EyeLink Clinical and Oculomotor Eye-Tracking Publications
EyeLink clinical and oculomotor research publications up until 2023 (with some early 2024s) are listed below by year. You can search the publications using keywords such as Saccadic Adaptation, Schizophrenia, Nystagmus, etc. You can also search for individual author names, and limit searches by year (choose the year then click the search button). If we missed any EyeLink clinical or oculomotor articles, please email us!
2018 |
Alain Guillaume; Jason R. Fuller; Riju Srimal; Clayton E. Curtis Cortico-cerebellar network involved in saccade adaptation Journal Article In: Journal of Neurophysiology, vol. 120, no. 5, pp. 2583–2594, 2018. @article{Guillaume2018, Saccade adaptation is the learning process that en- sures that vision and saccades remain calibrated. The central nervous system network involved in these adaptive processes remains unclear because of difficulties in isolating the learning process from the correlated visual and motor processes. Here we imaged the human brain during a novel saccade adaptation paradigm that allowed us to isolate neural signals involved in learning independent of the changes in the amplitude of corrective saccades usually correlated with adap- tation. We show that the changes in activation in the ipsiversive cerebellar vermis that track adaptation are not driven by the changes in corrective saccades and thus provide critical supporting evidence for previous findings. Similarly, we find that activation in the dorso- medial wall of the contraversive precuneus mirrors the pattern found in the cerebellum. Finally, we identify dorsolateral and dorsomedial cortical areas in the frontal and parietal lobes that encode the retinal errors following inaccurate saccades used to drive recalibration. To- gether, these data identify a distributed network of cerebellar and cortical areas and their specific roles in oculomotor learning. |
Seref Can Gurel; Miguel Castelo-Branco; Alexander T. Sack; Felix Duecker Assessing the functional role of frontal eye fields in voluntary and reflexive saccades using continuous theta burst stimulation Journal Article In: Frontiers in Neuroscience, vol. 12, pp. 944, 2018. @article{Gurel2018, The frontal eye fields (FEFs) are core nodes of the oculomotor system contributing to saccade planning, control, and execution. Here, we aimed to reveal hemispheric asymmetries between left and right FEF in both voluntary and reflexive saccades toward horizontal and vertical targets. To this end, we applied fMRI-guided continuous theta burst stimulation (cTBS) over either left or right FEF and assessed the consequences of this disruption on saccade latencies. Using a fully counterbalanced within-subject design, we measured saccade latencies before and after the application of cTBS in eighteen healthy volunteers. In general, saccade latencies on both tasks were susceptible to our experimental manipulations, that is, voluntary saccades were slower than reflexive saccades, and downward saccades were slower than upward saccades. Contrary to our expectations, we failed to reveal any TMS-related effects on saccade latencies, and Bayesian analyses provided strong support in favor of a TMS null result for both tasks. Keeping in mind the interpretative challenges of null results, we discuss possible explanations for this absence of behavioral TMS effects, focusing on methodological differences compared to previous studies (task parameters and online vs. offline TMS interventions). We also speculate about what our results might reveal about the functional role of FEF. |
Christopher K. Hauser; Dantong Zhu; Terrence R. Stanford; Emilio Salinas Motor selection dynamics in FEF explain the reaction time variance of saccades to single targets Journal Article In: eLife, vol. 7, pp. 1–32, 2018. @article{Hauser2018, In studies of voluntary movement, a most elemental quantity is the reaction time (RT) between the onset of a visual stimulus and a saccade toward it. However, this RT demonstrates extremely high variability which, in spite of extensive research, remains unexplained. It is well established that, when a visual target appears, oculomotor activity gradually builds up until a critical level is reached, at which point a saccade is triggered. Here, based on computational work and single-neuron recordings from monkey frontal eye field (FEF), we show that this rise-to-threshold process starts from a dynamic initial state that already contains other incipient, internally driven motor plans, which compete with the target-driven activity to varying degrees. The ensuing conflict resolution process, which manifests in subtle covariations between baseline activity, build-up rate, and threshold, consists of fundamentally deterministic interactions, and explains the observed RT distributions while invoking only a small amount of intrinsic randomness.As we examine the space around us our eyes move in short steps, looking toward a new location about four times a second. Neurons in a region of the brain called the frontal eye field help initiate these eye movements, which are known as saccades. Each neuron contributes to a saccade with a specific direction and size. Before a saccade, the relevant neurons in the frontal eye field steadily increase their activity. When this activity reaches a critical threshold, the visual system issues a command to move the eyes in the appropriate direction. So a saccade that moves the eyes to the right requires a specific group of neurons to be strongly activated – but, at the same time, the neurons responsible for movement to the left need to be less active.Imagine that you have to move your eyes as quickly as possible to look at a spot of light that appears on a screen. Some of the time your eyes will start to move about 100 milliseconds after the light appears. But on other attempts, your eyes will not start moving until 300 milliseconds after the light came on. What causes this variability?To find out, Hauser et al. recorded from neurons in monkeys trained to perform such a task. When the spot of light appeared many different neurons were active, suggesting there is conflict between the plan that would move the eyes toward the target and plans to look at other locations. That is, when the target appears, the monkey is already thinking of looking somewhere. The time required to resolve this conflict depends on how far apart the target and the competing locations are from one another, and on how much the competing neurons have increased their activity before the target appears.Similar mechanisms are likely to operate when we sit at the dinner table and look for the salt shaker, for example, and so the results presented by Hauser et al. will help us to understand how we direct our attention to different points in space. Understanding how these processes work in more detail will help us to discern what happens when they go wrong, as occurs in attention deficit disorders like ADHD. |
