognition. Children with DLD do not fully resolve this competition, but it is unclear what cognitive mechanisms underlie this. We examined lexical inhibition—the ability of more active words to suppress competitors—in 79 adolescents with and without DLD. Participants heard words (e.g. net) in which the onset was manipulated to briefly favor a competitor (neck). This was predicted to inhibit the target, slowing recognition. Word recognition was measured using a task in which participants heard the stimulus, and clicked on a picture of the item from an array of competitors, while eye-movements were monitored as a measure of how strongly the participant was committed to that interpretation over time. TD listeners showed evidence of inhibition with greater interference for stimuli that briefly activated a competitor word. DLD listeners did not. This suggests deficits in DLD may stem from a failure to engage lexical inhibition. This in turn could have ripple effects throughout the language system. This supports theoretical approaches to DLD that emphasize lexical-level deficits, and deficits in real-time processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Eight to 11% of children have a clinical disorder in oral language (Developmental Language Disorder, DLD). Language deficits in DLD can affect all levels of language and persist through adulthood. Word-level processing may be critical as words link phonology, orthography, syntax and semantics. Thus, a lexical deficit could cascade throughout language. Cognitively, word recognition is a competition process: as the input (e.g., lizard) unfolds, multiple candidates (liver, wizard) compete for recognition. Children with DLD do not fully resolve this competition, but it is unclear what cognitive mechanisms underlie this. We examined lexical inhibition—the ability of more active words to suppress competitors—in 79 adolescents with and without DLD. Participants heard words (e.g. net) in which the onset was manipulated to briefly favor a competitor (neck). This was predicted to inhibit the target, slowing recognition. Word recognition was measured using a task in which participants heard the stimulus, and clicked on a picture of the item from an array of competitors, while eye-movements were monitored as a measure of how strongly the participant was committed to that interpretation over time. TD listeners showed evidence of inhibition with greater interference for stimuli that briefly activated a competitor word. DLD listeners did not. This suggests deficits in DLD may stem from a failure to engage lexical inhibition. This in turn could have ripple effects throughout the language system. This supports theoretical approaches to DLD that emphasize lexical-level deficits, and deficits in real-time processing. |
Sabine Born Saccadic suppression of displacement does not reflect a saccade-specific bias to assume stability Journal Article Vision, 3 , pp. 1–22, 2019. @article{Born2019a, title = {Saccadic suppression of displacement does not reflect a saccade-specific bias to assume stability}, author = {Sabine Born}, doi = {10.3390/vision3040049}, year = {2019}, date = {2019-09-01}, journal = {Vision}, volume = {3}, pages = {1--22}, abstract = {Across saccades, small displacements of a visual target are harder to detect and their directions more difficult to discriminate than during steady fixation. Prominent theories of this effect, known as saccadic suppression of displacement, propose that it is due to a bias to assume object stability across saccades. Recent studies comparing the saccadic effect to masking effects suggest that suppression of displacement is not saccade-specific. Further evidence for this account is presented from two experiments where participants judged the size of displacements on a continuous scale in saccade and mask conditions, with and without blanking. Saccades and masks both reduced the proportion of correctly perceived displacements and increased the proportion of missed displacements. Blanking improved performance in both conditions by reducing the proportion of missed displacements. Thus, if suppression of displacement reflects a bias for stability, it is not a saccade-specific bias, but a more general stability assumption revealed under conditions of impoverished vision. Specifically, I discuss the potentially decisive role of motion or other transient signals for displacement perception. Without transients or motion, the quality of relative position signals is poor, and saccadic and mask-induced suppression of displacement reflects performance when the decision has to be made on these signals alone. Blanking may improve those position signals by providing a transient onset or a longer time to encode the pre-saccadic target position.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Across saccades, small displacements of a visual target are harder to detect and their directions more difficult to discriminate than during steady fixation. Prominent theories of this effect, known as saccadic suppression of displacement, propose that it is due to a bias to assume object stability across saccades. Recent studies comparing the saccadic effect to masking effects suggest that suppression of displacement is not saccade-specific. Further evidence for this account is presented from two experiments where participants judged the size of displacements on a continuous scale in saccade and mask conditions, with and without blanking. Saccades and masks both reduced the proportion of correctly perceived displacements and increased the proportion of missed displacements. Blanking improved performance in both conditions by reducing the proportion of missed displacements. Thus, if suppression of displacement reflects a bias for stability, it is not a saccade-specific bias, but a more general stability assumption revealed under conditions of impoverished vision. Specifically, I discuss the potentially decisive role of motion or other transient signals for displacement perception. Without transients or motion, the quality of relative position signals is poor, and saccadic and mask-induced suppression of displacement reflects performance when the decision has to be made on these signals alone. Blanking may improve those position signals by providing a transient onset or a longer time to encode the pre-saccadic target position. |
Lee Mcilreavy; Tom C A Freeman; Jonathan T Erichsen Two-dimensional analysis of smooth pursuit eye movements reveals quantitative deficits in precision and accuracy Journal Article Translational Vision Science & Technology, 8 (5), pp. 1–17, 2019. @article{Mcilreavy2019, title = {Two-dimensional analysis of smooth pursuit eye movements reveals quantitative deficits in precision and accuracy}, author = {Lee Mcilreavy and Tom C A Freeman and Jonathan T Erichsen}, doi = {10.1167/tvst.8.5.7}, year = {2019}, date = {2019-09-01}, journal = {Translational Vision Science & Technology}, volume = {8}, number = {5}, pages = {1--17}, publisher = {Association for Research in Vision and Ophthalmology (ARVO)}, abstract = {Purpose: Small moving targets are followed by pursuit eye movements, with success ubiquitously defined by gain. Gain quantifies accuracy, rather than precision, and only for eye movements along the target trajectory. Analogous to previous studies of fixation, we analyzed pursuit performance in two dimensions as a function of target direction, velocity, and amplitude. As a subsidiary experiment, we compared pursuit performance against that of fixation. Methods: Eye position was recorded from 15 observers during pursuit. The target was a 0.48 dot that moved across a large screen at 88/s or 168/s, either horizontally or vertically, through peak-to-peak amplitudes of 88,168,or 328. Two-dimensional eye velocity was expressed relative to the target, and a bivariate probability density function computed to obtain accuracy and precision. As a comparison, identical metrics were derived from fixation data. Results: For all target directions, eye velocity was less precise along the target trajectory. Eye velocities orthogonal to the target trajectory were more accurate during vertical pursuit than horizontal. Pursuit accuracy and precision along and orthogonal to the target trajectory decreased at the higher target velocity. Accuracy along the target trajectory decreased with smaller target amplitudes. Conclusions: Orthogonal to the target trajectory, pursuit was inaccurate and imprecise. Compared to fixation, pursuit was less precise and less accurate even when following the stimulus that gave the best performance. Translational Relevance: This analytical approach may help the detection of subtle deficits in slow phase eye movements that could be used as biomarkers for disease progression and/or treatment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Purpose: Small moving targets are followed by pursuit eye movements, with success ubiquitously defined by gain. Gain quantifies accuracy, rather than precision, and only for eye movements along the target trajectory. Analogous to previous studies of fixation, we analyzed pursuit performance in two dimensions as a function of target direction, velocity, and amplitude. As a subsidiary experiment, we compared pursuit performance against that of fixation. Methods: Eye position was recorded from 15 observers during pursuit. The target was a 0.48 dot that moved across a large screen at 88/s or 168/s, either horizontally or vertically, through peak-to-peak amplitudes of 88,168,or 328. Two-dimensional eye velocity was expressed relative to the target, and a bivariate probability density function computed to obtain accuracy and precision. As a comparison, identical metrics were derived from fixation data. Results: For all target directions, eye velocity was less precise along the target trajectory. Eye velocities orthogonal to the target trajectory were more accurate during vertical pursuit than horizontal. Pursuit accuracy and precision along and orthogonal to the target trajectory decreased at the higher target velocity. Accuracy along the target trajectory decreased with smaller target amplitudes. Conclusions: Orthogonal to the target trajectory, pursuit was inaccurate and imprecise. Compared to fixation, pursuit was less precise and less accurate even when following the stimulus that gave the best performance. Translational Relevance: This analytical approach may help the detection of subtle deficits in slow phase eye movements that could be used as biomarkers for disease progression and/or treatment. |
Eugene McSorley; Iain D Gilchrist; Rachel McCloy The role of fixation disengagement in the parallel programming of sequences of saccades Journal Article Experimental Brain Research, 237 (11), pp. 3033–3045, 2019. @article{McSorley2019, title = {The role of fixation disengagement in the parallel programming of sequences of saccades}, author = {Eugene McSorley and Iain D Gilchrist and Rachel McCloy}, doi = {10.1007/s00221-019-05641-9}, year = {2019}, date = {2019-09-01}, journal = {Experimental Brain Research}, volume = {237}, number = {11}, pages = {3033--3045}, abstract = {One of the core mechanisms involved in the control of saccade responses to selected target stimuli is the disengagement from the current fixation location, so that the next saccade can be executed. To carry out everyday visual tasks, we make multiple eye movements that can be programmed in parallel. However, the role of disengagement in the parallel programming of saccades has not been examined. It is well established that the need for disengagement slows down saccadic response time. This may be important in allowing the system to program accurate eye movements and have a role to play in the control of multiple eye movements but as yet this remains untested. Here, we report two experiments that seek to examine whether fixation disengagement reduces saccade latencies when the task completion demands multiple saccade responses. A saccade contingent paradigm was employed and participants were asked to execute saccadic eye movements to a series of seven targets while manipulating when these targets were shown. This both promotes fixation disengagement and controls the extent that parallel programming can occur. We found that trial duration decreased as more targets were made available prior to fixation: this was a result both of a reduction in the number of saccades being executed and in their saccade latencies. This supports the view that even when fixation disengagement is not required, parallel programming of multiple sequential saccadic eye movements is still present. By comparison with previous published data, we demonstrate a substantial speeded of response times in these condition (“a gap effect”) and that parallel programming is attenuated in these conditions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } One of the core mechanisms involved in the control of saccade responses to selected target stimuli is the disengagement from the current fixation location, so that the next saccade can be executed. To carry out everyday visual tasks, we make multiple eye movements that can be programmed in parallel. However, the role of disengagement in the parallel programming of saccades has not been examined. It is well established that the need for disengagement slows down saccadic response time. This may be important in allowing the system to program accurate eye movements and have a role to play in the control of multiple eye movements but as yet this remains untested. Here, we report two experiments that seek to examine whether fixation disengagement reduces saccade latencies when the task completion demands multiple saccade responses. A saccade contingent paradigm was employed and participants were asked to execute saccadic eye movements to a series of seven targets while manipulating when these targets were shown. This both promotes fixation disengagement and controls the extent that parallel programming can occur. We found that trial duration decreased as more targets were made available prior to fixation: this was a result both of a reduction in the number of saccades being executed and in their saccade latencies. This supports the view that even when fixation disengagement is not required, parallel programming of multiple sequential saccadic eye movements is still present. By comparison with previous published data, we demonstrate a substantial speeded of response times in these condition (“a gap effect”) and that parallel programming is attenuated in these conditions. |
Scott T Murdison; Gunnar Blohm; Frank Bremmer Saccade-induced changes in ocular torsion reveal predictive orientation perception Journal Article Journal of Vision, 19 (11), pp. 1–13, 2019. @article{Murdison2019, title = {Saccade-induced changes in ocular torsion reveal predictive orientation perception}, author = {Scott T Murdison and Gunnar Blohm and Frank Bremmer}, doi = {10.1167/19.11.10}, year = {2019}, date = {2019-09-01}, journal = {Journal of Vision}, volume = {19}, number = {11}, pages = {1--13}, abstract = {Natural orienting of gaze often results in a retinal image that is rotated relative to space due to ocular torsion. However, we perceive neither this rotation nor a moving world despite visual rotational motion on the retina. This perceptual stability is often attributed to the phenomenon known as predictive remapping, but the current remapping literature ignores this torsional component. In addition, studies often simply measure remapping across either space or features (e.g., orientation) but in natural circumstances, both components are bound together for stable perception. One natural circumstance in which the perceptual system must account for the current and future eye orientation to correctly interpret the orientation of external stimuli occurs during movements to or from oblique eye orientations (i.e., eye orientations with both a horizontal and vertical angular component relative to the primary position). Here we took advantage of oblique eye orientation-induced ocular torsion to examine perisaccadic orientation perception. First, we found that orientation perception was largely predicted by the rotated retinal image. Second, we observed a presaccadic remapping of orientation perception consistent with maintaining a stable (but spatially inaccurate) retinocentric perception throughout the saccade. These findings strongly suggest that our seamless perceptual stability relies on retinocentric signals that are predictively remapped in all three ocular dimensions with each saccade.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Natural orienting of gaze often results in a retinal image that is rotated relative to space due to ocular torsion. However, we perceive neither this rotation nor a moving world despite visual rotational motion on the retina. This perceptual stability is often attributed to the phenomenon known as predictive remapping, but the current remapping literature ignores this torsional component. In addition, studies often simply measure remapping across either space or features (e.g., orientation) but in natural circumstances, both components are bound together for stable perception. One natural circumstance in which the perceptual system must account for the current and future eye orientation to correctly interpret the orientation of external stimuli occurs during movements to or from oblique eye orientations (i.e., eye orientations with both a horizontal and vertical angular component relative to the primary position). Here we took advantage of oblique eye orientation-induced ocular torsion to examine perisaccadic orientation perception. First, we found that orientation perception was largely predicted by the rotated retinal image. Second, we observed a presaccadic remapping of orientation perception consistent with maintaining a stable (but spatially inaccurate) retinocentric perception throughout the saccade. These findings strongly suggest that our seamless perceptual stability relies on retinocentric signals that are predictively remapped in all three ocular dimensions with each saccade. |
Jonathan van Leeuwen; Artem V Belopolsky Detection of object displacement during a saccade is prioritized by the oculomotor system Journal Article Journal of Vision, 19 (11), pp. 1–15, 2019. @article{Leeuwen2019, title = {Detection of object displacement during a saccade is prioritized by the oculomotor system}, author = {Jonathan van Leeuwen and Artem V Belopolsky}, doi = {10.1167/19.11.11}, year = {2019}, date = {2019-09-01}, journal = {Journal of Vision}, volume = {19}, number = {11}, pages = {1--15}, abstract = {The human eye-movement system is equipped with a sophisticated updating mechanism that can adjust for large retinal displacements produced by saccadic eye movements. The nature of this updating mechanism is still highly debated. Previous studies have demonstrated that updating can occur very rapidly and is initiated before the start of a saccade. In the present study, we used saccade curvature to demonstrate that the oculomotor system is tuned for detecting object displacements during saccades. Participants made a sequence of saccades while ignoring an irrelevant distractor. Curvature of the second saccade relative to the distractor was used to estimate the time course of updating. Saccade curvature away from the presaccadic location of the distractor emerged as early as 80 ms after the first saccade when the distractor was displaced during a saccade. This is about 50 ms earlier than when a distractor was only present before a saccade, only present after a saccade, or remained stationary across a saccade. This shows that the oculomotor system prioritizes detection of object displacements during saccades, which may be useful for guiding corrective saccades. The results also challenge previous views by demonstrating the additional role of postsaccadic information in updating target–distractor competition across saccades.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The human eye-movement system is equipped with a sophisticated updating mechanism that can adjust for large retinal displacements produced by saccadic eye movements. The nature of this updating mechanism is still highly debated. Previous studies have demonstrated that updating can occur very rapidly and is initiated before the start of a saccade. In the present study, we used saccade curvature to demonstrate that the oculomotor system is tuned for detecting object displacements during saccades. Participants made a sequence of saccades while ignoring an irrelevant distractor. Curvature of the second saccade relative to the distractor was used to estimate the time course of updating. Saccade curvature away from the presaccadic location of the distractor emerged as early as 80 ms after the first saccade when the distractor was displaced during a saccade. This is about 50 ms earlier than when a distractor was only present before a saccade, only present after a saccade, or remained stationary across a saccade. This shows that the oculomotor system prioritizes detection of object displacements during saccades, which may be useful for guiding corrective saccades. The results also challenge previous views by demonstrating the additional role of postsaccadic information in updating target–distractor competition across saccades. |
Sabrina E Twilhaar; Artem V Belopolsky; Jorrit F Kieviet; Ruurd M Elburg; Jaap Oosterlaan Voluntary and involuntary control of attention in adolescents born very preterm: A study of eye movements Journal Article Child Development, pp. 1–12, 2019. @article{Twilhaar2019, title = {Voluntary and involuntary control of attention in adolescents born very preterm: A study of eye movements}, author = {Sabrina E Twilhaar and Artem V Belopolsky and Jorrit F Kieviet and Ruurd M Elburg and Jaap Oosterlaan}, doi = {10.1111/cdev.13310}, year = {2019}, date = {2019-09-01}, journal = {Child Development}, pages = {1--12}, abstract = {Very preterm birth is associated with attention deficits that interfere with academic performance. A better understanding of attention processes is necessary to support very preterm born children. This study examined voluntary and involuntary attentional control in very preterm born adolescents by measuring saccadic eye movements. Additionally, these control processes were related to symptoms of inattention, intelligence, and academic performance. Participants included 47 very preterm and 61 full-term born 13-years-old adolescents. Oculomotor control was assessed using the antisaccade and oculomotor capture paradigm. Very preterm born adolescents showed deficits in antisaccade but not in oculomotor capture performance, indicating impairments in voluntary but not involuntary attentional control. These impairments mediated the relation between very preterm birth and inattention, intelligence, and academic performance.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Very preterm birth is associated with attention deficits that interfere with academic performance. A better understanding of attention processes is necessary to support very preterm born children. This study examined voluntary and involuntary attentional control in very preterm born adolescents by measuring saccadic eye movements. Additionally, these control processes were related to symptoms of inattention, intelligence, and academic performance. Participants included 47 very preterm and 61 full-term born 13-years-old adolescents. Oculomotor control was assessed using the antisaccade and oculomotor capture paradigm. Very preterm born adolescents showed deficits in antisaccade but not in oculomotor capture performance, indicating impairments in voluntary but not involuntary attentional control. These impairments mediated the relation between very preterm birth and inattention, intelligence, and academic performance. |
Nils S Van Den Berg; Rients B Huitema; Jacoba M Spikman; Peter Jan Van Laar; Edward H F De Haan A shrunken world – micropsia after a right occipito-parietal ischemic stroke Journal Article Neurocase, 25 (5), pp. 202–208, 2019. @article{VanDenBerg2019, title = {A shrunken world – micropsia after a right occipito-parietal ischemic stroke}, author = {Nils S {Van Den Berg} and Rients B Huitema and Jacoba M Spikman and Peter Jan {Van Laar} and Edward H F {De Haan}}, doi = {10.1080/13554794.2019.1656751}, year = {2019}, date = {2019-09-01}, journal = {Neurocase}, volume = {25}, number = {5}, pages = {202--208}, publisher = {Informa UK Limited}, abstract = {Micropsia is a rare condition in which patients perceive the outside world smaller in size than it actually is. We examined a patient who, after a right occipito-parietal stroke, subjectively reported perceiving everything at seventy percent of the actual size. Using experimental tasks, we confirmed the extent of his micropsia at 70%. Visual half-field tests showed an impaired perception of shape, location and motion in the left visual field. As his micropsia concerns the complete visual field, we suggest that it is caused by a higher-order compensation process in order to reconcile the conflicting information from the two hemifields.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Micropsia is a rare condition in which patients perceive the outside world smaller in size than it actually is. We examined a patient who, after a right occipito-parietal stroke, subjectively reported perceiving everything at seventy percent of the actual size. Using experimental tasks, we confirmed the extent of his micropsia at 70%. Visual half-field tests showed an impaired perception of shape, location and motion in the left visual field. As his micropsia concerns the complete visual field, we suggest that it is caused by a higher-order compensation process in order to reconcile the conflicting information from the two hemifields. |
Ramina Adam; Kevin Johnston; Stefan Everling Journal of Neurophysiology, 122 (2), pp. 672–690, 2019. @article{Adam2019, title = {Recovery of contralesional saccade choice and reaction time deficits after a unilateral endothelin-1-induced lesion in the macaque caudal prefrontal cortex}, author = {Ramina Adam and Kevin Johnston and Stefan Everling}, doi = {10.1152/jn.00078.2019}, year = {2019}, date = {2019-08-01}, journal = {Journal of Neurophysiology}, volume = {122}, number = {2}, pages = {672--690}, publisher = {American Physiological Society Bethesda, MD}, abstract = {The caudal primate prefrontal cortex (PFC) is involved in target selection and visually guided saccades through both covert attention and overt orienting eye movements. Unilateral damage to the caudal PFC often leads to decreased awareness of a contralesional target alone, referred to as “neglect,” or when it is presented simultaneously with an ipsilesional target, referred to as “extinction.” In the current study, we examined whether deficits in contralesional target selection were due to contralesional oculomotor deficits, such as slower reaction times. We experimentally induced a focal ischemic lesion in the right caudal PFC of 4 male macaque monkeys using the vasoconstrictor endothelin-1 and measured saccade choice and reaction times on double-stimulus free-choice tasks and single-stimulus trials before and after the lesion. We found that 1) endothelin-1-induced lesions in the caudal PFC produced contralesional target selection deficits that varied in severity and duration based on lesion volume and location; 2) contralesional neglect-like deficits were transient and recovered by week 4 postlesion; 3) contralesional extinction-like deficits were longer lasting and recovered by weeks 8–16 postlesion; 4) contralesional reaction time returned to baseline well before the contralesional choice deficit had recovered; and 5) neither the mean reaction times nor the reaction time distributions could account for the degree of contralesional extinction on the free-choice task throughout recovery. These findings demonstrate that the saccade choice bias observed after a right caudal PFC lesion is not exclusively due to contralesional motor deficits, but instead reflects a combination of impaired motor and attentional processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The caudal primate prefrontal cortex (PFC) is involved in target selection and visually guided saccades through both covert attention and overt orienting eye movements. Unilateral damage to the caudal PFC often leads to decreased awareness of a contralesional target alone, referred to as “neglect,” or when it is presented simultaneously with an ipsilesional target, referred to as “extinction.” In the current study, we examined whether deficits in contralesional target selection were due to contralesional oculomotor deficits, such as slower reaction times. We experimentally induced a focal ischemic lesion in the right caudal PFC of 4 male macaque monkeys using the vasoconstrictor endothelin-1 and measured saccade choice and reaction times on double-stimulus free-choice tasks and single-stimulus trials before and after the lesion. We found that 1) endothelin-1-induced lesions in the caudal PFC produced contralesional target selection deficits that varied in severity and duration based on lesion volume and location; 2) contralesional neglect-like deficits were transient and recovered by week 4 postlesion; 3) contralesional extinction-like deficits were longer lasting and recovered by weeks 8–16 postlesion; 4) contralesional reaction time returned to baseline well before the contralesional choice deficit had recovered; and 5) neither the mean reaction times nor the reaction time distributions could account for the degree of contralesional extinction on the free-choice task throughout recovery. These findings demonstrate that the saccade choice bias observed after a right caudal PFC lesion is not exclusively due to contralesional motor deficits, but instead reflects a combination of impaired motor and attentional processing. |
Andrea Phillipou; Melissa Kirkovski; David J Castle; Caroline Gurvich; Larry A Abel; Stephanie Miles; Susan L Rossell High‐definition transcranial direct current stimulation in anorexia nervosa: A pilot study Journal Article International Journal of Eating Disorders, 52 (11), pp. 1274–1280, 2019. @article{Phillipou2019, title = {High‐definition transcranial direct current stimulation in anorexia nervosa: A pilot study}, author = {Andrea Phillipou and Melissa Kirkovski and David J Castle and Caroline Gurvich and Larry A Abel and Stephanie Miles and Susan L Rossell}, doi = {10.1002/eat.23146}, year = {2019}, date = {2019-08-01}, journal = {International Journal of Eating Disorders}, volume = {52}, number = {11}, pages = {1274--1280}, publisher = {Wiley}, abstract = {OBJECTIVE: Anorexia nervosa (AN) is a serious psychiatric condition often associated with poor outcomes. Biologically informed treatments for AN, such as brain stimulation, are lacking, in part due to the unclear nature of the neurobiological contributions to the illness. However, recent research has suggested a specific neurobiological target for the treatment of AN, namely stimulation of the inferior parietal lobe (IPL). The aim of this study was to stimulate-noninvasively-the left IPL in individuals with AN using high-definition transcranial direct current stimulation (HD-tDCS). METHOD: Twenty participants will be randomized to receive 10 daily sessions of HD-tDCS or sham HD-tDCS (placebo). Assessments will be carried out at baseline and end point, as well as 4- and 12-week follow-ups. DISCUSSION: This pilot investigation will primarily determine the feasibility and acceptability of this intervention.}, keywords = {}, pubstate = {published}, tppubtype = {article} } OBJECTIVE: Anorexia nervosa (AN) is a serious psychiatric condition often associated with poor outcomes. Biologically informed treatments for AN, such as brain stimulation, are lacking, in part due to the unclear nature of the neurobiological contributions to the illness. However, recent research has suggested a specific neurobiological target for the treatment of AN, namely stimulation of the inferior parietal lobe (IPL). The aim of this study was to stimulate-noninvasively-the left IPL in individuals with AN using high-definition transcranial direct current stimulation (HD-tDCS). METHOD: Twenty participants will be randomized to receive 10 daily sessions of HD-tDCS or sham HD-tDCS (placebo). Assessments will be carried out at baseline and end point, as well as 4- and 12-week follow-ups. DISCUSSION: This pilot investigation will primarily determine the feasibility and acceptability of this intervention. |
Emma E M Stewart; Preeti Verghese; Anna Ma-Wyatt The spatial and temporal properties of attentional selectivity for saccades and reaches Journal Article Journal of Vision, 19 (9), pp. 1–19, 2019. @article{Stewart2019bb, title = {The spatial and temporal properties of attentional selectivity for saccades and reaches}, author = {Emma E M Stewart and Preeti Verghese and Anna Ma-Wyatt}, doi = {10.1167/19.9.12}, year = {2019}, date = {2019-08-01}, journal = {Journal of Vision}, volume = {19}, number = {9}, pages = {1--19}, publisher = {Association for Research in Vision and Ophthalmology (ARVO)}, abstract = {The preparation and execution of saccades and goal-directed movements elicits an accompanying shift in attention at the locus of the impending movement. However, some key aspects of the spatiotemporal profile of this attentional shift between eye and hand movements are not resolved. While there is evidence that attention is improved at the target location when making a reach, it is not clear how attention shifts over space and time around the movement target as a saccade and a reach are made to that target. Determining this spread of attention is an important aspect in understanding how attentional resources are used in relation to movement planning and guidance in real world tasks. We compared performance on a perceptual discrimination paradigm during a saccade- alone task, reach-alone task, and a saccade-plus-reach task to map the temporal profile of the premotor attentional shift at the goal of the movement and at three surrounding locations. We measured performance relative to a valid baseline level to determine whether motor planning induces additional attentional facilitation compared to mere covert attention. Sensitivity increased relative to movement onset at the target and at the surrounding locations, for both the saccade-alone and saccade-plus-reach conditions. The results suggest that the temporal profile of the attentional shift is similar for the two tasks involving saccades (saccade-alone and saccade-plus-reach tasks), but is very different when the influence of the saccade is removed. In this case, performance in the saccade-plus- reach task reflects the lower sensitivity observed when a reach-alone task is being conducted. In addition, the spatial profile of this spread of attention is not symmetrical around the target. This suggests that when a saccade and reach are being planned together, the saccade drives the attentional shift, and the reach-alone carries little attentional weight.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The preparation and execution of saccades and goal-directed movements elicits an accompanying shift in attention at the locus of the impending movement. However, some key aspects of the spatiotemporal profile of this attentional shift between eye and hand movements are not resolved. While there is evidence that attention is improved at the target location when making a reach, it is not clear how attention shifts over space and time around the movement target as a saccade and a reach are made to that target. Determining this spread of attention is an important aspect in understanding how attentional resources are used in relation to movement planning and guidance in real world tasks. We compared performance on a perceptual discrimination paradigm during a saccade- alone task, reach-alone task, and a saccade-plus-reach task to map the temporal profile of the premotor attentional shift at the goal of the movement and at three surrounding locations. We measured performance relative to a valid baseline level to determine whether motor planning induces additional attentional facilitation compared to mere covert attention. Sensitivity increased relative to movement onset at the target and at the surrounding locations, for both the saccade-alone and saccade-plus-reach conditions. The results suggest that the temporal profile of the attentional shift is similar for the two tasks involving saccades (saccade-alone and saccade-plus-reach tasks), but is very different when the influence of the saccade is removed. In this case, performance in the saccade-plus- reach task reflects the lower sensitivity observed when a reach-alone task is being conducted. In addition, the spatial profile of this spread of attention is not symmetrical around the target. This suggests that when a saccade and reach are being planned together, the saccade drives the attentional shift, and the reach-alone carries little attentional weight. |
