EyeLink 临床和动眼神经眼球追踪出版物
EyeLink临床和oculomotor研究出版物至2023年(一些早于2024年)列在以下年份。您可以使用Saccadic Adaptation、Schizophrenia、Nystagmus等关键词搜索出版物。您还可以按年份搜索个人作者姓名和有限搜索(选择年份,然后单击搜索按钮)。如果我们错过了任何EyeLink临床或oculomotor文章,请给我们发电子邮件!
2019 |
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 In: Journal of Neurophysiology, vol. 121, no. 6, pp. 2101–2111, 2019. @article{Heeman2019, 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 In: PLoS ONE, vol. 14, no. 1, pp. e0210020, 2019. @article{Heins2019, 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 In: Vision, vol. 3, pp. 48, 2019. @article{James2019, 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 In: Journal of Neuroscience, vol. 39, no. 13, pp. 2497–2508, 2019. @article{Jarvstad2019, 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 In: NeuroImage, vol. 202, pp. 116160, 2019. @article{Jeong2019, 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. |
Inga Meyhöfer; Anna-Maria Kasparbauer; Maria Steffens; Ulrich Ettinger Effects of nicotine on smooth pursuit eye movements in healthy non-smokers Journal Article In: Psychopharmacology, vol. 236, no. 7, pp. 2259–2271, 2019. @article{Meyhoefer2019, 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 |
Stephanie M. Montenegro; Jay A. Edelman Impact of task-specific training on saccadic eye movement performance Journal Article In: Journal of Neurophysiology, vol. 122, pp. 1661–1674, 2019. @article{Montenegro2019, Prosaccades are saccadic eye movements made reflexively in response to the sudden appearance of visual stimuli, whereas antisaccades are saccades that are directed to a location opposite a stimulus. Bibi and Edelman (Bibi R, Edelman JA. J Neurophysiol 102: 3101-3110, 2009) demonstrated that decreases in reaction time resulting from training prosaccades along one spatial axis (horizontal or vertical) could transfer to prosaccades made along the other axis. To help determine whether visual or motor-related processes underlie this facilitation, in the present study we trained participants to make prosaccades and probed their performance (reaction time, error rate) on antisaccade trials and vice versa. Subjects were probed for the effects of training on saccade performance before, during, and after 12 sessions of training. Training on prosaccades improved performance on both pro-and antisaccade tasks. Antisaccade training, with either a classic step task or a gap task, improved performance on gap prosaccades, though by less than it improved antisaccade performance, but had limited effect on an overlap prosac-cade task. Across all subjects, training on one task only rarely had an adverse impact on an untrained task. These findings suggest that the predominant effect of saccade training is to facilitate fixation disengagement and motor preparation processes while having little impact on visual input to the saccadic system. |
Kentaro Morita; Kenichiro Miura; Michiko Fujimoto; Hidenaga Yamamori; Yuka Yasuda; Noriko Kudo; Hirotsugu Azechi; Naohiro Okada; Daisuke Koshiyama; Manabu Ikeda; Kiyoto Kasai; Ryota Hashimoto Eye movement abnormalities and their association with cognitive impairments in schizophrenia Journal Article In: Schizophrenia Research, vol. 209, pp. 255–262, 2019. @article{Morita2019, Background: Eye movement abnormalities have been identified in schizophrenia; however, their relevance to cognition is still unknown. In this study, we explored the general relationship between eye movements and cognitive function. Methods: The three eye movement measures (scanpath length, horizontal position gain, and duration of fixations) that were previously reported to be useful in distinguishing subjects with schizophrenia from healthy subjects, as well as Wechsler Adult Intelligence Scale-III (WAIS-III) scores, were collected and tested for association in 113 subjects with schizophrenia and 404 healthy subjects. Results: Scanpath length was positively correlated with matrix reasoning and digit symbol coding in subjects with schizophrenia and correlated with vocabulary and symbol search in healthy subjects. Upon testing for interaction effects of diagnosis and scanpath length on correlated WAIS-III scores, a significant interaction effect was only observed for matrix reasoning. The positive correlation between scanpath length and matrix reasoning, which was specific to subjects with schizophrenia, remained significant after controlling for demographic confounders such as medication and negative symptoms. No correlation was observed between the two other eye movement measures and any of the WAIS-III scores. Conclusions: Herein, we reveal novel findings on the association between eye-movement-based measures of visual exploration and cognitive scores requiring visual search in subjects with schizophrenia and in healthy subjects. The association between scanpath length and matrix reasoning, a measure of perceptual organization in subjects with schizophrenia, implies the existence of common cognitive processes, and subjects with longer scanpath length may be advantageous in performance of perceptual organization tasks. |
Judith Nicolas; Aurélie Bidet-Caulet; Denis Pélisson Inducing oculomotor plasticity to disclose the functional link between voluntary saccades and endogenous attention deployed perifoveally Journal Article In: Scientific Reports, vol. 9, pp. 1–12, 2019. @article{Nicolas2019, To what extent oculomotor and attention systems are linked remains strongly debated. Previous studies suggested that saccadic adaptation, a well-studied model of oculomotor plasticity, and orienting of attention rely on overlapping networks in the parietal cortex and can functionally interact. Using a Posner-like paradigm in healthy human subjects, we demonstrate for the first time that saccadic adaptation boosts endogenous attention orienting. Indeed, the discrimination of perifoveal targets benefits more from central cues after backward adaptation of leftward voluntary saccades than after a control saccade task. We propose that the overlap of underlying neural networks actually consists of neuronal populations co-activated by oculomotor plasticity and endogenous attention deployed perifoveally. The functional coupling demonstrated here plaids for conceptual models not belonging to the framework of the premotor theory of attention as the latter has been rejected precisely for this voluntary/endogenous modality. These results also open new perspective for rehabilitation of visuo-attentional deficits. |
Judith Nicolas; Aline Bompas; Romain Bouet; Olivier Sillan; Eric Koun; Christian Urquizar; Aurélie Bidet-Caulet; Denis Pélisson Saccadic adaptation boosts ongoing gamma activity in a subsequent visuoattentional task Journal Article In: Cerebral Cortex, vol. 29, no. 9, pp. 3606–3617, 2019. @article{Nicolas2019a, Attention and saccadic adaptation (SA) are critical components of visual perception, the former enhancing sensory processing of selected objects, the latter maintaining the eye movements accuracy toward them. Recent studies propelled the hypothesis of a tight functional coupling between these mechanisms, possibly due to shared neural substrates. Here, we used magnetoencephalography to investigate for the first time the neurophysiological bases of this coupling and of SA per se. We compared visual discrimination performance of 12 healthy subjects before and after SA. Eye movements and magnetic signals were recorded continuously. Analyses focused on gamma band activity (GBA) during the pretarget period of the discrimination and the saccadic tasks. We found that GBA increases after SA. This increase was found in the right hemisphere for both postadaptation saccadic and discrimination tasks. For the latter, GBA also increased in the left hemisphere. We conclude that oculomotor plasticity involves GBA modulation within an extended neural network which persists after SA, suggesting a possible role of gamma oscillations in the coupling between SA and attention. |
J. A. Nij Bijvank; L. J. Rijn; M. Kamminga; H. S. Tan; B. M. J. Uitdehaag; A. Petzold; L. J. Balk Saccadic fatigability in the oculomotor system Journal Article In: Journal of the Neurological Sciences, vol. 402, pp. 167–174, 2019. @article{NijBijvank2019, Background: Fatigue is one of the most common and disabling symptoms in multiple sclerosis (MS), but challenging to quantify. This prospective study investigated if repeated saccadic eye movements enable measurement of oculomotor fatigability and can reflect on perceived fatigue in MS. Methods: A standardized infrared oculography protocol (DEMoNS) was used for quantifying saccades in MS patients and healthy controls which included a first and a repeated pro-saccadic task (FPT and RPT). Saccadic peak velocity, latency, gain, area under the curve (AUC) and peak velocity divided by amplitude (Pv/Am) were calculated in both tasks. Perception based fatigue was assessed using the Checklist Individual Strength and the Neurological Fatigue Index (NFI). Linear regression models were used for assessing the relation between saccadic parameters and perceived fatigue. Results: This study included 181 MS patients and 58 healthy controls subjects. From FPT to RPT, there were significant changes in saccadic parameters. Latency of both tasks was significantly related to NFI summary score (FPT: β = 0.022 |
Kaiser Niknam; Amir Akbarian; Kelsey Clark; Yasin Zamani; Behrad Noudoost; Neda Nategh Characterizing and dissociating multiple time-varying modulatory computations influencing neuronal activity Journal Article In: PLoS Computational Biology, vol. 15, no. 9, pp. e1007275, 2019. @article{Niknam2019, In many brain areas, sensory responses are heavily modulated by factors including attentional state, context, reward history, motor preparation, learned associations, and other cognitive variables. Modelling the effect of these modulatory factors on sensory responses has proven challenging, mostly due to the time-varying and nonlinear nature of the underlying computations. Here we present a computational model capable of capturing and dissociating multiple time-varying modulatory effects on neuronal responses on the order of milliseconds. The model's performance is tested on extrastriate perisaccadic visual responses in nonhuman primates. Visual neurons respond to stimuli presented around the time of saccades differently than during fixation. These perisaccadic changes include sensitivity to the stimuli presented at locations outside the neuron's receptive field, which suggests a contribution of multiple sources to perisaccadic response generation. Current computational approaches cannot quantitatively characterize the contribution of each modulatory source in response generation, mainly due to the very short timescale on which the saccade takes place. In this study, we use a high spatiotemporal resolution experimental paradigm along with a novel extension of the generalized linear model framework (GLM), termed the sparse-variable GLM, to allow for time-varying model parameters representing the temporal evolution of the system with a resolution on the order of milliseconds. We used this model framework to precisely map the temporal evolution of the spatiotemporal receptive field of visual neurons in the middle temporal area during the execution of a saccade. Moreover, an extended model based on a factorization of the sparse-variable GLM allowed us to disassociate and quantify the contribution of individual sources to the perisaccadic response. Our results show that our novel framework can precisely capture the changes in sensitivity of neurons around the time of saccades, and provide a general framework to quantitatively track the role of multiple modulatory sources over time. |