Matthew Heath; Francisco L. Colino; Jillian Chan; Olave E. Krigolson Visuomotor mental rotation of a saccade: The contingent negative variation scales to the angle of rotation Journal Article In: Vision Research, vol. 143, pp. 82–88, 2018. @article{Heath2018, The visuomotor mental rotation (VMR) of a saccade requires a response to a region of space that is dissociated from a stimulus by a pre-specified angle, and work has shown a monotonic increase in reaction times as a function of increasing oblique angles of rotation. These results have been taken as evidence of a continuous process of rotation and have generated competing hypotheses. One hypothesis asserts that rotation is mediated via frontoparietal structures, whereas a second states that a continuous shift in the activity of direction-specific neurons in the superior colliculus (SC) supports rotation. Research to date, however, has not examined the neural mechanisms underlying VMR saccades and both hypotheses therefore remain untested. The present study measured the behavioural data and event-related brain potentials (ERP) of standard (i.e., 0° of rotation) and VMR saccades involving 35° 70° and 105° of rotation. Behavioural results showed that participants adhered to task-based rotation demands and ERP findings showed that the amplitude of the contingent negative variation (CNV) linearly decreased with increasing angle of rotation. The cortical generators of the CNV are linked to frontoparietal structures supporting movement preparation. Although our ERP design does not allow us to exclude a possible role of the SC in the rotation of a VMR saccade, they do demonstrate that such actions are supported by a continuous and cortically based rotation process. |
Stephen J. Heinen; Jeremy B. Badler; Scott N. J. Watamaniuk Choosing a foveal goal recruits the saccadic system during smooth pursuit Journal Article In: Journal of Neurophysiology, vol. 120, no. 2, pp. 489–496, 2018. @article{Heinen2018, Models of smooth pursuit eye movements stabilize an object's retinal image, yet pursuit is peppered with small, destabilizing “catch-up” saccades. Catch-up saccades might help follow a small, spot stimulus used in most pursuit experiments, since fewer of them occur with large stimuli. However, they can return when a large stimulus has a small central feature. It may be that a central feature on a large object automatically recruits the saccadic system. Alternatively, a cognitive choice is made that the feature is the pursuit goal, and the saccadic system is then recruited to pursue it. Observers pursued a 5-dot stimulus composed of a central dot surrounded by four peripheral dots arranged as a diamond. An attention task specified the pursuit goal as either the central element, or the diamond gestalt. Fewer catch-up saccades occurred with the Gestalt goal than with the central goal, although the additional saccades with the central goal neither enhanced nor impeded pursuit. Furthermore, removing the central element from the diamond goal further reduced catch-up saccade frequency, indicating that the central element automatically triggered some saccades. Higher saccade frequency was not simply due to narrowly focused attention, since attending a small peripheral diamond during pursuit elicited fewer saccades than attending the diamond positioned foveally. The results suggest some saccades are automatically elicited by a small central element, but when it is chosen as the pursuit goal the saccadic system is further recruited to pursue it. |
Anna E. Hughes Dissociation between perception and smooth pursuit eye movements in speed judgments of moving Gabor targets Journal Article In: Journal of Vision, vol. 18, no. 4, pp. 1–19, 2018. @article{Hughes2018, The relationship between eye movements and subjective perception is still relatively poorly understood. In this study, participants tracked the movement of a Gabor patch and made perceptual judgments of its speed using a two-interval forced choice task. The Gabor patch could either have a static carrier or a carrier moving in the same or opposite direction as the overall envelope motion. We found that smooth pursuit speed was strongly affected by the internal motion of the Gabor carrier, with faster smooth pursuit being made to targets with internal motion in the same direction as overall motion compared to targets with internal motion in the opposite direction. However, we found that there were only small and highly variable differences in the perceptual speed judgments made simultaneously, and that these perceptual and smooth pursuit measures did not significantly correlate with each other. This contrasts with the number of catch-up saccades (saccades made in the direction of overall target motion), which was significantly correlated with the simultaneous perceptual judgments. There was also a significant correlation between perceptual judgments and the difference between the target and eye position immediately before a saccade. These results suggest that it is possible to see dissociations between vision and action in this task, and that the specific type of visual action studied may determine the relationship with perception. |
Jukka Hyönä; Ming Yan; Seppo Vainio Morphological structure influences the initial landing position in words during reading Finnish Journal Article In: Quarterly Journal of Experimental Psychology, vol. 71, no. 1, pp. 122–130, 2018. @article{Hyoenae2018, The preferred viewing location in words [Rayner, K. (1979). Eye guidance in reading: Fixation locations within words. Perception, 8, 21–30] during reading is near the word centre. Parafoveal word length information is utilized to guide the eyes toward it. A recent study by Yan and colleagues [Yan, M., Zhou, W., Shu, H., Yusupu, R., Miao, D., Krügel, A., & Kliegl, R. (2014). Eye movements guided by morphological structure: Evidence from the Uighur language. Cognition, 132, 181–215] demonstrated that the word's morphological structure may also be used in saccadic targeting. The study was conducted in a morphologically rich language, Uighur. The present study aimed at replicating their main findings in another morphologically rich language, Finnish. Similarly to Yan et al., it was found that the initial fixation landed closer to the word beginning for morphologically complex than for monomorphemic words. Word frequency, saccade launch site, and word length were also found to influence the initial landing position. It is concluded that in addition to low-level factors (word length and saccade launch site), also higher level factors related to the word's morphological structure and frequency may be utilized in saccade programming during reading. |
Wolfgang Jaschinski Individual objective versus subjective fixation disparity as a function of forced vergence Journal Article In: PLoS ONE, vol. 13, no. 7, pp. e0199958, 2018. @article{Jaschinski2018, Inaccuracy in the vergence eye position (“fixation disparity”) can occur despite a fusion stimulus. When measured with eye trackers, this inaccuracy is referred to as “objective fixation disparity”. It is a matter of debate whether objective fixation disparity can be estimated with a technically simple psycho-physical procedure, i.e. the perceived offset of aligned dichoptic nonius targets, referred to as “subjective fixation disparity”. To investigate the relation between these two measures, simultaneous tests were made in far vision when placing prisms in front of the eyes (for a few seconds) in order to induce forced vergence, i.e. to vary the absolute disparity (from 1 deg divergent to 3.4 deg convergent). Frequent repeated measurements in 12 observers allowed for individual analyses. Generally, fixation disparity values and the effects of prisms were much smaller in the subjective than in the objective measures. Some observers differed systematically in the characteristics of the two types of prism-induced curves. Individual regressions showed that the subjective vs. objective slope was 8% on the average (with largest individual values of 18%). This suggests that sensory fusion shifts the visual direction of the (peripheral) binocular targets by the full amount of objective fixation disparity (since single vision was achieved); however, for the (central) monocular nonius lines this shift was more or less incomplete so that the dichoptic nonius targets indicated an individual percentage of objective fixation disparity. The subjective-to-objective ratio seems to be an individual characteristic of fixation disparity in terms of the amount and in terms of the effect of prism-induced forced vergence. Therefore, on the group level the subjective measures do not allow for a precise prediction of the objective measures. |