Jessica Klusek; Carly Moser; Joseph Schmidt; Leonard Abbeduto; Jane E Roberts A novel eye‐tracking paradigm for indexing social avoidance‐related behavior in fragile X syndrome Journal Article American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, pp. 1–12, 2019. @article{Klusek2019, title = {A novel eye‐tracking paradigm for indexing social avoidance‐related behavior in fragile X syndrome}, author = {Jessica Klusek and Carly Moser and Joseph Schmidt and Leonard Abbeduto and Jane E Roberts}, doi = {10.1002/ajmg.b.32757}, year = {2019}, date = {2019-08-01}, journal = {American Journal of Medical Genetics Part B: Neuropsychiatric Genetics}, pages = {1--12}, publisher = {Wiley}, abstract = {Fragile X syndrome (FXS) is characterized by hallmark features of gaze avoidance, reduced social approach, and social anxiety. The development of therapeutics to manage these symptoms has been hindered, in part, by the lack of sensitive outcome measures. This study investigated the utility of a novel eye-tracking paradigm for indexing social avoidance-related phenotypes. Adolescent/young adult-aged males with FXS (n = 24) and typical development (n = 23) participated in the study. Participants viewed faces displaying direct or averted gaze and the first fixation duration on the eyes was recorded as an index of initial stimulus registration. Fixation durations did not differ across the direction of gaze conditions in either group, although the control group showed longer initial fixations on the eyes relative to the FXS group. Shorter initial fixation on averted gaze in males with FXS was a robust predictor of the severity of their social avoidance behavior exhibited during a social greeting context, whereas parent-reported social avoidance symptoms were not related to performance in the semi-naturalistic context. This eye-tracking paradigm may represent a promising outcome measure for FXS clinical trials because it provides a quantitative index that closely maps onto core social avoidance phenotypes of FXS, can be completed in less than 20 min, and is suitable for use with individuals with low IQ.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Fragile X syndrome (FXS) is characterized by hallmark features of gaze avoidance, reduced social approach, and social anxiety. The development of therapeutics to manage these symptoms has been hindered, in part, by the lack of sensitive outcome measures. This study investigated the utility of a novel eye-tracking paradigm for indexing social avoidance-related phenotypes. Adolescent/young adult-aged males with FXS (n = 24) and typical development (n = 23) participated in the study. Participants viewed faces displaying direct or averted gaze and the first fixation duration on the eyes was recorded as an index of initial stimulus registration. Fixation durations did not differ across the direction of gaze conditions in either group, although the control group showed longer initial fixations on the eyes relative to the FXS group. Shorter initial fixation on averted gaze in males with FXS was a robust predictor of the severity of their social avoidance behavior exhibited during a social greeting context, whereas parent-reported social avoidance symptoms were not related to performance in the semi-naturalistic context. This eye-tracking paradigm may represent a promising outcome measure for FXS clinical trials because it provides a quantitative index that closely maps onto core social avoidance phenotypes of FXS, can be completed in less than 20 min, and is suitable for use with individuals with low IQ. |
Dong-Ho Lee; Sherryse L Corrow; Raika Pancaroglu; Jason J S Barton The scanpaths of subjects with developmental prosopagnosia during a face memory task Journal Article Brain Sciences, 9 , pp. 1–19, 2019. @article{Lee2019a, title = {The scanpaths of subjects with developmental prosopagnosia during a face memory task}, author = {Dong-Ho Lee and Sherryse L Corrow and Raika Pancaroglu and Jason J S Barton}, doi = {10.3390/brainsci9080188}, year = {2019}, date = {2019-08-01}, journal = {Brain Sciences}, volume = {9}, pages = {1--19}, publisher = {MDPI AG}, abstract = {The scanpaths of healthy subjects show biases towards the upper face, the eyes and the center of the face, which suggests that their fixations are guided by a feature hierarchy towards the regions most informative for face identification. However, subjects with developmental prosopagnosia have a lifelong impairment in face processing. Whether this is reflected in the loss of normal face-scanning strategies is not known. The goal of this study was to determine if subjects with developmental prosopagnosia showed anomalous scanning biases as they processed the identity of faces. We recorded the fixations of 10 subjects with developmental prosopagnosia as they performed a face memorization and recognition task, for comparison with 8 subjects with acquired prosopagnosia (four with anterior temporal lesions and four with occipitotemporal lesions) and 20 control subjects. The scanning of healthy subjects confirmed a bias to fixate the upper over the lower face, the eyes over the mouth, and the central over the peripheral face. Subjects with acquired prosopagnosia from occipitotemporal lesions had more dispersed fixations and a trend to fixate less informative facial regions. Subjects with developmental prosopagnosia did not differ from the controls. At a single-subject level, some developmental subjects performed abnormally, but none consistently across all metrics. Scanning distributions were not related to scores on perceptual or memory tests for faces. We conclude that despite lifelong difficulty with faces, subjects with developmental prosopagnosia still have an internal facial schema that guides their scanning behavior.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The scanpaths of healthy subjects show biases towards the upper face, the eyes and the center of the face, which suggests that their fixations are guided by a feature hierarchy towards the regions most informative for face identification. However, subjects with developmental prosopagnosia have a lifelong impairment in face processing. Whether this is reflected in the loss of normal face-scanning strategies is not known. The goal of this study was to determine if subjects with developmental prosopagnosia showed anomalous scanning biases as they processed the identity of faces. We recorded the fixations of 10 subjects with developmental prosopagnosia as they performed a face memorization and recognition task, for comparison with 8 subjects with acquired prosopagnosia (four with anterior temporal lesions and four with occipitotemporal lesions) and 20 control subjects. The scanning of healthy subjects confirmed a bias to fixate the upper over the lower face, the eyes over the mouth, and the central over the peripheral face. Subjects with acquired prosopagnosia from occipitotemporal lesions had more dispersed fixations and a trend to fixate less informative facial regions. Subjects with developmental prosopagnosia did not differ from the controls. At a single-subject level, some developmental subjects performed abnormally, but none consistently across all metrics. Scanning distributions were not related to scores on perceptual or memory tests for faces. We conclude that despite lifelong difficulty with faces, subjects with developmental prosopagnosia still have an internal facial schema that guides their scanning behavior. |
Matthew F Peterson; Ian Zaun; Harris Hoke; Guo Jiahui; Brad Duchaine; Nancy Kanwisher Eye movements and retinotopic tuning in developmental prosopagnosia Journal Article Journal of Vision, 19 (9), pp. 1–19, 2019. @article{Peterson2019, title = {Eye movements and retinotopic tuning in developmental prosopagnosia}, author = {Matthew F Peterson and Ian Zaun and Harris Hoke and Guo Jiahui and Brad Duchaine and Nancy Kanwisher}, doi = {10.1167/19.9.7}, year = {2019}, date = {2019-08-01}, journal = {Journal of Vision}, volume = {19}, number = {9}, pages = {1--19}, publisher = {The Association for Research in Vision and Ophthalmology}, abstract = {Despite extensive investigation, the causes and nature of developmental prosopagnosia (DP)—a severe face identification impairment in the absence of acquired brain injury—remain poorly understood. Drawing on previous work showing that individuals identified as being neurotypical (NT) show robust individual differences in where they fixate on faces, and recognize faces best when the faces are presented at this location, we defined and tested four novel hypotheses for how atypical face-looking behavior and/or retinotopic face encoding could impair face recognition in DP: (a) fixating regions of poor information, (b) inconsistent saccadic targeting, (c) weak retinotopic tuning, and (d) fixating locations not matched to the individual's own face tuning. We found no support for the first three hypotheses, with NTs and DPs consistently fixating similar locations and showing similar retinotopic tuning of their face perception performance. However, in testing the fourth hypothesis, we found preliminary evidence for two distinct phenotypes of DP: (a) Subjects characterized by impaired face memory, typical face perception, and a preference to look high on the face, and (b) Subjects characterized by profound impairments to both face memory and perception and a preference to look very low on the face. Further, while all NTs and upper-looking DPs performed best when faces were presented near their preferred fixation location, this was not true for lower-looking DPs. These results suggest that face recognition deficits in a substantial proportion of people with DP may arise not from aberrant face gaze or compromised retinotopic tuning, but from the suboptimal matching of gaze to tuning.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Despite extensive investigation, the causes and nature of developmental prosopagnosia (DP)—a severe face identification impairment in the absence of acquired brain injury—remain poorly understood. Drawing on previous work showing that individuals identified as being neurotypical (NT) show robust individual differences in where they fixate on faces, and recognize faces best when the faces are presented at this location, we defined and tested four novel hypotheses for how atypical face-looking behavior and/or retinotopic face encoding could impair face recognition in DP: (a) fixating regions of poor information, (b) inconsistent saccadic targeting, (c) weak retinotopic tuning, and (d) fixating locations not matched to the individual's own face tuning. We found no support for the first three hypotheses, with NTs and DPs consistently fixating similar locations and showing similar retinotopic tuning of their face perception performance. However, in testing the fourth hypothesis, we found preliminary evidence for two distinct phenotypes of DP: (a) Subjects characterized by impaired face memory, typical face perception, and a preference to look high on the face, and (b) Subjects characterized by profound impairments to both face memory and perception and a preference to look very low on the face. Further, while all NTs and upper-looking DPs performed best when faces were presented near their preferred fixation location, this was not true for lower-looking DPs. These results suggest that face recognition deficits in a substantial proportion of people with DP may arise not from aberrant face gaze or compromised retinotopic tuning, but from the suboptimal matching of gaze to tuning. |
Quan Wang; Carla A Wall; Erin C Barney; Jessica L Bradshaw; Suzanne L Macari; Katarzyna Chawarska; Frederick Shic Promoting social attention in 3‐year‐olds with ASD through gaze‐contingent eye tracking Journal Article Autism Research, 13 (1), pp. 61–73, 2019. @article{Wang2019h, title = {Promoting social attention in 3‐year‐olds with ASD through gaze‐contingent eye tracking}, author = {Quan Wang and Carla A Wall and Erin C Barney and Jessica L Bradshaw and Suzanne L Macari and Katarzyna Chawarska and Frederick Shic}, doi = {10.1002/aur.2199}, year = {2019}, date = {2019-08-01}, journal = {Autism Research}, volume = {13}, number = {1}, pages = {61--73}, publisher = {Wiley}, abstract = {Young children with autism spectrum disorder (ASD) look less toward faces compared to their non-ASD peers, limiting access to social learning. Currently, no technologies directly target these core social attention difficulties. This study examines the feasibility of automated gaze modification training for improving attention to faces in 3-year-olds with ASD. Using free-viewing data from typically developing (TD) controls (n = 41), we implemented gaze-contingent adaptive cueing to redirect children with ASD toward normative looking patterns during viewing of videos of an actress. Children with ASD were randomly assigned to either (a) an adaptive Cue condition (Cue}, keywords = {}, pubstate = {published}, tppubtype = {article} } Young children with autism spectrum disorder (ASD) look less toward faces compared to their non-ASD peers, limiting access to social learning. Currently, no technologies directly target these core social attention difficulties. This study examines the feasibility of automated gaze modification training for improving attention to faces in 3-year-olds with ASD. Using free-viewing data from typically developing (TD) controls (n = 41), we implemented gaze-contingent adaptive cueing to redirect children with ASD toward normative looking patterns during viewing of videos of an actress. Children with ASD were randomly assigned to either (a) an adaptive Cue condition (Cue |
Peng Zhou; Likan Zhan; Huimin Ma Understanding others' minds: Social inference in preschool children with autism spectrum disorder Journal Article Journal of Autism and Developmental Disorders, pp. 1–12, 2019. @article{Zhou2019a, title = {Understanding others' minds: Social inference in preschool children with autism spectrum disorder}, author = {Peng Zhou and Likan Zhan and Huimin Ma}, doi = {10.1007/s10803-019-04167-x}, year = {2019}, date = {2019-08-01}, journal = {Journal of Autism and Developmental Disorders}, pages = {1--12}, publisher = {Springer Science and Business Media LLC}, abstract = {The study used an eye-tracking task to investigate whether preschool children with autism spectrum disorder (ASD) are able to make inferences about others' behavior in terms of their mental states in a social setting. Fifty typically developing (TD) 4- and 5-year-olds and 22 5-year-olds with ASD participated in the study, where their eye-movements were recorded as automatic responses to given situations. The results show that unlike their TD peers, children with ASD failed to exhibit eye gaze patterns that reflect their ability to infer about others' behavior by spontaneously encoding socially relevant information and attributing mental states to others. Implications of the findings were discussed in relation to the proposal that implicit/spontaneous Theory of Mind is persistently impaired in ASD.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The study used an eye-tracking task to investigate whether preschool children with autism spectrum disorder (ASD) are able to make inferences about others' behavior in terms of their mental states in a social setting. Fifty typically developing (TD) 4- and 5-year-olds and 22 5-year-olds with ASD participated in the study, where their eye-movements were recorded as automatic responses to given situations. The results show that unlike their TD peers, children with ASD failed to exhibit eye gaze patterns that reflect their ability to infer about others' behavior by spontaneously encoding socially relevant information and attributing mental states to others. Implications of the findings were discussed in relation to the proposal that implicit/spontaneous Theory of Mind is persistently impaired in ASD. |
Guillaume Doucet; Roberto A Gulli; Benjamin W Corrigan; Lyndon R Duong; Julio C Martinez‐Trujillo Modulation of local field potentials and neuronal activity in primate hippocampus during saccades Journal Article Hippocampus, pp. 1–18, 2019. @article{Doucet2019, title = {Modulation of local field potentials and neuronal activity in primate hippocampus during saccades}, author = {Guillaume Doucet and Roberto A Gulli and Benjamin W Corrigan and Lyndon R Duong and Julio C Martinez‐Trujillo}, doi = {10.1002/hipo.23140}, year = {2019}, date = {2019-07-01}, journal = {Hippocampus}, pages = {1--18}, publisher = {Wiley}, abstract = {Primates use saccades to gather information about objects and their relative spatial arrangement, a process essential for visual perception and memory. It has been proposed that signals linked to saccades reset the phase of local field potential (LFP) oscillations in the hippocampus, providing a temporal window for visual signals to activate neurons in this region and influence memory formation. We investigated this issue by measuring hippocampal LFPs and spikes in two macaques performing different tasks with unconstrained eye movements. We found that LFP phase clustering (PC) in the alpha/beta (8-16 Hz) frequencies followed foveation onsets, while PC in frequencies lower than 8 Hz followed spontaneous saccades, even on a homogeneous background. Saccades to a solid grey background were not followed by increases in local neuronal firing, whereas saccades toward appearing visual stimuli were. Finally, saccade parameters correlated with LFPs phase and amplitude: saccade direction correlated with delta (≤4 Hz) phase, and saccade amplitude with theta (4-8 Hz) power. Our results suggest that signals linked to saccades reach the hippocampus, producing synchronization of delta/theta LFPs without a general activation of local neurons. Moreover, some visual inputs co-occurring with saccades produce LFP synchronization in the alpha/beta bands and elevated neuronal firing. Our findings support the hypothesis that saccade-related signals enact sensory input-dependent plasticity and therefore memory formation in the primate hippocampus.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Primates use saccades to gather information about objects and their relative spatial arrangement, a process essential for visual perception and memory. It has been proposed that signals linked to saccades reset the phase of local field potential (LFP) oscillations in the hippocampus, providing a temporal window for visual signals to activate neurons in this region and influence memory formation. We investigated this issue by measuring hippocampal LFPs and spikes in two macaques performing different tasks with unconstrained eye movements. We found that LFP phase clustering (PC) in the alpha/beta (8-16 Hz) frequencies followed foveation onsets, while PC in frequencies lower than 8 Hz followed spontaneous saccades, even on a homogeneous background. Saccades to a solid grey background were not followed by increases in local neuronal firing, whereas saccades toward appearing visual stimuli were. Finally, saccade parameters correlated with LFPs phase and amplitude: saccade direction correlated with delta (≤4 Hz) phase, and saccade amplitude with theta (4-8 Hz) power. Our results suggest that signals linked to saccades reach the hippocampus, producing synchronization of delta/theta LFPs without a general activation of local neurons. Moreover, some visual inputs co-occurring with saccades produce LFP synchronization in the alpha/beta bands and elevated neuronal firing. Our findings support the hypothesis that saccade-related signals enact sensory input-dependent plasticity and therefore memory formation in the primate hippocampus. |
Alexander Goettker; Doris I Braun; Karl R Gegenfurtner Dynamic combination of position and motion information when tracking moving targets Journal Article Journal of Vision, 19 (7), pp. 1–22, 2019. @article{Goettker2019a, title = {Dynamic combination of position and motion information when tracking moving targets}, author = {Alexander Goettker and Doris I Braun and Karl R Gegenfurtner}, doi = {10.1167/19.7.2}, year = {2019}, date = {2019-07-01}, journal = {Journal of Vision}, volume = {19}, number = {7}, pages = {1--22}, publisher = {The Association for Research in Vision and Ophthalmology}, abstract = {To accurately foveate a moving target, the oculomotor system needs to estimate the position of the target at the saccade end, based on information about its position and ongoing movement, while accounting for neuronal delays and execution time of the saccade. We investigated human interceptive saccades and pursuit responses to moving targets defined by high and low luminance contrast or by chromatic contrast only (isoluminance). We used step-ramps with perpendicular directions between vertical target steps of 10 deg/s and horizontal ramps of 2.5 to 20 deg/s to separate errors with respect to the position step of the target in the vertical dimension, and errors related to target motion in the horizontal dimension. Interceptive saccades to targets of high and low luminance contrast landed close to the actual target positions, suggesting relatively accurate estimates of the amount of target displacement. Interceptive saccades to isoluminant targets were less accurate. They landed at positions the target had on average 100 ms before saccade onset. One account of this finding is that the integration of target motion is compromised for isoluminant targets moving in the periphery. In this case, the oculomotor system can use an accurate, but delayed position component, but cannot account for target movement. This deficit was also present for the postsaccadic pursuit speed. For the two luminance conditions, pursuit direction and speed were adjusted depending on the saccadic landing position. The rapid postsaccadic pursuit adjustments suggest shared position- and motion-related signals of target and eye for saccade and pursuit control.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To accurately foveate a moving target, the oculomotor system needs to estimate the position of the target at the saccade end, based on information about its position and ongoing movement, while accounting for neuronal delays and execution time of the saccade. We investigated human interceptive saccades and pursuit responses to moving targets defined by high and low luminance contrast or by chromatic contrast only (isoluminance). We used step-ramps with perpendicular directions between vertical target steps of 10 deg/s and horizontal ramps of 2.5 to 20 deg/s to separate errors with respect to the position step of the target in the vertical dimension, and errors related to target motion in the horizontal dimension. Interceptive saccades to targets of high and low luminance contrast landed close to the actual target positions, suggesting relatively accurate estimates of the amount of target displacement. Interceptive saccades to isoluminant targets were less accurate. They landed at positions the target had on average 100 ms before saccade onset. One account of this finding is that the integration of target motion is compromised for isoluminant targets moving in the periphery. In this case, the oculomotor system can use an accurate, but delayed position component, but cannot account for target movement. This deficit was also present for the postsaccadic pursuit speed. For the two luminance conditions, pursuit direction and speed were adjusted depending on the saccadic landing position. The rapid postsaccadic pursuit adjustments suggest shared position- and motion-related signals of target and eye for saccade and pursuit control. |
Sanuji Gajamange; Annie Shelton; Meaghan Clough; Owen White; Joanne Fielding; Scott Kolbe Functional correlates of cognitive dysfunction in clinically isolated syndromes Journal Article PLOS ONE, 14 (7), pp. 1–13, 2019. @article{Gajamange2019, title = {Functional correlates of cognitive dysfunction in clinically isolated syndromes}, author = {Sanuji Gajamange and Annie Shelton and Meaghan Clough and Owen White and Joanne Fielding and Scott Kolbe}, editor = {Friedemann Paul}, doi = {10.1371/journal.pone.0219590}, year = {2019}, date = {2019-07-01}, journal = {PLOS ONE}, volume = {14}, number = {7}, pages = {1--13}, publisher = {Public Library of Science}, abstract = {Cognitive dysfunction can be identified in patients with clinically isolated syndromes suggestive of multiple sclerosis using ocular motor testing. This study aimed to identify the functional neural correlates of cognitive dysfunction in patients with clinically isolated syndrome using MRI. Eighteen patients with clinically isolated syndrome and 17 healthy controls were recruited. Subjects underwent standard neurological and neuropsychological testing. Subjects also underwent functional MRI (fMRI) during a cognitive ocular motor task, involving pro-saccade (direct gaze towards target) and anti-saccade (direct gaze away from target) trials. Ocular motor performance variables (averaged response time and error rate) were calculated for each subject. Patients showed a trend towards a greater rate of anti-saccade errors (p = 0.09) compared to controls. Compared to controls, patients exhibited increased activation in the right postcentral, right supramarginal gyrus, and the right parietal operculum during the anti-saccadetextgreaterpro-saccade contrast. This study demonstrated that changes in functional organisation of cognitive brain networks is associated with subtle cognitive changes in patients with clinically isolated syndrome.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cognitive dysfunction can be identified in patients with clinically isolated syndromes suggestive of multiple sclerosis using ocular motor testing. This study aimed to identify the functional neural correlates of cognitive dysfunction in patients with clinically isolated syndrome using MRI. Eighteen patients with clinically isolated syndrome and 17 healthy controls were recruited. Subjects underwent standard neurological and neuropsychological testing. Subjects also underwent functional MRI (fMRI) during a cognitive ocular motor task, involving pro-saccade (direct gaze towards target) and anti-saccade (direct gaze away from target) trials. Ocular motor performance variables (averaged response time and error rate) were calculated for each subject. Patients showed a trend towards a greater rate of anti-saccade errors (p = 0.09) compared to controls. Compared to controls, patients exhibited increased activation in the right postcentral, right supramarginal gyrus, and the right parietal operculum during the anti-saccadetextgreaterpro-saccade contrast. This study demonstrated that changes in functional organisation of cognitive brain networks is associated with subtle cognitive changes in patients with clinically isolated syndrome. |
Mervyn G Thomas; Gail D E Maconachie; Cris S Constantinescu; Wai-Man Chan; Brenda Barry; Michael Hisaund; Viral Sheth; Helen J Kuht; Rob A Dineen; Sreemathi Harieaswar; Elizabeth C Engle; Irene Gottlob Congenital monocular elevation deficiency associated with a novel TUBB3 gene variant Journal Article British Journal of Ophthalmology, pp. 1–4, 2019. @article{Thomas2019, title = {Congenital monocular elevation deficiency associated with a novel TUBB3 gene variant}, author = {Mervyn G Thomas and Gail D E Maconachie and Cris S Constantinescu and Wai-Man Chan and Brenda Barry and Michael Hisaund and Viral Sheth and Helen J Kuht and Rob A Dineen and Sreemathi Harieaswar and Elizabeth C Engle and Irene Gottlob}, doi = {10.1136/bjophthalmol-2019-314293}, year = {2019}, date = {2019-07-01}, journal = {British Journal of Ophthalmology}, pages = {1--4}, publisher = {BMJ Publishing Group Ltd}, abstract = {BACKGROUND :The genetic basis of monocular elevation deficiency (MED) is unclear. It has previously been considered to arise due to a supranuclear abnormality. METHODS: Two brothers with MED were referred to Leicester Royal Infirmary, UK from the local opticians. Their father had bilateral ptosis and was unable to elevate both eyes, consistent with the diagnosis of congenital fibrosis of extraocular muscles (CFEOM). Candidate sequencing was performed in all family members. RESULTS: Both affected siblings (aged 7 and 12 years) were unable to elevate the right eye. Their father had bilateral ptosis, left esotropia and bilateral limitation of elevation. Chin up head posture was present in the older sibling and the father. Bell's phenomenon and vertical rotational vestibulo-ocular reflex were absent in the right eye for both children. Mild bilateral facial nerve palsy was present in the older sibling and the father. Both siblings had slight difficulty with tandem gait. MRI revealed hypoplastic oculomotor nerve. Left anterior insular focal cortical dysplasia was seen in the older sibling. Sequencing of TUBB3 revealed a novel heterozygous variant (c.1263GtextgreaterC, p.E421D) segregating with the phenotype. This residue is in the C-terminal H12 $alpha$-helix of $beta$-tubulin and is one of three putative kinesin binding sites. CONCLUSION: We show that familial MED can arise from a TUBB3 variant and could be considered a limited form of CFEOM. Neurological features such as mild facial palsy and cortical malformations can be present in patients with MED. Thus, in individuals with congenital MED, consideration may be made for TUBB3 mutation screening.}, keywords = {}, pubstate = {published}, tppubtype = {article} } BACKGROUND :The genetic basis of monocular elevation deficiency (MED) is unclear. It has previously been considered to arise due to a supranuclear abnormality. METHODS: Two brothers with MED were referred to Leicester Royal Infirmary, UK from the local opticians. Their father had bilateral ptosis and was unable to elevate both eyes, consistent with the diagnosis of congenital fibrosis of extraocular muscles (CFEOM). Candidate sequencing was performed in all family members. RESULTS: Both affected siblings (aged 7 and 12 years) were unable to elevate the right eye. Their father had bilateral ptosis, left esotropia and bilateral limitation of elevation. Chin up head posture was present in the older sibling and the father. Bell's phenomenon and vertical rotational vestibulo-ocular reflex were absent in the right eye for both children. Mild bilateral facial nerve palsy was present in the older sibling and the father. Both siblings had slight difficulty with tandem gait. MRI revealed hypoplastic oculomotor nerve. Left anterior insular focal cortical dysplasia was seen in the older sibling. Sequencing of TUBB3 revealed a novel heterozygous variant (c.1263GtextgreaterC, p.E421D) segregating with the phenotype. This residue is in the C-terminal H12 $alpha$-helix of $beta$-tubulin and is one of three putative kinesin binding sites. CONCLUSION: We show that familial MED can arise from a TUBB3 variant and could be considered a limited form of CFEOM. Neurological features such as mild facial palsy and cortical malformations can be present in patients with MED. Thus, in individuals with congenital MED, consideration may be made for TUBB3 mutation screening. |