Bahman Abdi Sargezeh; Niloofar Tavakoli; Mohammad Reza Daliri Gender-based eye movement differences in passive indoor picture viewing: An eye-tracking study Journal Article In: Physiology and Behavior, vol. 206, pp. 43–50, 2019. @article{AbdiSargezeh2019a, Male and female brains have different structures, which can make genders produce various eye- movement patterns. This study presents the results of an eye tracking experiment in which we analyzed the eye movements of 25 male and 20 female participants during passive indoor picture viewing. We examined eye-movement parameters, namely fixation duration, scan path length, number of saccades, spatial density, saccade amplitude, and the ratio of total fixation duration to total saccade duration so as to investigate gender differences in eye-movement patterns while indoor picture viewing. We found significant differences in eye-movement patterns between genders. The results of eye-movement analysis also indicated that females showed more explorative gaze behavior, indicated by larger saccade amplitudes, and by longer scan paths. Furthermore, owing to shorter ratio of fixation durations to saccade duration in females as compared to male, we speculate that females inspect the images faster than males. In addition, we classified the genders into two subgroups—males and females—based on their eye-movement parameters by using a support vector machine classifier achieving an accuracy of 70%. We have come to the result males and females – with same culture – see the environment differently. Our findings have profound implications for researches employing gaze-based models. |
Roy Amit; Dekel Abeles; Marisa Carrasco; Shlomit Yuval-Greenberg Oculomotor inhibition reflects temporal expectations Journal Article In: NeuroImage, vol. 184, pp. 279–292, 2019. @article{Amit2019a, 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 In: Journal of Vision, vol. 19, no. 1, pp. 1–23, 2019. @article{Amit2019, 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. |
Kevin D. Johnston; Liya Ma; Lauren Schaeffer Alpha oscillations modulate preparatory activity in marmoset area 8Ad Journal Article In: Journal of Neuroscience, vol. 39, no. 10, pp. 855–1866, 2019. @article{Johnston2019, 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 In: Journal of Neurophysiology, vol. 121, pp. 1368–1380, 2019. @article{Jonikaitis2019, 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 In: Journal of Eye Movement Research, vol. 12, no. 1, pp. 1–12, 2019. @article{Kanari2019, 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. Rijn; Geert Jan Groeneveld Treatment of internuclear ophthalmoparesis in multiple sclerosis with fampridine: A randomized double-blind, placebo-controlled cross-over trial Journal Article In: CNS Neuroscience and Therapeutics, vol. 25, no. 6, pp. 697–703, 2019. @article{Kanhai2019, 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 < 0.0001) and FPA-VDI (−12.5%, 95% CI: −18.9%, −5.5%; P < 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 In: Experimental Eye Research, vol. 183, pp. 29–37, 2019. @article{Kelly2019a, 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 P. 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 In: Vision Research, vol. 163, pp. 1–13, 2019. @article{Kelly2019b, 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 In: Journal of Neuroscience, vol. 39, no. 23, pp. 4511–4526, 2019. @article{Khanna2019, 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 In: Frontiers in Systems Neuroscience, vol. 13, pp. 71, 2019. @article{Kim2019d, 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 In: Neuropsychologia, vol. 128, pp. 276–281, 2019. @article{Koller2019a, 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. |
Eva Krueger; Andrea Schneider; Ben Sawyer; Alain Chavaillaz; Andreas Sonderegger; Rudolf Groner; Peter Hancock Microsaccades distinguish looking from seeing Journal Article In: Journal of Eye Movement Research, vol. 12, no. 6, pp. 1–14, 2019. @article{Krueger2019, Understanding our visual world requires both looking and seeing. Dissociation of these processes can result in the phenomenon of inattentional blindness or ‘looking without seeing‘. Concomitant errors in applied settings can be serious, and even deadly. Current visual data analysis cannot differentiate between just ‘looking‘ and actual processing of visual information, i.e., ‘seeing‘. Differentiation may be possible through the examination of microsaccades; the involuntary, small- magnitude saccadic eye movements that occur during processed visual fixation. Recent work has suggested that microsaccades are post-attentional biosignals, potentially modulated by task. Specifically, microsaccade rates decrease with increased mental task demand, and increase with growing visual task difficulty. Such findings imply that there are fundamental differences in microsaccadic activity between visual and nonvisual tasks. To evaluate this proposition, we used a high-speed eye tracker to record participants in looking for differences between two images or, doing mental arithmetic, or both tasks in combination. Results showed that microsaccade rate was significantly increased in conditions that require high visual attention, and decreased in conditions that require less visual attention. The results support microsaccadic rate reflecting visual attention, and level of visual information processing. A measure that reflects to what extent and how an operator is processing visual information represents a critical step for the application of sophisticated visual assessment to real world tasks. |
Wee K. Lau; Gerrit W. Maus Directional biases for blink adaptation in voluntary and reflexive eye blinks Journal Article In: Journal of Vision, vol. 19, no. 3, pp. 1–13, 2019. @article{Lau2019, 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. |
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 In: Frontiers in Behavioral Neuroscience, vol. 13, pp. 194, 2019. @article{Flierman2019, 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 In: Journal of Neurophysiology, vol. 122, no. 4, pp. 1765–1776, 2019. @article{Ghahremani2019, 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 In: Journal of Neuroscience, vol. 39, no. 15, pp. 2877–2888, 2019. @article{Gibaldi2019, 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 In: Scientific Reports, vol. 9, pp. 17412, 2019. @article{Giesel2019, 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 In: Experimental Brain Research, vol. 237, no. 11, pp. 2841–2851, 2019. @article{Goelz2019, 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 < 0.001), unilateral STN DBS (p < 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 Malla Corrective saccades influence velocity judgments and interception Journal Article In: Scientific Reports, vol. 9, pp. 5395, 2019. @article{Goettker2019, 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 In: Experimental Eye Research, vol. 183, pp. 3–8, 2019. @article{Gonzalez2019, 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 In: Journal of Neurophysiology, vol. 122, no. 5, pp. 1909–1917, 2019. @article{Gremmler2019, 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. |
Jeremy B. Badler; Scott N. J. Watamaniuk; Stephen J. Heinen A common mechanism modulates saccade timing during pursuit and fixation Journal Article In: Journal of Neurophysiology, vol. 122, no. 5, pp. 1981–1988, 2019. @article{Badler2019, 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 In: Attention, Perception, and Psychophysics, vol. 81, pp. 98–108, 2019. @article{Balp2019, 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 In: Journal of Neurophysiology, vol. 121, no. 2, pp. 646–661, 2019. @article{Bellet2019, 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; M. Concetta Morrone Visual sensitivity and bias oscillate phase-locked to saccadic eye movements Journal Article In: Journal of vision, vol. 19, no. 14, pp. 1–16, 2019. @article{Benedetto2019, 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 In: European Archives of Psychiatry and Clinical Neuroscience, vol. 269, no. 2, pp. 235–243, 2019. @article{Bey2019, 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. Rijn; L. J. Balk; H. S. Tan; Bernard M. J. Uitdehaag; A. Petzold Diagnosing and quantifying a common deficit in multiple sclerosis: Internuclear ophthalmoplegia Journal Article In: Neurology, vol. 92, no. 20, pp. E2299–E2308, 2019. @article{Bijvank2019, 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 In: Journal of Experimental Psychology: Human Perception and Performance, vol. 45, no. 2, pp. 264–284, 2019. @article{Bonetti2019, 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 Zoest The role of eye movements in manual responses to social and nonsocial cues Journal Article In: Attention, Perception, and Psychophysics, vol. 81, no. 5, pp. 1236–1252, 2019. @article{Bonmassar2019, 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 In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 45, no. 12, pp. 2165–2173, 2019. @article{Born2019b, 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 In: Frontiers in Aging Neuroscience, vol. 11, pp. 77, 2019. @article{Camacho2019, 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. |
Roman Liepelt; Emanuele Porcu; Anna Stenzel; Markus Lappe Saccadic eye movements do not trigger a joint Simon effect Journal Article In: Psychonomic Bulletin & Review, vol. 26, no. 6, pp. 1896–1904, 2019. @article{Liepelt2019, 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 In: Journal of Experimental Psychology: Human Perception and Performance, vol. 45, no. 4, pp. 537–552, 2019. @article{Liu2019, 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 In: Quarterly Journal of Experimental Psychology, vol. 72, no. 7, pp. 1620–1631, 2019. @article{Ma2019a, 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 In: Communications Biology, vol. 2, pp. 1–14, 2019. @article{Massot2019, 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 In: Experimental Brain Research, vol. 237, no. 4, pp. 1009–1018, 2019. @article{McSorley2019a, 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. |
Jing Chen; Matteo Valsecchi; Karl R. Gegenfurtner Saccadic suppression measured by steady-state visual evoked potentials Journal Article In: Journal of Neurophysiology, vol. 122, no. 1, pp. 251–258, 2019. @article{Chen2019e, 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 In: Frontiers in Neuroscience, vol. 12, pp. 960, 2019. @article{Costela2019, 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 Self-related shapes can hold the eyes Journal Article In: Quarterly Journal of Experimental Psychology, vol. 72, no. 9, pp. 2249–2260, 2019. @article{Dalmaso2019a, 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. |
Mario Dalmaso; Luigi Castelli; Giovanni Galfano Anticipation of cognitive conflict is reflected in microsaccades: Evidence from a cued-flanker task Journal Article In: Journal of Eye Movement Research, vol. 12, no. 6, pp. 1–9, 2019. @article{Dalmaso2019, 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. |