Jayne Morriss; Eugene McSorley; Carien M. Reekum I don't know where to look: the impact of intolerance of uncertainty on saccades towards non-predictive emotional face distractors Journal Article In: Cognition and Emotion, vol. 32, no. 5, pp. 953–962, 2018. @article{Morriss2018, Attentional bias to uncertain threat is associated with anxiety disorders. Here we examine the extent to which emotional face distractors (happy, angry and neutral) and individual differences in intolerance of uncertainty (IU), impact saccades in two versions of the “follow a cross” task. In both versions of the follow the cross task, the probability of receiving an emotional face distractor was 66.7%. To increase perceived uncertainty regarding the location of the face distractors, in one of the tasks additional non-predictive cues were presented before the onset of the face distractors and target. We did not find IU to impact saccades towards non-cued face distractors. However, we found IU, over Trait Anxiety, to impact saccades towards non-predictive cueing of face distractors. Under these conditions, IU individuals' eyes were pulled towards angry face distractors and away from happy face distractors overall, and the speed of this deviation of the eyes was determined by the combination of the cue and emotion of the face. Overall, these results suggest a specific role of IU on attentional bias to threat during uncertainty. These findings highlight the potential of intolerance of uncertainty-based mechanisms to help understand anxiety disorder pathology and inform potential treatment targets. |
Takaya Ogasawara; Masafumi Nejime; Masahiko Takada; Masayuki Matsumoto Primate nigrostriatal dopamine system regulates saccadic response inhibition Journal Article In: Neuron, vol. 100, no. 6, pp. 1513–1526.e4, 2018. @article{Ogasawara2018, Animals need to inhibit inappropriate actions that would lead to unwanted outcomes. Although this ability, called response inhibition, is impaired in neurological/psychiatric disorders with dopaminergic dysfunctions, how dopamine regulates response inhibition remains unclear. Here we investigated neuronal signals of the nigrostriatal dopamine system in monkeys performing a saccadic countermanding task. Subsets of dopamine neurons in the substantia nigra and striatal neurons receiving the dopaminergic input were activated when the monkey was required to cancel a planned saccadic eye movement. These activations were stronger when canceling the eye movements was successful compared with failed and were enhanced in demanding trials. The activated dopamine neurons were distributed mainly in the dorsolateral, but not in the ventromedial, part of the nigra. Furthermore, pharmacological blockade of dopaminergic neurotransmission in the striatum dampened the performance of canceling saccadic eye movements. The present findings indicate that disruption of nigrostriatal dopamine signaling causes impairments in response inhibition. |
Markus Ostarek; Adil Ishag; Dennis Joosen; Falk Huettig Saccade trajectories reveal dynamic interactions of semantic and spatial information during the processing of implicitly spatial words Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 44, no. 10, pp. 1658–1670, 2018. @article{Ostarek2018, Implicit up/down words, such as bird and foot, systematically influence performance on visual tasks involving immediately following targets in compatible versus incompatible locations. Recent studies have observed that the semantic relation between prime words and target pictures can strongly influence the size and even the direction of the effect: Semantically related targets are processed faster in congruent versus incongruent locations (location-specific priming), whereas unrelated targets are processed slower in congruent locations. Here, we used eye-tracking to investigate the moment-to-moment processes underlying this pattern. Our reaction time (RT) results for related targets replicated the location-specific priming effect and showed a trend toward interference for unrelated targets. We then used growth curve analysis to test how up/down words and their match versus mismatch with immediately following targets in terms of semantics and vertical location influence concurrent saccadic eye movements. There was a strong main effect of spatial association on linear growth, with up words biasing changes in y-coordinates over time upward relative to down words (and vice versa). Similar to the case with the RT data, this effect was strongest for semantically related targets and reversed for unrelated targets. It is intriguing that all conditions showed a bias in the congruent direction in the initial stage of the saccade. Then, at around halfway into the saccade the effect kept increasing in the semantically related condition and reversed in the unrelated condition. These results suggest that online processing of up/down words triggers direction- specific oculomotor processes that are dynamically modulated by the semantic relation between prime words and targets. |
Kiki Arkesteijn; Jeroen B. J. Smeets; Mieke Donk; Artem V. Belopolsky Target-distractor competition cannot be resolved across a saccade Journal Article In: Scientific Reports, vol. 8, pp. 15709, 2018. @article{Arkesteijn2018, When a distractor is presented in close spatial proximity to a target, a saccade tends to land in between the two objects rather than on the target. This robust phenomenon (also referred to as the global efect) is thought to refect unresolved competition between target and distractor. It is unclear whether this landing bias persists across saccades since a saccade displaces the retinotopic representations of target and distractor. In the present study participants made successive saccades towards two saccadic targets which were presented simultaneously with an irrelevant distractor in close proximity to the second saccade target. The second saccade was either visually-guided or memory-guided. For the memory-guided trials, the second saccade showed a landing bias towards the location of the distractor, despite the disappearance of the distractor after the frst saccade. In contrast, for the visually-guided trials, the bias was corrected and the landing bias was eliminated, even for saccades with the shortest intersaccadic intervals. This suggests that the biased saccade plan was remapped across the frst saccade. Therefore, we conclude that the target-distractor competition was not resolved across a saccade, but can be resolved based on visual information that is available after a saccade. |