Shira Klorfeld-Auslender; Nitzan Censor Visual-oculomotor interactions facilitate consolidation of perceptual learning Journal Article Journal of Vision, 19 (6), pp. 1–10, 2019. @article{Klorfeld-Auslender2019, title = {Visual-oculomotor interactions facilitate consolidation of perceptual learning}, author = {Shira Klorfeld-Auslender and Nitzan Censor}, doi = {10.1167/19.6.11}, year = {2019}, date = {2019-06-01}, journal = {Journal of Vision}, volume = {19}, number = {6}, pages = {1--10}, publisher = {The Association for Research in Vision and Ophthalmology}, abstract = {Visual skill learning is commonly considered a manifestation of brain plasticity. Following encoding, consolidation of the skill may result in between-session performance gains. A great volume of studies have demonstrated that during the offline consolidation interval, the skill is susceptible to external inputs that modify the preformed representation of the memory, affecting future performance. However, while basic visual perceptual learning is thought to be mediated by sensory brain regions or their higher-order readout pathways, the possibility of visual-oculomotor interactions affecting the consolidation interval and reshaping visual learning remains uncharted. Motivated by findings mapping connections between oculomotor behavior and visual performance, we examined whether visual consolidation can be facilitated by visual-oculomotor interactions. To this aim, we paired reactivation of an oculomotor memory with consolidation of a typical visual texture discrimination task. Importantly, the oculomotor memory was encoded by learning of the pure motor component of the movement, removing visual cues. When brief reactivation of the oculomotor memory preceded the visual task, visual gains were substantially enhanced compared with those achieved by visual practice per se and were strongly related to the magnitude of oculomotor gains, suggesting that the brain utilizes oculomotor memory to enhance basic visual perception.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Visual skill learning is commonly considered a manifestation of brain plasticity. Following encoding, consolidation of the skill may result in between-session performance gains. A great volume of studies have demonstrated that during the offline consolidation interval, the skill is susceptible to external inputs that modify the preformed representation of the memory, affecting future performance. However, while basic visual perceptual learning is thought to be mediated by sensory brain regions or their higher-order readout pathways, the possibility of visual-oculomotor interactions affecting the consolidation interval and reshaping visual learning remains uncharted. Motivated by findings mapping connections between oculomotor behavior and visual performance, we examined whether visual consolidation can be facilitated by visual-oculomotor interactions. To this aim, we paired reactivation of an oculomotor memory with consolidation of a typical visual texture discrimination task. Importantly, the oculomotor memory was encoded by learning of the pure motor component of the movement, removing visual cues. When brief reactivation of the oculomotor memory preceded the visual task, visual gains were substantially enhanced compared with those achieved by visual practice per se and were strongly related to the magnitude of oculomotor gains, suggesting that the brain utilizes oculomotor memory to enhance basic visual perception. |
Benjamin Tari; Mohammed A Fadel; Matthew Heath Response suppression produces a switch-cost for spatially compatible saccades Journal Article Experimental Brain Research, 237 (5), pp. 1195–1203, 2019. @article{Tari2019b, title = {Response suppression produces a switch-cost for spatially compatible saccades}, author = {Benjamin Tari and Mohammed A Fadel and Matthew Heath}, doi = {10.1007/s00221-019-05497-z}, year = {2019}, date = {2019-05-01}, journal = {Experimental Brain Research}, volume = {237}, number = {5}, pages = {1195--1203}, abstract = {Executive function supports the rapid alternation between tasks for online reconfiguration of attentional and motor goals. The oculomotor literature has found that a prosaccade (i.e., saccade to veridical target location) preceded by an antisaccade (i.e., saccade mirror symmetrical to a target) elicits an increase in reaction time (RT), whereas the converse switch does not. This switch-cost has been attributed to the antisaccade task's requirement of inhibiting a prosaccade (i.e., response suppression) and transforming a target's coordinate (i.e., vector inversion)—executive processes thought to contribute to a task-set inertia that proactively interferes with the planning of a subsequent prosaccade. It is, however, unclear whether response suppression and vector inversion contribute to a task-set inertia or whether the phenomenon relates to a unitary component (e.g., response suppression). Here, the same stimulus-driven (SD) prosaccades (i.e., respond at target onset) as used in previous work were used with minimally delayed (MD) prosaccades (i.e., respond at target offset) and arranged in an AABB paradigm (i.e.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Executive function supports the rapid alternation between tasks for online reconfiguration of attentional and motor goals. The oculomotor literature has found that a prosaccade (i.e., saccade to veridical target location) preceded by an antisaccade (i.e., saccade mirror symmetrical to a target) elicits an increase in reaction time (RT), whereas the converse switch does not. This switch-cost has been attributed to the antisaccade task's requirement of inhibiting a prosaccade (i.e., response suppression) and transforming a target's coordinate (i.e., vector inversion)—executive processes thought to contribute to a task-set inertia that proactively interferes with the planning of a subsequent prosaccade. It is, however, unclear whether response suppression and vector inversion contribute to a task-set inertia or whether the phenomenon relates to a unitary component (e.g., response suppression). Here, the same stimulus-driven (SD) prosaccades (i.e., respond at target onset) as used in previous work were used with minimally delayed (MD) prosaccades (i.e., respond at target offset) and arranged in an AABB paradigm (i.e. |
Sergio Delle Monache; Francesco Lacquaniti; Gianfranco Bosco Ocular tracking of occluded ballistic trajectories: Effects of visual context and of target law of motion Journal Article Journal of Vision, 19 (4), pp. 1–21, 2019. @article{Monache2019, title = {Ocular tracking of occluded ballistic trajectories: Effects of visual context and of target law of motion}, author = {Sergio Delle Monache and Francesco Lacquaniti and Gianfranco Bosco}, doi = {10.1167/19.4.13}, year = {2019}, date = {2019-04-01}, journal = {Journal of Vision}, volume = {19}, number = {4}, pages = {1--21}, publisher = {The Association for Research in Vision and Ophthalmology}, abstract = {In tracking a moving target, the visual context may provide cues for an observer to interpret the causal nature of the target motion and extract features to which the visual system is weakly sensitive, such as target acceleration. This information could be critical when vision of the target is temporarily impeded, requiring visual motion extrapolation processes. Here we investigated how visual context influences ocular tracking of motion either congruent or not with natural gravity. To this end, 28 subjects tracked computer-simulated ballistic trajectories either perturbed in the descending segment with altered gravity effects (0g/2g) or retaining natural-like motion (1g). Shortly after the perturbation (550 ms), targets disappeared for either 450 or 650 ms and became visible again until landing. Target motion occurred with either quasi-realistic pictorial cues or a uniform background, presented in counterbalanced order. We analyzed saccadic and pursuit movements after 0g and 2g target-motion perturbations and for corresponding intervals of unperturbed 1g trajectories, as well as after corresponding occlusions. Moreover, we considered the eye-to-target distance at target reappearance. Tracking parameters differed significantly between scenarios: With a neutral background, eye movements did not depend consistently on target motion, whereas with pictorial background they showed significant dependence, denoting better tracking of accelerated targets. These results suggest that oculomotor control is tuned to realistic properties of the visual scene.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In tracking a moving target, the visual context may provide cues for an observer to interpret the causal nature of the target motion and extract features to which the visual system is weakly sensitive, such as target acceleration. This information could be critical when vision of the target is temporarily impeded, requiring visual motion extrapolation processes. Here we investigated how visual context influences ocular tracking of motion either congruent or not with natural gravity. To this end, 28 subjects tracked computer-simulated ballistic trajectories either perturbed in the descending segment with altered gravity effects (0g/2g) or retaining natural-like motion (1g). Shortly after the perturbation (550 ms), targets disappeared for either 450 or 650 ms and became visible again until landing. Target motion occurred with either quasi-realistic pictorial cues or a uniform background, presented in counterbalanced order. We analyzed saccadic and pursuit movements after 0g and 2g target-motion perturbations and for corresponding intervals of unperturbed 1g trajectories, as well as after corresponding occlusions. Moreover, we considered the eye-to-target distance at target reappearance. Tracking parameters differed significantly between scenarios: With a neutral background, eye movements did not depend consistently on target motion, whereas with pictorial background they showed significant dependence, denoting better tracking of accelerated targets. These results suggest that oculomotor control is tuned to realistic properties of the visual scene. |
Shlomit Yuval-Greenberg; Anat Keren; Rinat Hilo; Adar Paz; Navah Ratzon Gaze control during simulator driving in adolescents with and without attention deficit hyperactivity disorder Journal Article American Journal of Occupational Therapy, 73 (3), pp. 1–8, 2019. @article{Yuval-Greenberg2019, title = {Gaze control during simulator driving in adolescents with and without attention deficit hyperactivity disorder}, author = {Shlomit Yuval-Greenberg and Anat Keren and Rinat Hilo and Adar Paz and Navah Ratzon}, doi = {10.5014/ajot.2019.031500}, year = {2019}, date = {2019-04-01}, journal = {American Journal of Occupational Therapy}, volume = {73}, number = {3}, pages = {1--8}, publisher = {American Occupational Therapy Association}, abstract = {Importance: Attention deficit hyperactivity disorder (ADHD) is associated with driving deficits. Visual standards for driving define minimum qualifications for safe driving, including acuity and field of vision, but they do not consider the ability to explore the environment efficiently by shifting the gaze, which is a critical element of safe driving. Objective: To examine visual exploration during simulated driving in adolescents with and without ADHD. Design: Adolescents with and without ADHD drove a driving simulator for approximately 10 min while their gaze was monitored. They then completed a battery of questionnaires. Setting: University lab. Participants: Participants with (n = 16) and without (n = 15) ADHD were included. Participants had a history of neurological disorders other than ADHD and normal or corrected-to-normal vision. Control participants reported not having a diagnosis of ADHD. Participants with ADHD had been previously diagnosed by a qualified professional. Outcomes and Measures: We compared the following measures between ADHD and non-ADHD groups: dashboard dwell times, fixation variance, entropy, and fixation duration. Results: Findings showed that participants with ADHD were more restricted in their patterns of exploration than control group participants. They spent considerably more time gazing at the dashboard and had longer periods of fixation with lower variability and randomness. Conclusions and Relevance: The results support the hypothesis that adolescents with ADHD engage in less active exploration during simulated driving. What This Article Adds: This study raises concerns regarding the driving competence of people with ADHD and opens up new directions for potential training programs that focus on exploratory gaze control.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Importance: Attention deficit hyperactivity disorder (ADHD) is associated with driving deficits. Visual standards for driving define minimum qualifications for safe driving, including acuity and field of vision, but they do not consider the ability to explore the environment efficiently by shifting the gaze, which is a critical element of safe driving. Objective: To examine visual exploration during simulated driving in adolescents with and without ADHD. Design: Adolescents with and without ADHD drove a driving simulator for approximately 10 min while their gaze was monitored. They then completed a battery of questionnaires. Setting: University lab. Participants: Participants with (n = 16) and without (n = 15) ADHD were included. Participants had a history of neurological disorders other than ADHD and normal or corrected-to-normal vision. Control participants reported not having a diagnosis of ADHD. Participants with ADHD had been previously diagnosed by a qualified professional. Outcomes and Measures: We compared the following measures between ADHD and non-ADHD groups: dashboard dwell times, fixation variance, entropy, and fixation duration. Results: Findings showed that participants with ADHD were more restricted in their patterns of exploration than control group participants. They spent considerably more time gazing at the dashboard and had longer periods of fixation with lower variability and randomness. Conclusions and Relevance: The results support the hypothesis that adolescents with ADHD engage in less active exploration during simulated driving. What This Article Adds: This study raises concerns regarding the driving competence of people with ADHD and opens up new directions for potential training programs that focus on exploratory gaze control. |
Lynn Huestegge; Oliver Herbort; Nora Gosch; Wilfried Kunde; Aleks Pieczykolan Free-choice saccades and their underlying determinants: Explorations of high-level voluntary oculomotor control Journal Article Journal of Vision, 19 (3), pp. 1–15, 2019. @article{Huestegge2019, title = {Free-choice saccades and their underlying determinants: Explorations of high-level voluntary oculomotor control}, author = {Lynn Huestegge and Oliver Herbort and Nora Gosch and Wilfried Kunde and Aleks Pieczykolan}, doi = {10.1167/19.3.14}, year = {2019}, date = {2019-03-01}, journal = {Journal of Vision}, volume = {19}, number = {3}, pages = {1--15}, publisher = {The Association for Research in Vision and Ophthalmology}, abstract = {Models of eye-movement control distinguish between different control levels, ranging from automatic (bottom-up, stimulus-driven selection) and automatized (based on well-learned routines) to voluntary (top-down, goal-driven selection, e.g., based on instructions). However, one type of voluntary control has yet only been examined in the manual and not in the oculomotor domain, namely free-choice selection among arbitrary targets, that is, targets that are of equal interest from both a bottom-up and topdown processing perspective. Here, we ask which features of targets (identity- or location-related) are used to determine such oculomotor free-choice behavior. In two experiments, participants executed a saccade to one of four peripheral targets in three different choice conditions: unconstrained free choice, constrained free choice based on target identity (color), and constrained free choice based on target location. The analysis of choice frequencies revealed that unconstrained free-choice selection closely resembled constrained choice based on target location. The results suggest that free-choice oculomotor control is mainly guided by spatial (location-based) target characteristics. We explain these results by assuming that participants tend to avoid less parsimonious recoding of target-identity representations into spatial codes, the latter being a necessary prerequisite to configure oculomotor commands.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Models of eye-movement control distinguish between different control levels, ranging from automatic (bottom-up, stimulus-driven selection) and automatized (based on well-learned routines) to voluntary (top-down, goal-driven selection, e.g., based on instructions). However, one type of voluntary control has yet only been examined in the manual and not in the oculomotor domain, namely free-choice selection among arbitrary targets, that is, targets that are of equal interest from both a bottom-up and topdown processing perspective. Here, we ask which features of targets (identity- or location-related) are used to determine such oculomotor free-choice behavior. In two experiments, participants executed a saccade to one of four peripheral targets in three different choice conditions: unconstrained free choice, constrained free choice based on target identity (color), and constrained free choice based on target location. The analysis of choice frequencies revealed that unconstrained free-choice selection closely resembled constrained choice based on target location. The results suggest that free-choice oculomotor control is mainly guided by spatial (location-based) target characteristics. We explain these results by assuming that participants tend to avoid less parsimonious recoding of target-identity representations into spatial codes, the latter being a necessary prerequisite to configure oculomotor commands. |
Matthew O Kimble; Andrew S Hyatt Vigilance/avoidance to expected and presented stimuli in trauma survivors: An eye-tracking study Journal Article Journal of Trauma & Dissociation, 20 (2), pp. 228–241, 2019. @article{Kimble2019, title = {Vigilance/avoidance to expected and presented stimuli in trauma survivors: An eye-tracking study}, author = {Matthew O Kimble and Andrew S Hyatt}, doi = {10.1080/15299732.2019.1572041}, year = {2019}, date = {2019-03-01}, journal = {Journal of Trauma & Dissociation}, volume = {20}, number = {2}, pages = {228--241}, publisher = {Routledge}, abstract = {Attention in trauma-related disorders has been characterized by both vigilance and avoidance of trauma-related or aversive stimuli. This study used eye-tracking technology to investigate how cumulative trauma, as well as hypervigilance and dissociative symptoms, affected attentional patterns to anticipated negative stimuli and actual negative stimuli. A sample of forty-two trauma participants recruited from the community had a choice about where to look on a computer screen knowing which segments of the screen negative stimuli were likely to appear. Participants could look at those stimuli for as long as they chose before pushing a button to move onto the next trial. A measure of hypervigilance predicted looking to quadrants in which a negative stimulus was to appear. Cumulative trauma predicted avoidance of those stimuli. Neither cumulative trauma or symptom profiles predicted how long participants looked at the negative pictures once they were presented. These data suggest that hypervigilance is associated with looking for threats that are not yet present, and that cumulative trauma may be associated with motivation to avoid negative stimuli. The findings are discussed with respect to the characteristics of the sample and the limited dissociative pathology.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Attention in trauma-related disorders has been characterized by both vigilance and avoidance of trauma-related or aversive stimuli. This study used eye-tracking technology to investigate how cumulative trauma, as well as hypervigilance and dissociative symptoms, affected attentional patterns to anticipated negative stimuli and actual negative stimuli. A sample of forty-two trauma participants recruited from the community had a choice about where to look on a computer screen knowing which segments of the screen negative stimuli were likely to appear. Participants could look at those stimuli for as long as they chose before pushing a button to move onto the next trial. A measure of hypervigilance predicted looking to quadrants in which a negative stimulus was to appear. Cumulative trauma predicted avoidance of those stimuli. Neither cumulative trauma or symptom profiles predicted how long participants looked at the negative pictures once they were presented. These data suggest that hypervigilance is associated with looking for threats that are not yet present, and that cumulative trauma may be associated with motivation to avoid negative stimuli. The findings are discussed with respect to the characteristics of the sample and the limited dissociative pathology. |
Roy Amit; Dekel Abeles; Marisa Carrasco; Shlomit Yuval-Greenberg Oculomotor inhibition reflects temporal expectations Journal Article NeuroImage, 184 , pp. 279–292, 2019. @article{Amit2019a, title = {Oculomotor inhibition reflects temporal expectations}, author = {Roy Amit and Dekel Abeles and Marisa Carrasco and Shlomit Yuval-Greenberg}, doi = {10.1016/j.neuroimage.2018.09.026}, year = {2019}, date = {2019-01-01}, journal = {NeuroImage}, volume = {184}, pages = {279--292}, abstract = {The accurate extraction of signals out of noisy environments is a major challenge of the perceptual system. Forming temporal expectations and continuously matching them with perceptual input can facilitate this process. In humans, temporal expectations are typically assessed using behavioral measures, which provide only retrospective but no real-time estimates during target anticipation, or by using electrophysiological measures, which require extensive preprocessing and are difficult to interpret. Here we show a new correlate of temporal expectations based on oculomotor behavior. Observers performed an orientation-discrimination task on a central grating target, while their gaze position and EEG were monitored. In each trial, a cue preceded the target by a varying interval (“foreperiod”). In separate blocks, the cue was either predictive or non-predictive regarding the timing of the target. Results showed that saccades and blinks were inhibited more prior to an anticipated regular target than a less-anticipated irregular one. This consistent oculomotor inhibition effect enabled a trial-by-trial classification according to interval-regularity. Additionally, in the regular condition the slope of saccade-rate and drift were shallower for longer than shorter foreperiods, indicating their adjustment according to temporal expectations. Comparing the sensitivity of this oculomotor marker with those of other common predictability markers (e.g. alpha-suppression) showed that it is a sensitive marker for cue-related anticipation. In contrast, temporal changes in conditional probabilities (hazard-rate) modulated alpha-suppression more than cue-related anticipation. We conclude that pre-target oculomotor inhibition is a correlate of temporal predictions induced by cue-target associations, whereas alpha-suppression is more sensitive to conditional probabilities across time.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The accurate extraction of signals out of noisy environments is a major challenge of the perceptual system. Forming temporal expectations and continuously matching them with perceptual input can facilitate this process. In humans, temporal expectations are typically assessed using behavioral measures, which provide only retrospective but no real-time estimates during target anticipation, or by using electrophysiological measures, which require extensive preprocessing and are difficult to interpret. Here we show a new correlate of temporal expectations based on oculomotor behavior. Observers performed an orientation-discrimination task on a central grating target, while their gaze position and EEG were monitored. In each trial, a cue preceded the target by a varying interval (“foreperiod”). In separate blocks, the cue was either predictive or non-predictive regarding the timing of the target. Results showed that saccades and blinks were inhibited more prior to an anticipated regular target than a less-anticipated irregular one. This consistent oculomotor inhibition effect enabled a trial-by-trial classification according to interval-regularity. Additionally, in the regular condition the slope of saccade-rate and drift were shallower for longer than shorter foreperiods, indicating their adjustment according to temporal expectations. Comparing the sensitivity of this oculomotor marker with those of other common predictability markers (e.g. alpha-suppression) showed that it is a sensitive marker for cue-related anticipation. In contrast, temporal changes in conditional probabilities (hazard-rate) modulated alpha-suppression more than cue-related anticipation. We conclude that pre-target oculomotor inhibition is a correlate of temporal predictions induced by cue-target associations, whereas alpha-suppression is more sensitive to conditional probabilities across time. |
Roy Amit; Dekel Abeles; Shlomit Yuval-Greenberg Transient and sustained effects of stimulus properties on the generation of microsaccades Journal Article Journal of Vision, 19 (1), pp. 1–23, 2019. @article{Amit2019b, title = {Transient and sustained effects of stimulus properties on the generation of microsaccades}, author = {Roy Amit and Dekel Abeles and Shlomit Yuval-Greenberg}, doi = {10.1167/19.1.6}, year = {2019}, date = {2019-01-01}, journal = {Journal of Vision}, volume = {19}, number = {1}, pages = {1--23}, publisher = {The Association for Research in Vision and Ophthalmology}, abstract = {Saccades shift the gaze rapidly every few hundred milliseconds from one fixated location to the next, producing a flow of visual input into the visual system even in the absence of changes in the environment. During fixation, small saccades called microsaccades are produced 1–3 times per second, generating a flow of visual input. The characteristics of this visual flow are determined by the timings of the saccades and by the characteristics of the visual stimuli on which they are performed. Previous models of microsaccade generation have accounted for the effects of external stimulation on the production of microsaccades, but they have not considered the effects of the prolonged background stimulus on which microsaccades are performed. The effects of this stimulus on the process of microsaccade generation could be sustained, following its prolonged presentation, or transient, through the visual transients produced by the microsaccades themselves. In four experiments, we varied the properties of the constant displays and examined the resulting modulation of microsaccade properties: their sizes, their timings, and the correlations between properties of consecutive microsaccades. Findings show that displays of higher spatial frequency and contrast produce smaller microsaccades and longer minimal intervals between consecutive microsaccades; and smaller microsaccades are followed by smaller and delayed microsaccades. We explain these findings in light of previous models and suggest a conceptual model by which both sustained and transient effects of the stimulus have central roles in determining the generation of microsaccades.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccades shift the gaze rapidly every few hundred milliseconds from one fixated location to the next, producing a flow of visual input into the visual system even in the absence of changes in the environment. During fixation, small saccades called microsaccades are produced 1–3 times per second, generating a flow of visual input. The characteristics of this visual flow are determined by the timings of the saccades and by the characteristics of the visual stimuli on which they are performed. Previous models of microsaccade generation have accounted for the effects of external stimulation on the production of microsaccades, but they have not considered the effects of the prolonged background stimulus on which microsaccades are performed. The effects of this stimulus on the process of microsaccade generation could be sustained, following its prolonged presentation, or transient, through the visual transients produced by the microsaccades themselves. In four experiments, we varied the properties of the constant displays and examined the resulting modulation of microsaccade properties: their sizes, their timings, and the correlations between properties of consecutive microsaccades. Findings show that displays of higher spatial frequency and contrast produce smaller microsaccades and longer minimal intervals between consecutive microsaccades; and smaller microsaccades are followed by smaller and delayed microsaccades. We explain these findings in light of previous models and suggest a conceptual model by which both sustained and transient effects of the stimulus have central roles in determining the generation of microsaccades. |
Jeremy B Badler; Scott N J Watamaniuk; Stephen J Heinen A common mechanism modulates saccade timing during pursuit and fixation Journal Article Journal of Neurophysiology, 122 (5), pp. 1981–1988, 2019. @article{Badler2019, title = {A common mechanism modulates saccade timing during pursuit and fixation}, author = {Jeremy B Badler and Scott N J Watamaniuk and Stephen J Heinen}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {122}, number = {5}, pages = {1981--1988}, abstract = {Smooth pursuit is punctuated by catch-up saccades, which are thought to automatically correct sensory errors in retinal position and velocity. Recent studies have shown that the timing of catch-up saccades is susceptible to cognitive modulation, as is the timing of fixational microsaccades. Are the timing of catchup and microsaccades thus modulated by the same mechanism? Here, we test directly whether pursuit catch-up saccades and fixational microsaccades exhibit the same temporal pattern of task-related bursts and subsidence. Observers pursued a linear array of 15 alphanumeric characters that translated across the screen and simultaneously performed a character identification task on it. At a fixed time, a cue briefly surrounded the central element to specify it as the pursuit target. After a random delay, a probe (E or 3) appeared briefly at a randomly selected character location, and observers identified it. For comparison, a fixation condition was also tested with trial parameters identical to the pursuit condition, except that the array remained stationary. We found that during both pursuit and fixation tasks, saccades paused after the cue and then rebounded as expected but also subsided in anticipation of the task. The time courses of the reactive pause, rebound, and anticipatory subsidence were similar, and idiosyncratic subject behavior was consistent across pursuit and fixation. The results provide evidence for a common mechanism of saccade control during pursuit and fixation, which is predictive as well as reactive and has an identifiable temporal signature in individual observers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Smooth pursuit is punctuated by catch-up saccades, which are thought to automatically correct sensory errors in retinal position and velocity. Recent studies have shown that the timing of catch-up saccades is susceptible to cognitive modulation, as is the timing of fixational microsaccades. Are the timing of catchup and microsaccades thus modulated by the same mechanism? Here, we test directly whether pursuit catch-up saccades and fixational microsaccades exhibit the same temporal pattern of task-related bursts and subsidence. Observers pursued a linear array of 15 alphanumeric characters that translated across the screen and simultaneously performed a character identification task on it. At a fixed time, a cue briefly surrounded the central element to specify it as the pursuit target. After a random delay, a probe (E or 3) appeared briefly at a randomly selected character location, and observers identified it. For comparison, a fixation condition was also tested with trial parameters identical to the pursuit condition, except that the array remained stationary. We found that during both pursuit and fixation tasks, saccades paused after the cue and then rebounded as expected but also subsided in anticipation of the task. The time courses of the reactive pause, rebound, and anticipatory subsidence were similar, and idiosyncratic subject behavior was consistent across pursuit and fixation. The results provide evidence for a common mechanism of saccade control during pursuit and fixation, which is predictive as well as reactive and has an identifiable temporal signature in individual observers. |
Rodrigo Balp; Florian Waszak; Thérèse Collins Remapping versus short-term memory in visual stability across saccades Journal Article Attention, Perception, & Psychophysics, 81 , pp. 98–108, 2019. @article{Balp2019, title = {Remapping versus short-term memory in visual stability across saccades}, author = {Rodrigo Balp and Florian Waszak and Thér{è}se Collins}, doi = {10.3758/s13414-018-1602-z}, year = {2019}, date = {2019-01-01}, journal = {Attention, Perception, & Psychophysics}, volume = {81}, pages = {98--108}, publisher = {Attention, Perception, & Psychophysics}, abstract = {Saccadic eye movements cause displacements of the image of the visual world projected on the retina. Despite the ubiquitous nature of saccades, subjective experience of the world is continuous and stable. In five experiments, we addressed the mechanisms that may support visual stability: matching of pre- and postsaccadic locations of the target by an internal copy of the saccade, or retention of the visual attributes of the target in short-term memory across the saccade. Healthy human adults were instructed to make a saccade to a peripheral Gabor patch. While the saccade was in midflight, the patch could change location, orientation, or both. The change occurred either immediately or following a 250-ms blank during which no visual stimuli were available. In separate experiments, subjects had to report either whether the patch stepped to the left or right or whether the orientation rotated clockwise or counterclockwise. Consistent with previous findings, we found that transsaccadic displacement discrimination was enhanced by the addition of the blank. However, contrary to previous findings reported in the literature, the feature change did not improve performance. Transsaccadic orientation change discrimination did not depend on either an irrelevant temporal blank or a simultaneous irrelevant target displacement. Taken together, these findings suggest that orientation is not a relevant visual feature for transsaccadic correspondence.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccadic eye movements cause displacements of the image of the visual world projected on the retina. Despite the ubiquitous nature of saccades, subjective experience of the world is continuous and stable. In five experiments, we addressed the mechanisms that may support visual stability: matching of pre- and postsaccadic locations of the target by an internal copy of the saccade, or retention of the visual attributes of the target in short-term memory across the saccade. Healthy human adults were instructed to make a saccade to a peripheral Gabor patch. While the saccade was in midflight, the patch could change location, orientation, or both. The change occurred either immediately or following a 250-ms blank during which no visual stimuli were available. In separate experiments, subjects had to report either whether the patch stepped to the left or right or whether the orientation rotated clockwise or counterclockwise. Consistent with previous findings, we found that transsaccadic displacement discrimination was enhanced by the addition of the blank. However, contrary to previous findings reported in the literature, the feature change did not improve performance. Transsaccadic orientation change discrimination did not depend on either an irrelevant temporal blank or a simultaneous irrelevant target displacement. Taken together, these findings suggest that orientation is not a relevant visual feature for transsaccadic correspondence. |