Souto David; Jayesha Chudasama; Dirk Kerzel; Alan Johnston Motion integration is anisotropic during smooth pursuit eye movements Journal Article In: Journal of Neurophysiology, vol. 121, pp. 1787–1797, 2019. @article{David2019, 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 In: Journal of Neuroscience, vol. 39, no. 2, pp. 353–363, 2019. @article{Denison2019, 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 In: Visual Cognition, vol. 27, no. 2, pp. 142–157, 2019. @article{DiCaro2019, 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; Kévin 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 In: Nature Communications, vol. 10, pp. 1400, 2019. @article{Dizeux2019, 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 T. Duchowski; Krzysztof Krejtz; Justyna Zurawska; Donald House Using microsaccades to estimate task difficulty during visual search of layered surfaces Journal Article In: IEEE Transactions on Visualization and Computer Graphics, vol. 14, no. 8, pp. 1–16, 2019. @article{Duchowski2019, 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 In: Experimental Eye Research, vol. 183, pp. 46–51, 2019. @article{Dyer2019, 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. |
2018 |
Melissa E. Milanak; Matt R. Judah; Howard Berenbaum; Arthur F. Kramer; Mark Neider PTSD symptoms and overt attention to contextualized emotional faces: Evidence from eye tracking Journal Article In: Psychiatry Research, vol. 269, pp. 408–413, 2018. @article{Milanak2018, Abnormal patterns of attention to emotional faces and images are proposed by theories of posttraumatic stress disorder (PTSD), and this has been demonstrated empirically. However, few studies have examined how PTSD symptoms are associated with attention to emotional faces in the context of emotional background images. Eye tracking data were collected from seventy-eight undergraduates with a history of experiencing at least one traumatic event as they completed the Contextual Recognition of Affective Faces Task (CRAFT; Milanak and Berenbaum, 2014), which requires subjects to identify the emotion depicted by faces superimposed on an emotional background image. Greater PTSD symptom severity was associated with more time spent looking at background contexts and less time looking at target faces. This is consistent with greater susceptibility to distraction by task-irrelevant emotional stimuli. The duration of each gaze fixation upon fear faces was shorter for those with greater PTSD symptoms, and this pattern was marginally significant for disgust faces. These findings suggest that PTSD symptoms may relate to greater attention toward non-facial background scenes and less attention toward facial stimuli, especially when conveying a fear or disgust expression. |
Hazel I. Blythe; Jonathan H. Dickins; Colin R. Kennedy; Simon P. Liversedge Phonological processing during silent reading in teenagers who are deaf/hard of hearing: An eye movement investigation Journal Article In: Developmental Science, vol. 21, pp. 1–19, 2018. @article{Blythe2018, There has been considerable variability within the literature concerning the extent to which deaf/hard of hearing individuals are able to process phonological codes during reading. Two experiments are reported in which participants' eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). We examined both foveal processing and parafoveal pre‐processing of phonology for three participant groups—teenagers with permanent childhood hearing loss (PCHL), chronological age‐matched controls, and reading age‐matched controls. The teenagers with PCHL showed a pseudohomophone advantage from both directly fixated words and parafoveal preview, similar to their hearing peers. These data provide strong evidence for phonological recoding during silent reading in teenagers with PCHL. |
Ulrich Ettinger; Désirée S. Aichert; Nicola Wöstmann; Sandra Dehning; Michael Riedel; Veena Kumari Response inhibition and interference control: Effects of schizophrenia, genetic risk, and schizotypy Journal Article In: Journal of Neuropsychology, vol. 12, no. 3, pp. 484–510, 2018. @article{Ettinger2018a, The ability to inhibit inappropriate responses and suppress irrelevant information is a core feature of executive control. In this study, we provide a detailed analysis of prepotent response inhibition and interference in patients with schizophrenia. To further test the role of genetic factors and subclinical schizophrenia‐like traits, we additionally studied clinically unaffected, first‐degree relatives of schizophrenia patients and assessed dimensions of schizotypy in both relatives and healthy controls. Inhibition and interference control were assessed using a battery comprising the antisaccade, Stroop, stop signal, go/no‐go, flanker, and Simon tasks. Schizophrenia patients differed from both relatives and controls in making more errors on the antisaccade task and having longer response times on the Stroop task, especially the incongruent condition. Patients also had general, that is, condition independent, increases in reaction times on the go/no‐go and flanker tasks and made more errors on the flanker and Simon tasks, suggesting general performance impairments independent of inhibitory demand. Relatives were characterized by hypometric antisaccade amplitude gain despite normal prosaccades, suggesting a selective deficit in non‐standard sensorimotor transformations. Schizotypy was correlated with inhibitory performance across a number of tasks in both relatives and controls. Generally, these effects were independent of verbal intelligence levels. Overall, the findings point to rather selective impairments of inhibitory control in the schizophrenia spectrum and confirm a previously observed deficit in antisaccade spatial accuracy as an endophenotype of schizophrenia. |
Daniel S. Asfaw; Pete R. Jones; Nicholas D. Smith; David P. Crabb Data on eye movements in people with glaucoma and peers with normal vision Journal Article In: Data in Brief, vol. 19, pp. 1266–1273, 2018. @article{Asfaw2018, Eye movements of glaucoma patients have been shown to differ from age-similar control groups when performing everyday tasks, such as reading (Burton et al., 2012; Smith et al., 2014) [1,2], visual search (Smith et al., 2012) [3], face recognition (Glen et al., 2013) [4], driving, and viewing static images (Smith et al., 2012) [5]. Described here is the dataset from a recent publication in which we compared the eye movements of 44 glaucoma patients and 32 age-similar controls, while they watched a series of short video clips taken from television programs (Crabb et al., 2018) [6]. Gaze was recorded at 1000 Hz using a remote eye-tracker. We also provide demographic information and results from a clinical examination of vision for each participant. |
Eleanor J. Cole; Nick E. Barraclough; Peter G. Enticott Investigating mirror system (MS) activity in adults with ASD when inferring others' intentions using both TMS and EEG Journal Article In: Journal of Autism and Developmental Disorders, vol. 48, no. 7, pp. 2350–2367, 2018. @article{Cole2018, ASD is associated with mentalizing deficits that may correspond with atypical mirror system (MS) activation. We investigated MS activity in adults with and without ASD when inferring others' intentions using TMS-induced motor evoked potentials (MEPs) and mu suppression measured by EEG. Autistic traits were measured for all participants. Our EEG data show, high levels of autistic traits predicted reduced right mu (8–10 Hz) suppression when mentalizing. Higher left mu (8–10 Hz) suppression was associated with superior mentalizing performances. Eye-tracking and TMS data showed no differences associated with autistic traits. Our data suggest ASD is associated with reduced right MS activity when mentalizing, TMS-induced MEPs and mu suppression measure different aspects of MS functioning and the MS is directly involved in inferring intentions. |
Douwe P. Bergsma; Mies Genderen; Carlien Roelofzen; Serge O. Dumoulin; Alessio Fracasso; Giorgio L. Porro; Marnix Naber Gaze-contingent flicker pupil perimetry detects scotomas in patients with cerebral visual impairments or glaucoma Journal Article In: Frontiers in Neurology, vol. 9, pp. 558, 2018. @article{Bergsma2018, Background: The pupillary light reflex is weaker for stimuli presented inside as compared to outside absolute scotomas. Pupillograph perimetry could thus be an objective measure of impaired visual processing. However, the diagnostic accuracy in detecting scotomas has remained unclear. We quantitatively investigated the accuracy of a novel form of pupil perimetry. Methods: The new perimetry method, termed gaze-contingent flicker pupil perimetry, consists of the repetitive on, and off flickering of a bright disk (2 hz; 320 cd/m2; 4◦ diameter) on a gray background (160 cd/m2) for 4 seconds per stimulus location. The disk evokes continuous pupil oscillations at the same rate as its flicker frequency, and the oscillatory power of the pupil reflects visual sensitivity. We monocularly presented the disk at a total of 80 locations in the central visual field (max. 15◦). The location of the flickering disk moved along with gaze to reduce confounds of eye movements (gaze-contingent paradigm). The test lasted ∼5min per eye and was performed on 7 patients with cerebral visual impairment (CVI), 8 patients with primary open angle glaucoma (age > 45), and 14 healthy, age/gender-matched controls. Results: For all patients, pupil oscillation power (FFT based response amplitude to flicker) was significantly weaker when the flickering disk was presented in the impaired as compared to the intact visual field (CVI: 12% |
Jo Black; David Williams; Heather J. Ferguson Imagining counterfactual worlds in autism spectrum disorder Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 44, no. 9, pp. 1444–1463, 2018. @article{Black2018, Two experiments are presented that explore online counterfactual processing in autism spectrum disorder (ASD) using eye-tracking. Participants' eye movements were tracked while they read factual and counterfactual sentences in an anomaly detection task. In Experiment 1, the sentences depicted everyday counterfactual situations (e.g., If Joanne had remembered her umbrella, her hair would have been dry/wet when she arrived home). Sentences in Experiment 2 depicted counterfactual versions of real world events (e.g., If the Titanic had not hit an iceberg, it would have survived/sunk along with all the passengers). Results from both experiments suggest that counterfactual understanding is undiminished in adults with ASD. In fact, participants with ASD were faster than Typically Developing (TD) participants to detect anomalies within realistic, discourse-based counterfactuals (Experiment 1). Detection was comparable for TD and ASD groups when understanding could be grounded in knowledge about reality (Experiment 2), though the 2 groups used subtly different strategies for responding to and recovering from counterfactual inconsistent words. These data argue against general difficulties in global coherence and complex integration in ASD. |