Yanping Liu; Siyuan Guo; Lei Yu; Erik D. Reichle Word predictability affects saccade length in Chinese reading: An evaluation of the dynamic-adjustment model Journal Article In: Psychonomic Bulletin & Review, vol. 25, no. 5, pp. 1891–1899, 2018. @article{Liu2018, How does a word's within-sentence predictability influence saccade length during reading? An eye-movement experiment manipulating the predictability of target words in- dicates that, relative to low-predictability target words, high- predictability targets elicit longer saccades to themselves. Simulations using computational models that respectively in- stantiate the targeting of saccades to default locations (Yan, Kliegl, Richter, Nuthmann, & Shu in Journal ofExperimental Psychology, 63,705–725, 2010) versus the dynamic adjust- ment of saccade length (Liu, Reichle, & Li in Journal of Experimental Psychology Learning Memory and Cognition, 41, 1229–1236, 2015, Journal ofExperimental Psychology: Human Perception and Performance, 42, 1008–1025, 2016) indicate that the latter model provides a more accurate and parsimonious account of saccade-targeting behavior in Chinese reading. The implications of these conclusions are discussed with respect to current models ofeye-movement control during reading and the necessity to explain eye movements in languages as different as Chinese versus English. |
Gerard M. Loughnane; Daniel P. Newman; Sarita Tamang; Simon P. Kelly; Redmond G. O'Connell Antagonistic interactions between microsaccades and evidence accumulation processes during decision formation Journal Article In: Journal of Neuroscience, vol. 38, no. 9, pp. 2163–2176, 2018. @article{Loughnane2018, Despite their small size, microsaccades can impede stimulus detections if executed at inopportune times. Although it has been shown that microsaccades evoke both inhibitory and excitatory responses across different visual regions, their impact on the higher-level neural decision processes that bridge sensory responses to action selection has yet to be examined. Here, we show that when human observers monitor stimuli for subtle feature changes, the occurrence of microsaccades long after (up to 800 ms) change onset predicts slower reaction times and this is accounted for by momentary suppression of neural signals at each key stage of decision formation: visual evidence encoding, evidence accumulation, and motor preparation. Our data further reveal that, independent of the timing of the change events, the onset of neural decision formation coincides with a systematic inhibition of microsaccade production, persisting until the perceptual report is executed. Our combined behavioral and neural measures highlight antagonistic interactions between microsaccade occurrence and evidence accumulation during visual decision-making tasks. |
Eric Lowet; Bruno Gomes; Karthik Srinivasan; Huihui Zhou; Robert John Schafer; Robert Desimone Enhanced neural processing by covert attention only during microsaccades directed toward the attended stimulus Journal Article In: Neuron, vol. 99, no. 1, pp. 207–214.e3, 2018. @article{Lowet2018, Attention can be “covertly” directed without eye movements; yet, even during fixation, there are continuous microsaccades (MSs). In areas V4 and IT of macaques, we found that firing rates and stimulus representations were enhanced by attention but only following a MS toward the attended stimulus. The onset of neural attentional modulations was tightly coupled to the MS onset. The results reveal a major link between the effects of covert attention on cortical visual processing and the overt movement of the eyes. |
Heather D. Lucas; Melissa C. Duff; Neal J. Cohen The hippocampus promotes effective saccadic information gathering in humans Journal Article In: Journal of Cognitive Neuroscience, vol. 31, no. 2, pp. 186–201, 2018. @article{Lucas2018, It is well established that the hippocampus is critical for memory. Recent evidence suggests that one function of hippocampal memory processing is to optimize how people actively explore the world. Here we demonstrate that the link between the hippocampus and exploration extends even to the moment-to-moment use of eye movements during visuospatial memory encoding. In Experiment 1, we examined relationships between study-phase eye movements in healthy individuals and subsequent performance on a spatial reconstruction test. In addition to quantitative measures of viewing behaviors (e.g., how many fixations or saccades were deployed during study), we used the information–theoretic measure of entropy to assess the amount of randomness or disorganization in participants' scanning behaviors. We found that the use of scanpaths during study that were lower in entropy (e.g., more organized, less random) predicted more accurate spatial reconstruction both within and between participants. Scanpath entropy was a better predictor of reconstruction accuracy than were the quantitative measures of viewing. In Experiment 2, we found that individuals with hippocampal amnesia tended to engage in viewing patterns that were higher in entropy (less organized) relative to healthy comparisons. These findings reveal a critical role of the hippocampus in guiding eye movement exploration to optimize visuospatial relational memory. |
W. Joseph MacInnes; Roopali Bhatnagar No supplementary evidence of attention to a spatial cue when saccadic facilitation is absent Journal Article In: Scientific Reports, vol. 8, pp. 13289, 2018. @article{MacInnes2018, Attending a location in space facilitates responses to targets at that location when the time between cue and target is short. Certain types of exogenous cues – such as sudden peripheral onsets – have been described as reflexive and automatic. Recent studies however, have been showing many cases where exogenous cues are less automatic than previously believed and do not always result in facilitation. A lack of the behavioral facilitation, however, does not automatically necessitate a lack of underlying attention to that location. We test exogenous cueing in two experiments where facilitation is and is not likely to be observed with saccadic responses. We also test alternate measures linked to the allocation of attention such as saccadic curvature, microsaccades and pupil size. As expected, we find early facilitation as measured by saccadic reaction time when CTOAs are predictable but not when they are randomized within a block. We find no impact of the cue on microsaccade direction for either experiment, and only a slight dip in the frequency of microsaccades after the cue. We do find that change in pupil size to the cue predicts the magnitude of the validity effect, but only in the experiment where facilitation was observed. In both experiments, we observed a tendency for saccadic curvature to deviate away from the cued location and this was stronger for early CTOAs and toward vertical targets. Overall, we find that only change in pupil size is consistent with observed facilitation. Saccadic curvature is influenced by the onset of the cue, buts its direction is indicative of oculomotor inhibition whether we see RT facilitation or not. Microsaccades were not diagnostic in either experiment. Finally, we see little to no evidence of attention at the cued location in any additional measures when facilitation of saccadic responses is absent. |
Anton Malienko; Vanessa Harrar; Aarlenne Zein Khan Contrasting effects of exogenous attention on saccades and reaches Journal Article In: Journal of Vision, vol. 18, no. 9, pp. 1–16, 2018. @article{Malienko2018, Previous studies have shown that eye and arm movements tend to be intrinsically coupled in their behavior. There is, however, no consensus on whether planning of eye and arm movements is based on shared or independent representations. One way to gain insight into these processes is to compare how exogenous attentional modulation influences the temporal and spatial characteristics of the eye and the arm during single or combined movements. Thirteen participants (M ¼22.8 years old, SD¼1.5) performed single or combined movements to an eccentric target. A behaviorally irrelevant cue flashed just before the target at different locations. There was no effect of the cue on the saccade or reach amplitudes, whether they were performed alone or together. We found no differences in overall reaction times (RTs) between single and combined movements. With respect to the effect of the cue, both saccades and reaches followed a similar pattern with the shortest RTs when the cue was closest to the target, which we propose reflects effector-independent processes. Compared to when no cue was presented before the target, saccade RTs were generally inhibited by the irrelevant cue with increasing cue-target distance. In contrast, reach RTs showed strong facilitation at the target location and less facilitation at farther distances. We propose that this reflects the presence of effector- dependent processes. The similarities and differences in RTs between the saccades and reaches are consistent with effector-dependent and -independent processes working in parallel. |