Marie E Bellet; Joachim Bellet; Hendrikje Nienborg; Ziad M Hafed; Philipp Berens Human-level saccade detection performance using deep neural networks Journal Article Journal of Neurophysiology, 121 (2), pp. 646–661, 2019. @article{Bellet2019, title = {Human-level saccade detection performance using deep neural networks}, author = {Marie E Bellet and Joachim Bellet and Hendrikje Nienborg and Ziad M Hafed and Philipp Berens}, doi = {10.1152/jn.00601.2018}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {121}, number = {2}, pages = {646--661}, abstract = {Saccades are ballistic eye movements that rapidly shift gaze from one location of visual space to another. Detecting saccades in eye movement recordings is important not only for studying the neural mechanisms underlying sensory, motor, and cognitive processes, but also as a clinical and diagnostic tool. However, automatically detecting saccades can be difficult, particularly when such saccades are generated in coordination with other tracking eye movements, like smooth pursuits, or when the saccade amplitude is close to eye tracker noise levels, like with microsaccades. In such cases, labeling by human experts is required, but this is a tedious task prone to variability and error. We developed a convolutional neural network to automatically detect saccades at human-level accuracy and with minimal training examples. Our algorithm surpasses state of the art according to common performance metrics and could facilitate studies of neurophysiological processes underlying saccade generation and visual processing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccades are ballistic eye movements that rapidly shift gaze from one location of visual space to another. Detecting saccades in eye movement recordings is important not only for studying the neural mechanisms underlying sensory, motor, and cognitive processes, but also as a clinical and diagnostic tool. However, automatically detecting saccades can be difficult, particularly when such saccades are generated in coordination with other tracking eye movements, like smooth pursuits, or when the saccade amplitude is close to eye tracker noise levels, like with microsaccades. In such cases, labeling by human experts is required, but this is a tedious task prone to variability and error. We developed a convolutional neural network to automatically detect saccades at human-level accuracy and with minimal training examples. Our algorithm surpasses state of the art according to common performance metrics and could facilitate studies of neurophysiological processes underlying saccade generation and visual processing. |
Alessandro Benedetto; Maria Concetta Morrone Visual sensitivity and bias oscillate phase-locked to saccadic eye movements Journal Article Journal of vision, 19 (14), pp. 1–16, 2019. @article{Benedetto2019, title = {Visual sensitivity and bias oscillate phase-locked to saccadic eye movements}, author = {Alessandro Benedetto and Maria Concetta Morrone}, doi = {10.1167/19.14.15}, year = {2019}, date = {2019-01-01}, journal = {Journal of vision}, volume = {19}, number = {14}, pages = {1--16}, abstract = {Oscillations in perceptual performance have been observed before and after a voluntary action, like hand, finger, and eye movements. In particular, discrimination accuracy of suprathreshold contrast stimuli oscillates in the delta range (2-3 Hz) phase-locked to saccadic eye movements. Importantly, saccadic suppression is embedded in phase with these long-lasting perceptual oscillations. It is debated whether these rhythmic modulations affect only appearance of high-contrast stimuli or whether absolute detection threshold is also modulated rhythmically. Here we measured location discrimination of a brief Gabor patch presented randomly between 1 s before and after a voluntary saccade and demonstrated that absolute contrast thresholds oscillated at a similar frequency to suprathreshold contrast discrimination. Importantly, saccadic suppression is also embedded in phase with absolute threshold oscillations. Interestingly, response bias was also found to oscillate at the same frequency in both tasks. However, the frequency was in the alpha range for bias, while it was in the delta range for sensitivity. These results demonstrate the presence of perisaccadic delta oscillations in visual sensitivity phase-locked to saccadic onset, and independent from response bias alpha oscillations. Overall, the present findings reinforce the suggestion of a leading role of oscillations in the temporal binding between eye-movement and visual processing timing.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Oscillations in perceptual performance have been observed before and after a voluntary action, like hand, finger, and eye movements. In particular, discrimination accuracy of suprathreshold contrast stimuli oscillates in the delta range (2-3 Hz) phase-locked to saccadic eye movements. Importantly, saccadic suppression is embedded in phase with these long-lasting perceptual oscillations. It is debated whether these rhythmic modulations affect only appearance of high-contrast stimuli or whether absolute detection threshold is also modulated rhythmically. Here we measured location discrimination of a brief Gabor patch presented randomly between 1 s before and after a voluntary saccade and demonstrated that absolute contrast thresholds oscillated at a similar frequency to suprathreshold contrast discrimination. Importantly, saccadic suppression is also embedded in phase with absolute threshold oscillations. Interestingly, response bias was also found to oscillate at the same frequency in both tasks. However, the frequency was in the alpha range for bias, while it was in the delta range for sensitivity. These results demonstrate the presence of perisaccadic delta oscillations in visual sensitivity phase-locked to saccadic onset, and independent from response bias alpha oscillations. Overall, the present findings reinforce the suggestion of a leading role of oscillations in the temporal binding between eye-movement and visual processing timing. |
Katharina Bey; Inga Meyhöfer; Leonhard Lennertz; Rosa Grützmann; Stephan Heinzel; Christian Kaufmann; Julia Klawohn; Anja Riesel; Ulrich Ettinger; Norbert Kathmann; Michael Wagner Schizotypy and smooth pursuit eye movements as potential endophenotypes of obsessive-compulsive disorder Journal Article European Archives of Psychiatry and Clinical Neuroscience, 269 (2), pp. 235–243, 2019. @article{Bey2019, title = {Schizotypy and smooth pursuit eye movements as potential endophenotypes of obsessive-compulsive disorder}, author = {Katharina Bey and Inga Meyhöfer and Leonhard Lennertz and Rosa Grützmann and Stephan Heinzel and Christian Kaufmann and Julia Klawohn and Anja Riesel and Ulrich Ettinger and Norbert Kathmann and Michael Wagner}, doi = {10.1007/s00406-018-0899-x}, year = {2019}, date = {2019-01-01}, journal = {European Archives of Psychiatry and Clinical Neuroscience}, volume = {269}, number = {2}, pages = {235--243}, publisher = {Springer Berlin Heidelberg}, abstract = {Patients with obsessive-compulsive disorder (OCD) show dysfunctions of the fronto-striatal circuitry, which imply corresponding oculomotor deficits including smooth pursuit eye movements (SPEM). However, evidence for a deficit in SPEM is inconclusive, with some studies reporting reduced velocity gain while others did not find any SPEM dysfunctions in OCD patients. Interestingly, psychosis-like traits have repeatedly been linked to both OCD and impaired SPEM. Here, we examined a large sample of n = 168 patients with OCD}, keywords = {}, pubstate = {published}, tppubtype = {article} } Patients with obsessive-compulsive disorder (OCD) show dysfunctions of the fronto-striatal circuitry, which imply corresponding oculomotor deficits including smooth pursuit eye movements (SPEM). However, evidence for a deficit in SPEM is inconclusive, with some studies reporting reduced velocity gain while others did not find any SPEM dysfunctions in OCD patients. Interestingly, psychosis-like traits have repeatedly been linked to both OCD and impaired SPEM. Here, we examined a large sample of n = 168 patients with OCD |
J A Bijvank; L J Van Rijn; L J Balk; H S Tan; B M J Uitdehaag; A Petzold Diagnosing and quantifying a common deficit in multiple sclerosis: Internuclear ophthalmoplegia Journal Article Neurology, 92 (20), pp. E2299–E2308, 2019. @article{Bijvank2019, title = {Diagnosing and quantifying a common deficit in multiple sclerosis: Internuclear ophthalmoplegia}, author = {J A Bijvank and L J {Van Rijn} and L J Balk and H S Tan and B M J Uitdehaag and A Petzold}, doi = {10.1212/WNL.0000000000007499}, year = {2019}, date = {2019-01-01}, journal = {Neurology}, volume = {92}, number = {20}, pages = {E2299--E2308}, abstract = {Objective: We present an objective and quantitative approach for diagnosing internuclear ophthalmoplegia (INO) in multiple sclerosis (MS). Methods: A validated standardized infrared oculography protocol (DEMoNS [Demonstrate Eye Movement Networks with Saccades]) was used for quantifying prosaccades in patients with MS and healthy controls (HCs). The versional dysconjugacy index (VDI) was calculated, which describes the ratio between the abducting and adducting eye. The VDI was determined for peak velocity, peak acceleration, peak velocity divided by amplitude, and area under the curve (AUC) of the saccadic trajectory. We calculated the diagnostic accuracy for the several VDI parameters by a receiver operating characteristic analysis comparing HCs and patients with MS. The National Eye Institute Visual Function Questionnaire-25 was used to investigate vision-related quality of life of MS patients with INO. Results: Two hundred ten patients with MS and 58 HCs were included. The highest diagnostic accuracy was achieved by the VDI AUC of 15° horizontal prosaccades. Based on a combined VDI AUC and peak velocity divided by amplitude detection, the prevalence of an INO in MS calculated to 34%. In the INO group, 35.2% of the patients with MS reported any complaints of double vision, compared to 18.4% in the non-INO group (p = 0.010). MS patients with an INO had a lower overall vision-related quality of life (median 89.9, interquartile range 12.8) compared to patients without an INO (median 91.8, interquartile range 9.3}, keywords = {}, pubstate = {published}, tppubtype = {article} } Objective: We present an objective and quantitative approach for diagnosing internuclear ophthalmoplegia (INO) in multiple sclerosis (MS). Methods: A validated standardized infrared oculography protocol (DEMoNS [Demonstrate Eye Movement Networks with Saccades]) was used for quantifying prosaccades in patients with MS and healthy controls (HCs). The versional dysconjugacy index (VDI) was calculated, which describes the ratio between the abducting and adducting eye. The VDI was determined for peak velocity, peak acceleration, peak velocity divided by amplitude, and area under the curve (AUC) of the saccadic trajectory. We calculated the diagnostic accuracy for the several VDI parameters by a receiver operating characteristic analysis comparing HCs and patients with MS. The National Eye Institute Visual Function Questionnaire-25 was used to investigate vision-related quality of life of MS patients with INO. Results: Two hundred ten patients with MS and 58 HCs were included. The highest diagnostic accuracy was achieved by the VDI AUC of 15° horizontal prosaccades. Based on a combined VDI AUC and peak velocity divided by amplitude detection, the prevalence of an INO in MS calculated to 34%. In the INO group, 35.2% of the patients with MS reported any complaints of double vision, compared to 18.4% in the non-INO group (p = 0.010). MS patients with an INO had a lower overall vision-related quality of life (median 89.9, interquartile range 12.8) compared to patients without an INO (median 91.8, interquartile range 9.3 |
Francesca Bonetti; Massimo Turatto Habituation of oculomotor capture by sudden onsets: Stimulus specificity, spontaneous recovery and dishabituation Journal Article Journal of Experimental Psychology: Human Perception and Performance, 45 (2), pp. 264–284, 2019. @article{Bonetti2019, title = {Habituation of oculomotor capture by sudden onsets: Stimulus specificity, spontaneous recovery and dishabituation}, author = {Francesca Bonetti and Massimo Turatto}, doi = {10.1037/xhp0000605}, year = {2019}, date = {2019-01-01}, journal = {Journal of Experimental Psychology: Human Perception and Performance}, volume = {45}, number = {2}, pages = {264--284}, abstract = {Previous studies have confirmed that visual onsets are very powerful in attracting our gaze. The reflexive saccades triggered by sudden onsets have a high adaptive value because they ensure a rapid inspection of potentially appetitive or dangerous events. Here we showed, however, that such exogenously driven saccades are rapidly attenuated as the exposure to the same irrelevant onset progresses. Crucially, we found that such decrement in oculomotor capture conforms to several key features of habituation, an ancestral and widespread form of learning, consisting in a response reduction to a repeated irrelevant stimulation. In addition, we documented both spontaneous recovery and specificity of habituation, the phenomenon of dishabituation, and that habituation of capture was stimulation-frequency dependent. We also found both short-term and long-term habituation of oculomotor capture. Although we cannot exclude the contribution of top-down strategic inhibitory mechanisms to filter the onset distractors, the oculomotor capture reduction that we have documented finds a straightforward explanation in the neural and cognitive mechanisms underlying habituation of the orienting reflex, as originally suggested by Sokolov. Our study lends support to the idea that habituation plays a key filtering role in regulating the exogenous saccadic response triggered by peripheral onset distractors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Previous studies have confirmed that visual onsets are very powerful in attracting our gaze. The reflexive saccades triggered by sudden onsets have a high adaptive value because they ensure a rapid inspection of potentially appetitive or dangerous events. Here we showed, however, that such exogenously driven saccades are rapidly attenuated as the exposure to the same irrelevant onset progresses. Crucially, we found that such decrement in oculomotor capture conforms to several key features of habituation, an ancestral and widespread form of learning, consisting in a response reduction to a repeated irrelevant stimulation. In addition, we documented both spontaneous recovery and specificity of habituation, the phenomenon of dishabituation, and that habituation of capture was stimulation-frequency dependent. We also found both short-term and long-term habituation of oculomotor capture. Although we cannot exclude the contribution of top-down strategic inhibitory mechanisms to filter the onset distractors, the oculomotor capture reduction that we have documented finds a straightforward explanation in the neural and cognitive mechanisms underlying habituation of the orienting reflex, as originally suggested by Sokolov. Our study lends support to the idea that habituation plays a key filtering role in regulating the exogenous saccadic response triggered by peripheral onset distractors. |
Claudia Bonmassar; Francesco Pavani; Wieske van Zoest The role of eye movements in manual responses to social and nonsocial cues Journal Article Attention, Perception, & Psychophysics, 81 (5), pp. 1236–1252, 2019. @article{Bonmassar2019, title = {The role of eye movements in manual responses to social and nonsocial cues}, author = {Claudia Bonmassar and Francesco Pavani and Wieske van Zoest}, doi = {10.3758/s13414-019-01669-9}, year = {2019}, date = {2019-01-01}, journal = {Attention, Perception, & Psychophysics}, volume = {81}, number = {5}, pages = {1236--1252}, publisher = {Attention, Perception, & Psychophysics}, abstract = {Gaze and arrow cues cause covert attention shifts even when they are uninformative. Nonetheless, it is unclear to what extent oculomotor behavior influences manual responses to social and nonsocial stimuli. In two experiments, we tracked the gaze of participants during the cueing task with nonpredictive gaze and arrow cues. In Experiment 1, the discrimination task was easy and eye movements were not necessary, whereas in Experiment 2 they were instrumental in identifying the target. Validity effects on manual response time (RT) were similar for the two cues in Experiment 1 and in Experiment 2, though in the presence of eye movements observers were overall slower to respond to the arrow cue compared with the gaze cue. Cue direction had an effect on saccadic performance before the discrimination was presented and throughout the duration of the trial. Furthermore, we found evidence of a distinct impact of the type of cue on diverse oculomotor components. While saccade latencies were affected by the type of cue, both before and after the target onset, saccade landing positions were not. Critically, the manual validity effect was predicted by the landing position of the initial eye movement. This work suggests that the relationship between eye movements and attention is not straightforward. In the presence of overt selection, saccade latency related to the overall speed of manual response, while eye movements landing position was closely related to manual performance in response to different cues.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Gaze and arrow cues cause covert attention shifts even when they are uninformative. Nonetheless, it is unclear to what extent oculomotor behavior influences manual responses to social and nonsocial stimuli. In two experiments, we tracked the gaze of participants during the cueing task with nonpredictive gaze and arrow cues. In Experiment 1, the discrimination task was easy and eye movements were not necessary, whereas in Experiment 2 they were instrumental in identifying the target. Validity effects on manual response time (RT) were similar for the two cues in Experiment 1 and in Experiment 2, though in the presence of eye movements observers were overall slower to respond to the arrow cue compared with the gaze cue. Cue direction had an effect on saccadic performance before the discrimination was presented and throughout the duration of the trial. Furthermore, we found evidence of a distinct impact of the type of cue on diverse oculomotor components. While saccade latencies were affected by the type of cue, both before and after the target onset, saccade landing positions were not. Critically, the manual validity effect was predicted by the landing position of the initial eye movement. This work suggests that the relationship between eye movements and attention is not straightforward. In the presence of overt selection, saccade latency related to the overall speed of manual response, while eye movements landing position was closely related to manual performance in response to different cues. |
Sabine Born; Michael Puntiroli; Damien Jordan; Dirk Kerzel Saccadic selection does not eliminate attribute amnesia Journal Article Journal of Experimental Psychology: Learning, Memory, and Cognition, 45 (12), pp. 2165–2173, 2019. @article{Born2019b, title = {Saccadic selection does not eliminate attribute amnesia}, author = {Sabine Born and Michael Puntiroli and Damien Jordan and Dirk Kerzel}, doi = {10.1037/xlm0000703}, year = {2019}, date = {2019-01-01}, journal = {Journal of Experimental Psychology: Learning, Memory, and Cognition}, volume = {45}, number = {12}, pages = {2165--2173}, abstract = {Attribute amnesia (Chen & Wyble, 2015, 2016) demonstrates that we may not always be able to spontaneously retrieve a simple attribute of a visual object (e.g., its color) for conscious report, even though the object had just been the target in a visual task. Attribute amnesia has been suggested to reflect a lack of consolidation of the task-irrelevant attribute in visual working memory. Here we tested whether saccadic selection eliminates or attenuates attribute amnesia. Saccade targets have been shown to be preferentially encoded into visual working memory and may therefore be spared. We used simple color pop-out displays, asking participants to indicate the location of the color singleton letter target on each trial either by keypress or by making a saccade toward it. After a couple of trials and unannounced to the participants, we asked for the color and identity of the last target letter on a surprise trial. We found that saccade targets were not spared from attribute amnesia: Participants were as bad in correctly reporting the color in the saccade as in the keypress condition. For letter identity, the effect was attenuated but not abolished when the target was foveated for a short period of time. We argue that the current results do not refute an obligatory coupling between saccadic selection and encoding in visual working memory. However, the encoded information may not necessarily be stored in a manner that is robust enough to persist in the face of a surprise question.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Attribute amnesia (Chen & Wyble, 2015, 2016) demonstrates that we may not always be able to spontaneously retrieve a simple attribute of a visual object (e.g., its color) for conscious report, even though the object had just been the target in a visual task. Attribute amnesia has been suggested to reflect a lack of consolidation of the task-irrelevant attribute in visual working memory. Here we tested whether saccadic selection eliminates or attenuates attribute amnesia. Saccade targets have been shown to be preferentially encoded into visual working memory and may therefore be spared. We used simple color pop-out displays, asking participants to indicate the location of the color singleton letter target on each trial either by keypress or by making a saccade toward it. After a couple of trials and unannounced to the participants, we asked for the color and identity of the last target letter on a surprise trial. We found that saccade targets were not spared from attribute amnesia: Participants were as bad in correctly reporting the color in the saccade as in the keypress condition. For letter identity, the effect was attenuated but not abolished when the target was foveated for a short period of time. We argue that the current results do not refute an obligatory coupling between saccadic selection and encoding in visual working memory. However, the encoded information may not necessarily be stored in a manner that is robust enough to persist in the face of a surprise question. |
Paul B Camacho; Ronald Carbonari; Sa Shen; Cindy Zadikoff; Arthur F Kramer; Citlali López-Ortiz Voluntary saccade training protocol in persons with Parkinson's disease and healthy adults Journal Article Frontiers in Aging Neuroscience, 11 , pp. 1–14, 2019. @article{Camacho2019, title = {Voluntary saccade training protocol in persons with Parkinson's disease and healthy adults}, author = {Paul B Camacho and Ronald Carbonari and Sa Shen and Cindy Zadikoff and Arthur F Kramer and Citlali López-Ortiz}, doi = {10.3389/fnagi.2019.00077}, year = {2019}, date = {2019-01-01}, journal = {Frontiers in Aging Neuroscience}, volume = {11}, pages = {1--14}, abstract = {Background: Voluntary saccade function gradually decreases during both the progression of Parkinson's disease (PD) and neurologically healthy adult aging. Voluntary saccades display decreased length and increased saccade latency, duration, and the number of compensatory saccades in aging and PD. Saccades serve as the key eye movement for maintaining salient features of the visual environment on the high visual acuity fovea of the retina. Abnormal saccade behavior has been associated with freezing of gait in PD. We have not identified any studies that have investigated improvement in voluntary saccade function using voluntary saccade training. Objective: We report an experimental protocol that tests a training paradigm following the principle of specificity to improve voluntary saccade velocity and amplitude, while decreasing latency and the number of compensatory saccades. Methods: Persons with PD (n = 22) and persons with no known neurological disorders (n = 22) between the ages of 40 and 65 years will be recruited. In a randomized-block study design, all participants will perform voluntary saccades to targets in eight cardinal and intercardinal directions. In each of the eight sessions during the four-week intervention period, participants will train at three target amplitudes. Participants will perform 40 trials for each amplitude block, consisting of five randomly presented repetitions for each direction. Voluntary and reflexive saccades will be recorded pre- and post-intervention, along with clinical mobility assessment using the Movement Disorder Society Unified Parkinson's Disease Rating Scale. Mobility scores, the amplitude, latency, and duration of the first saccade, and the number of saccades to reach the fixation target will be analyzed using an ANOVA of mixed effects. Discussion: This protocol holds promise as a potential method to improve voluntary saccade function in persons with PD. Should persons with PD not improve on any outcome following the intervention, this lack of response may support the use of saccade assessment as a response biomarker for the diagnosis of PD.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Background: Voluntary saccade function gradually decreases during both the progression of Parkinson's disease (PD) and neurologically healthy adult aging. Voluntary saccades display decreased length and increased saccade latency, duration, and the number of compensatory saccades in aging and PD. Saccades serve as the key eye movement for maintaining salient features of the visual environment on the high visual acuity fovea of the retina. Abnormal saccade behavior has been associated with freezing of gait in PD. We have not identified any studies that have investigated improvement in voluntary saccade function using voluntary saccade training. Objective: We report an experimental protocol that tests a training paradigm following the principle of specificity to improve voluntary saccade velocity and amplitude, while decreasing latency and the number of compensatory saccades. Methods: Persons with PD (n = 22) and persons with no known neurological disorders (n = 22) between the ages of 40 and 65 years will be recruited. In a randomized-block study design, all participants will perform voluntary saccades to targets in eight cardinal and intercardinal directions. In each of the eight sessions during the four-week intervention period, participants will train at three target amplitudes. Participants will perform 40 trials for each amplitude block, consisting of five randomly presented repetitions for each direction. Voluntary and reflexive saccades will be recorded pre- and post-intervention, along with clinical mobility assessment using the Movement Disorder Society Unified Parkinson's Disease Rating Scale. Mobility scores, the amplitude, latency, and duration of the first saccade, and the number of saccades to reach the fixation target will be analyzed using an ANOVA of mixed effects. Discussion: This protocol holds promise as a potential method to improve voluntary saccade function in persons with PD. Should persons with PD not improve on any outcome following the intervention, this lack of response may support the use of saccade assessment as a response biomarker for the diagnosis of PD. |
Johan Chandra; André Krügel; Ralf Engbert Experimental test of Bayesian saccade targeting under reversed reading direction Journal Article Attention, Perception, & Psychophysics, pp. 1–11, 2019. @article{Chandra2019, title = {Experimental test of Bayesian saccade targeting under reversed reading direction}, author = {Johan Chandra and André Krügel and Ralf Engbert}, doi = {10.3758/s13414-019-01814-4}, year = {2019}, date = {2019-01-01}, journal = {Attention, Perception, & Psychophysics}, pages = {1--11}, abstract = {During reading, rapid eye movements (saccades) shift the reader's line of sight from one word to another for high-acuity visual information processing. While experimental data and theoretical models show that readers aim at word centers, the eye-movement (oculomotor) accuracy is low compared to other tasks. As a consequence, distributions of saccadic landing positions indicate large (i) random errors and (ii) systematic over-and undershoot of word centers, which additionally depend on saccade lengths (McConkie et al. Visual Research, 28(10), 1107-1118, 1988). Here we show that both error components can be simultaneously reduced by reading texts from right to left in German language (N = 32). We used our experimental data to test a Bayesian model of saccade planning. First, experimental data are consistent with the model. Second, the model makes specific predictions of the effects of the precision of prior and (sensory) likelihood. Our results suggest that it is a more precise sensory likelihood that can explain the reduction of both random and systematic error components.}, keywords = {}, pubstate = {published}, tppubtype = {article} } During reading, rapid eye movements (saccades) shift the reader's line of sight from one word to another for high-acuity visual information processing. While experimental data and theoretical models show that readers aim at word centers, the eye-movement (oculomotor) accuracy is low compared to other tasks. As a consequence, distributions of saccadic landing positions indicate large (i) random errors and (ii) systematic over-and undershoot of word centers, which additionally depend on saccade lengths (McConkie et al. Visual Research, 28(10), 1107-1118, 1988). Here we show that both error components can be simultaneously reduced by reading texts from right to left in German language (N = 32). We used our experimental data to test a Bayesian model of saccade planning. First, experimental data are consistent with the model. Second, the model makes specific predictions of the effects of the precision of prior and (sensory) likelihood. Our results suggest that it is a more precise sensory likelihood that can explain the reduction of both random and systematic error components. |
Jing Chen; Matteo Valsecchi; Karl R Gegenfurtner Saccadic suppression measured by steady-state visual evoked potentials Journal Article Journal of Neurophysiology, 122 (1), pp. 251–258, 2019. @article{Chen2019e, title = {Saccadic suppression measured by steady-state visual evoked potentials}, author = {Jing Chen and Matteo Valsecchi and Karl R Gegenfurtner}, doi = {10.1152/jn.00712.2018}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {122}, number = {1}, pages = {251--258}, abstract = {Visual sensitivity is severely impaired during the execution of saccadic eye movements. This phenomenon has been extensively characterized in human psychophysics and nonhuman primate single-neuron studies, but a physiological characterization in humans is less established. Here, we used a method based on steadystate visually evoked potential (SSVEP), an oscillatory brain response to periodic visual stimulation, to examine how saccades affect visual sensitivity. Observers made horizontal saccades back and forth, while horizontal black-and-white gratings flickered at 5-30 Hz in the background. We analyzed EEG epochs with a length of 0.3 s either centered at saccade onset (saccade epochs) or centered at fixations half a second before the saccade (fixation epochs). Compared with fixation epochs, saccade epochs showed a broadband power increase, which most likely resulted from saccade-related EEG activity. The execution of saccades, however, led to an average reduction of 57% in the SSVEP amplitude at the stimulation frequency. This result provides additional evidence for an active saccadic suppression in the early visual cortex in humans. Compared with previous functional MRI and EEG studies, an advantage of this approach lies in its capability to trace the temporal dynamics of neural activity throughout the time course of a saccade. In contrast to previous electrophysiological studies in nonhuman primates, we did not find any evidence for postsaccadic enhancement, even though simulation results show that our method would have been able to detect it. We conclude that SSVEP is a useful technique to investigate the neural correlates of visual perception during saccadic eye movements in humans.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Visual sensitivity is severely impaired during the execution of saccadic eye movements. This phenomenon has been extensively characterized in human psychophysics and nonhuman primate single-neuron studies, but a physiological characterization in humans is less established. Here, we used a method based on steadystate visually evoked potential (SSVEP), an oscillatory brain response to periodic visual stimulation, to examine how saccades affect visual sensitivity. Observers made horizontal saccades back and forth, while horizontal black-and-white gratings flickered at 5-30 Hz in the background. We analyzed EEG epochs with a length of 0.3 s either centered at saccade onset (saccade epochs) or centered at fixations half a second before the saccade (fixation epochs). Compared with fixation epochs, saccade epochs showed a broadband power increase, which most likely resulted from saccade-related EEG activity. The execution of saccades, however, led to an average reduction of 57% in the SSVEP amplitude at the stimulation frequency. This result provides additional evidence for an active saccadic suppression in the early visual cortex in humans. Compared with previous functional MRI and EEG studies, an advantage of this approach lies in its capability to trace the temporal dynamics of neural activity throughout the time course of a saccade. In contrast to previous electrophysiological studies in nonhuman primates, we did not find any evidence for postsaccadic enhancement, even though simulation results show that our method would have been able to detect it. We conclude that SSVEP is a useful technique to investigate the neural correlates of visual perception during saccadic eye movements in humans. |