James Blundell; Steven Frisson; Anupam Chakrapani; Paul Gissen; Chris Hendriksz; Suresh Vijay; Andrew Olson Oculomotor abnormalities in children with Niemann-Pick type C Journal Article In: Molecular Genetics and Metabolism, vol. 123, no. 2, pp. 159–168, 2018. @article{Blundell2018, Niemann-Pick type C (NP-C) is a rare recessive disorder associated with progressive supranuclear gaze palsy. Degeneration occurs initially for vertical saccades and later for horizontal saccades. There are studies of oculo- motor degeneration in adult NP-C patients [1, 2] but no comparable studies in children. We used high-resolution video-based eye tracking to record monocular vertical and horizontal eye movements in 2 neurological NP-C pa- tients (children with clinically observable oculomotor abnormalities) and 3 pre-neurological NP-C patients (children without clinically observable oculomotor abnormalities). Saccade onset latency, saccade peak velocity and saccade curvature were compared to healthy controls (N= 77). NP-C patients had selective impairments of vertical sac- cade peak velocity and vertical saccade curvature, with slower peak velocities and greater curvature. Changes were more pronounced in neurological than pre-neurological patients, showing that these measures are sensitive to disease progress, but abnormal curvature and slowed downward saccades were present in both groups, showing that eye- tracking can register disease-related changes before these are evident in a clinical exam. Both slowing, curvature and the detailed characteristics of the curvature we observed are predicted by the detailed characteristics of RIMLF population codes. Onset latencies were not different from healthy controls. High-resolution video-based eye tracking is a promising sensitive and objective method to measure NP-C disease severity and neurological onset. It may also help evaluate responses to therapeutic interventions. |
James Blundell; Steven Frisson; Anupam Chakrapani; Shauna Kearney; Suresh Vijay; Anita MacDonald; Paul Gissen; Chris Hendriksz; Andrew Olson Markers of cognitive function in individuals with metabolic disease: Morquio syndrome and tyrosinemia type III Journal Article In: Cognitive Neuropsychology, vol. 35, no. 3-4, pp. 120–147, 2018. @article{Blundell2018a, We characterized cognitive function in two metabolic diseases. MPS–IVa (mucopolysaccharidosis IVa, Morquio) and tyrosinemia type III individuals were assessed using tasks of attention, language and oculomotor function. MPS–IVa individuals were slower in visual search, but the display size effects were normal, and slowing was not due to long reaction times (ruling out slow item processing or distraction). Maintaining gaze in an oculomotor task was difficult. Results implicated sustained attention and task initiation or response processing. Shifting attention, accumulating evidence and selecting targets were unaffected. Visual search was also slowed in tyrosinemia type III, and patterns in visual search and fixation tasks pointed to sustained attention impairments, although there were differences from MPS–IVa. Language was impaired in tyrosinemia type III but not MPS–IVa. Metabolic diseases produced selective cognitive effects. Our results, incorporating new methods for developmental data and model selection, illustrate how cognitive data can contribute to understanding function in biochemical brain systems. |
Jessica Bourgin; Nathalie Guyader; Alan Chauvin; Alexandra Juphard; Mathilde Sauvée; Olivier Moreaud; Laetitia Silvert; Pascal Hot Early emotional attention is impacted in Alzheimer's disease: An eye-tracking study Journal Article In: Journal of Alzheimer's Disease, vol. 63, no. 4, pp. 1445–1458, 2018. @article{Bourgin2018, Emotional deficits have been repetitively reported in Alzheimer's disease (AD) without clearly identifying how emotional processing is impaired in this pathology. This paper describes an investigation of early emotional processing, as measured by the effects of emotional visual stimuli on a saccadic task involving both pro (PS) and anti (AS) saccades. Sixteen patients with AD and 25 age-matched healthy controls were eye-tracked while they had to quickly move their gaze toward a positive, negative, or neutral image presented on a computer screen (in the PS condition) or away from the image (in the AS condition). The age-matched controls made more AS mistakes for negative stimuli than for other stimuli, and triggered PSs toward negative stimuli more quickly than toward other stimuli. In contrast, patients with AD showed no difference with regard to the emotional category in any of the tasks. The present study is the first to highlight a lack of early emotional attention in patients with AD. These results should be taken into account in the care provided to patients with AD, since this early impairment might seriously degrade their overall emotional functioning. |
Helen L. Breadmore; Julia M. Carroll Sublexical and syntactic processing during reading: Evidence from eye movements of typically developing and dyslexic readers Journal Article In: Journal of Cognitive Psychology, vol. 30, no. 2, pp. 177–197, 2018. @article{Breadmore2018, Skilled, typically developing readers and children with dyslexia read correct sentences and sentences that contained verb errors that were pseudo-homophones, morphological over-regularisations or syntactic errors. All errors increased looking time but the nature of the error and participant group influenced the time course of the effects. The pseudo-homophone effect was significant in all eye-movement measures for adults (N= 26), intermediate (N= 37) and novice typically developing readers (N= 38). This effect was larger for intermediate readers than other groups in total duration. In contrast, morphological over-regularisations increased gaze and total duration (but not first fixation) for intermediate and novice readers, and only total duration for adult readers. Syntactic errors only increased total duration. Children with dyslexia (N= 19) demonstrated smaller effects of pseudo-homophones and over-regularisations than controls, but their processing of syntactic errors was similar. We conclude that dyslexic children's difficulties with reading are linked to overreliance on phonological decoding and underspecified morphological processing, which impacts on word level reading. We highlight that the findings fit well within the grain-size model of word reading [Grainger, J., & Ziegler, J. C. (2011). A dual-route approach to orthographic processing. Frontiers in Psychology, 2, 54. doi:10.3389/fpsyg.2011.00054]. |
Aurélie Calabrèse; Carlos Aguilar; Géraldine Faure; Frédéric Matonti; Louis Hoffart; Eric Castet A vision enhancement system to improve face recognition with central vision loss Journal Article In: Optometry and Vision Science, vol. 95, no. 9, pp. 738–746, 2018. @article{Calabrese2018, SIGNIFICANCE: The overall goal of this work is to validate a low vision aid system that uses gaze as a pointing tool and provides smart magnification. We conclude that smart visual enhancement techniques as well as gaze contingency should improve the efficiency of assistive technology for the visually impaired. PURPOSE: A low vision aid, using gaze-contingent visual enhancement and primarily intended to help reading with central vision loss, was recently designed and tested with simulated scotoma. Here, we present a validation of this system for face recognition in age-related macular degeneration patients. METHODS: Twelve individuals with binocular central vision loss were recruited and tested on a face identification-matching task. Gaze position was measured in real time, thanks to an eye tracker. In the visual enhancement condition, at any time during the screen exploration, the fixated face was segregated from background and considered as a region of interest that could be magnified into a region of augmented vision by the participant, if desired. In the natural exploration condition, participants also performed the matching task but without the visual aid. Response time and accuracy were analyzed with mixed-effects models to (1) compare the performance with and without visual aid and (2) estimate the usability of the system. RESULTS: On average, the percentage of correct response for the natural exploration condition was 41%. This value was significantly increased to 63% with visual enhancement (95% confidence interval, 45 to 78%). For the large majority of our participants (83%), this improvement was accompanied by moderate increase in response time, suggesting a real functional benefit for these individuals. CONCLUSIONS Without visual enhancement, participants with age-related macular degeneration performed poorly, confirming their struggle for face recognition and the need to use efficient visual aids. Our system significantly improved face identification accuracy by 55%, proving to be helpful under laboratory conditions. |
Leanne Chukoskie; Marissa Westerfield; Jeanne Townsend A novel approach to training attention and gaze in ASD: A feasibility and efficacy pilot study Journal Article In: Developmental Neurobiology, vol. 78, no. 5, pp. 546–554, 2018. @article{Chukoskie2018, In addition to the social, communicative and behavioral symptoms that define the disorder, individuals with ASD have difficulty reorienting attention quickly and accurately. Similarly, fast reorienting saccadic eye movements are also inaccurate and more variable in both endpoint and timing. Atypical gaze and attention are among the earliest symptoms observed in ASD. Disruption of these foundation skills critically affects the development of higher level cognitive and social behavior. We propose that interventions aimed at these early deficits that support social and cognitive skills will be broadly effective. We conducted a pilot clinical trial designed to demonstrate the feasibility and preliminary efficacy of using gaze-contingent video games for low-cost in-home training of attention and eye movement. Eight adolescents with ASD participated in an 8-week training, with pre-, mid-and post-testing of eye movement and attention control. Six of the eight adolescents completed the 8 weeks of training and all six showed improvement in attention (orienting, disengagement) and eye movement control or both. All game systems remained intact for the duration of training and all participants could use the system independently. We delivered a robust, low-cost, gaze-contingent game system for home use that, in our pilot training sample, improved the attention orienting and eye movement performance of adolescent participants in 8 weeks of training. We are currently conducting a clinical trial to replicate these results and to examine what, if any, aspects of training transfer to more real-world tasks. |