Diako Mardanbegi; Rebecca Killick; Baiqiang Xia; Thomas D. W. Wilcockson; Hans Gellersen; Peter Sawyer; Trevor J. Crawford Effect of aging on post-saccadic oscillations Journal Article In: Vision Research, vol. 143, pp. 1–8, 2018. @article{Mardanbegi2018, Recent research have shown that the eye movement data measured by an eye tracker does not necessarily reflect the exact rotations of the eyeball. For example, post-saccadic eye movements may be more reflecting the relative movements between the pupil and the iris rather than the eyeball oscillations. Since, accurate measurement of eye movements is important in many studies, it is crucial to identify different factors that influence the dynamics of the eye movements measured by an eye tracker. Previous studies have shown that deformation of the internal structure of the iris and size of the pupil directly affect the amplitude of the post-saccadic oscillations that are measured by video-based eye trackers that are pupil-based. In this paper, we look at the effect of aging on post-saccadic oscillations. We recorded eye movements from a group of 43 young and 22 older participants during an abstract and a more natural viewing task. The recording was conducted with a video-based eye tracker using the pupil center and corneal reflection. We anticipated that changes in the muscle strength as an effect of aging might affect, directly or indirectly, the post-saccadic oscillations. Results showed that the size of the post-saccadic oscillations were significantly larger for our older group. The results suggests that aging has to be considered as an important factor when studying the post-saccadic eye movements. |
Jun Maruta; Lisa A. Spielman; Umesh Rajashekar; Jamshid Ghajar Association of visual tracking metrics with post-concussion symptomatology Journal Article In: Frontiers in Neurology, vol. 9, pp. 611, 2018. @article{Maruta2018, Attention impairment may provide a cohesive neurobiological explanation for clusters of clinical symptoms that occur after a concussion; therefore, objective quantification of attention is needed. Visually tracking a moving target is an attention-dependent sensorimotor function, and eye movement can be recorded easily and objectively to quantify performance. Our previous work suggested the utility of gaze-target synchronization metrics of a predictive visual tracking task in concussion screening and recovery monitoring. Another objectively quantifiable performance measure frequently suggested for concussion screening is simple visuo-manual reaction time (simple reaction time, SRT). Here, we used visual tracking and SRT tasks to assess changes between pre- and post-concussion performances and explore their relationships to post-concussion symptomatology. Athletes participating in organized competitive sports were recruited. Visual tracking and SRT records were collected from the recruited athlete pool as baseline measures over a four-year period. When athletes experienced a concussion, they were re-assessed within two weeks of their injury. We present the data from a total of 29 concussed athletes. Post-concussion symptom burden were assessed with the Rivermead Post-Concussion Symptoms Questionnaire and subscales of the Brain Injury Screening Questionnaire. Post-concussion changes in visual tracking and SRT performance were examined using a paired t-test. Correlations of changes in visual tracking and SRT performance to symptom burden were examined using Pearson's coefficients. Post-concussion changes in visual tracking performance were not consistent among the athletes. However, changes in several visual tracking metrics had moderate to strong correlations to symptom scales (|r| up to 0.68). On the other hand, while post-concussion SRT performance was reduced (p < 0.01), the changes in the performance metrics were not meaningfully correlated to symptomatology (|r| ≤ 0.33). Results suggest that visual tracking performance metrics reflect clinical symptoms when assessed within two weeks of concussion. Evaluation of concussion requires assessments in multiple domains because the clinical profiles are heterogeneous. While most individuals show recovery within a week of injury, others experience prolonged recovery periods. Visual tracking performance metrics may serve as a biomarker of debilitating symptoms of concussion implicating attention as a root cause of such pathologies. |
Delphine Massendari; Matteo Lisi; Thérèse Collins; Patrick Cavanagh Memory-guided saccades show effect of perceptual illusion whereas visually-guided saccades do not Journal Article In: Journal of Neurophysiology, vol. 119, pp. 62–72, 2018. @article{Massendari2018, The double-drift stimulus (a drifting Gabor with orthogonal internal motion) generates a large discrepancy between its physical and perceived path. Surprisingly, saccades directed to the double-drift stimulus land along the physical, and not perceived, path (Lisi M, Cavanagh P. Curr Biol 25: 2535⫺2540, 2015). We asked whether memory-guided saccades exhibited the same dissociation from perception. Participants were asked to keep their gaze centered on a fixation dot while the double- drift stimulus moved back and forth on a linear path in the periphery. The offset of the fixation was the go signal to make a saccade to the target. In the visually guided saccade condition, the Gabor kept moving on its trajectory after the go signal but was removed once the saccade began. In the memory conditions, the Gabor disappeared before or at the same time as the go-signal (0- to 1,000-ms delay) and participants made a saccade to its remembered location. The results showed that visually guided saccades again targeted the physical rather than the perceived location. However, memory saccades, even with 0-ms delay, had landing positions shifted toward the perceived location. Our result shows that memory- and visually guided saccades are based on different spatial information |