Francisco M Costela; Russell L Woods When watching video, many saccades are curved and deviate from a velocity profile model Journal Article Frontiers in Neuroscience, 12 , pp. 1–15, 2019. @article{Costela2019b, title = {When watching video, many saccades are curved and deviate from a velocity profile model}, author = {Francisco M Costela and Russell L Woods}, doi = {10.3389/fnins.2018.00960}, year = {2019}, date = {2019-01-01}, journal = {Frontiers in Neuroscience}, volume = {12}, pages = {1--15}, abstract = {Commonly, saccades are thought to be ballistic eye movements, not modified during flight, with a straight path and a well-described velocity profile. However, they do not always follow a straight path and studies of saccade curvature have been reported previously. In a prior study, we developed a real-time, saccade-trajectory prediction algorithm to improve the updating of gaze-contingent displays and found that saccades with a curved path or that deviated from the expected velocity profile were not well fit by our saccade-prediction algorithm (velocity-profile deviation), and thus had larger updating errors than saccades that had a straight path and had a velocity profile that was fit well by the model. Further, we noticed that the curved saccades and saccades with high velocity-profile deviations were more common than we had expected when participants performed a natural-viewing task. Since those saccades caused larger display updating errors, we sought a better understanding of them. Here we examine factors that could affect curvature and velocity profile of saccades using a pool of 218,744 saccades from 71 participants watching “Hollywood” video clips. Those factors included characteristics of the participants (e.g., age), of the videos (importance of faces for following the story, genre), of the saccade (e.g., magnitude, direction), time during the session (e.g., fatigue) and presence and timing of scene cuts. While viewing the video clips, saccades were most likely horizontal or vertical over oblique. Measured curvature and velocity-profile deviation had continuous, skewed frequency distributions. We used mixed-effects regression models that included cubic terms and found a complex relationship between curvature, velocity-profile deviation and saccade duration (or magnitude). Curvature and velocity-profile deviation were related to some video-dependent features such as lighting, face presence, or nature and human figure content. Time during the session was a predictor for velocity profile deviations. Further, we found a relationship for saccades that were in flight at the time of a scene cut to have higher velocity-profile deviations and lower curvature in univariable models. Saccades characteristics vary with a variety of factors, which suggests complex interactions between oculomotor control and scene content that could be explored further.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Commonly, saccades are thought to be ballistic eye movements, not modified during flight, with a straight path and a well-described velocity profile. However, they do not always follow a straight path and studies of saccade curvature have been reported previously. In a prior study, we developed a real-time, saccade-trajectory prediction algorithm to improve the updating of gaze-contingent displays and found that saccades with a curved path or that deviated from the expected velocity profile were not well fit by our saccade-prediction algorithm (velocity-profile deviation), and thus had larger updating errors than saccades that had a straight path and had a velocity profile that was fit well by the model. Further, we noticed that the curved saccades and saccades with high velocity-profile deviations were more common than we had expected when participants performed a natural-viewing task. Since those saccades caused larger display updating errors, we sought a better understanding of them. Here we examine factors that could affect curvature and velocity profile of saccades using a pool of 218,744 saccades from 71 participants watching “Hollywood” video clips. Those factors included characteristics of the participants (e.g., age), of the videos (importance of faces for following the story, genre), of the saccade (e.g., magnitude, direction), time during the session (e.g., fatigue) and presence and timing of scene cuts. While viewing the video clips, saccades were most likely horizontal or vertical over oblique. Measured curvature and velocity-profile deviation had continuous, skewed frequency distributions. We used mixed-effects regression models that included cubic terms and found a complex relationship between curvature, velocity-profile deviation and saccade duration (or magnitude). Curvature and velocity-profile deviation were related to some video-dependent features such as lighting, face presence, or nature and human figure content. Time during the session was a predictor for velocity profile deviations. Further, we found a relationship for saccades that were in flight at the time of a scene cut to have higher velocity-profile deviations and lower curvature in univariable models. Saccades characteristics vary with a variety of factors, which suggests complex interactions between oculomotor control and scene content that could be explored further. |
Mario Dalmaso; Luigi Castelli; Giovanni Galfano Anticipation of cognitive conflict is reflected in microsaccades: Evidence from a cued-flanker task Journal Article Journal of Eye Movement Research, 12 (6), pp. 1–9, 2019. @article{Dalmaso2019, title = {Anticipation of cognitive conflict is reflected in microsaccades: Evidence from a cued-flanker task}, author = {Mario Dalmaso and Luigi Castelli and Giovanni Galfano}, doi = {10.16910/jemr.12.6.3}, year = {2019}, date = {2019-01-01}, journal = {Journal of Eye Movement Research}, volume = {12}, number = {6}, pages = {1--9}, abstract = {Microsaccade frequency has recently been shown to be sensitive to high-level cognitive processes such as attention and memory. In the present study we explored the effects of anticipated cognitive conflict. Participants were administered a variant of the flanker task, which is known to elicit cognitive interference. At the beginning of each trial, participants received a colour cue providing information about the upcoming target frame. In two thirds of the trials, the cue reliably informed the participants that in the upcoming trial the flankers either matched the central target letter or not. Hence, participants could accurately anticipate whether cognitive conflict would arise or not. On neutral trials, the cue provided no useful information. The results showed that microsaccadic rate time-locked to cue onset was reduced on trials in which an upcoming cognitive conflict was expected. These findings provide new insights about top-down modulations of microsaccade dynamics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Microsaccade frequency has recently been shown to be sensitive to high-level cognitive processes such as attention and memory. In the present study we explored the effects of anticipated cognitive conflict. Participants were administered a variant of the flanker task, which is known to elicit cognitive interference. At the beginning of each trial, participants received a colour cue providing information about the upcoming target frame. In two thirds of the trials, the cue reliably informed the participants that in the upcoming trial the flankers either matched the central target letter or not. Hence, participants could accurately anticipate whether cognitive conflict would arise or not. On neutral trials, the cue provided no useful information. The results showed that microsaccadic rate time-locked to cue onset was reduced on trials in which an upcoming cognitive conflict was expected. These findings provide new insights about top-down modulations of microsaccade dynamics. |
Mario Dalmaso; Luigi Castelli; Giovanni Galfano Microsaccadic rate and pupil size dynamics in pro-/anti-saccade preparation: The impact of intermixed vs. blocked trial administration Journal Article Psychological Research, pp. 1–13, 2019. @article{Dalmaso2019a, title = {Microsaccadic rate and pupil size dynamics in pro-/anti-saccade preparation: The impact of intermixed vs. blocked trial administration}, author = {Mario Dalmaso and Luigi Castelli and Giovanni Galfano}, doi = {10.1007/s00426-018-01141-7}, year = {2019}, date = {2019-01-01}, journal = {Psychological Research}, pages = {1--13}, publisher = {Springer Berlin Heidelberg}, abstract = {Prolonged fixation can lead to the generation of tiny and fast eye movements called microsaccades, whose dynamics can be associated with higher cognitive mechanisms. Saccade preparation is also reflected in microsaccadic activity, but the few studies on this topic provided mixed results. For instance, fewer microsaccades have been observed when participants were asked to prepare for an anti-saccade (i.e., a saccade in the opposite direction to the target) as compared to a pro-saccade (i.e., a saccade executed towards a target), but null results have also been reported. In the attempt to shed new light on this topic, two experiments were carried out in which the context of presentation of pro- and anti-saccade trials was manipulated. Pupil size was also recorded, as a further index of cognitive load. In Experiment 1, participants were asked to prepare and perform pro- and anti-saccades in response to a peripheral target, according to a central instruction cue provided at the beginning of each trial (intermixed condition). In Experiment 2, the same task was employed, but pro- and anti-saccade trials were delivered in two distinct blocks (blocked condition). In both experiments, greater saccadic latencies and lower accuracy emerged for anti- than for pro-saccades. However, in the intermixed condition, a lower microsaccadic rate and a greater pupil size emerged when participants prepared for anti- rather than pro-saccades, whereas these differences disappeared in the blocked condition. These results suggest that contextual factors may play a key role in shaping oculomotor dynamics linked to saccade preparation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Prolonged fixation can lead to the generation of tiny and fast eye movements called microsaccades, whose dynamics can be associated with higher cognitive mechanisms. Saccade preparation is also reflected in microsaccadic activity, but the few studies on this topic provided mixed results. For instance, fewer microsaccades have been observed when participants were asked to prepare for an anti-saccade (i.e., a saccade in the opposite direction to the target) as compared to a pro-saccade (i.e., a saccade executed towards a target), but null results have also been reported. In the attempt to shed new light on this topic, two experiments were carried out in which the context of presentation of pro- and anti-saccade trials was manipulated. Pupil size was also recorded, as a further index of cognitive load. In Experiment 1, participants were asked to prepare and perform pro- and anti-saccades in response to a peripheral target, according to a central instruction cue provided at the beginning of each trial (intermixed condition). In Experiment 2, the same task was employed, but pro- and anti-saccade trials were delivered in two distinct blocks (blocked condition). In both experiments, greater saccadic latencies and lower accuracy emerged for anti- than for pro-saccades. However, in the intermixed condition, a lower microsaccadic rate and a greater pupil size emerged when participants prepared for anti- rather than pro-saccades, whereas these differences disappeared in the blocked condition. These results suggest that contextual factors may play a key role in shaping oculomotor dynamics linked to saccade preparation. |
Mario Dalmaso; Luigi Castelli; Giovanni Galfano Self-related shapes can hold the eyes Journal Article Quarterly Journal of Experimental Psychology, 72 (9), pp. 2249–2260, 2019. @article{Dalmaso2019b, title = {Self-related shapes can hold the eyes}, author = {Mario Dalmaso and Luigi Castelli and Giovanni Galfano}, doi = {10.1177/1747021819839668}, year = {2019}, date = {2019-01-01}, journal = {Quarterly Journal of Experimental Psychology}, volume = {72}, number = {9}, pages = {2249--2260}, abstract = {Increasing evidence suggests that individuals are highly sensitive to self-related stimuli. Here, we report two experiments conducted to assess whether two schematic stimuli, arbitrarily associated with either the self or a stranger, can shape attention holding in an oculomotor task. In both experiments, participants first completed a manual matching task in which they were asked to associate the self and a stranger with two shapes (triangle vs. square). Then, in an oculomotor task, they were asked to perform a saccade from the centre of the screen towards a peripheral target while either the triangle or the square were centrally presented. In Experiment 1, saccades had to be performed on each trial-irrespective of the central shape-while in Experiment 2, saccades had to be performed only when the central shape was associated with either the self or the stranger, depending on block instruction. Participants were slower to initiate a saccade away from the central shape when this was associated with the self rather than with the stranger, but this pattern of results emerged only in Experiment 2. Overall, these data suggest that stimuli associated with the self through episodic learning can hold attention when the self/other distinction is a task-relevant dimension.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Increasing evidence suggests that individuals are highly sensitive to self-related stimuli. Here, we report two experiments conducted to assess whether two schematic stimuli, arbitrarily associated with either the self or a stranger, can shape attention holding in an oculomotor task. In both experiments, participants first completed a manual matching task in which they were asked to associate the self and a stranger with two shapes (triangle vs. square). Then, in an oculomotor task, they were asked to perform a saccade from the centre of the screen towards a peripheral target while either the triangle or the square were centrally presented. In Experiment 1, saccades had to be performed on each trial-irrespective of the central shape-while in Experiment 2, saccades had to be performed only when the central shape was associated with either the self or the stranger, depending on block instruction. Participants were slower to initiate a saccade away from the central shape when this was associated with the self rather than with the stranger, but this pattern of results emerged only in Experiment 2. Overall, these data suggest that stimuli associated with the self through episodic learning can hold attention when the self/other distinction is a task-relevant dimension. |
Souto David; Jayesha Chudasama; Dirk Kerzel; Alan Johnston Motion integration is anisotropic during smooth pursuit eye movements Journal Article Journal of Neurophysiology, 121 , pp. 1787–1797, 2019. @article{David2019, title = {Motion integration is anisotropic during smooth pursuit eye movements}, author = {Souto David and Jayesha Chudasama and Dirk Kerzel and Alan Johnston}, doi = {10.1152/jn.00591.2018.-Smooth}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {121}, pages = {1787--1797}, abstract = {Smooth pursuit eye movements (pursuit) are used to minimize the retinal motion of moving objects. During pursuit, the pattern of motion on the retina carries not only information about the object movement but also reafferent information about the eye movement itself. The latter arises from the retinal flow of the stationary world in the direction opposite to the eye movement. To extract the global direction of motion of the tracked object and stationary world, the visual system needs to integrate ambiguous local motion measurements (i.e., the aperture problem). Unlike the tracked object, the stationary world's global motion is entirely determined by the eye movement and thus can be approximately derived from motor commands sent to the eye (i.e., from an efference copy). Because retinal motion opposite to the eye movement is dominant during pursuit, different motion integration mechanisms might be used for retinal motion in the same direction and opposite to pursuit. To investigate motion integration during pursuit, we tested direction discrimination of a brief change in global object motion. The global motion stimulus was a circular array of small static apertures within which one-dimensional gratings moved. We found increased coherence thresholds and a qualitatively different reflexive ocular tracking for global motion opposite to pursuit. Both effects suggest reduced sampling of motion opposite to pursuit, which results in an impaired ability to extract coherence in motion signals in the reafferent direction. We suggest that anisotropic motion integration is an adaptation to asymmetric retinal motion patterns experienced during pursuit eye movements.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Smooth pursuit eye movements (pursuit) are used to minimize the retinal motion of moving objects. During pursuit, the pattern of motion on the retina carries not only information about the object movement but also reafferent information about the eye movement itself. The latter arises from the retinal flow of the stationary world in the direction opposite to the eye movement. To extract the global direction of motion of the tracked object and stationary world, the visual system needs to integrate ambiguous local motion measurements (i.e., the aperture problem). Unlike the tracked object, the stationary world's global motion is entirely determined by the eye movement and thus can be approximately derived from motor commands sent to the eye (i.e., from an efference copy). Because retinal motion opposite to the eye movement is dominant during pursuit, different motion integration mechanisms might be used for retinal motion in the same direction and opposite to pursuit. To investigate motion integration during pursuit, we tested direction discrimination of a brief change in global object motion. The global motion stimulus was a circular array of small static apertures within which one-dimensional gratings moved. We found increased coherence thresholds and a qualitatively different reflexive ocular tracking for global motion opposite to pursuit. Both effects suggest reduced sampling of motion opposite to pursuit, which results in an impaired ability to extract coherence in motion signals in the reafferent direction. We suggest that anisotropic motion integration is an adaptation to asymmetric retinal motion patterns experienced during pursuit eye movements. |
Rachel N Denison; Shlomit Yuval-greenberg; Marisa Carrasco Directing voluntary temporal attention increases fixational stability Journal Article The Journal of Neuroscience, 39 (2), pp. 353–363, 2019. @article{Denison2019, title = {Directing voluntary temporal attention increases fixational stability}, author = {Rachel N Denison and Shlomit Yuval-greenberg and Marisa Carrasco}, year = {2019}, date = {2019-01-01}, journal = {The Journal of Neuroscience}, volume = {39}, number = {2}, pages = {353--363}, abstract = {Our visual input is constantly changing, but not all moments are equally relevant. Visual temporal attention, the prioritization of visual information at specific points in time, increases perceptual sensitivity at behaviorally relevant times. The dynamic processes underlying this increase are unclear. During fixation, humans make small eye movements called microsaccades, and inhibiting microsaccades improves perception o fbrief stimuli. Here, we investigated whether temporal attention changes the pattern ofmicrosaccades in antici- pation of brief stimuli. Human observers (female and male) judged stimuli presented within a short sequence. Observers were given either aninformative precue to attend to one of the stimuli, which was likely to be probed, or an uninformative (neutral) precue. We found strong microsaccadic inhibition before the stimulus sequence, likely due to its predictable onset. Critically, this anticipatory inhibition was stronger when the first target in the sequence (T1) was precued (task-relevant) than when the precue was uninformative. Moreover, the timing of the last microsaccade before T1 and the first microsaccade after T1 shifted such that both occurred earlier when T1 was precued than when the precue was uninformative. Finally, the timing of the nearest pre- and post-T1 microsaccades affected task performance. Directing voluntary temporal attention therefore affects microsaccades, helping to stabilize fixation at the most relevant moments over and above the effect ofpredictability. Just as saccading to a relevant stimulus can be an overt correlate ofthe allocation of spatial attention, precisely timed gaze stabilization can be an overt correlate ofthe allocation oftemporal attention.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Our visual input is constantly changing, but not all moments are equally relevant. Visual temporal attention, the prioritization of visual information at specific points in time, increases perceptual sensitivity at behaviorally relevant times. The dynamic processes underlying this increase are unclear. During fixation, humans make small eye movements called microsaccades, and inhibiting microsaccades improves perception o fbrief stimuli. Here, we investigated whether temporal attention changes the pattern ofmicrosaccades in antici- pation of brief stimuli. Human observers (female and male) judged stimuli presented within a short sequence. Observers were given either aninformative precue to attend to one of the stimuli, which was likely to be probed, or an uninformative (neutral) precue. We found strong microsaccadic inhibition before the stimulus sequence, likely due to its predictable onset. Critically, this anticipatory inhibition was stronger when the first target in the sequence (T1) was precued (task-relevant) than when the precue was uninformative. Moreover, the timing of the last microsaccade before T1 and the first microsaccade after T1 shifted such that both occurred earlier when T1 was precued than when the precue was uninformative. Finally, the timing of the nearest pre- and post-T1 microsaccades affected task performance. Directing voluntary temporal attention therefore affects microsaccades, helping to stabilize fixation at the most relevant moments over and above the effect ofpredictability. Just as saccading to a relevant stimulus can be an overt correlate ofthe allocation of spatial attention, precisely timed gaze stabilization can be an overt correlate ofthe allocation oftemporal attention. |
Valeria Di Caro; Jan Theeuwes; Chiara Della Libera Suppression history of distractor location biases attentional and oculomotor control Journal Article Visual Cognition, 27 (2), pp. 142–157, 2019. @article{DiCaro2019, title = {Suppression history of distractor location biases attentional and oculomotor control}, author = {Valeria {Di Caro} and Jan Theeuwes and Chiara {Della Libera}}, doi = {10.1080/13506285.2019.1617376}, year = {2019}, date = {2019-01-01}, journal = {Visual Cognition}, volume = {27}, number = {2}, pages = {142--157}, publisher = {Taylor & Francis}, abstract = {Past selection experience greatly affects the deployment of attention such that targets are more readily selected if their features or locations were more frequently selected in the past. Crucially, recent studies have shown similar experience-dependent effects also for salient task irrelevant stimuli: distractors exerted less interference if they appeared at a location where they were presented more often, relatively to other possible locations. Here we investigated the effects of such suppression history on the immediate behavioural correlates of attentional deployment, i.e., eye movements. Participants were to make saccadic eye movements to a target stimulus, while ignoring a highly distracting irrelevant visual onset appearing abruptly on the screen in a proportion of trials. Crucially, this irrelevant onset occurred more frequently in two locations on the visual display and our results showed that, relatively to distractors elsewhere, onsets presented at these locations became easier to ignore, giving rise to reduced oculomotor capture. Consistent with the notion that experience can alter attentional deployment towards spatial locations, these findings indicate that, through learning, the priority of high frequency locations becomes suppressed, attenuating the intrinsic saliency of distractors appearing therein. Traces left by individual events of attentional suppression decrease the processing priority of coordinates within topographic maps of the visual space.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Past selection experience greatly affects the deployment of attention such that targets are more readily selected if their features or locations were more frequently selected in the past. Crucially, recent studies have shown similar experience-dependent effects also for salient task irrelevant stimuli: distractors exerted less interference if they appeared at a location where they were presented more often, relatively to other possible locations. Here we investigated the effects of such suppression history on the immediate behavioural correlates of attentional deployment, i.e., eye movements. Participants were to make saccadic eye movements to a target stimulus, while ignoring a highly distracting irrelevant visual onset appearing abruptly on the screen in a proportion of trials. Crucially, this irrelevant onset occurred more frequently in two locations on the visual display and our results showed that, relatively to distractors elsewhere, onsets presented at these locations became easier to ignore, giving rise to reduced oculomotor capture. Consistent with the notion that experience can alter attentional deployment towards spatial locations, these findings indicate that, through learning, the priority of high frequency locations becomes suppressed, attenuating the intrinsic saliency of distractors appearing therein. Traces left by individual events of attentional suppression decrease the processing priority of coordinates within topographic maps of the visual space. |
Alexandre Dizeux; Marc Gesnik; Harry Ahnine; Kevin Blaize; Fabrice Arcizet; Serge Picaud; José Alain Sahel; Thomas Deffieux; Pierre Pouget; Mickael Tanter Functional ultrasound imaging of the brain reveals propagation of task-related brain activity in behaving primates Journal Article Nature Communications, 10 , pp. 1–9, 2019. @article{Dizeux2019, title = {Functional ultrasound imaging of the brain reveals propagation of task-related brain activity in behaving primates}, author = {Alexandre Dizeux and Marc Gesnik and Harry Ahnine and Kevin Blaize and Fabrice Arcizet and Serge Picaud and José Alain Sahel and Thomas Deffieux and Pierre Pouget and Mickael Tanter}, doi = {10.1038/s41467-019-09349-w}, year = {2019}, date = {2019-01-01}, journal = {Nature Communications}, volume = {10}, pages = {1--9}, abstract = {Neuroimaging modalities such as MRI and EEG are able to record from the whole brain, but this comes at the price of either limited spatiotemporal resolution or limited sensitivity. Here, we show that functional ultrasound imaging (fUS) of the brain is able to assess local changes in cerebral blood volume during cognitive tasks, with sufficient temporal resolution to measure the directional propagation of signals. In two macaques, we observed an abrupt transient change in supplementary eye field (SEF) activity when animals were required to modify their behaviour associated with a change of saccade tasks. SEF activation could be observed in a single trial, without averaging. Simultaneous imaging of anterior cingulate cortex and SEF revealed a time delay in the directional functional connectivity of 0.27 ± 0.07 s and 0.9 ± 0.2 s for both animals. Cerebral hemodynamics of large brain areas can be measured at high spatiotemporal resolution using fUS.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Neuroimaging modalities such as MRI and EEG are able to record from the whole brain, but this comes at the price of either limited spatiotemporal resolution or limited sensitivity. Here, we show that functional ultrasound imaging (fUS) of the brain is able to assess local changes in cerebral blood volume during cognitive tasks, with sufficient temporal resolution to measure the directional propagation of signals. In two macaques, we observed an abrupt transient change in supplementary eye field (SEF) activity when animals were required to modify their behaviour associated with a change of saccade tasks. SEF activation could be observed in a single trial, without averaging. Simultaneous imaging of anterior cingulate cortex and SEF revealed a time delay in the directional functional connectivity of 0.27 ± 0.07 s and 0.9 ± 0.2 s for both animals. Cerebral hemodynamics of large brain areas can be measured at high spatiotemporal resolution using fUS. |
Andrew Duchowski; Krzysztof Krejtz; Justyna Zurawska; Donald House Using microsaccades to estimate task difficulty during visual search of layered surfaces Journal Article IEEE Transactions on Visualization and Computer Graphics, 14 (8), pp. 1–16, 2019. @article{Duchowski2019, title = {Using microsaccades to estimate task difficulty during visual search of layered surfaces}, author = {Andrew Duchowski and Krzysztof Krejtz and Justyna Zurawska and Donald House}, doi = {10.1109/tvcg.2019.2901881}, year = {2019}, date = {2019-01-01}, journal = {IEEE Transactions on Visualization and Computer Graphics}, volume = {14}, number = {8}, pages = {1--16}, abstract = {We develop an approach to using microsaccade dynamics for the measurement of task difficulty/cognitive load imposed by a visual search task of a layered surface. Previous studies provide converging evidence that task difficulty/cognitive load can influence microsaccade activity. We corroborate this notion. Specifically, we explore this relationship during visual search for features embedded in a terrain-like surface, with the eyes allowed to move freely during the task. We make two relevant contributions. First, we validate an approach to distinguishing between the ambient and focal phases of visual search. We show that this spectrum of visual behavior can be quantified by a single previously reported estimator, known as Krejtz's K coefficient. Second, we use ambient/focal segments based on K as a moderating factor for microsaccade analysis in response to task difficulty. We find that during the focal phase of visual search (a) microsaccade magnitude increases significantly, and (b) microsaccade rate decreases significantly, with increased task difficulty. We conclude that the combined use of K and microsaccade analysis may be helpful in building effective tools that provide an indication of the level of cognitive activity within a task while the task is being performed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We develop an approach to using microsaccade dynamics for the measurement of task difficulty/cognitive load imposed by a visual search task of a layered surface. Previous studies provide converging evidence that task difficulty/cognitive load can influence microsaccade activity. We corroborate this notion. Specifically, we explore this relationship during visual search for features embedded in a terrain-like surface, with the eyes allowed to move freely during the task. We make two relevant contributions. First, we validate an approach to distinguishing between the ambient and focal phases of visual search. We show that this spectrum of visual behavior can be quantified by a single previously reported estimator, known as Krejtz's K coefficient. Second, we use ambient/focal segments based on K as a moderating factor for microsaccade analysis in response to task difficulty. We find that during the focal phase of visual search (a) microsaccade magnitude increases significantly, and (b) microsaccade rate decreases significantly, with increased task difficulty. We conclude that the combined use of K and microsaccade analysis may be helpful in building effective tools that provide an indication of the level of cognitive activity within a task while the task is being performed. |
Reuben K Dyer; Larry A Abel Effects of age and visual attention demands on optokinetic nystagmus suppression Journal Article Experimental Eye Research, 183 , pp. 46–51, 2019. @article{Dyer2019, title = {Effects of age and visual attention demands on optokinetic nystagmus suppression}, author = {Reuben K Dyer and Larry A Abel}, doi = {10.1016/j.exer.2018.08.011}, year = {2019}, date = {2019-01-01}, journal = {Experimental Eye Research}, volume = {183}, pages = {46--51}, publisher = {Elsevier}, abstract = {Introduction: The utility of optokinetic nystagmus suppression as an index of visual attention has been demonstrated; however, a gap exists in our understanding of the effects of aging on attentional division. The purpose of this study was to explore the effect of a subject's age upon their ability to allocate visual attention among multiple salient elements which varied in location and complexity. Method: Large-field optokinetic nystagmus (OKN)-inducing animations were presented along with a central flashing fixation point to 27 subjects: 15 younger adults (range 19–23, mean age 21.4); and 12 older adults (range 65–89, mean age 74). Subjects were instructed to fixate on a central point while attending to either moving features of the background or solely to the fixation target. Failure of subjects to accurately divide their attention was quantified by optokinetic gain (eye velocity/background velocity). Gain was analysed in two separate 3-way ANOVAs: one at the central location with the between-subjects variable of age and within-subjects variables of complexity and dynamism; and one using only the dynamic tasks, including a between-subjects variable of age and within-subjects variables of complexity and location. Results: A strong effect of age was found between subjects during the more attentionally demanding dynamic tasks, but there was only a marginal effect during the static tasks. All within-subjects variables were highly significant, and there were several significant 2- and 3-way interactions. Conclusion: This study provides strong evidence for the compounding effects of senescence and stimulus characteristics on an adult's ability to accurately allocate visual attention. These findings show that OKN suppression may be a useful framework for quantification of attentional resources in older subjects.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Introduction: The utility of optokinetic nystagmus suppression as an index of visual attention has been demonstrated; however, a gap exists in our understanding of the effects of aging on attentional division. The purpose of this study was to explore the effect of a subject's age upon their ability to allocate visual attention among multiple salient elements which varied in location and complexity. Method: Large-field optokinetic nystagmus (OKN)-inducing animations were presented along with a central flashing fixation point to 27 subjects: 15 younger adults (range 19–23, mean age 21.4); and 12 older adults (range 65–89, mean age 74). Subjects were instructed to fixate on a central point while attending to either moving features of the background or solely to the fixation target. Failure of subjects to accurately divide their attention was quantified by optokinetic gain (eye velocity/background velocity). Gain was analysed in two separate 3-way ANOVAs: one at the central location with the between-subjects variable of age and within-subjects variables of complexity and dynamism; and one using only the dynamic tasks, including a between-subjects variable of age and within-subjects variables of complexity and location. Results: A strong effect of age was found between subjects during the more attentionally demanding dynamic tasks, but there was only a marginal effect during the static tasks. All within-subjects variables were highly significant, and there were several significant 2- and 3-way interactions. Conclusion: This study provides strong evidence for the compounding effects of senescence and stimulus characteristics on an adult's ability to accurately allocate visual attention. These findings show that OKN suppression may be a useful framework for quantification of attentional resources in older subjects. |