Meaghan Clough; Steven Mutimer; David K. Wright; Adrian Tsang; Daniel M. Costello; Andrew J. Gardner; Peter Stanwell; Richelle Mychasiuk; Mujun Sun; Rhys D. Brady; Stuart J. McDonald; Kyria M. Webster; Maddison R. Johnstone; Bridgette D. Semple; Denes V. Agoston; Owen B. White; Richard Frayne; Joanne Fielding; Terence J. O'Brien; Sandy R. Shultz Oculomotor cognitive control abnormalities in Australian rules football players with a history of concussion Journal Article In: Journal of Neurotrauma, vol. 35, no. 5, pp. 730–738, 2018. @article{Clough2018, This study used oculomotor, cognitive, and multi-modal magnetic resonance imaging (MRI) measures to assess for neurological abnormalities in current asymptomatic amateur Australian rules footballers (i.e., Australia's most participated collision sport) with a history of sports-related concussion (SRC). Participants were 15 male amateur Australian rules football players with a history of SRC greater than 6 months previously, and 15 sex-, age-, and education-matched athlete control subjects that had no history of neurotrauma or participation in collision sports. Participants completed a clinical interview, neuropsychological measures, and oculomotor measures of cognitive control. MRI investigation involved structural imaging, as well as diffusion tensor imaging and resting-state functional MRI sequences. Despite no group differences on conventional neuropsychological tests and multi-modal MRI measures, Australian rules football players with a history of SRC performed significantly worse on an oculomotor switch task: a measure of cognitive control that interleaves the response of looking towards a target (i.e., a prosaccade) with the response of looking away from a target (i.e., an antisaccade). Specifically, Australian footballers performed significantly shorter latency prosaccades and found changing from an antisaccade trial to a prosaccade trial (switch cost) significantly more difficult than control subjects. Poorer switch cost was related to poorer performance on a number of neuropsychological measures of inhibitory control. Further, when comparing performance on the cognitively more demanding switch task with performance on simpler, antisaccade/prosaccades tasks which require a single response, Australian footballers demonstrated a susceptibility to increased cognitive load, compared to the control group who were unaffected. These initial results suggest that current asymptomatic amateur Australian rules football players with a history of SRC may have persisting, subtle, cognitive changes, which are demonstrable on oculomotor cognitive measures. Future studies are required in order to further elucidate the full nature and clinical relevance of these findings. |
Luca Wollenberg; Heiner Deubel; Martin Szinte Visual attention is not deployed at the endpoint of averaging saccades Journal Article In: PLoS Biology, vol. 16, no. 6, pp. e2006548, 2018. @article{Wollenberg2018, The premotor theory of attention postulates that spatial attention arises from the activation of saccade areas and that the deployment of attention is the consequence of motor programming. Yet attentional and oculomotor processes have been shown to be dissociable at the neuronal level in covert attention tasks. To investigate a potential dissociation at the behavioral level, we instructed human participants to move their eyes (saccade) towards 1 of 2 nearby, competing saccade targets. The spatial distribution of visual attention was determined using oriented visual stimuli presented either at the target locations, between them, or at several other equidistant locations. Results demonstrate that accurate saccades towards one of the targets were associated with presaccadic enhancement of visual sensitivity at the respective saccade endpoint compared to the nonsaccaded target location. In contrast, averaging saccades, landing between the 2 targets, were not associated with attentional facilitation at the saccade endpoint. Rather, attention before averaging saccades was equally deployed at the 2 target locations. Taken together, our results reveal that visual attention is not obligatorily coupled to the endpoint of a subsequent saccade. Rather, our results suggest that the oculomotor program depends on the state of attentional selection before saccade onset and that saccade averaging arises from unresolved attentional selection. |
Chia-Chien Wu; Bo Cao; Veena Dali; Celia Gagliardi; Olivier J. Barthelemy; Robert D. Salazar; Marc Pomplun; Alice Cronin-Golomb; Arash Yazdanbakhsh Eye movement control during visual pursuit in Parkinson's disease Journal Article In: PeerJ, vol. 2018, no. 8, pp. 1–22, 2018. @article{Wu2018c, Background: Prior studies of oculomotor function in Parkinson's disease (PD) have either focused on saccades without considering smooth pursuit, or tested smooth pursuit while excluding saccades. The present study investigated the control of saccadic eye movements during pursuit tasksand assessed the quality of binocular coordinationas potential sensitive markers of PD. Methods: Observers fixated on a central cross while a target moved toward it. Once the target reached the fixation cross, observers began to pursue the moving target. To further investigate binocular coordination, the moving target was presented on both eyes (binocular condition), or on one eye only (dichoptic condition). Results: The PD group made more saccades than age-matched normal control adults (NC) both during fixation and pursuit. The difference between left and right gaze positions increased over time during the pursuit period for PD but not for NC. The findings were not related to age, as NC and young-adult control group (YC) performed similarly on most of the eye movement measures, and were not correlated with classical measures of PD severity (e.g., Unified Parkinson's Disease Rating Scale (UPDRS) score). Discussion: Our results suggest that PD may be associated with impairment not only in saccade inhibition, but also in binocular coordination during pursuit, and these aspects of dysfunction may be useful in PD diagnosis or tracking of disease course. |
Rachel Yep; Stephen Soncin; Donald C. Brien; Brian C. Coe; Alina Marin; Douglas P. Munoz In: Brain and Cognition, vol. 124, pp. 1–13, 2018. @article{Yep2018, Despite distinct diagnostic criteria, attention-deficit hyperactivity disorder (ADHD) and bipolar disorder (BD) share cognitive and emotion processing deficits that complicate diagnoses. The goal of this study was to use an emotional saccade task to characterize executive functioning and emotion processing in adult ADHD and BD. Participants (21 control, 20 ADHD, 20 BD) performed an interleaved pro/antisaccade task (look toward vs. look away from a visual target, respectively) in which the sex of emotional face stimuli acted as the cue to perform either the pro- or antisaccade. Both patient groups made more direction (erroneous prosaccades on antisaccade trials) and anticipatory (saccades made before cue processing) errors than controls. Controls exhibited lower microsaccade rates preceding correct anti- vs. prosaccade initiation, but this task-related modulation was absent in both patient groups. Regarding emotion processing, the ADHD group performed worse than controls on neutral face trials, while the BD group performed worse than controls on trials presenting faces of all valence. These findings support the role of fronto-striatal circuitry in mediating response inhibition deficits in both ADHD and BD, and suggest that such deficits are exacerbated in BD during emotion processing, presumably via dysregulated limbic system circuitry involving the anterior cingulate and orbitofrontal cortex. |
Xiaoli Zhang; Julie D. Golomb Target localization after saccades and at fixation: Nontargets both facilitate and bias responses Journal Article In: Visual Cognition, vol. 26, no. 9, pp. 734–752, 2018. @article{Zhang2018c, The image on our retina changes every time we make an eye movement. To maintain visual stability after saccades, specifically to locate visual targets, we may use nontarget objects as “landmarks”. In the current study, we compared how the presence of nontargets affects target localization after saccades and during sustained fixation. Participants fixated a target object, which either maintained its location on the screen (sustained-fixation trials), or displaced to trigger a saccade (saccade trials). After the target disappeared, participants reported the most recent target location with a mouse click. We found that the presence of nontargets decreased response error magnitude and variability. However, this nontarget facilitation effect was not larger for saccade trials than sustained-fixation trials, indicating that nontarget facilitation might be a general effect for target localization, rather than of particular importance to post-saccadic stability. Additionally, participants' responses were biased towards the nontarget locations, particularly when the nontarget-target relationships were preserved in relative coordinates across the saccade. This nontarget bias interacted with biases from other spatial references, e.g., eye movement paths, possibly in a way that emphasized non-redundant information. In summary, the presence of nontargets is one of several sources of reference that combine to influence (both facilitate and bias) target localization. |
Eckart Zimmermann; M. Concetta Morrone; P. Binda Perception during double-step saccades Journal Article In: Scientific Reports, vol. 8, pp. 320, 2018. @article{Zimmermann2018, How the visual system achieves perceptual stability across saccadic eye movements is a long-standing question in neuroscience. It has been proposed that an efference copy informs vision about upcoming saccades, and this might lead to shifting spatial coordinates and suppressing image motion. Here we ask whether these two aspects of visual stability are interdependent or may be dissociated under special conditions. We study a memory-guided double-step saccade task, where two saccades are executed in quick succession. Previous studies have led to the hypothesis that in this paradigm the two saccades are planned in parallel, with a single efference copy signal generated at the start of the double-step sequence, i.e. before the first saccade. In line with this hypothesis, we find that visual stability is impaired during the second saccade, which is consistent with (accurate) efference copy information being unavailable during the second saccade. However, we find that saccadic suppression is normal during the second saccade. Thus, the second saccade of a double-step sequence instantiates a dissociation between visual stability and saccadic suppression: stability is impaired even though suppression is strong. |
Clara Mestre; Carles Otero; Fernando Díaz-Doutón; Josselin Gautier; Jaume Pujol An automated and objective cover test to measure heterophoria Journal Article In: PLoS ONE, vol. 13, no. 11, pp. e0206674, 2018. @article{Mestre2018, Heterophoria is the relative deviation of the eyes in absence of fusional vergence. Fusional vergence can be deprived by, for example, occluding one eye while the other fixates a visual target. Then, the occluded eye will presumably deviate from its initial position by an amount that corresponds to the heterophoria. Its assessment in clinical practice is crucial for the diagnosis of non-strabismic binocular dysfunctions such as convergence insufficiency. Traditional clinical methods, like the cover test or the modified Thorington test, suffer from practitioner's subjectivity, impossibility to observe the occluding eye or unusual viewing conditions. These limitations could be overcome by using eye tracking systems to measure objectively the heterophoria. The main purpose of this study was to compare the performance of an automated and objective method to measure near heterophoria using an eye-tracker with two conventional methods: the cover-uncover test and the modified Thorington test. The eye tracking method gave us the possibility to measure the heterophoria as the deviation of the occluded eye (mimicking the cover test) or as the deviations of the occluded and fixating eyes (adhering to the theoretical definition of heterophoria). The latter method provided smaller results than the former, although on average the differences might not be clinically relevant. The proposed objective method exhibited considerably better repeatabil-ity than the two conventional clinical methods. It showed better agreement with the modified Thorington test than with the cover-uncover test, and a similar level of agreement was obtained between the two clinical methods. To conclude, the use of eye-trackers to measure heterophoria provides objective and more repeatable measures. As eye-trackers become common tools in clinical settings, their use to measure heterophoria should be the new gold standard. |