James Mathew; Frederic R. Danion Ups and downs in catch-up saccades following single-pulse TMS-methodological considerations Journal Article In: PLoS ONE, vol. 13, no. 10, pp. e0205208, 2018. @article{Mathew2018a, Transcranial magnetic stimulation (TMS) can interfere with smooth pursuit or with saccades initiated from a fixed position toward a fixed target, but little is known about the effect of TMS on catch-up saccade made to assist smooth pursuit. Here we explored the effect of TMS on catch-up saccades by means of a situation in which the moving target was driven by an external agent, or moved by the participants' hand, a condition known to decrease the occurrence of catch-up saccade. Two sites of stimulation were tested, the vertex and M1 hand area. Compared to conditions with no TMS, we found a consistent modulation of saccadic activity after TMS such that it decreased at 40-100ms, strongly resumed at 100-160ms, and then decreased at 200-300ms. Despite this modulatory effect, the accuracy of catch-up saccade was maintained, and the mean saccadic activity over the 0-300ms period remained unchanged. Those findings are discussed in the context of studies showing that single-pulse TMS can induce widespread effects on neural oscillations as well as perturbations in the latency of saccades during reaction time protocols. At a more general level, despite challenges and interpretational limitations making uncertain the origin of this modulatory effect, our study provides direct evidence that TMS over presumably non-oculomotor regions interferes with the initiation of catch-up saccades, and thus offers methodological considerations for future studies that wish to investigate the underlying neural circuitry of catch-up saccades using TMS. |
Geoffrey Mégardon; Petroc Sumner The fate of nonselected activity in saccadic decisions: Distinct goal-related and history-related modulation Journal Article In: Journal of Neurophysiology, vol. 119, no. 2, pp. 608–620, 2018. @article{Megardon2018, The global effect (GE) traditionally refers to the tendency of effectors (e.g., hand, eyes) to first land in between two nearby stimuli, forming a unimodal distribution. By measuring a shift of this distribution, recent studies used the GE to assess the presence of decision-related inputs on the motor map for eye movements. However, this method cannot distinguish whether one stimulus is inhibited or the other is facilitated and could not detect situations where both stimuli are inhibited or facilitated. Here, we detect deviations in the bimodal distribution of landing positions for remote stimuli and find that this bimodal GE reveals the presence, location, and polarity (facilitation or inhibition) of history-related and goal-related modulation of the nonselected activity (e.g., the distractor activity in correct trials, and the target activity in error trials). We tested, for different interstimulus distances, the effect of the rarity of double-stimulus trials and the difference between performing a discrimination task compared with free choice. Our work shows that the effect of rarity is symmetric and decreases with interstimulus distances, while the effect of goal-directed discrimination is asymmetric - occurring only when the distractor is selected for the saccade - and maintained across interstimulus distances. These results suggest that the former effect changes the response property of the motor map, while the latter specifically facilitates the target location. |
Ian M. Erkelens; William R. Bobier Adaptation of reflexive fusional vergence is directionally biased Journal Article In: Vision Research, vol. 149, pp. 66–76, 2018. @article{Erkelens2018, Divergence is known to differ from convergence across a wide range of clinical parameters. We have postulated that a limited neural substrate results in reduced fusional divergence velocities and subsequently a reduced capacity to adapt tonic vergence to uncrossed disparities. We further investigated this hypothesis by characterizing the degree of plasticity in reflexive fusional vergence to repetitive end-point errors using a disparity-based double-step paradigm. 10 adults completed 4 study visits where reflexive fusional convergence or divergence was measured (250 Hz infrared oculography) to a 2° disparity step and then lengthened or shortened via a repeated double-step (2° ± 1.5°). Stimuli were presented dichoptically at 40 cm. Adaptive modification of vergence responses was similar between directions for the shortening conditions, suggesting a common neural mechanism responds to overshooting errors. In comparison, adaptive lengthening of convergence was slower, but of equal magnitude, suggesting a second neural mechanism with a longer time constant for undershooting errors. Divergence response velocities were slower at baseline and did not increase after adaptive lengthening. Instead, increases in divergence response amplitudes were a result of increased response duration, implying saturation of the reflexive, preprogrammed response. Adaptive responses serving to increase or decrease reflexive fusional vergence recruitment were asymmetric. Adaptive lengthening of convergence and divergence identified further directional asymmetries. The results support the hypothesis that the neural substrate underlying divergence is attenuated, resulting in reduced reflexive plasticity when compared to convergence. The clinical and technological implications of these results are discussed. |
Ulrich Ettinger; Inga Meyhöfer; Mitul A. Mehta; Veena Kumari; Philip J. Corr; Steve C. R. Williams; Adam M. Perkins Effects of lorazepam on saccadic eye movements: The role of sex, task characteristics and baseline traits Journal Article In: Journal of Psychopharmacology, vol. 32, no. 6, pp. 678–690, 2018. @article{Ettinger2018, Background: Saccadic eye movements are controlled by a network of parietal, frontal, striatal, cerebellar and brainstem regions. The saccadic peak velocity is an established biomarker of benzodiazepine effects, with benzodiazepines reliably reducing the peak velocity. Aims: In this study, we aimed to replicate the effects of benzodiazepines on peak velocity and we investigated effects on previously less studied measures of saccades. We also explored the roles of sex, task characteristics and the baseline variables age, intelligence and trait anxiety in these effects. Method: Healthy adults (N = 34) performed a horizontal step prosaccade task under 1 mg lorazepam, 2 mg lorazepam and placebo in a double-blind, within-subjects design. Results: We replicated the dose-dependent reduction in peak velocity with lorazepam and showed that this effect is stronger for saccades to targets at smaller eccentricities. We also demonstrated that this effect is independent of sex and other baseline variables. Lorazepam effects were widespread, however, occurring on mean and variability measures of most saccadic variables. Additionally, there were sex-dependent lorazepam effects on spatial consistency of saccades, indicating more adverse effects in females. Conclusions: We conclude that saccadic peak velocity is a sensitive and robust biomarker of benzodiazepine effects. However, lorazepam has pronounced effects also on other parameters of horizontal saccades. Sex-dependent drug effects on spatial consistency may reflect cerebellar mechanisms, given the role of the cerebellum in saccadic spatial accuracy. |
Marzieh Salehi Fadardi; Larry Allen Abel Saccades under mental load in infantile nystagmus syndrome and controls Journal Article In: Optometry and Vision Science, vol. 95, no. 4, pp. 373–383, 2018. @article{Fadardi2018, Significance: This study compares saccades and visual task performance in patients with infantile nystagmus syndrome (INS) with that in normally sighted individuals under mental load. The results highlighted that to more completely evaluate INS therapies recognition time should also be measured with mental load, resembling real-world conditions. Purpose: Patients with INS may complain of "being slow to see." Stress is reported to worsen nystagmus and to prolong visual recognition time. We hypothesized that the effects of mental load on timing indices of visual recognition, for example, saccade latency, target acquisition time, target viewing time, and subjects' reaction time, differ between the INS and control groups. Methods: Eye movements were recorded when participants (INS group |