Nico A Flierman; Alla Ignashchenkova; Mario Negrello; Peter Thier; Chris I De Zeeuw; Aleksandra Badura Glissades are altered by lesions to the oculomotor vermis but not by saccadic adaptation Journal Article Frontiers in Behavioral Neuroscience, 13 , pp. 1–17, 2019. @article{Flierman2019, title = {Glissades are altered by lesions to the oculomotor vermis but not by saccadic adaptation}, author = {Nico A Flierman and Alla Ignashchenkova and Mario Negrello and Peter Thier and Chris I {De Zeeuw} and Aleksandra Badura}, doi = {10.3389/fnbeh.2019.00194}, year = {2019}, date = {2019-01-01}, journal = {Frontiers in Behavioral Neuroscience}, volume = {13}, pages = {1--17}, abstract = {Saccadic eye movements enable fast and precise scanning of the visual field, which is partially controlled by the posterior cerebellar vermis. Textbook saccades have a straight trajectory and a unimodal velocity profile, and hence have well-defined epochs of start and end. However, in practice only a fraction of saccades matches this description. One way in which a saccade can deviate from its trajectory is the presence of an overshoot or undershoot at the end of a saccadic eye movement just before fixation. This additional movement, known as a glissade, is regarded as a motor command error and was characterized decades ago but was almost never studied. Using rhesus macaques, we investigated the properties of glissades and changes to glissade kinematics following cerebellar lesions. Additionally, in monkeys with an intact cerebellum, we investigated whether the glissade amplitude can be modulated using multiple adaptation paradigms. Our results show that saccade kinematics are altered by the presence of a glissade, and that glissades do not appear to have any adaptive function as they do not bring the eye closer to the target. Quantification of these results establishes a detailed description of glissades. Further, we show that lesions to the posterior cerebellum have a deleterious effect on both saccade and glissade properties, which recovers over time. Finally, the saccadic adaptation experiments reveal that glissades cannot be modulated by this training paradigm. Together our work offers a functional study of glissades and provides new insight into the cerebellar involvement in this type of motor error.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccadic eye movements enable fast and precise scanning of the visual field, which is partially controlled by the posterior cerebellar vermis. Textbook saccades have a straight trajectory and a unimodal velocity profile, and hence have well-defined epochs of start and end. However, in practice only a fraction of saccades matches this description. One way in which a saccade can deviate from its trajectory is the presence of an overshoot or undershoot at the end of a saccadic eye movement just before fixation. This additional movement, known as a glissade, is regarded as a motor command error and was characterized decades ago but was almost never studied. Using rhesus macaques, we investigated the properties of glissades and changes to glissade kinematics following cerebellar lesions. Additionally, in monkeys with an intact cerebellum, we investigated whether the glissade amplitude can be modulated using multiple adaptation paradigms. Our results show that saccade kinematics are altered by the presence of a glissade, and that glissades do not appear to have any adaptive function as they do not bring the eye closer to the target. Quantification of these results establishes a detailed description of glissades. Further, we show that lesions to the posterior cerebellum have a deleterious effect on both saccade and glissade properties, which recovers over time. Finally, the saccadic adaptation experiments reveal that glissades cannot be modulated by this training paradigm. Together our work offers a functional study of glissades and provides new insight into the cerebellar involvement in this type of motor error. |
Maryam Ghahremani; Kevin D Johnston; Liya Ma; Lauren K Hayrynen; Stefan Everling Electrical microstimulation evokes saccades in posterior parietal cortex of common marmosets Journal Article Journal of Neurophysiology, 122 (4), pp. 1765–1776, 2019. @article{Ghahremani2019, title = {Electrical microstimulation evokes saccades in posterior parietal cortex of common marmosets}, author = {Maryam Ghahremani and Kevin D Johnston and Liya Ma and Lauren K Hayrynen and Stefan Everling}, doi = {10.1152/jn.00417.2019}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {122}, number = {4}, pages = {1765--1776}, abstract = {The common marmoset (Callithrix jacchus) is a small-bodied New World primate increasing in prominence as a model animal for neuroscience research. The lissencephalic cortex of this primate species provides substantial advantages for the application of electrophysiological techniques such as high-density and laminar recordings, which have the capacity to advance our understanding of local and laminar cortical circuits and their roles in cognitive and motor functions. This is particularly the case with respect to the oculomotor system, as critical cortical areas of this network such as the frontal eye fields (FEF) and lateral intraparietal area (LIP) lie deep within sulci in macaques. Studies of cytoarchitecture and connectivity have established putative homologies between cortical oculomotor fields in marmoset and macaque, but physiological investigations of these areas, particularly in awake marmosets, have yet to be carried out. Here we addressed this gap by probing the function of posterior parietal cortex of the common marmoset with electrical microstimulation. We implanted two animals with 32-channel Utah arrays at the location of the putative area LIP and applied microstimulation while they viewed a video display and made untrained eye movements. Similar to previous studies in macaques, stimulation evoked fixed-vector and goal-directed saccades, staircase saccades, and eyeblinks. These data demonstrate that area LIP of the marmoset plays a role in the regulation of eye movements, provide additional evidence that this area is homologous with that of the macaque, and further establish the marmoset as a valuable model for neurophysiological investigations of oculomotor and cognitive control.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The common marmoset (Callithrix jacchus) is a small-bodied New World primate increasing in prominence as a model animal for neuroscience research. The lissencephalic cortex of this primate species provides substantial advantages for the application of electrophysiological techniques such as high-density and laminar recordings, which have the capacity to advance our understanding of local and laminar cortical circuits and their roles in cognitive and motor functions. This is particularly the case with respect to the oculomotor system, as critical cortical areas of this network such as the frontal eye fields (FEF) and lateral intraparietal area (LIP) lie deep within sulci in macaques. Studies of cytoarchitecture and connectivity have established putative homologies between cortical oculomotor fields in marmoset and macaque, but physiological investigations of these areas, particularly in awake marmosets, have yet to be carried out. Here we addressed this gap by probing the function of posterior parietal cortex of the common marmoset with electrical microstimulation. We implanted two animals with 32-channel Utah arrays at the location of the putative area LIP and applied microstimulation while they viewed a video display and made untrained eye movements. Similar to previous studies in macaques, stimulation evoked fixed-vector and goal-directed saccades, staircase saccades, and eyeblinks. These data demonstrate that area LIP of the marmoset plays a role in the regulation of eye movements, provide additional evidence that this area is homologous with that of the macaque, and further establish the marmoset as a valuable model for neurophysiological investigations of oculomotor and cognitive control. |
Agostino Gibaldi; Martin S Banks Binocular eye movements are adapted to the natural environment Journal Article The Journal of Neuroscience, 39 (15), pp. 2877–2888, 2019. @article{Gibaldi2019a, title = {Binocular eye movements are adapted to the natural environment}, author = {Agostino Gibaldi and Martin S Banks}, doi = {10.1523/JNEUROSCI.2591-18.2018}, year = {2019}, date = {2019-01-01}, journal = {The Journal of Neuroscience}, volume = {39}, number = {15}, pages = {2877--2888}, abstract = {Humans and many animals make frequent saccades requiring coordinated movements of the eyes. When landing on the new fixation point, the eyes must converge accurately or double images will be perceived. We asked whether the visual system uses statistical regularities in the natural environment to aid eye alignment at the end of saccades. We measured the distribution of naturally occurring disparities in different parts of the visual field. The central tendency of the distributions was crossed (nearer than fixation) in the lower field and uncrossed (farther) in the upper field in male and female participants. It was uncrossed in the left and right fields. We also measured horizontal vergence after completion of vertical, horizontal, and oblique saccades.Whenthe eyes first landed near the eccentric target, vergence was quite consistent with the natural-disparity distribution. For example, when making an upward saccade, the eyes diverged to be aligned with the most probable uncrossed disparity in that part of the visual field. Likewise, when making a downward saccade, the eyes converged to enable alignment with crossed disparity in that part of the field. Our results show that rapid binocular eye movements are adapted to the statistics of the 3D environment, minimizing the need for large corrective vergence movements at the end of saccades. The results are relevant to the debate about whether eye movements are derived from separate saccadic and vergence neural commands that control both eyes or from separate monocular commands that control the eyes independently.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Humans and many animals make frequent saccades requiring coordinated movements of the eyes. When landing on the new fixation point, the eyes must converge accurately or double images will be perceived. We asked whether the visual system uses statistical regularities in the natural environment to aid eye alignment at the end of saccades. We measured the distribution of naturally occurring disparities in different parts of the visual field. The central tendency of the distributions was crossed (nearer than fixation) in the lower field and uncrossed (farther) in the upper field in male and female participants. It was uncrossed in the left and right fields. We also measured horizontal vergence after completion of vertical, horizontal, and oblique saccades.Whenthe eyes first landed near the eccentric target, vergence was quite consistent with the natural-disparity distribution. For example, when making an upward saccade, the eyes diverged to be aligned with the most probable uncrossed disparity in that part of the visual field. Likewise, when making a downward saccade, the eyes converged to enable alignment with crossed disparity in that part of the field. Our results show that rapid binocular eye movements are adapted to the statistics of the 3D environment, minimizing the need for large corrective vergence movements at the end of saccades. The results are relevant to the debate about whether eye movements are derived from separate saccadic and vergence neural commands that control both eyes or from separate monocular commands that control the eyes independently. |
Martin Giesel; Alexandra Yakovleva; Marina Bloj; Alex R Wade; Anthony M Norcia; Julie M Harris Relative contributions to vergence eye movements of two binocular cues for motion-in-depth Journal Article Scientific Reports, 9 , pp. 1–14, 2019. @article{Giesel2019, title = {Relative contributions to vergence eye movements of two binocular cues for motion-in-depth}, author = {Martin Giesel and Alexandra Yakovleva and Marina Bloj and Alex R Wade and Anthony M Norcia and Julie M Harris}, doi = {10.1038/s41598-019-53902-y}, year = {2019}, date = {2019-01-01}, journal = {Scientific Reports}, volume = {9}, pages = {1--14}, abstract = {When we track an object moving in depth, our eyes rotate in opposite directions. This type of “disjunctive” eye movement is called horizontal vergence. The sensory control signals for vergence arise from multiple visual cues, two of which, changing binocular disparity (CD) and inter-ocular velocity differences (IOVD), are specifically binocular. While it is well known that the CD cue triggers horizontal vergence eye movements, the role of the IOVD cue has only recently been explored. To better understand the relative contribution of CD and IOVD cues in driving horizontal vergence, we recorded vergence eye movements from ten observers in response to four types of stimuli that isolated or combined the two cues to motion-in-depth, using stimulus conditions and CD/IOVD stimuli typical of behavioural motion-in-depth experiments. An analysis of the slopes of the vergence traces and the consistency of the directions of vergence and stimulus movements showed that under our conditions IOVD cues provided very little input to vergence mechanisms. The eye movements that did occur coinciding with the presentation of IOVD stimuli were likely not a response to stimulus motion, but a phoria initiated by the absence of a disparity signal.}, keywords = {}, pubstate = {published}, tppubtype = {article} } When we track an object moving in depth, our eyes rotate in opposite directions. This type of “disjunctive” eye movement is called horizontal vergence. The sensory control signals for vergence arise from multiple visual cues, two of which, changing binocular disparity (CD) and inter-ocular velocity differences (IOVD), are specifically binocular. While it is well known that the CD cue triggers horizontal vergence eye movements, the role of the IOVD cue has only recently been explored. To better understand the relative contribution of CD and IOVD cues in driving horizontal vergence, we recorded vergence eye movements from ten observers in response to four types of stimuli that isolated or combined the two cues to motion-in-depth, using stimulus conditions and CD/IOVD stimuli typical of behavioural motion-in-depth experiments. An analysis of the slopes of the vergence traces and the consistency of the directions of vergence and stimulus movements showed that under our conditions IOVD cues provided very little input to vergence mechanisms. The eye movements that did occur coinciding with the presentation of IOVD stimuli were likely not a response to stimulus motion, but a phoria initiated by the absence of a disparity signal. |
Lisa C Goelz; Maya Cottongim; Leonard Verhagen Metman; Daniel M Corcos; Fabian J David Experimental Brain Research, 237 (11), pp. 2841–2851, 2019. @article{Goelz2019, title = {Bilateral subthalamic nucleus deep brain stimulation increases fixational saccades during movement preparation: Evidence for impaired preparatory set}, author = {Lisa C Goelz and Maya Cottongim and Leonard Verhagen Metman and Daniel M Corcos and Fabian J David}, doi = {10.1007/s00221-019-05636-6}, year = {2019}, date = {2019-01-01}, journal = {Experimental Brain Research}, volume = {237}, number = {11}, pages = {2841--2851}, publisher = {Springer Berlin Heidelberg}, abstract = {People with Parkinson's disease (PD) exhibit an increase in fixational saccades during the preparatory period prior to target onset in the antisaccade task and this increase is related to an increase in prosaccade errors in the antisaccade task. It was previously shown that bilateral, but not unilateral, subthalamic nucleus deep brain stimulation (STN DBS) in people with PD further increases the prosaccade error rate on the antisaccade task. We investigated whether bilateral STN DBS also increases the number of fixational saccades in the preparatory period of the antisaccade task and if this increase in the number of fixational saccades is related to prosaccade errors. We found that: (1) there were a greater number of fixational saccades during the preparatory period of the antisaccade task during bilateral STN DBS compared to no STN DBS (p textless 0.001), unilateral STN DBS (p textless 0.001), and healthy controls (p = 0.02), and (2) the increase in the number of fixational saccades increased the probability of a prosaccade error for the antisaccade task during bilateral STN DBS (p = 0.005). This association between number of fixational saccades and probability of a prosaccade error was similar across no STN DBS, unilateral stimulation, and healthy controls. In addition, we found that the proportion of express prosaccade errors and prosaccade error latency were similar across stimulation conditions. We propose that bilateral STN DBS disrupts the integrated activity of cortico-basal ganglia-collicular processes underlying antisaccade preparation and that this disruption manifests as an increase in both fixational saccades and prosaccade error rate.}, keywords = {}, pubstate = {published}, tppubtype = {article} } People with Parkinson's disease (PD) exhibit an increase in fixational saccades during the preparatory period prior to target onset in the antisaccade task and this increase is related to an increase in prosaccade errors in the antisaccade task. It was previously shown that bilateral, but not unilateral, subthalamic nucleus deep brain stimulation (STN DBS) in people with PD further increases the prosaccade error rate on the antisaccade task. We investigated whether bilateral STN DBS also increases the number of fixational saccades in the preparatory period of the antisaccade task and if this increase in the number of fixational saccades is related to prosaccade errors. We found that: (1) there were a greater number of fixational saccades during the preparatory period of the antisaccade task during bilateral STN DBS compared to no STN DBS (p textless 0.001), unilateral STN DBS (p textless 0.001), and healthy controls (p = 0.02), and (2) the increase in the number of fixational saccades increased the probability of a prosaccade error for the antisaccade task during bilateral STN DBS (p = 0.005). This association between number of fixational saccades and probability of a prosaccade error was similar across no STN DBS, unilateral stimulation, and healthy controls. In addition, we found that the proportion of express prosaccade errors and prosaccade error latency were similar across stimulation conditions. We propose that bilateral STN DBS disrupts the integrated activity of cortico-basal ganglia-collicular processes underlying antisaccade preparation and that this disruption manifests as an increase in both fixational saccades and prosaccade error rate. |
Alexander Goettker; Eli Brenner; Karl R Gegenfurtner; Cristina de la Malla Corrective saccades influence velocity judgments and interception Journal Article Scientific Reports, 9 , pp. 1–12, 2019. @article{Goettker2019b, title = {Corrective saccades influence velocity judgments and interception}, author = {Alexander Goettker and Eli Brenner and Karl R Gegenfurtner and Cristina de la Malla}, doi = {10.1038/s41598-019-41857-z}, year = {2019}, date = {2019-01-01}, journal = {Scientific Reports}, volume = {9}, pages = {1--12}, publisher = {Nature Publishing Group}, abstract = {In daily life we often interact with moving objects in tasks that involve analyzing visual motion, like catching a ball. To do so successfully we track objects with our gaze, using a combination of smooth pursuit and saccades. Previous work has shown that the occurrence and direction of corrective saccades leads to changes in the perceived velocity of moving objects. Here we investigate whether such changes lead to equivalent biases in interception. Participants had to track moving targets with their gaze, and in separate sessions either judge the targets' velocities or intercept them by tapping on them. We separated trials in which target movements were tracked with pure pursuit from trials in which identical target movements were tracked with a combination of pursuit and corrective saccades. Our results show that interception errors are shifted in accordance with the observed influence of corrective saccades on velocity judgments. Furthermore, while the time at which corrective saccades occurred did not affect velocity judgments, it did influence their effect in the interception task. Corrective saccades around 100 ms before the tap had a stronger effect on the endpoint error than earlier saccades. This might explain why participants made earlier corrective saccades in the interception task.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In daily life we often interact with moving objects in tasks that involve analyzing visual motion, like catching a ball. To do so successfully we track objects with our gaze, using a combination of smooth pursuit and saccades. Previous work has shown that the occurrence and direction of corrective saccades leads to changes in the perceived velocity of moving objects. Here we investigate whether such changes lead to equivalent biases in interception. Participants had to track moving targets with their gaze, and in separate sessions either judge the targets' velocities or intercept them by tapping on them. We separated trials in which target movements were tracked with pure pursuit from trials in which identical target movements were tracked with a combination of pursuit and corrective saccades. Our results show that interception errors are shifted in accordance with the observed influence of corrective saccades on velocity judgments. Furthermore, while the time at which corrective saccades occurred did not affect velocity judgments, it did influence their effect in the interception task. Corrective saccades around 100 ms before the tap had a stronger effect on the endpoint error than earlier saccades. This might explain why participants made earlier corrective saccades in the interception task. |
Esther G González; Henry Liu; Luminita Tarita-Nistor; Efrem Mandelcorn; Mark Mandelcorn Smooth pursuit of amodally completed images Journal Article Experimental Eye Research, 183 , pp. 3–8, 2019. @article{Gonzalez2019, title = {Smooth pursuit of amodally completed images}, author = {Esther G González and Henry Liu and Luminita Tarita-Nistor and Efrem Mandelcorn and Mark Mandelcorn}, doi = {10.1016/j.exer.2018.07.015}, year = {2019}, date = {2019-01-01}, journal = {Experimental Eye Research}, volume = {183}, pages = {3--8}, publisher = {Elsevier}, abstract = {In order to evaluate the effect of the parafoveal area of the retina on smooth pursuit, we compared the horizontal smooth pursuit of visible and amodally completed stimuli in people with central vision loss and controls. In the amodally completed stimuli, a black mask covered the bottom vertex of a moving diamond which is the feature whose movement participants had to track. Both the visible and the amodally completed stimuli moved along regular and irregular sinusoidal motion paths. Our results show that people with central vision loss are able to track a perceptually completed moving stimulus albeit with lower gain, larger tracking errors, and more saccadic eye movements than people with normal vision. Just as the controls, however, people with central vision do better in the no mask condition showing that visual feedback from eccentric vision can improve performance.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In order to evaluate the effect of the parafoveal area of the retina on smooth pursuit, we compared the horizontal smooth pursuit of visible and amodally completed stimuli in people with central vision loss and controls. In the amodally completed stimuli, a black mask covered the bottom vertex of a moving diamond which is the feature whose movement participants had to track. Both the visible and the amodally completed stimuli moved along regular and irregular sinusoidal motion paths. Our results show that people with central vision loss are able to track a perceptually completed moving stimulus albeit with lower gain, larger tracking errors, and more saccadic eye movements than people with normal vision. Just as the controls, however, people with central vision do better in the no mask condition showing that visual feedback from eccentric vision can improve performance. |
Svenja Gremmler; Markus Lappe Postsaccadic eye position contributes to oculomotor error estimation in saccadic adaptation Journal Article Journal of Neurophysiology, 122 (5), pp. 1909–1917, 2019. @article{Gremmler2019, title = {Postsaccadic eye position contributes to oculomotor error estimation in saccadic adaptation}, author = {Svenja Gremmler and Markus Lappe}, doi = {10.1152/jn.00095.2019}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {122}, number = {5}, pages = {1909--1917}, abstract = {We investigated whether the proprioceptive eye position signal after the execution of a saccadic eye movement is used to estimate the accuracy of the movement. If so, saccadic adaptation, the mechanism that maintains saccade accuracy, could use this signal in a similar way as it uses visual feedback after the saccade. To manipulate the availability of the proprioceptive eye position signal we utilized the finding that proprioceptive eye position information builds up gradually after a saccade over a time interval comparable to typical saccade latencies. We confined the retention time of gaze at the saccade landing point by asking participants to make fast return saccades to the fixation point that preempt the usability of proprioceptive eye position signals. In five experimental conditions we measured the influence of the visual and proprioceptive feedback, together and separately, on the development of adaptation. We found that the adaptation of the previously shortened saccades in the case of visual feedback being unavailable after the saccade was significantly weaker when the use of proprioceptive eye position information was impaired by fast return saccades. We conclude that adaptation can be driven by proprioceptive eye position feedback.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated whether the proprioceptive eye position signal after the execution of a saccadic eye movement is used to estimate the accuracy of the movement. If so, saccadic adaptation, the mechanism that maintains saccade accuracy, could use this signal in a similar way as it uses visual feedback after the saccade. To manipulate the availability of the proprioceptive eye position signal we utilized the finding that proprioceptive eye position information builds up gradually after a saccade over a time interval comparable to typical saccade latencies. We confined the retention time of gaze at the saccade landing point by asking participants to make fast return saccades to the fixation point that preempt the usability of proprioceptive eye position signals. In five experimental conditions we measured the influence of the visual and proprioceptive feedback, together and separately, on the development of adaptation. We found that the adaptation of the previously shortened saccades in the case of visual feedback being unavailable after the saccade was significantly weaker when the use of proprioceptive eye position information was impaired by fast return saccades. We conclude that adaptation can be driven by proprioceptive eye position feedback. |
Nina M Hanning; Martin Szinte; Heiner Deubel Visual attention is not limited to the oculomotor range Journal Article Proceedings of the National Academy of Sciences, 116 (19), pp. 9665–9670, 2019. @article{Hanning2019b, title = {Visual attention is not limited to the oculomotor range}, author = {Nina M Hanning and Martin Szinte and Heiner Deubel}, doi = {10.1073/pnas.1813465116}, year = {2019}, date = {2019-01-01}, journal = {Proceedings of the National Academy of Sciences}, volume = {116}, number = {19}, pages = {9665--9670}, abstract = {Both patients with eye movement disorders and healthy participants whose oculomotor range had been experimentally reduced have been reported to show attentional deficits at locations unreachable by their eyes. Whereas previous studies were mainly based on the evaluation of reaction times, we measured visual sensitivity before saccadic eye movements and during fixation at locations either within or beyond participants' oculomotor range. Participants rotated their heads to prevent them from performing large rightward saccades. In this posture, an attentional cue was presented inside or outside their oculomotor range. Participants either made a saccade to the cue or maintained fixation while they discriminated the orientation of a visual noise patch. In contrast to previous reports, we found that the cue attracted visual attention regardless of whether it was presented within or beyond participants' oculomotor range during both fixation and saccade preparation. Moreover, when participants aimed to look to a cue that they could not reach with their eyes, we observed no benefit at their actual saccade endpoint. This demonstrates that spatial attention is not coupled to the executed oculomotor program but instead can be deployed unrestrictedly also toward locations to which no saccade can be executed. Our results are compatible with the view that covert and overt attentional orienting are guided by feedback projections of visual and visuomotor neurons of the gaze control system, irrespective of oculomotor limitations.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Both patients with eye movement disorders and healthy participants whose oculomotor range had been experimentally reduced have been reported to show attentional deficits at locations unreachable by their eyes. Whereas previous studies were mainly based on the evaluation of reaction times, we measured visual sensitivity before saccadic eye movements and during fixation at locations either within or beyond participants' oculomotor range. Participants rotated their heads to prevent them from performing large rightward saccades. In this posture, an attentional cue was presented inside or outside their oculomotor range. Participants either made a saccade to the cue or maintained fixation while they discriminated the orientation of a visual noise patch. In contrast to previous reports, we found that the cue attracted visual attention regardless of whether it was presented within or beyond participants' oculomotor range during both fixation and saccade preparation. Moreover, when participants aimed to look to a cue that they could not reach with their eyes, we observed no benefit at their actual saccade endpoint. This demonstrates that spatial attention is not coupled to the executed oculomotor program but instead can be deployed unrestrictedly also toward locations to which no saccade can be executed. Our results are compatible with the view that covert and overt attentional orienting are guided by feedback projections of visual and visuomotor neurons of the gaze control system, irrespective of oculomotor limitations. |
Jessica Heeman; Stefan Van der Stigchel; Douglas P Munoz; Jan Theeuwes Discriminating between anticipatory and visually triggered saccades: Measuring minimal visual saccadic response time using luminance Journal Article Journal of Neurophysiology, 121 (6), pp. 2101–2111, 2019. @article{Heeman2019, title = {Discriminating between anticipatory and visually triggered saccades: Measuring minimal visual saccadic response time using luminance}, author = {Jessica Heeman and Stefan {Van der Stigchel} and Douglas P Munoz and Jan Theeuwes}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {121}, number = {6}, pages = {2101--2111}, abstract = {We describe a novel behavioral method to accurately discriminate anticipatory (i.e., saccades not generated by visual input) from visually triggered saccades and to identify the minimal visual saccadic reaction time (SRT). This method can be used to calculate a feasible lower bound cutoff for latencies of visually triggered saccades within a certain experimental context or participant group. We apply this method to compute the minimal visual SRT for two different saccade target luminance levels. Three main findings are presented: 1) the minimal visual SRT for all participants was 46 ms shorter for bright targets than for dim targets, 2) the transition from non-visually triggered to visually triggered saccades occurred abruptly, independent of target luminance, and 3) although the absolute minimal visual SRTs varied between participants, the response pattern (response to bright targets being faster than to dim targets) was consistent across participants. These results are consistent with variability in saccadic and neural responses to luminance as has been reported in monkeys. On the basis of these results, we argue that differences in the minimal visual SRT can easily occur when stimuli vary in luminance or other saliency features. Applying an absolute cutoff (i.e., 70–90 ms) that approaches the minimal neuronal conduction delays, which is general practice in many laboratories, may result in the wrongful inclusion of saccades that are not visually triggered. It is suggested to assess the lower SRT bound for visually triggered saccades when piloting an experimental setup and before including saccades based on particular latency criteria.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We describe a novel behavioral method to accurately discriminate anticipatory (i.e., saccades not generated by visual input) from visually triggered saccades and to identify the minimal visual saccadic reaction time (SRT). This method can be used to calculate a feasible lower bound cutoff for latencies of visually triggered saccades within a certain experimental context or participant group. We apply this method to compute the minimal visual SRT for two different saccade target luminance levels. Three main findings are presented: 1) the minimal visual SRT for all participants was 46 ms shorter for bright targets than for dim targets, 2) the transition from non-visually triggered to visually triggered saccades occurred abruptly, independent of target luminance, and 3) although the absolute minimal visual SRTs varied between participants, the response pattern (response to bright targets being faster than to dim targets) was consistent across participants. These results are consistent with variability in saccadic and neural responses to luminance as has been reported in monkeys. On the basis of these results, we argue that differences in the minimal visual SRT can easily occur when stimuli vary in luminance or other saliency features. Applying an absolute cutoff (i.e., 70–90 ms) that approaches the minimal neuronal conduction delays, which is general practice in many laboratories, may result in the wrongful inclusion of saccades that are not visually triggered. It is suggested to assess the lower SRT bound for visually triggered saccades when piloting an experimental setup and before including saccades based on particular latency criteria. |