Andra Mihali; Allison G. Young; Lenard A. Adler; Michael M. Halassa; Wei Ji Ma A low-level perceptual correlate of behavioral and clinical deficits in ADHD Journal Article In: Computational Psychiatry, vol. 2, pp. 141–163, 2018. @article{Mihali2018, In many studies of attention-deficit hyperactivity disorder (ADHD), stimulus encoding and processing (perceptual function) and response selection (executive function) have been intertwined. To dissociate deficits in these functions, we introduced a task that parametrically varied low-level stimulus features (orientation and color) for fine-grained analysis of perceptual function. It also required participants to switch their attention between feature dimensions on a trial-by-trial basis, thus taxing executive processes. Furthermore, we used a response paradigm that captured task-irrelevant motor output (TIMO), reflecting failures to use the correct stimulus-response rule. ADHD participants had substantially higher perceptual variability than controls, especially for orientation, as well as higher TIMO. In both ADHD and controls, TIMO was strongly affected by the switch manipulation. Across participants, the perceptual variability parameter was correlated with TIMO, suggesting that perceptual deficits are associated with executive function deficits. Based on perceptual variability alone, we were able to classify participants into ADHD and controls with a mean accuracy of about 77%. Participants' self-reported General Executive Composite score correlated not only with TIMO but also with the perceptual variability parameter. Our results highlight the role of perceptual deficits in ADHD and the usefulness of computational modeling of behavior in dissociating perceptual from executive processes. |
Elena Mikulskaya; Frances Heritage Martin Contrast sensitivity and motion discrimination in cannabis users Journal Article In: Psychopharmacology, vol. 235, no. 8, pp. 2459–2469, 2018. @article{Mikulskaya2018, Rationale: Cannabis use impairs visual attention; however, it is unclear whether cannabis use also impairs low level visual processing or whether low level visual deficits can be related to lower dopaminergic functioning found in cannabis users. Objectives: To investigate whether spatiotemporal contrast sensitivity and motion discrimination under normal and low lumi- nance conditions differ in cannabis users and non-users. Methods: Control (n = 20) and cannabis (n = 21) participants completed a visual acuity test, a saliva test and self-report measures. Spatial and temporal contrast thresholds, motion coherence thresholds for translational and radial motion and the spontaneous eye blink rate were then collected. Results: Cannabis users showed decreased spatial contrast sensitivity under low luminance conditions and increased motion coherence thresholds under all luminance levels tested compared to non-users. No differences in temporal contrast sensitivity were found between the groups. Frequency ofcannabis use correlated significantly and negatively with contrast sensitivity, both spatial and temporal, in the cannabis group and higher motion coherence thresholds for radial motion were also associated with more frequent cannabis use in this group. The eye blink rate was significantly lower in cannabis users compared to non-users. Conclusions: The present study shows that cannabis use is associated with deficits in low level visual processing. Such deficits are suggested to relate to lower dopamine, in a similar manner as in clinical populations. The implications for driving safety under reduced visibility (e.g. night) in abstaining cannabis users are discussed. |
Rachel Millin; Tamar Kolodny; Anastasia V. Flevaris; Alexander M. Kale; Michael Paul Schallmo; Jennifer Gerdts; Raphael A. Bernier; Scott Murray Reduced auditory cortical adaptation in autism spectrum disorder Journal Article In: eLife, vol. 7, pp. 1–15, 2018. @article{Millin2018, <p>Adaptation is a fundamental property of cortical neurons and has been suggested to be altered in individuals with autism spectrum disorder (ASD). We used fMRI to measure adaptation induced by repeated audio-visual stimulation in early sensory cortical areas in individuals with ASD and neurotypical (NT) controls. The initial transient responses were equivalent between groups in both visual and auditory cortices and when stimulation occurred with fixed-interval and randomized-interval timing. However, in auditory but not visual cortex, the post-transient sustained response was greater in individuals with ASD than NT controls in the fixed-interval timing condition, reflecting reduced adaptation. Further, individual differences in the sustained response in auditory cortex correlated with ASD symptom severity. These findings are consistent with hypotheses that ASD is associated with increased neural responsiveness but that responsiveness differences only manifest after repeated stimulation, are specific to the temporal pattern of stimulation, and are confined to specific cortical regions.</p> |
Olga Mishulina; Olga Skripko; Anastasia Korosteleva Some features of eye movements during reading and retelling the text by people with stuttering Journal Article In: Procedia Computer Science, vol. 123, pp. 328–333, 2018. @article{Mishulina2018, The connection between cognitive processes and the movement of the human eye during the reading and retelling the text is investigated. A series of experiments were performed, in which people with normal speech, people with stuttering and in the treatment stage of stuttering took part. The results of the experiment were fixed by the eye tracker and the functional magnetic resonance tomograph. The statistical processing of the tracking data was performed, which discovered stable differences of fixation duration in groups of participants when performing test tasks. |
Kentaro Morita; Kenichiro Miura; Michiko Fujimoto; Emiko Shishido; Tomoko Shiino; Junichi Takahashi; Hidenaga Yamamori; Yuka Yasuda; Noriko Kudo; Yoji Hirano; Daisuke Koshiyama; Naohiro Okada; Manabu Ikeda; Toshiaki Onitsuka; Norio Ozaki; Kiyoto Kasai; Ryota Hashimoto Abnormalities of eye movement are associated with work hours in schizophrenia Journal Article In: Schizophrenia Research, vol. 202, pp. 420–422, 2018. @article{Morita2018, Eye movement abnormalities have been reported in schizophrenia; however, their influences on everyday life remain unknown. From data on 69 subjects with schizophrenia and 246 healthy subjects, we found positive correlations between eye movement measures and work hours, which were only significant in subjects with schizophrenia. This relationship was also confirmed in a multi-site dataset including 118 subjects with schizophrenia and 280 healthy subjects. These findings further strengthen our understanding of eye movement abnormalities and their relevance in clinical recovery. |
Christoph Naegeli; Thomas Zeffiro; Marco Piccirelli; Assia Jaillard; Anina Weilenmann; Katayun Hassanpour; Matthis Schick; Michael Rufer; Scott P. Orr; Christoph Mueller-Pfeiffer Locus coeruleus activity mediates hyperresponsiveness in posttraumatic stress disorder Journal Article In: Biological Psychiatry, vol. 83, no. 3, pp. 254–262, 2018. @article{Naegeli2018, Background: Patients with posttraumatic stress disorder (PTSD) are hyperresponsive to unexpected or potentially threatening environmental stimuli. Research in lower animals and humans suggests that sensitization of the locus coeruleus–norepinephrine system may underlie behavioral and autonomic hyperresponsiveness in PTSD. However, direct evidence linking locus coeruleus system hyperactivity to PTSD hyperresponsiveness is sparse. Methods: Psychophysiological recording and functional magnetic resonance imaging were used during passive listening to brief, 95-dB sound pressure level, white noise bursts presented intermittently to determine whether behavioral and autonomic hyperresponsiveness to sudden sounds in PTSD is associated with locus coeruleus hyperresponsiveness. Results: Participants with PTSD (n = 28) showed more eye-blink reflexes and larger heart rate, skin conductance, and pupil area responses to loud sounds (multivariate p =.007) compared with trauma-exposed participants without PTSD (n = 26). PTSD participants exhibited larger responses in locus coeruleus (t = 2.60, region of interest familywise error corrected), intraparietal sulcus, caudal dorsal premotor cortex, and cerebellar lobule VI (t ≥ 4.18, whole-brain familywise error corrected). Caudal dorsal premotor cortex activity was associated with both psychophysiological response magnitude and levels of exaggerated startle responses in daily life in PTSD participants (t ≥ 4.39, whole-brain familywise error corrected). Conclusions: Behavioral and autonomic hyperresponsiveness in PTSD may arise from a hyperactive alerting/orienting system in which processes related to attention and motor preparation localized to lateral premotor cortex, intraparietal sulcus, and posterior superior cerebellar cortex are modulated by atypically high phasic noradrenergic influences originating in the locus coeruleus. |
Martijn J. Schut; Nathan Van der Stoep; Jasper H. Fabius; Stefan Van der Stigchel Feature integration is unaffected by saccade landing point, even when saccades land outside of the range of regular oculomotor variance Journal Article In: Journal of Vision, vol. 18, no. 7, pp. 1–17, 2018. @article{Schut2018, The experience of our visual surroundings appears continuous, contradicting the erratic nature of visual processing due to saccades. A possible way the visual system can construct a continuous experience is by integrating presaccadic and postsaccadic visual input. However, saccades rarely land exactly at the intended location. Feature integration would therefore need to be robust against variations in saccade execution to facilitate visual continuity. In the current study, observers reported a feature (color) of the saccade target, which occasionally changed slightly during the saccade. In transsaccadic change-trials, observers reported a mixture of the pre- and postsaccadic color, indicating transsaccadic feature integration. Saccade landing distance was not a significant predictor of the reported color. Next, to investigate the influence of more extreme deviations of saccade landing point on color reports, we used a global effect paradigm in a second experiment. In global effect trials, a distractor appeared together with the saccade target, causing most saccades to land in between the saccade target and the distractor. Strikingly, even when saccades land further away (up to 4°) from the saccade target than one would expect under single target conditions, there was no effect of saccade landing point on the reported color. We reason that saccade landing point does not affect feature integration, due to dissociation between the intended saccade target and the actual saccade landing point. Transsaccadic feature integration seems to be a mechanism that is dependent on visual spatial attention, and, as a result, is robust against variance in saccade landing point. |