Yu Fang; Christopher Gill; Martina Poletti; Michele Rucci Monocular microsaccades: Do they really occur? Journal Article In: Journal of Vision, vol. 18, no. 3, pp. 1–14, 2018. @article{Fang2018, Small saccades, known as microsaccades, occur frequently during fixation. Several recent studies have argued that a considerable fraction of these movements are present in the traces from one eye only. This claim contrasts with the findings of older reports, which concluded that microsaccades, like larger saccades, are virtually always binocular events. Here we examined the characteristics of small saccades by means of two of the most established high-resolution eye-tracking techniques available. A binocular Dual Purkinje Image eye-tracker was used to record eye movements while observers fixated, with their head immobilized, on markers displayed on a monitor. A specially designed eye-coil system was used to measure eye movements during normal head-free viewing, while subjects fixated on markers at various distances. Monocular microsaccades were virtually absent in both datasets. In the head-fixed data, not a single monocular microsaccade was observed. In the head-free data, only one event appeared to be monocular out of more than a thousand saccades. Monocular microsaccades do not seem to occur during normal head-free or head-immobilized fixation. |
Moritz Feil; Meinrad Abegg; Mathias Abegg Timing of concurrent visual stimuli determines modulation of saccadic amplitude Journal Article In: Journal of Vision, vol. 18, no. 11, pp. 1–14, 2018. @article{Feil2018, The temporal relation of competing visual stimuli may determine the corresponding oculomotor response. In this study we systematically varied the temporal coincidence of two conflicting stimuli and investigated saccades that were elicited from such stimuli. We varied the time of presentation of two identical spatially separated stimuli between 0 and þ165 ms and measured the amplitude of the saccade elicited by these stimuli using infrared eye tracking. In the first experiment, all stimuli were shown for 36 ms only. In the second experiment, stimuli remained on the screen until the subsequent stimulus appeared, whereas in the third experiment all stimuli were removed after saccade onset. Up to an interstimulus interval of 82 ms, we found a significant shift of the saccadic endpoint toward the location of the second stimulus as compared to saccades toward the first stimulus alone. The strongest saccadic bias was observed if a stimulus was shown 36 ms after or before another stimulus. In contrast, time intervals longer than 82 ms elicited saccade adaptation—that is, the saccadic landing point gradually moved toward the second location over time. In more than 99% of trials, the second stimulus appeared before the saccade reached its endpoint. The timing of a conflicting stimulus determines the associated saccadic response: Simultaneous presentation of two stimuli results in a saccadic endpoint at an averaged intermediate position, short interstimulus intervals result in a strong shift of the saccadic endpoint toward the location of the second of two consecutive stimuli, and longer interstimulus intervals elicit saccade adaptation. The timing of two stimuli thus is associated with distinct processes, which complement each other in order to provide an optimal oculomotor response. |
Anna Maria Felßberg; Isabel Dombrowe The effect of different brightness conditions on visually and memory guided saccades Journal Article In: Vision Research, vol. 142, pp. 20–26, 2018. @article{Felssberg2018, It is commonly assumed that saccades in the dark are slower than saccades in a lit room. Early studies that investigated this issue using electrooculography (EOG) often compared memory guided saccades in darkness to visually guided saccades in an illuminated room. However, later studies showed that memory guided saccades are generally slower than visually guided saccades. Research on this topic is further complicated by the fact that the different existing eyetracking methods do not necessarily lead to consistent measurements. In the present study, we independently manipulated task (memory guided/visually guided) and screen brightness (dark, medium and light) in an otherwise completely dark room, and measured the peak velocity and the duration of the participant's saccades using a popular pupil-cornea reflection (p-cr) eyetracker (Eyelink 1000). Based on a critical reading of the literature, including a recent study using cornea-reflection (cr) eye tracking, we did not expect any velocity or duration differences between the three brightness conditions. We found that memory guided saccades were generally slower than visually guided saccades. In both tasks, eye movements on a medium and light background were equally fast and had similar durations. However, saccades on the dark background were slower and had shorter durations, even after we corrected for the effect of pupil size changes. This means that this is most likely an artifact of current pupil-based eye tracking. We conclude that the common assumption that saccades in the dark are slower than in the light is probably not true, however pupil-based eyetrackers tend to underestimate the peak velocity of saccades on very dark backgrounds, creating the impression that this might be the case. |
Gerardo Fernandez; Nora P. Rotstein; Luis E. Politi; Liliana Castro; Osvaldo Agamennoni; Gerardo Fernandez; Nora P. Rotstein; Luis E. Politi; Liliana Castro; Osvaldo Agamennoni Microsaccadic behavior when developing a complex dynamical activity Journal Article In: Journal of Integrative Neuroscience, vol. 17, no. 3, pp. 287–290, 2018. @article{Fernandez2018, Microsaccades are sensitive to changes of perceptual inputs as well as modulations of cognitive states. There are just a few works analyzing microsaccades while subjects are processing complex information and fewer when subjects make predictions about upcoming events. To evaluate whether contextual predictability might change microsaccadic behavior, microsaccades were evaluated for twenty-one subjects when reading 40 regular sentences and 40 proverbs. Maxjump was defined as the word with the largest difference between the cloze predictability of two consecutive words. Analysis of microsaccades while reading proverbs and regular sentences revealed that microsaccadic rate on words before maxjump, during maxjump and words after maxjump varied depending on the kind of sentence and on the word predictability. Words of low and high predictability required either less or more microsaccades to previous words, during and on maxjump, depending upon the semantic context and a readers' predictions of upcoming words. The present study demonstrates that the rate of microsaccades showed significant differences for reading either proverbs or regular sentences. Hence, evaluation of microsaccades while reading sentences with different contextual predictability may provide information concerning specific effects of cue attention during a complex task. |
Tom C. A. Freeman; Maria O. Cucu; Laura Smith A preference for visual speed during smooth pursuit eye movement Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 44, no. 10, pp. 1629–1636, 2018. @article{Freeman2018, Does the preference for visual speed extend to motion perception when the eye moves? Current evidence from psychophysics and neuroscience is limited to small patches of image motion and stationary fixation. Active observers, however, are more likely to use large patches of retinal flow and extraretinal signals accompanying eye movement to judge motion. We therefore investigated whether speed remains a primary dimension during smooth pursuit using a "discrimination-contour" technique. Our results showed that observers struggled most when trying to discriminate pursued stimuli that traveled at the same speed but moved over different distances and durations. This remained the case when retinal flow was added, and when we isolated trials in which extraretinal signals were the only salient cue to motion. Our results suggest that preferential sensitivity for visual speed is quite general, supported by the many different types of motion mechanism used by active observers. |