Frauke Heins; Annegret Meermeier; Markus Lappe Volitional control of saccadic adaptation Journal Article PLoS ONE, 14 (1), pp. 1–20, 2019. @article{Heins2019, title = {Volitional control of saccadic adaptation}, author = {Frauke Heins and Annegret Meermeier and Markus Lappe}, doi = {10.1371/journal.pone.0210020}, year = {2019}, date = {2019-01-01}, journal = {PLoS ONE}, volume = {14}, number = {1}, pages = {1--20}, abstract = {Saccadic adaptation is assumed to be driven by an unconscious and automatic mechanism. We wondered if the adaptation process is accessible to volitional control, specifically whether any change in saccade gain can be inhibited. Participants were exposed to post-saccadic error by using the double-step paradigm in which a target is presented in a peripheral location and then stepped during the saccade to another location. In one condition, participants were instructed to follow the target step and look at the final target location. In the other condition they were instructed to inhibit the adjustment of saccade amplitude and look at the initial target location. We conducted two experiments, which differed in the size of the intra-saccadic target step. We found that when told to inhibit amplitude adjustment, gain change was close to zero for outward steps, but some adaptation remained for inward steps. Saccadic latency was not affected by the instruction type for inward steps, but when the target was stepped outward, latencies were longer in the inhibition than in the adaptation condition. The results show that volitional control can be exerted on saccadic adaptation. We suggest that volitional control affects the remapping of the target, thus having a larger impact on outward adaptation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccadic adaptation is assumed to be driven by an unconscious and automatic mechanism. We wondered if the adaptation process is accessible to volitional control, specifically whether any change in saccade gain can be inhibited. Participants were exposed to post-saccadic error by using the double-step paradigm in which a target is presented in a peripheral location and then stepped during the saccade to another location. In one condition, participants were instructed to follow the target step and look at the final target location. In the other condition they were instructed to inhibit the adjustment of saccade amplitude and look at the initial target location. We conducted two experiments, which differed in the size of the intra-saccadic target step. We found that when told to inhibit amplitude adjustment, gain change was close to zero for outward steps, but some adaptation remained for inward steps. Saccadic latency was not affected by the instruction type for inward steps, but when the target was stepped outward, latencies were longer in the inhibition than in the adaptation condition. The results show that volitional control can be exerted on saccadic adaptation. We suggest that volitional control affects the remapping of the target, thus having a larger impact on outward adaptation. |
Warren R G James; Josephine Reuther; Ellen Angus; Alasdair D F Clarke; Amelia R Hunt Inefficient eye movements: Gamification improves task execution, but not fixation strategy Journal Article Vision, 3 , pp. 1–14, 2019. @article{James2019, title = {Inefficient eye movements: Gamification improves task execution, but not fixation strategy}, author = {Warren R G James and Josephine Reuther and Ellen Angus and Alasdair D F Clarke and Amelia R Hunt}, doi = {10.3390/vision3030048}, year = {2019}, date = {2019-01-01}, journal = {Vision}, volume = {3}, pages = {1--14}, abstract = {Decisions about where to fixate are highly variable and often inefficient. In the current study, we investigated whether such decisions would improve with increased motivation. Participants had to detect a discrimination target, which would appear in one of two boxes, but only after they chose a location to fixate. The distance between boxes determines which location to fixate to maximise the probability of being able to see the target: participants should fixate between the two boxes when they are close together, and on one of the two boxes when they are far apart. We “gamified” this task, giving participants easy-to-track rewards that were contingent on discrimination accuracy. Their decisions and performance were compared to previous results that were gathered in the absence of this additional motivation. We used a Bayesian beta regression model to estimate the size of the effect and associated variance. The results demonstrate that discrimination accuracy does indeed improve in the presence of performance-related rewards. However, there was no difference in eye movement strategy between the two groups, suggesting this improvement in accuracy was not due to the participants making more optimal eye movement decisions. Instead, the motivation encouraged participants to expend more effort on other aspects of the task, such as paying more attention to the boxes and making fewer response errors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Decisions about where to fixate are highly variable and often inefficient. In the current study, we investigated whether such decisions would improve with increased motivation. Participants had to detect a discrimination target, which would appear in one of two boxes, but only after they chose a location to fixate. The distance between boxes determines which location to fixate to maximise the probability of being able to see the target: participants should fixate between the two boxes when they are close together, and on one of the two boxes when they are far apart. We “gamified” this task, giving participants easy-to-track rewards that were contingent on discrimination accuracy. Their decisions and performance were compared to previous results that were gathered in the absence of this additional motivation. We used a Bayesian beta regression model to estimate the size of the effect and associated variance. The results demonstrate that discrimination accuracy does indeed improve in the presence of performance-related rewards. However, there was no difference in eye movement strategy between the two groups, suggesting this improvement in accuracy was not due to the participants making more optimal eye movement decisions. Instead, the motivation encouraged participants to expend more effort on other aspects of the task, such as paying more attention to the boxes and making fewer response errors. |
Andreas Jarvstad; Iain D Gilchrist Cognitive control of saccadic selection and inhibition from within the core cortical saccadic network Journal Article The Journal of Neuroscience, 39 (13), pp. 2497–2508, 2019. @article{Jarvstad2019, title = {Cognitive control of saccadic selection and inhibition from within the core cortical saccadic network}, author = {Andreas Jarvstad and Iain D Gilchrist}, doi = {10.1523/JNEUROSCI.1419-18.2018}, year = {2019}, date = {2019-01-01}, journal = {The Journal of Neuroscience}, volume = {39}, number = {13}, pages = {2497--2508}, abstract = {The ability to select the task-relevant stimulus for a saccadic eye movement, while inhibiting saccades to task-irrelevant stimuli, is crucial for active vision. Here, we present a novel saccade-contingent behavioral paradigm and investigate the neural basis of the central cognitive functions underpinning such behavior, saccade selection, saccade inhibition, and saccadic choice, in female and male human participants. The paradigm allows for exceptionally well-matched contrasts, with task demands formalized with stochastic accumulation-to-threshold models. Using fMRI, we replicated the core cortical eye-movement network for saccade generation (frontal eye fields, posterior parietal cortex, and higher-level visual areas). However, in contrast to previously published tasks, saccadic selection and inhibition recruited only this core network. Brain-behavior analyses further showed that inhibition efficiency may be underpinned by white-matter integrity of tracts between key saccade-generating regions, and that inhibition efficiency is associated with right inferior frontal gyrus engagement, potentially implementing general-purpose inhibition. The core network, however, was insufficient for saccadic choice, which recruited anterior regions commonly attributed to saccadic action selection, including dorsolateral prefrontal cortex and anterior cingulate cortex. Jointly, the results indicate that extra-saccadic activity observed for free choice, and in previously published tasks probing saccadic control, is likely due to increased load on higher-level cognitive processes, and not saccadic selection per se, which is achieved within the canonical cortical eye movement network.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The ability to select the task-relevant stimulus for a saccadic eye movement, while inhibiting saccades to task-irrelevant stimuli, is crucial for active vision. Here, we present a novel saccade-contingent behavioral paradigm and investigate the neural basis of the central cognitive functions underpinning such behavior, saccade selection, saccade inhibition, and saccadic choice, in female and male human participants. The paradigm allows for exceptionally well-matched contrasts, with task demands formalized with stochastic accumulation-to-threshold models. Using fMRI, we replicated the core cortical eye-movement network for saccade generation (frontal eye fields, posterior parietal cortex, and higher-level visual areas). However, in contrast to previously published tasks, saccadic selection and inhibition recruited only this core network. Brain-behavior analyses further showed that inhibition efficiency may be underpinned by white-matter integrity of tracts between key saccade-generating regions, and that inhibition efficiency is associated with right inferior frontal gyrus engagement, potentially implementing general-purpose inhibition. The core network, however, was insufficient for saccadic choice, which recruited anterior regions commonly attributed to saccadic action selection, including dorsolateral prefrontal cortex and anterior cingulate cortex. Jointly, the results indicate that extra-saccadic activity observed for free choice, and in previously published tasks probing saccadic control, is likely due to increased load on higher-level cognitive processes, and not saccadic selection per se, which is achieved within the canonical cortical eye movement network. |
Woojae Jeong; Seolmin Kim; Yee Joon Kim; Joonyeol Lee Motion direction representation in multivariate electroencephalography activity for smooth pursuit eye movements Journal Article NeuroImage, 202 , pp. 1–10, 2019. @article{Jeong2019, title = {Motion direction representation in multivariate electroencephalography activity for smooth pursuit eye movements}, author = {Woojae Jeong and Seolmin Kim and Yee Joon Kim and Joonyeol Lee}, doi = {10.1016/j.neuroimage.2019.116160}, year = {2019}, date = {2019-01-01}, journal = {NeuroImage}, volume = {202}, pages = {1--10}, publisher = {Elsevier Ltd}, abstract = {Visually-guided smooth pursuit eye movements are composed of initial open-loop and later steady-state periods. Feedforward sensory information dominates the motor behavior during the open-loop pursuit, and a more complex feedback loop regulates the steady-state pursuit. To understand the neural representations of motion direction during open-loop and steady-state smooth pursuits, we recorded electroencephalography (EEG) responses from human observers while they tracked random-dot kinematograms as pursuit targets. We estimated population direction tuning curves from multivariate EEG activity using an inverted encoding model. We found significant direction tuning curves as early as about 60 ms from stimulus onset. Direction tuning responses were generalized to later times during the open-loop smooth pursuit, but they became more dynamic during the later steady-state pursuit. The encoding quality of retinal motion direction information estimated from the early direction tuning curves was predictive of trial-by-trial variation in initial pursuit directions. These results suggest that the movement directions of open-loop smooth pursuit are guided by the representation of the retinal motion present in the multivariate EEG activity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Visually-guided smooth pursuit eye movements are composed of initial open-loop and later steady-state periods. Feedforward sensory information dominates the motor behavior during the open-loop pursuit, and a more complex feedback loop regulates the steady-state pursuit. To understand the neural representations of motion direction during open-loop and steady-state smooth pursuits, we recorded electroencephalography (EEG) responses from human observers while they tracked random-dot kinematograms as pursuit targets. We estimated population direction tuning curves from multivariate EEG activity using an inverted encoding model. We found significant direction tuning curves as early as about 60 ms from stimulus onset. Direction tuning responses were generalized to later times during the open-loop smooth pursuit, but they became more dynamic during the later steady-state pursuit. The encoding quality of retinal motion direction information estimated from the early direction tuning curves was predictive of trial-by-trial variation in initial pursuit directions. These results suggest that the movement directions of open-loop smooth pursuit are guided by the representation of the retinal motion present in the multivariate EEG activity. |
Kevin Johnston; Liya Ma; Lauren Schaeffer Alpha oscillations modulate preparatory activity in marmoset area 8Ad Journal Article The Journal of Neuroscience, 39 (10), pp. 855–1866, 2019. @article{Johnston2019, title = {Alpha oscillations modulate preparatory activity in marmoset area 8Ad}, author = {Kevin Johnston and Liya Ma and Lauren Schaeffer}, doi = {10.1523/JNEUROSCI.2703-18.2019}, year = {2019}, date = {2019-01-01}, journal = {The Journal of Neuroscience}, volume = {39}, number = {10}, pages = {855--1866}, abstract = {Cognitive control often requires suppression of prepotent stimulus-driven responses in favor of less potent alternatives. Suppression of prepotent saccades has been shown to require proactive inhibition in the frontoparietal saccade network. Electrophysiological evidence in macaque monkeys has revealed neural correlates of such inhibition in this network; however, the interlaminar instantiation of inhibitory processes remains poorly understood because these areas lie deep within sulci in macaques, rendering them inaccessible to laminar recordings. Here, we addressed this gap by exploiting the mostly lissencephalic cortex of the common marmoset (Callithrix jacchus). We inserted linear electrode arrays into areas 8Ad-the putative marmoset frontal eye field-and the lateral intraparietal area of two male marmosets and recorded neural activity during performance of a task comprised of alternating blocks of trials requiring a saccade either toward a large, high-luminance stimulus or the inhibition of this prepotent response in favor of a saccade toward a small, low-luminance stimulus. We observed prominent task-dependent activity in both alpha/gamma bands of the LFP and discharge rates of single neurons in area 8Ad during a prestimulus task epoch in which the animals had been instructed which of these two tasks to perform but before peripheral stimulus onset. These data are consistent with a model in which rhythmic alpha-band activity in deeper layers inhibits spiking in upper layers to support proactive inhibitory saccade control.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Cognitive control often requires suppression of prepotent stimulus-driven responses in favor of less potent alternatives. Suppression of prepotent saccades has been shown to require proactive inhibition in the frontoparietal saccade network. Electrophysiological evidence in macaque monkeys has revealed neural correlates of such inhibition in this network; however, the interlaminar instantiation of inhibitory processes remains poorly understood because these areas lie deep within sulci in macaques, rendering them inaccessible to laminar recordings. Here, we addressed this gap by exploiting the mostly lissencephalic cortex of the common marmoset (Callithrix jacchus). We inserted linear electrode arrays into areas 8Ad-the putative marmoset frontal eye field-and the lateral intraparietal area of two male marmosets and recorded neural activity during performance of a task comprised of alternating blocks of trials requiring a saccade either toward a large, high-luminance stimulus or the inhibition of this prepotent response in favor of a saccade toward a small, low-luminance stimulus. We observed prominent task-dependent activity in both alpha/gamma bands of the LFP and discharge rates of single neurons in area 8Ad during a prestimulus task epoch in which the animals had been instructed which of these two tasks to perform but before peripheral stimulus onset. These data are consistent with a model in which rhythmic alpha-band activity in deeper layers inhibits spiking in upper layers to support proactive inhibitory saccade control. |
Donatas Jonikaitis; Saurabh Dhawan; Heiner Deubel Saccade selection and inhibition: Motor and attentional components Journal Article Journal of Neurophysiology, 121 , pp. 1368–1380, 2019. @article{Jonikaitis2019, title = {Saccade selection and inhibition: Motor and attentional components}, author = {Donatas Jonikaitis and Saurabh Dhawan and Heiner Deubel}, doi = {10.1152/jn.00726}, year = {2019}, date = {2019-01-01}, journal = {Journal of Neurophysiology}, volume = {121}, pages = {1368--1380}, abstract = {Motor responses are fundamentally spatial in their function and neural organization. However, studies of inhibitory motor control, focused on global stopping of all actions, have ignored whether inhibitory control can be exercised selectively for specific actions. We used a new approach to elicit and measure motor inhibition by asking human participants to either look at (select) or avoid looking at (inhibit) a location in space. We found that instructing a location to be avoided resulted in an inhibitory bias specific to that location. When compared with the facilitatory bias observed in the Look task, it differed significantly in both its spatiotemporal dynamics and its modulation of attentional processing. While action selection was evident in oculomotor system and interacted with attentional processing , action inhibition was evident mainly in the oculomotor system. Our findings suggest that action inhibition is implemented by spatially specific mechanisms that are separate from action selection.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Motor responses are fundamentally spatial in their function and neural organization. However, studies of inhibitory motor control, focused on global stopping of all actions, have ignored whether inhibitory control can be exercised selectively for specific actions. We used a new approach to elicit and measure motor inhibition by asking human participants to either look at (select) or avoid looking at (inhibit) a location in space. We found that instructing a location to be avoided resulted in an inhibitory bias specific to that location. When compared with the facilitatory bias observed in the Look task, it differed significantly in both its spatiotemporal dynamics and its modulation of attentional processing. While action selection was evident in oculomotor system and interacted with attentional processing , action inhibition was evident mainly in the oculomotor system. Our findings suggest that action inhibition is implemented by spatially specific mechanisms that are separate from action selection. |
Kei Kanari; Hirohiko Kaneko Effect of visual attention and horizontal vergence in three-dimensional space on occurrence of optokinetic nystagmus Journal Article Journal of Eye Movement Research, 12 (1), pp. 1–12, 2019. @article{Kanari2019, title = {Effect of visual attention and horizontal vergence in three-dimensional space on occurrence of optokinetic nystagmus}, author = {Kei Kanari and Hirohiko Kaneko}, doi = {10.16910/jemr.12.1.2}, year = {2019}, date = {2019-01-01}, journal = {Journal of Eye Movement Research}, volume = {12}, number = {1}, pages = {1--12}, abstract = {OKN corresponding to the motion of the fixating area occurs when a stimulus has two areas separated in depth containing motion in different directions. However, when attention and vergence are separately directed to areas with different motions and depths, it remains unclear which property of attention and vergence is prioritized to initiate OKN. In this study, we investigated whether OKN corresponding to motion in the attending or fixating area occurred when two motions with different directions were presented in the central and peripheral visual fields separated in depth. Results show that OKN corresponding to attended motion occurred when observers maintained vergence on the peripheral stimulus and attended to the central stimulus. However, OKN corresponding to each motion in the attending area and in the fixating area occurred when observers maintained vergence on the central stimulus and attended to the peripheral stimulus. The accuracy rate of the attentional task was the lowest in this condition. These results support the idea that motion in the attended area is essential for occurrence of OKN, and vergence and retinal position affect the strength of attention.}, keywords = {}, pubstate = {published}, tppubtype = {article} } OKN corresponding to the motion of the fixating area occurs when a stimulus has two areas separated in depth containing motion in different directions. However, when attention and vergence are separately directed to areas with different motions and depths, it remains unclear which property of attention and vergence is prioritized to initiate OKN. In this study, we investigated whether OKN corresponding to motion in the attending or fixating area occurred when two motions with different directions were presented in the central and peripheral visual fields separated in depth. Results show that OKN corresponding to attended motion occurred when observers maintained vergence on the peripheral stimulus and attended to the central stimulus. However, OKN corresponding to each motion in the attending area and in the fixating area occurred when observers maintained vergence on the central stimulus and attended to the peripheral stimulus. The accuracy rate of the attentional task was the lowest in this condition. These results support the idea that motion in the attended area is essential for occurrence of OKN, and vergence and retinal position affect the strength of attention. |
Kawita M S Kanhai; Jenny A Nij Bijvank; Yorick L Wagenaar; Erica S Klaassen; KyoungSoo Lim; Sandrin C Bergheanu; Axel Petzold; Ajay Verma; Jacob Hesterman; Mike P Wattjes; Bernard M J Uitdehaag; Laurentius J van Rijn; Geert Jan Groeneveld Treatment of internuclear ophthalmoparesis in multiple sclerosis with fampridine: A randomized double-blind, placebo-controlled cross-over trial Journal Article CNS Neuroscience and Therapeutics, 25 (6), pp. 697–703, 2019. @article{Kanhai2019, title = {Treatment of internuclear ophthalmoparesis in multiple sclerosis with fampridine: A randomized double-blind, placebo-controlled cross-over trial}, author = {Kawita M S Kanhai and Jenny A {Nij Bijvank} and Yorick L Wagenaar and Erica S Klaassen and KyoungSoo Lim and Sandrin C Bergheanu and Axel Petzold and Ajay Verma and Jacob Hesterman and Mike P Wattjes and Bernard M J Uitdehaag and Laurentius J van Rijn and Geert {Jan Groeneveld}}, doi = {10.1111/cns.13096}, year = {2019}, date = {2019-01-01}, journal = {CNS Neuroscience and Therapeutics}, volume = {25}, number = {6}, pages = {697--703}, abstract = {Aim: To examine whether the velocity of saccadic eye movements in internuclear ophthalmoparesis (INO) improves with fampridine treatment in patients with multiple sclerosis (MS). Methods: Randomized, double-blind, placebo-controlled, cross-over trial with fampridine in patients with MS and INO. Horizontal saccades were recorded at baseline and at multiple time points post-dose. Main outcome measures were the change of peak velocity versional dysconjugacy index (PV-VDI) and first-pass amplitude VDI (FPA-VDI). Both parameters were compared between fampridine and placebo using a mixed model analysis of variance taking patients as their own control. Pharmacokinetics was determined by serial blood sampling. Results: Thirteen patients had a bilateral and 10 had a unilateral INO. One patient had an INO of abduction (posterior INO of Lutz) and was excluded. Fampridine significantly reduced both PV-VDI (−17.4%, 95% CI: −22.4%, −12.1%; P textless 0.0001) and FPA-VDI (−12.5%, 95% CI: −18.9%, −5.5%; P textless 0.01). Pharmacokinetics demonstrated that testing coincided with the average tmax at 2.08 hours (SD 45 minutes). The main adverse event reported after administration of fampridine was dizziness (61%). Conclusion: Fampridine improves saccadic eye movements due to INO in MS. Treatment response to fampridine may gauge patient selection for inclusion to remyelination strategies in MS using saccadic eye movements as primary outcome measure.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Aim: To examine whether the velocity of saccadic eye movements in internuclear ophthalmoparesis (INO) improves with fampridine treatment in patients with multiple sclerosis (MS). Methods: Randomized, double-blind, placebo-controlled, cross-over trial with fampridine in patients with MS and INO. Horizontal saccades were recorded at baseline and at multiple time points post-dose. Main outcome measures were the change of peak velocity versional dysconjugacy index (PV-VDI) and first-pass amplitude VDI (FPA-VDI). Both parameters were compared between fampridine and placebo using a mixed model analysis of variance taking patients as their own control. Pharmacokinetics was determined by serial blood sampling. Results: Thirteen patients had a bilateral and 10 had a unilateral INO. One patient had an INO of abduction (posterior INO of Lutz) and was excluded. Fampridine significantly reduced both PV-VDI (−17.4%, 95% CI: −22.4%, −12.1%; P textless 0.0001) and FPA-VDI (−12.5%, 95% CI: −18.9%, −5.5%; P textless 0.01). Pharmacokinetics demonstrated that testing coincided with the average tmax at 2.08 hours (SD 45 minutes). The main adverse event reported after administration of fampridine was dizziness (61%). Conclusion: Fampridine improves saccadic eye movements due to INO in MS. Treatment response to fampridine may gauge patient selection for inclusion to remyelination strategies in MS using saccadic eye movements as primary outcome measure. |
Krista R Kelly; Christina S Cheng-Patel; Reed M Jost; Yi Zhong Wang; Eileen E Birch Fixation instability during binocular viewing in anisometropic and strabismic children Journal Article Experimental Eye Research, 183 , pp. 29–37, 2019. @article{Kelly2019a, title = {Fixation instability during binocular viewing in anisometropic and strabismic children}, author = {Krista R Kelly and Christina S Cheng-Patel and Reed M Jost and Yi Zhong Wang and Eileen E Birch}, doi = {10.1016/j.exer.2018.07.013}, year = {2019}, date = {2019-01-01}, journal = {Experimental Eye Research}, volume = {183}, pages = {29--37}, publisher = {Elsevier Ltd}, abstract = {Purpose: Strabismus or anisometropia disrupts binocularity and results in fixation instability, which is increased with amblyopia. Fixation instability has typically been assessed for each eye individually. Recently, vergence instability was reported in exotropic adults and monkeys during binocular viewing. We evaluated fixation instability during binocular viewing in children treated for anisometropia and/or strabismus. Methods: 160 children age 4–12 years with treated esotropia and/or anisometropia (98 amblyopic, 62 nonamblyopic) were compared to 46 age-similar controls. Fixation instability was recorded during binocular fixation of a 0.3 deg diameter dot for 20 s using a 500 Hz remote video binocular eye tracker (EyeLink 1000; SR Research). The bivariate contour ellipse area (BCEA; log deg2) for fixation instability was calculated for each eye (nonpreferred, preferred) and for vergence instability (left eye position – right eye position). Best-corrected visual acuity, Randot Preschool stereoacuity, and extent of suppression scotoma (Worth 4-Dot) were also obtained. Results: When binocularly viewing, both amblyopic and nonamblyopic children treated for anisometropia and/or strabismus had larger fixation instability and vergence instability than controls. Amblyopia primarily added to the instability of the nonpreferred eye. Anisometropic children had less nonpreferred eye instability and vergence instability than those with strabismus or combined mechanism. Nonpreferred eye instability and vergence instability were related to poorer stereoacuity and a larger suppression scotoma. Preferred eye instability was not related to any visual outcome measure. No relationships were found with visual acuity. Conclusions: Fixation instability and vergence instability during binocular viewing suggests that discordant binocular visual experience during childhood, especially strabismus, interferes with ocular motor development. Amblyopia adds to instability of the nonpreferred eye. Vergence instability may limit potential for recovery of binocular vision in these children.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Purpose: Strabismus or anisometropia disrupts binocularity and results in fixation instability, which is increased with amblyopia. Fixation instability has typically been assessed for each eye individually. Recently, vergence instability was reported in exotropic adults and monkeys during binocular viewing. We evaluated fixation instability during binocular viewing in children treated for anisometropia and/or strabismus. Methods: 160 children age 4–12 years with treated esotropia and/or anisometropia (98 amblyopic, 62 nonamblyopic) were compared to 46 age-similar controls. Fixation instability was recorded during binocular fixation of a 0.3 deg diameter dot for 20 s using a 500 Hz remote video binocular eye tracker (EyeLink 1000; SR Research). The bivariate contour ellipse area (BCEA; log deg2) for fixation instability was calculated for each eye (nonpreferred, preferred) and for vergence instability (left eye position – right eye position). Best-corrected visual acuity, Randot Preschool stereoacuity, and extent of suppression scotoma (Worth 4-Dot) were also obtained. Results: When binocularly viewing, both amblyopic and nonamblyopic children treated for anisometropia and/or strabismus had larger fixation instability and vergence instability than controls. Amblyopia primarily added to the instability of the nonpreferred eye. Anisometropic children had less nonpreferred eye instability and vergence instability than those with strabismus or combined mechanism. Nonpreferred eye instability and vergence instability were related to poorer stereoacuity and a larger suppression scotoma. Preferred eye instability was not related to any visual outcome measure. No relationships were found with visual acuity. Conclusions: Fixation instability and vergence instability during binocular viewing suggests that discordant binocular visual experience during childhood, especially strabismus, interferes with ocular motor development. Amblyopia adds to instability of the nonpreferred eye. Vergence instability may limit potential for recovery of binocular vision in these children. |