Martijn J. Schut; Nathan Van der Stoep; Stefan Van der Stigchel Auditory spatial attention is encoded in a retinotopic reference frame across eye-movements Journal Article In: PLoS ONE, vol. 13, no. 8, pp. e020414, 2018. @article{Schut2018a, The retinal location of visual information changes each time we move our eyes. Although it is now known that visual information is remapped in retinotopic coordinates across eye movements (saccades), it is currently unclear how head-centered auditory information is remapped across saccades. Keeping track of the location of a sound source in retinotopic coordinates requires a rapid multi-modal reference frame transformation when making saccades. To reveal this reference frame transformation, we designed an experiment where participants attended an auditory or visual cue and executed a saccade. After the saccade had landed, an auditory or visual target could be presented either at the prior retinotopic location or at an uncued location. We observed that both auditory and visual targets presented at prior retinotopic locations were reacted to faster than targets at other locations. In a second experiment, we observed that spatial attention pointers obtained via audition are available in retinotopic coordinates immediately after an eye-movement is made. In a third experiment, we found evidence for an asymmetric cross-modal facilitation of information that is presented at the retinotopic location. In line with prior single cell recording studies, this study provides the first behavioral evidence for immediate auditory and cross-modal transsaccadic updating of spatial attention. These results indicate that our brain has efficient solutions for solving the challenges in localizing sensory input that arise in a dynamic context. |
Joshua A. Seideman; Terrence R. Stanford; Emilio Salinas Saccade metrics reflect decision-making dynamics during urgent choices Journal Article In: Nature Communications, vol. 9, pp. 2907, 2018. @article{Seideman2018, A perceptual judgment is typically characterized by constructing psychometric and chronometric functions, i.e., by mapping the accuracies and reaction times of motor choices as functions of a sensory stimulus feature dimension. Here, we show that various saccade metrics (e.g., peak velocity) are similarly modulated as functions of sensory cue viewing time during performance of an urgent-decision task. Each of the newly discovered functions reveals the dynamics of the perceptual evaluation process inherent to the underlying judgment. Remarkably, saccade peak velocity correlates with statistical decision confidence, suggesting that saccade kinematics reflect the degree of certainty with which an urgent perceptual decision is made. The data were explained by a race-to-threshold model that also replicates standard performance measures and cortical oculomotor neuronal activity in the task. The results indicate that, although largely stereotyped, saccade metrics carry subtle but reliable traces of the underlying cognitive processes that give rise to each oculomotor choice. |
David Souto; Sabine Born; Dirk Kerzel The contribution of forward masking to saccadic inhibition of return Journal Article In: Attention, Perception, and Psychophysics, vol. 80, no. 5, pp. 1182–1192, 2018. @article{Souto2018, Inhibition of return is the name typically given to the prolonged latency of motor responses directed to a previously cued target location. There is intense debate about the origins of this effect and its function, but most take for granted (despite lack of evidence) that it depends little on forward masking. Therefore, we re-examined the role of forward masking in inhibition of return. Forward masking was indexed by slower saccadic reaction times (SRTs) when the target orientation repeated the cue orientation at the same location. We confirmed effects of orientation repetition in the absence of an attentional bias when cues were presented on both sides of fixation (bilateral presentation). The effect of orientation repetition was reduced with high target contrast, consistent with a low-level origin such as contrast gain control in early visual areas. When presenting cues on only one side of fixation (unilateral presentation), we obtained inhibition of return with longer cue-target intervals and facilitation with targets presented shortly after the cue. The effect of orientation repetition was reduced when facilitation was observed, but was as strong as with bilateral cues when inhibition of return was observed. Therefore, forward masking may contribute to the inhibition of return effect by delaying reaction times to repeated features at the same location, but is not a principal cause of inhibition of return; in agreement with previous views. |
Jacob L. Stubbs; Sherryse L. Corrow; Benjamin R. Kiang; William J. Panenka; Jason J. S. Barton The effects of enhanced attention and working memory on smooth pursuit eye movement Journal Article In: Experimental Brain Research, vol. 236, no. 2, pp. 485–495, 2018. @article{Stubbs2018, It has long been suggested that increasing attentional demands can alter smooth pursuit eye movements, but the precise nature of the changes generated is not clear. Our goal was to examine smooth pursuit with a task that enhanced attention to the target and that increased demands on working memory, without distracting from the target. 15 subjects tracked a target moving around a predictable circular trajectory at a constant tangential velocity. An n-back task with two levels of additional working memory load was integrated into the pursuit target to increase cognitive demands. In the single-task conditions, subjects either performed pursuit alone or the n-back task with a stationary target. In the dual-task conditions, pursuit and the n-back task were performed together. Performance of the n-back tasks was not impaired by simultaneous smooth pursuit. The n-back tasks had negligible effects on horizontal or vertical pursuit gain, but generated increased phase lag and reduced the variability of position error during pursuit. Increasing the difficulty of the n-back task further reduced the variability of position errors. We conclude that enhanced attention does not alter the velocity gain of smooth pursuit but rather improves its consistency. As long as attention remains focused on the target, increased attentional demands further reduce pursuit variability. Increases in phase lag may serve to improve attentional processing of the target. |
Martin Szinte; Donatas Jonikaitis; Dragan Rangelov; Heiner Deubel Pre-saccadic remapping relies on dynamics of spatial attention Journal Article In: eLife, vol. 7, pp. 1–16, 2018. @article{Szinte2018, Each saccade shifts the projections of the visual scene on the retina. It has been proposed that the receptive fields of neurons in oculomotor areas are predictively remapped to account for these shifts. While remapping of the whole visual scene seems prohibitively complex, selection by attention may limit these processes to a subset of attended locations. Because attentional selection consumes time, remapping of attended locations should evolve in time, too. In our study, we cued a spatial location by presenting an attention-capturing cue at different times before a saccade and constructed maps of attentional allocation across the visual field. We observed no remapping of attention when the cue appeared shortly before saccade. In contrast, when the cue appeared sufficiently early before saccade, attentional resources were reallocated precisely to the remapped location. Our results show that pre-saccadic remapping takes time to develop suggesting that it relies on the spatial and temporal dynamics of spatial attention. |
Jérôme Tagu; Karine Doré-Mazars; Judith Vergne; Christelle Lemoine-Lardennois; Dorine Vergilino-Perez Recentering bias for temporal saccades only: Evidence from binocular recordings of eye movements Journal Article In: Journal of Vision, vol. 18, no. 1, pp. 1–16, 2018. @article{Tagu2018a, It is well known that the saccadic system presents multiple asymmetries. Notably, temporal (as opposed to nasal) saccades, centripetal (as opposed to centrifugal) saccades (i.e., the recentering bias) and saccades from the abducting eye (as opposed to the concomitant saccades from the adducting eye) exhibit higher peak velocities. However, these naso-temporal and centripetal-centrifugal asymmetries have always been studied separately. It is thus unknown which asymmetry prevails when there is a confli ct between both asymmetries, i.e., in case of centripetal nasal saccades or centrifugal temporal saccades. This study involved binocular recordings of eye movements to examine both the naso-temporal and centripetal-centrifugal asymmetries so as to determine how they work together. Twenty-eight participants had to make saccades toward stimuli presented either centrally or in the periphery in binocular conditions. We found that temporal and abducting saccades always exhibit higher peak velocities than nasal and adducting saccades, irrespective of their centripetal or centrifugal nature. However, we showed that the velocity advantage for centripetal saccades is only found for temporal and not for nasal saccades. Such a result is of importance as it could provide new insights about the physiological origins of the asymmetries found in the saccadic system. |
Jérôme Tagu; Karine Doré-Mazars; Judith Vergne; Christelle Lemoine-Lardennois; Dorine Vergilino-Perez Quantifying eye dominance strength – New insights into the neurophysiological bases of saccadic asymmetries Journal Article In: Neuropsychologia, vol. 117, pp. 530–540, 2018. @article{Tagu2018, The saccadic system presents asymmetries. Notably, saccadic peak velocity is higher in temporal than in nasal saccades, and in centripetal than in centrifugal saccades. It has already been shown that eye dominance strength relates to naso-temporal asymmetry, but its links with centripetal-centrifugal asymmetry has never been tested. The current study tested both naso-temporal and centripetal-centrifugal asymmetries simultaneously to provide a finer and continuous measure of eye dominance strength. We asked 63 participants to make centripetal and centrifugal saccades from five different locations. Analysis of saccadic peak velocity shows that eye dominance strength modulates every saccadic asymmetry tested. For the first time, we propose a graduated measure of eye dominance strength on a continuum model. The model ranges from weak to very strong eye dominance. Weak eye dominance corresponds to increased saccadic asymmetries whereas strong eye dominance corresponds to no asymmetries. Furthermore, our results provide new insights into the neurophysiological origins of saccadic asymmetries. Modulation of both naso-temporal and centripetal-centrifugal asymmetries by eye dominance strength supports the involvement of V1 in these saccadic asymmetries. |
Jordy Thielen; Rob Lier; Marcel A. J. Gerven No evidence for confounding orientation-dependent fixational eye movements under baseline conditions Journal Article In: Scientific Reports, vol. 8, pp. 11644, 2018. @article{Thielen2018, Decoding has become a standard analysis technique for contemporary cognitive neuroscience. Already more than a decade ago, it was shown that orientation information could be decoded from functional magnetic resonance imaging voxel time series. However, the underlying neural mechanism driving the decodable information is still under debate. Here, we investigated whether eye movements and pupil dilation during attempted fixation and passive viewing of visually presented square-wave grating stimuli could explain orientation decoding. We hypothesized that there are confounding orientation-dependent fixational eye movements (e.g., microsaccades), which systematically alter brain activity, and hence can be the source of decodable information. We repeated one of the original orientation decoding studies, but recorded eye movements instead of brain activity. We found no evidence that stimulus orientation can be decoded from eye movements under baseline conditions, but cannot rule out the potential confounding effect of eye movements under different conditions. With this study, we emphasize the importance, and show the implications of such potential confounding eye movements for decoding studies and cognitive neuroscience in general. |
Philip Tseng; Mu-Chen Wang; Yu Hui Lo; Chi-Hung Juan Anodal and cathodal tDCS over the right frontal eye fields impacts spatial probability processing differently in pro- and anti-saccades Journal Article In: Frontiers in Neuroscience, vol. 12, pp. 421, 2018. @article{Tseng2018, Learning regularities that exist in the environment can help the visual system achieve optimal efficiency while reducing computational burden. Using a pro-and anti-saccade task, studies have shown that probabilistic information regarding spatial locations can be a strong modulator of frontal eye fields (FEF) activities and consequently alter saccadic behavior. One recent study has also shown that FEF activities can be modulated by transcranial direct current stimulation, where anodal tDCS facilitated prosaccades but cathodal tDCS prolonged antisaccades. These studies together suggest that location probability and tDCS can both alter FEF activities and oculomotor performance, yet how these two modulators interact with each other remains unclear. In this study, we applied anodal or cathodal tDCS over right FEF, and participants performed an interleaved pro-and anti-saccade task. Location probability was manipulated in prosaccade trials but not antisaccade trials. We observed that anodal tDCS over rFEF facilitated prosaccdes toward low-probability locations but not to high-probability locations; whereas cathodal tDCS facilitated antisaccades away from the high-probability location (i.e., same location as the low-probability locations in prosaccades). These observed effects were specific to rFEF as tDCS over the SEF in a separate control experiment did not yield similar patterns. These effects were also more pronounced in low-performers who had slower saccade reaction time. Together, we conclude that (1) the overlapping spatial endpoint between prosaccades (i.e., toward low-probability location) and antisaccades (i.e., away from high-probability location) possibly suggest an endpoint-selective mechanism within right FEF, (2) anodal tDCS and location probability cannot be combined to produce a bigger facilitative effect, and (3) anodal rFEF tDCS works best on low-performers who had slower saccade reaction time. These observations are consistent with the homeostasis account of tDCS effect and FEF functioning. |
Jonathan Leeuwen; Artem V. Belopolsky Distractor displacements during saccades are reflected in the time-course of saccade curvature Journal Article In: Scientific Reports, vol. 8, pp. 2469, 2018. @article{Leeuwen2018, Every time we make a saccade we form a prediction about where objects are going to be when the eye lands. This is crucial since the oculomotor system is retinotopically organized and every saccade drastically changes the projection of objects on the retina. We investigated how quickly the oculomotor system accommodates new spatial information when a distractor is displaced during a saccade. Participants performed sequences of horizontal and vertical saccades and oculomotor competition was induced by presenting a task-irrelevant distractor before the first saccade. On half of the trials the distractor remained in the same location after the first saccade and on the other half the distractor moved during the first saccade. Curvature of the second saccade was used to track target-distractor competition. At short intersaccadic intervals, saccades curved away from the original distractor location, confirming that in the oculomotor system spatiotopic representations emerge rapidly and automatically. Approximately 190 ms after the first saccade, second saccades curved away from the new distractor location. These results show that after a saccade the oculomotor system is initially driven by the spatial prediction made before the saccade, but it is able to quickly update these spatial predictions based on new visual information. |
Chin-An Wang; Jeff Huang; Rachel Yep; Douglas P. Munoz Comparing pupil light response modulation between saccade planning and working memory Journal Article In: Journal of Cognition, vol. 1, no. 1, pp. 1–14, 2018. @article{Wang2018g, The signature of spatial attention effects has been demonstrated through saccade planning and working memory. Although saccade planning and working memory have been commonly linked to attention, the comparison of effects resulting from saccade planning and working memory is less explored. It has recently been shown that spatial attention interacts with local luminance at the attended location. When bright and dark patch stimuli are presented simultaneously in the periphery, thereby producing no change in global luminance, pupil size is nonetheless smaller when the locus of attention overlaps with the bright, compared to the dark patch stimulus (referred to as the local luminance modulation). Here, we used the local luminance modulation to directly compare the effects of saccade planning and spatial working memory. Participants were required to make a saccade towards a visual target location (visual-delay) or a remembered target location (memory-delay) after a variable delay, and the bright and dark patch stimuli were presented during the delay period between target onset and go signal. Greater pupil constriction was observed when the bright patch, compared to the dark patch, was spatially aligned with the target location in both tasks. However, the effects were diminished when there was no contingency implemented between the patch and target locations, particularly in the memory-delay task. Together, our results suggest the involvement of similar, but not identical, attentional mechanisms through saccade planning and working memory, and highlight a promising potential of local pupil luminance responses for probing visuospatial processing. |
Wen Wen; Sujia Wu; Shu Wang; Leilei Zou; Yan Liu; Rui Liu; Peng Zhang; Sheng He; Hong Liu A novel dichoptic optokinetic nystagmus paradigm to quantify interocular suppression in monocular amblyopia Journal Article In: Investigative Ophthalmology & Visual Science, vol. 59, pp. 4775–4782, 2018. @article{Wen2018a, PURPOSE. To develop a novel dichoptic optokinetic nystagmus (OKN) paradigm and investigate its effectiveness in objectively quantifying the interocular suppression in subjects with monocular amblyopia. METHODS. Centripetal moving gratings with different contrast ratios and constant velocity were dichoptically presented to eight monocular anisometropic amblyopes and eight normal subjects. We analyzed the OKN records with an eye tracker (EyeLink; SR-Research, Ontario, Canada) to obtain the relationship between ocular-dominance of OKN and the interocular contrast ratio by fitting power curves, and examined the correlation between the effective contrast ratio for a balanced OKN and the visual acuity of the amblyopic eye in amblyopes. RESULTS. In normal subjects, the OKN pursuit times were roughly balanced for opposite directions when stimulated with centripetal gratings of same contrast; however, in amblyopes, the OKN pursuit times of the dominant eye exceeded that of the amblyopic eye. Increasing the contrast of one eye's grating led to an increase in its OKN dominance. The OKN directional ratio (y) could be well fitted by a power function of the interocular contrast ratio (x): y ¼ axb. Moreover, in amblyopes, the effective contrast ratio (xb) for a balanced OKN correlated significantly positively with the visual acuity of the amblyopic eye (Spearman's correlation coefficient, 0.9698). CONCLUSIONS. The OKN induced by dichoptic gratings moving centripetally could be used as a reliable measure to objectively quantify the interocular suppression. This paradigm, avoiding the need for subjective report from patients, offers a promising alternative index for research on the mechanisms of amblyopia and in clinical practice. |
Chinh T. Nguyen; Christine Goh; Patricia Desmond; Larry A. Abel; Chris H. L. Lim; R. C. Andrew Symons; Thomas G. Hardy Congenital achiasma and see-saw nystagmus in VATER syndrome association with hydrocephalus Journal Article In: Journal of Clinical Neuroscience, vol. 51, pp. 63–65, 2018. @article{Nguyen2018, Congenital achiasma, characterized by the absence of decussation of nasal optic nerve fibers, is an unique disorder which may possess a genetic aetiology [1]. VATER/VACTERL association is a congenital condition defined by the presence of at least three of the following malformations: vertebral defects, anal atresia, cardiac defects, trachea-esophageal fistula, renal anomalies and limb abnormalities [2]. We describe, to the best of our knowledge, the first case of congenital achiasma and see-saw nystagmus in a patient with VATER association who also had hydrocephalus. |
Ewa Niechwiej-Szwedo; Anthony Tapper; David A. Gonzalez; Ryan M. Bradley; Robin Duncan Saccade latency delays in young apolipoprotein E (APOE) epsilon 4 carriers Journal Article In: Behavioural Brain Research, vol. 353, pp. 91–97, 2018. @article{NiechwiejSzwedo2018, The apolipoprotein E (APOE) epsilon 4 isoform has been associated with a significantly greater risk of developing late onset Alzheimer's disease (AD). However, the negative effects of APOE-ε4 allele on cognitive function vary across the lifespan: reduced memory and executive function have been found in older individuals but, paradoxically, young APOE-ε4 carriers perform better on cognitive tests and show higher neural efficiency. This study aimed to assess the association between APOE genotype and saccade latency using a prosaccade and antisaccade task in young individuals (N = 97, age: 17–35 years). Results showed that prosaccade latency was significantly delayed in a group of ε4 carriers in comparison to non-carriers, which was due to a lower rate of signal accumulation rather than a change in the criterion threshold. In contrast, there was no significant genotype difference for antisaccade latency in this young cohort. These results indicate that prosaccade latency may be useful in establishing the APOE behavioural phenotype, which could ultimately assist with distinguishing between normal and pathological aging. |