Shane Kelly; Weiwei Zhou; Sonia Bansal; Matthew S Peterson; Wilsaan M Joiner The temporal and spatial constraints of saccade planning to double-step target displacements Journal Article Vision Research, 163 , pp. 1–13, 2019. @article{Kelly2019b, title = {The temporal and spatial constraints of saccade planning to double-step target displacements}, author = {Shane Kelly and Weiwei Zhou and Sonia Bansal and Matthew S Peterson and Wilsaan M Joiner}, doi = {10.1016/j.visres.2019.08.003}, year = {2019}, date = {2019-01-01}, journal = {Vision Research}, volume = {163}, pages = {1--13}, publisher = {Elsevier}, abstract = {The double-step paradigm investigates the characteristics of planning and execution when the motor system must rapidly adjust for a new goal location. Studies have provided detailed temporal information based on the duration available for the motor system to prepare a new movement trajectory (here referred to as re-preparation time). However, previous work has largely examined single displacement sizes, limiting the spatiotemporal understanding of movement planning and execution. The lack of a description of this behavioral timecourse across increasing displacement sizes is true for saccades, rapid eye movements that redirect the fovea. Furthermore, during the double-step paradigm, the primary saccade often fails to accurately foveate the final target location and a secondary saccade brings the target onto the fovea. However, it is also unknown how this compensation is concurrently modified with the exposure duration and displacement of the movement goal. Here, we examined the amount of time required to change the initial saccade direction to a new target location for relatively small (20°, 30°, and 40°) and large (60° and 90°) target spatial separations. Interestingly, we found a clear relationship between the saccade direction and the amount of time allowed to redirect the movement; across separations, intermediate saccades occurred when approximately 60–140 ms was available to readjust the movement plan. Additionally, there was a consistent relationship between the timing of the secondary saccade and the re-preparation time across jump sizes, suggesting that concurrent movement correction planning was dependent on the amount of exposure to the final movement goal.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The double-step paradigm investigates the characteristics of planning and execution when the motor system must rapidly adjust for a new goal location. Studies have provided detailed temporal information based on the duration available for the motor system to prepare a new movement trajectory (here referred to as re-preparation time). However, previous work has largely examined single displacement sizes, limiting the spatiotemporal understanding of movement planning and execution. The lack of a description of this behavioral timecourse across increasing displacement sizes is true for saccades, rapid eye movements that redirect the fovea. Furthermore, during the double-step paradigm, the primary saccade often fails to accurately foveate the final target location and a secondary saccade brings the target onto the fovea. However, it is also unknown how this compensation is concurrently modified with the exposure duration and displacement of the movement goal. Here, we examined the amount of time required to change the initial saccade direction to a new target location for relatively small (20°, 30°, and 40°) and large (60° and 90°) target spatial separations. Interestingly, we found a clear relationship between the saccade direction and the amount of time allowed to redirect the movement; across separations, intermediate saccades occurred when approximately 60–140 ms was available to readjust the movement plan. Additionally, there was a consistent relationship between the timing of the secondary saccade and the re-preparation time across jump sizes, suggesting that concurrent movement correction planning was dependent on the amount of exposure to the final movement goal. |
Sanjeev B Khanna; Adam C Snyder; Matthew A Smith Distinct sources of variability affect eye movement preparation Journal Article The Journal of Neuroscience, 39 (23), pp. 4511–4526, 2019. @article{Khanna2019, title = {Distinct sources of variability affect eye movement preparation}, author = {Sanjeev B Khanna and Adam C Snyder and Matthew A Smith}, doi = {10.1523/JNEUROSCI.2329-18.2019}, year = {2019}, date = {2019-01-01}, journal = {The Journal of Neuroscience}, volume = {39}, number = {23}, pages = {4511--4526}, abstract = {The sequence of events leading to an eye movement to a target begins the moment visual information has reached the brain, well in advance of the eye movement itself. The process by which visual information is encoded and used to generate a motor plan has been the focus of substantial interest partly because of the rapid and reproducible nature of saccadic eye movements, and the key role that they play in primate behavior. Signals related to eye movements are present in much of the primate brain, yet most neurophysiological studies of the transition from vision to eye movements have measured the activity of one neuron at a time. Less is known about how the coordinated action of populations of neurons contribute to the initiation of eye movements. One cortical area of particular interest in this process is the frontal eye fields, a region of prefrontal cortex that has descending projections to oculomotor control centers. We recorded from populations of frontal eye field neurons in macaque monkeys engaged in a memory-guided saccade task. We found a variety of neurons with visually evoked responses, saccade-aligned responses, and mixtures of both. We took advantage of the simultaneous nature of the recordings to measure variability in individual neurons and pairs of neurons from trial-to-trial, as well as the moment-to-moment population activity structure.Wefound that these measures were related to saccadic reaction times, suggesting that the population-level organization of frontal eye field activity is important for the transition from perception to movement.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The sequence of events leading to an eye movement to a target begins the moment visual information has reached the brain, well in advance of the eye movement itself. The process by which visual information is encoded and used to generate a motor plan has been the focus of substantial interest partly because of the rapid and reproducible nature of saccadic eye movements, and the key role that they play in primate behavior. Signals related to eye movements are present in much of the primate brain, yet most neurophysiological studies of the transition from vision to eye movements have measured the activity of one neuron at a time. Less is known about how the coordinated action of populations of neurons contribute to the initiation of eye movements. One cortical area of particular interest in this process is the frontal eye fields, a region of prefrontal cortex that has descending projections to oculomotor control centers. We recorded from populations of frontal eye field neurons in macaque monkeys engaged in a memory-guided saccade task. We found a variety of neurons with visually evoked responses, saccade-aligned responses, and mixtures of both. We took advantage of the simultaneous nature of the recordings to measure variability in individual neurons and pairs of neurons from trial-to-trial, as well as the moment-to-moment population activity structure.Wefound that these measures were related to saccadic reaction times, suggesting that the population-level organization of frontal eye field activity is important for the transition from perception to movement. |
Seolmin Kim; Jeongjun Park; Joonyeol Lee Effect of prior direction expectation on the accuracy and precision of smooth pursuit eye movements Journal Article Frontiers in Systems Neuroscience, 13 , pp. 1–12, 2019. @article{Kim2019d, title = {Effect of prior direction expectation on the accuracy and precision of smooth pursuit eye movements}, author = {Seolmin Kim and Jeongjun Park and Joonyeol Lee}, doi = {10.3389/fnsys.2019.00071}, year = {2019}, date = {2019-01-01}, journal = {Frontiers in Systems Neuroscience}, volume = {13}, pages = {1--12}, abstract = {The integration of sensory with top–down cognitive signals for generating appropriate sensory–motor behaviors is an important issue in understanding the brain's information processes. Recent studies have demonstrated that the interplay between sensory and high-level signals in oculomotor behavior could be explained by Bayesian inference. Specifically, prior knowledge for motion speed introduces a bias in the speed of smooth pursuit eye movements. The other important prediction of Bayesian inference is variability reduction by prior expectation; however, there is insufficient evidence in oculomotor behaviors to support this prediction. In the present study, we trained monkeys to switch the prior expectation about motion direction and independently controlled the strength of the motion stimulus. Under identical sensory stimulus conditions, we tested if prior knowledge about the motion direction reduced the variability of open-loop smooth pursuit eye movements. We observed a significant reduction when the prior expectation was strong; this was consistent with the prediction of Bayesian inference. Taking advantage of the open-loop smooth pursuit, we investigated the temporal dynamics of the effect of the prior to the pursuit direction bias and variability. This analysis demonstrated that the strength of the sensory evidence depended not only on the strength of the sensory stimulus but also on the time required for the pursuit system to form a neural sensory representation. Finally, we demonstrated that the variability and directional bias change by prior knowledge were quantitatively explained by the Bayesian observer model.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The integration of sensory with top–down cognitive signals for generating appropriate sensory–motor behaviors is an important issue in understanding the brain's information processes. Recent studies have demonstrated that the interplay between sensory and high-level signals in oculomotor behavior could be explained by Bayesian inference. Specifically, prior knowledge for motion speed introduces a bias in the speed of smooth pursuit eye movements. The other important prediction of Bayesian inference is variability reduction by prior expectation; however, there is insufficient evidence in oculomotor behaviors to support this prediction. In the present study, we trained monkeys to switch the prior expectation about motion direction and independently controlled the strength of the motion stimulus. Under identical sensory stimulus conditions, we tested if prior knowledge about the motion direction reduced the variability of open-loop smooth pursuit eye movements. We observed a significant reduction when the prior expectation was strong; this was consistent with the prediction of Bayesian inference. Taking advantage of the open-loop smooth pursuit, we investigated the temporal dynamics of the effect of the prior to the pursuit direction bias and variability. This analysis demonstrated that the strength of the sensory evidence depended not only on the strength of the sensory stimulus but also on the time required for the pursuit system to form a neural sensory representation. Finally, we demonstrated that the variability and directional bias change by prior knowledge were quantitatively explained by the Bayesian observer model. |
Kristin Koller; Robert D Rafal Saccade latency bias toward temporal hemifield: Evidence for role of retinotectal tract in mediating reflexive saccades Journal Article Neuropsychologia, 128 , pp. 276–281, 2019. @article{Koller2019a, title = {Saccade latency bias toward temporal hemifield: Evidence for role of retinotectal tract in mediating reflexive saccades}, author = {Kristin Koller and Robert D Rafal}, doi = {10.1016/j.neuropsychologia.2018.01.028}, year = {2019}, date = {2019-01-01}, journal = {Neuropsychologia}, volume = {128}, pages = {276--281}, publisher = {Elsevier Ltd}, abstract = {The superior colliculus (SC) plays a critical role in mediating reflexive eye movements. Under optimal conditions, for example including a temporal ‘gap' of 200 ms after fixation offset and prior to target onset, it is possible to isolate a population of ‘express saccades' with very short latencies between 80 and 120 ms. Ablation of the SC abolishes express saccades in monkeys. However, it remains to be established whether express saccade generation is dependent upon visual afferents transmitting direct retinal projections to SC via the retinotectal tract (RTT). In nineteen healthy human participants, we used a gap paradigm to investigate whether express saccades demonstrate shorter latencies to targets in the temporal hemifield, a marker for RTT function. A population of predominantly reflexive saccades (with latencies between 70 and 150 ms) was isolated in which latencies toward temporal hemifield targets were shown to be shorter than toward nasal hemifield targets. The advantages for reflexive saccades toward temporal hemifield targets suggest that visual efferents from the retina to the superior colliculus contribute to generating reflexively triggered saccades.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The superior colliculus (SC) plays a critical role in mediating reflexive eye movements. Under optimal conditions, for example including a temporal ‘gap' of 200 ms after fixation offset and prior to target onset, it is possible to isolate a population of ‘express saccades' with very short latencies between 80 and 120 ms. Ablation of the SC abolishes express saccades in monkeys. However, it remains to be established whether express saccade generation is dependent upon visual afferents transmitting direct retinal projections to SC via the retinotectal tract (RTT). In nineteen healthy human participants, we used a gap paradigm to investigate whether express saccades demonstrate shorter latencies to targets in the temporal hemifield, a marker for RTT function. A population of predominantly reflexive saccades (with latencies between 70 and 150 ms) was isolated in which latencies toward temporal hemifield targets were shown to be shorter than toward nasal hemifield targets. The advantages for reflexive saccades toward temporal hemifield targets suggest that visual efferents from the retina to the superior colliculus contribute to generating reflexively triggered saccades. |
Wee K Lau; Gerrit W Maus Directional biases for blink adaptation in voluntary and reflexive eye blinks Journal Article Journal of Vision, 19 (3), pp. 1–13, 2019. @article{Lau2019, title = {Directional biases for blink adaptation in voluntary and reflexive eye blinks}, author = {Wee K Lau and Gerrit W Maus}, doi = {10.1167/19.3.13}, year = {2019}, date = {2019-01-01}, journal = {Journal of Vision}, volume = {19}, number = {3}, pages = {1--13}, abstract = {The oculomotor system is subject to noise, and adaptive processes compensate for consistent errors in gaze targeting. Recent evidence suggests that positional errors induced by eye blinks are also corrected by an adaptive process: When a fixation target is displaced during repeated blinks, subsequent blinks are accompanied by an automatic compensating eye movement anticipating the updated target location after the blink. Here, we further tested the extent of this ''blink adaptation.'' Participants were tasked to look at a white target dot on a black screen and encouraged to blink voluntarily, or air puffs were used to elicit reflexive blinks. In separate runs, the target was displaced by 0.78 in either of the four cardinal directions during blinks. Participants adapted to positional changes during blinks, i.e., the postblink gaze position was biased in the direction of the dot displacement. Adaptation occurred for both voluntary and reflexive blinks. However, adaptation was unequal across different adaptation directions: Horizontally, temporal displacements experienced larger adaptation than nasal displacements; vertically, downward displacements led to larger adaptation than upward displacements. Results paralleled anisotropies commonly found for saccade amplitudes, and thus it is likely that gaze corrections across eye blinks share general constraints of the oculomotor system with saccades.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The oculomotor system is subject to noise, and adaptive processes compensate for consistent errors in gaze targeting. Recent evidence suggests that positional errors induced by eye blinks are also corrected by an adaptive process: When a fixation target is displaced during repeated blinks, subsequent blinks are accompanied by an automatic compensating eye movement anticipating the updated target location after the blink. Here, we further tested the extent of this ''blink adaptation.'' Participants were tasked to look at a white target dot on a black screen and encouraged to blink voluntarily, or air puffs were used to elicit reflexive blinks. In separate runs, the target was displaced by 0.78 in either of the four cardinal directions during blinks. Participants adapted to positional changes during blinks, i.e., the postblink gaze position was biased in the direction of the dot displacement. Adaptation occurred for both voluntary and reflexive blinks. However, adaptation was unequal across different adaptation directions: Horizontally, temporal displacements experienced larger adaptation than nasal displacements; vertically, downward displacements led to larger adaptation than upward displacements. Results paralleled anisotropies commonly found for saccade amplitudes, and thus it is likely that gaze corrections across eye blinks share general constraints of the oculomotor system with saccades. |
Roman Liepelt; Emanuele Porcu; Anna Stenzel; Markus Lappe Saccadic eye movements do not trigger a joint Simon effect Journal Article Psychonomic Bulletin & Review, 26 , pp. pages1896–1904, 2019. @article{Liepelt2019, title = {Saccadic eye movements do not trigger a joint Simon effect}, author = {Roman Liepelt and Emanuele Porcu and Anna Stenzel and Markus Lappe}, doi = {10.3758/s13423-019-01639-0}, year = {2019}, date = {2019-01-01}, journal = {Psychonomic Bulletin & Review}, volume = {26}, pages = {pages1896--1904}, abstract = {Although the joint Simon task (JST) has been investigated for more than a decade, its cause is still unclear. According to ideomotor views of action control, action effects are a commonly cited explanation. However, action effects are usually confounded with the actions producing such effects. We combined a JST with eye tracking and asked participants to respond by performing specific saccades. Saccades were followed by visual feedback (central vs. lateral feedback), serving as the action effect. This arrangement allowed us to isolate actions from action effects and, also to prevent each actor from seeing the reciprocal actions of the other actor. In this saccadic JST, we found a significant compatibility effect in the individual setting. The typical enhanced compatibility effect in the joint setting of the JST was absent with central action feedback and even when lateralized visual action feedback was provided. Our findings suggest that the perception of action effects alone might not be sufficient to modulate compatibility effects for eye movements. The presence of a compatibility effect in the individual setting shows the specific requirements of a saccadic compatibility task-the requirement to perform prosaccades to compatible and antisaccades to incompatible target locations. The lack of a difference between compatibility effects in joint and individual settings and the lack of a modulation of the compatibility effect through lateralized visual action feedback shows that the finding of a joint Simon effect that has frequently been reported for manual responses is absent for saccadic responses.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Although the joint Simon task (JST) has been investigated for more than a decade, its cause is still unclear. According to ideomotor views of action control, action effects are a commonly cited explanation. However, action effects are usually confounded with the actions producing such effects. We combined a JST with eye tracking and asked participants to respond by performing specific saccades. Saccades were followed by visual feedback (central vs. lateral feedback), serving as the action effect. This arrangement allowed us to isolate actions from action effects and, also to prevent each actor from seeing the reciprocal actions of the other actor. In this saccadic JST, we found a significant compatibility effect in the individual setting. The typical enhanced compatibility effect in the joint setting of the JST was absent with central action feedback and even when lateralized visual action feedback was provided. Our findings suggest that the perception of action effects alone might not be sufficient to modulate compatibility effects for eye movements. The presence of a compatibility effect in the individual setting shows the specific requirements of a saccadic compatibility task-the requirement to perform prosaccades to compatible and antisaccades to incompatible target locations. The lack of a difference between compatibility effects in joint and individual settings and the lack of a modulation of the compatibility effect through lateralized visual action feedback shows that the finding of a joint Simon effect that has frequently been reported for manual responses is absent for saccadic responses. |
Yanping Liu; Lei Yu; Erik D Reichle The influence of parafoveal preview, character transposition, and word frequency on saccadic targeting in Chinese reading Journal Article Journal of Experimental Psychology: Human Perception and Performance, 45 (4), pp. 537–552, 2019. @article{Liu2019d, title = {The influence of parafoveal preview, character transposition, and word frequency on saccadic targeting in Chinese reading}, author = {Yanping Liu and Lei Yu and Erik D Reichle}, doi = {10.1037/xhp0000630}, year = {2019}, date = {2019-01-01}, journal = {Journal of Experimental Psychology: Human Perception and Performance}, volume = {45}, number = {4}, pages = {537--552}, abstract = {This article reports the results of an eye-movement experiment which manipulated the frequency and parafoveal preview (i.e., nonword, transposed-character, or identical) of 2-character Chinese target words using a gaze-contingent boundary paradigm (Rayner, 1975). The key findings were that progressive saccades were longer into high-than low-frequency target words, and that this word-frequency effect was more pronounced for identical than transposed previews. These findings suggest that Chinese readers adjust their saccade lengths in response to variables that influence the rate of parafoveal lexical processing. To examine the feasibility of this hypothesis, 2 computer simulations were completed that pitted this dynamic-adjustment account (Liu, Huang, Gao, & Reichle, 2017) against an account in which readers simply move their eyes to a small number of default saccade targets (e.g., the beginning or center of the upcoming word; Yan, Kliegl, Richter, Nuthmann, & Shu, 2010). The simulation results show that the dynamic-adjustment hypothesis more accurately describes our experimental findings using fewer parameters. The theoretical implications of the dynamic-adjustment account of saccadic targeting are discussed relevant to both models of eye-movement control in reading and modes of Chinese word identification.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This article reports the results of an eye-movement experiment which manipulated the frequency and parafoveal preview (i.e., nonword, transposed-character, or identical) of 2-character Chinese target words using a gaze-contingent boundary paradigm (Rayner, 1975). The key findings were that progressive saccades were longer into high-than low-frequency target words, and that this word-frequency effect was more pronounced for identical than transposed previews. These findings suggest that Chinese readers adjust their saccade lengths in response to variables that influence the rate of parafoveal lexical processing. To examine the feasibility of this hypothesis, 2 computer simulations were completed that pitted this dynamic-adjustment account (Liu, Huang, Gao, & Reichle, 2017) against an account in which readers simply move their eyes to a small number of default saccade targets (e.g., the beginning or center of the upcoming word; Yan, Kliegl, Richter, Nuthmann, & Shu, 2010). The simulation results show that the dynamic-adjustment hypothesis more accurately describes our experimental findings using fewer parameters. The theoretical implications of the dynamic-adjustment account of saccadic targeting are discussed relevant to both models of eye-movement control in reading and modes of Chinese word identification. |
Guojie Ma; Ziang Li; Fengfeng Xu; Xingshan Li The modulation of eye movement control by word length in reading Chinese Journal Article Quarterly Journal of Experimental Psychology, 72 (7), pp. 1620–1631, 2019. @article{Ma2019a, title = {The modulation of eye movement control by word length in reading Chinese}, author = {Guojie Ma and Ziang Li and Fengfeng Xu and Xingshan Li}, doi = {10.1177/1747021818799994}, year = {2019}, date = {2019-01-01}, journal = {Quarterly Journal of Experimental Psychology}, volume = {72}, number = {7}, pages = {1620--1631}, abstract = {Given there are no interword spaces marking word boundaries in Chinese text, it remains unclear how information about word length influences eye movement control during the reading of Chinese text. In this research, we set up strict controls for word frequency and other word properties, to study this knowledge gap. In Experiment 1A and Experiment 1B, a between-subjects design was used. Forty-eight pairs of one- and two-character words were selected as target words in Experiment 1A, while the same amount of two- and three-character words were selected in Experiment 1B. Conversely, a within-subjects design was used in Experiment 2. Sixty sets of one-, two- and three-character words were selected as target words. The results showed that long words were skipped less often and fixated on more often than short words. Total time was shorter for shorter than for longer words but first fixation durations were longer for one- than for two-character words. Most importantly, we did not find reliable evidence to support the view that word length could modulate initial landing position and incoming saccade length in the length-matched region analyses. These findings suggest that word length influences eye movement control during reading Chinese in a way that is slightly different from that in the process of reading English.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Given there are no interword spaces marking word boundaries in Chinese text, it remains unclear how information about word length influences eye movement control during the reading of Chinese text. In this research, we set up strict controls for word frequency and other word properties, to study this knowledge gap. In Experiment 1A and Experiment 1B, a between-subjects design was used. Forty-eight pairs of one- and two-character words were selected as target words in Experiment 1A, while the same amount of two- and three-character words were selected in Experiment 1B. Conversely, a within-subjects design was used in Experiment 2. Sixty sets of one-, two- and three-character words were selected as target words. The results showed that long words were skipped less often and fixated on more often than short words. Total time was shorter for shorter than for longer words but first fixation durations were longer for one- than for two-character words. Most importantly, we did not find reliable evidence to support the view that word length could modulate initial landing position and incoming saccade length in the length-matched region analyses. These findings suggest that word length influences eye movement control during reading Chinese in a way that is slightly different from that in the process of reading English. |
Corentin Massot; Uday K Jagadisan; Neeraj J Gandhi Communications Biology, 2 , pp. 1–14, 2019. @article{Massot2019, title = {Sensorimotor transformation elicits systematic patterns of activity along the dorsoventral extent of the superior colliculus in the macaque monkey}, author = {Corentin Massot and Uday K Jagadisan and Neeraj J Gandhi}, doi = {10.1038/s42003-019-0527-y}, year = {2019}, date = {2019-01-01}, journal = {Communications Biology}, volume = {2}, pages = {1--14}, abstract = {The superior colliculus (SC) is an excellent substrate to study sensorimotor transformations. To date, the spatial and temporal properties of population activity along its dorsoventral axis have been inferred from single electrode studies. Here, we recorded SC population activity in non-human primates using a linear multi-contact array during delayed saccade tasks. We show that during the visual epoch, information appeared first in dorsal layers and systematically later in ventral layers. During the delay period, the laminar organization of low-spiking rate activity matched that of the visual epoch. During the pre-saccadic epoch, spiking activity emerged first in a more ventral layer, ~ 100 ms before saccade onset. This buildup of activity appeared later on nearby neurons situated both dorsally and ventrally, culminating in a synchronous burst across the dorsoventral axis, ~ 28 ms before saccade onset. Collectively, these results reveal a principled spatiotemporal organization of SC population activity underlying sensorimotor transformation for the control of gaze.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The superior colliculus (SC) is an excellent substrate to study sensorimotor transformations. To date, the spatial and temporal properties of population activity along its dorsoventral axis have been inferred from single electrode studies. Here, we recorded SC population activity in non-human primates using a linear multi-contact array during delayed saccade tasks. We show that during the visual epoch, information appeared first in dorsal layers and systematically later in ventral layers. During the delay period, the laminar organization of low-spiking rate activity matched that of the visual epoch. During the pre-saccadic epoch, spiking activity emerged first in a more ventral layer, ~ 100 ms before saccade onset. This buildup of activity appeared later on nearby neurons situated both dorsally and ventrally, culminating in a synchronous burst across the dorsoventral axis, ~ 28 ms before saccade onset. Collectively, these results reveal a principled spatiotemporal organization of SC population activity underlying sensorimotor transformation for the control of gaze. |
Eugene Mcsorley; Iain D Gilchrist; Rachel Mccloy The programming of sequences of saccades Journal Article Experimental Brain Research, 237 , pp. 1009–1018, 2019. @article{Mcsorley2019b, title = {The programming of sequences of saccades}, author = {Eugene Mcsorley and Iain D Gilchrist and Rachel Mccloy}, doi = {10.1007/s00221-019-05481-7}, year = {2019}, date = {2019-01-01}, journal = {Experimental Brain Research}, volume = {237}, pages = {1009--1018}, abstract = {Saccadic eye movements move the high-resolution fovea to point at regions of interest. Saccades can only be generated serially (i.e., one at a time). However, what remains unclear is the extent to which saccades are programmed in parallel (i.e., a series of such moments can be planned together) and how far ahead such planning occurs. In the current experiment, we investigate this issue with a saccade contingent preview paradigm. Participants were asked to execute saccadic eye movements in response to seven small circles presented on a screen. The extent to which participants were given prior information about target locations was varied on a trial-by-trial basis: participants were aware of the location of the next target only, the next three, five, or all seven targets. The addition of new targets to the display was made during the saccade to the next target in the sequence. The overall time taken to complete the sequence was decreased as more targets were available up to all seven targets. This was a result of a reduction in the number of saccades being executed and a reduction in their saccade latencies. Surprisingly, these results suggest that, when faced with a demand to saccade to a large number of target locations, saccade preparation about all target locations is carried out in parallel.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Saccadic eye movements move the high-resolution fovea to point at regions of interest. Saccades can only be generated serially (i.e., one at a time). However, what remains unclear is the extent to which saccades are programmed in parallel (i.e., a series of such moments can be planned together) and how far ahead such planning occurs. In the current experiment, we investigate this issue with a saccade contingent preview paradigm. Participants were asked to execute saccadic eye movements in response to seven small circles presented on a screen. The extent to which participants were given prior information about target locations was varied on a trial-by-trial basis: participants were aware of the location of the next target only, the next three, five, or all seven targets. The addition of new targets to the display was made during the saccade to the next target in the sequence. The overall time taken to complete the sequence was decreased as more targets were available up to all seven targets. This was a result of a reduction in the number of saccades being executed and a reduction in their saccade latencies. Surprisingly, these results suggest that, when faced with a demand to saccade to a large number of target locations, saccade preparation about all target locations is carried out in parallel. |
Inga Meyhöfer; Anna-Maria Kasparbauer; Maria Steffens; Ulrich Ettinger Effects of nicotine on smooth pursuit eye movements in healthy non-smokers Journal Article Psychopharmacology, 236 , pp. 2259–2271, 2019. @article{Meyhoefer2019, title = {Effects of nicotine on smooth pursuit eye movements in healthy non-smokers}, author = {Inga Meyhöfer and Anna-Maria Kasparbauer and Maria Steffens and Ulrich Ettinger}, doi = {10.1007/s00213-019-05223-1}, year = {2019}, date = {2019-01-01}, journal = {Psychopharmacology}, volume = {236}, pages = {2259--2271}, abstract = {Rationale: The non-selective nicotinic acetylcholine receptor (nAChR) agonist nicotine has been argued to improve attention via enhanced filtering of irrelevant stimuli. Here, we tested this hypothesis in the context of smooth pursuit eye movements (SPEMs), an oculomotor function previously shown to improve with nicotine in some but not all studies. Objectives: In order to test whether nicotine improves performance particularly when the inhibition of distracting stimuli is required, SPEM was elicited in conditions with or without peripheral distractors. Additionally, different target frequencies were employed in order to parametrically vary general processing demands on the SPEM system. Methods: Healthy adult non-smokers (N = 18 females}, keywords = {}, pubstate = {published}, tppubtype = {article} } Rationale: The non-selective nicotinic acetylcholine receptor (nAChR) agonist nicotine has been argued to improve attention via enhanced filtering of irrelevant stimuli. Here, we tested this hypothesis in the context of smooth pursuit eye movements (SPEMs), an oculomotor function previously shown to improve with nicotine in some but not all studies. Objectives: In order to test whether nicotine improves performance particularly when the inhibition of distracting stimuli is required, SPEM was elicited in conditions with or without peripheral distractors. Additionally, different target frequencies were employed in order to parametrically vary general processing demands on the SPEM system. Methods: Healthy adult non-smokers (N = 18 females |