Christina Gambacorta; Jian Ding; Suzanne P. McKee; Dennis M. Levi Both saccadic and manual responses in the amblyopic eye of strabismics are irreducibly delayed Journal Article In: Journal of Vision, vol. 18, no. 3, pp. 1–18, 2018. @article{Gambacorta2018, Abnormal early visual development can result in a constellation of neural and visual deficits collectively known as amblyopia. Among the many deficits, a common finding is that both saccadic and manual reaction times to targets presented to the amblyopic eye are substantially delayed when compared to the fellow eye or to normal eyes. Given the well-known deficits in contrast sensitivity in the amblyopic eye, a natural question is whether the prolonged reaction times are simply a consequence of reduced stimulus visibility. To address this question, in Experiment 1 we measure saccadic reaction times (RT) to perifoveal stimuli as a function of effective stimulus contrast (i.e., contrast scaled by the amblyopic eye's contrast threshold). We find that when sensory differences between the eyes are minimized, the asymptotic RTs of our anisometropic amblyopes were similar in the two eyes. However, our results suggest that some strabismic amblyopes have an irreducible delay at the asymptote. That is, even when the sensory differences of the stimulus were accounted for, these observers still had large interocular differences (on average, 77 ms) in saccadic reaction time. In Experiment 2, to assess the role of fixation on saccadic reaction time we compared reaction time with and without a foveal target (the "gap effect"). Our results suggest that, while removing the fixation target does indeed speed up reaction time in the amblyopic eye, the gap effect is similar in the two eyes. Therefore, the gap effect does not eliminate the irreducible delay in the amblyopic eye. Finally, in Experiment 3 we compared the interocular differences in saccadic and manual reaction times in the same observers. This allowed us to determine the relationship between the latencies in the two modalities. We found a strong correlation between the differences in saccadic and manual reaction times; however, the manual RT difference is about half that of saccadic RT, suggesting that there may be two separable effects on saccadic reaction time: (a) a central problem with directing actions to a target, related to disengagement of attention at the fovea, which results in delays in both saccadic and manual reaction times, and (b) a further delay in saccadic reaction times because of the motor refractory period from a previous saccade or microsaccade, made in an attempt to stabilize the amblyopic eye of strabismics. |
Ying Gao; Carl Huber; Bernhard A. Sabel Stable microsaccades and microsaccade-induced global alpha band phase reset across the life span Journal Article In: Investigative Ophthalmology & Visual Science, vol. 59, no. 5, pp. 2032–2041, 2018. @article{Gao2018, PURPOSE. To understand the effect of aging on microsaccade functions and brain physiologic responses, we quantified microsaccades and their physiologic correlates (including their interaction with alpha band brain oscillation) in normal subjects of different ages. METHODS. Twenty-two normally sighted young (18 to 29 years), 22 middle-aged (31 to 55 years), and 22 elderly subjects (56 to 77 years) participated in this cross-sectional study. Dense array EEG and high-resolution eye-tracking data were simultaneously recorded during a fixation task. We quantified microsaccade features, spike potential (SP), microsaccadic lambda response (MLR) and microsaccade-related spectral perturbation (ERSP), and intertrial coherence (ITC) in the alpha and beta frequency bands and compared them between three age groups. RESULTS. After microsaccade onset, (1) alpha band ERSP increased (100 to 150 ms) occipitally and ITC increased (150 to 220 ms) globally in the brain; (2) low beta ITC increased (150 to 220 ms) in occipital and central regions and peaked (0 to 50 ms) in frontal region; and (3) high beta ITC increased (0 to 50 ms) globally with no beta band ERSP changes. Microsaccade features, the latency and amplitude of SP and MLR, and microsaccade-related temporal-spectral power and synchronization dynamics were all stable across different age groups. CONCLUSIONS. Microsaccades are well preserved in aging and can be used as reference points for studying neurodegenerative or neuro-ophthalmologic diseases where the oculomotor system is affected. Microsaccade-induced alpha band activity is a potential biomarker to better understand and monitor these diseases, and we propose that microsaccades trigger ''cortical refreshment'' by resetting alpha band phase globally to prepare (sensitize) the brain for subsequent visual processing. |
Delia A. Gheorghe; Muriel T. N. Panouillères; Nicholas D. Walsh Psychosocial stress affects the acquisition of cerebellar-dependent sensorimotor adaptation Journal Article In: Psychoneuroendocrinology, vol. 92, pp. 41–49, 2018. @article{Gheorghe2018, Despite being overlooked in theoretical models of stress-related disorders, differences in cerebellar structure and function are consistently reported in studies of individuals exposed to current and early-life stressors. However, the mediating processes through which stress impacts upon cerebellar function are currently unknown. The aim of the current experiment was to test the effects of experimentally-induced acute stress on cerebellar functioning, using a classic, forward saccadic adaptation paradigm in healthy, young men and women. Stress induction was achieved by employing the Montreal Imaging Stress Task (MIST), a task employing mental arithmetic and negative social feedback to generate significant physiological and endocrine stress responses. Saccadic adaptation was elicited using the double-step target paradigm. In the experiment, 48 participants matched for gender and age were exposed to either a stress (n = 25) or a control (n = 23) condition. Saliva for cortisol analysis was collected before, immediately after, and 10, and 30 min after the MIST. Saccadic adaptation was assessed approximately 10 min after stress induction, when cortisol levels peaked. Participants in the stress group reported significantly more stress symptoms and exhibited greater total cortisol output compared to controls. The stress manipulation was associated with slower learning rates in the stress group, while control participants acquired adaptation faster. Learning rates were negatively associated with cortisol output and mood disturbance. Results suggest that experimentally-induced stress slowed acquisition of cerebellar-dependent saccadic adaptation, related to increases in cortisol output. These ‘proof-of-principle' data demonstrate that stress modulates cerebellar-related functions. |
Kurtis G. Gruters; David L. K. Murphy; Cole D. Jensona; David W. Smithd; Christopher A. Sherae; Jennifer M. Groh The eardrums move when the eyes move: A multisensory effect on the mechanics of hearing Journal Article In: Proceedings of the National Academy of Sciences, vol. 1115, no. 6, pp. E1309–E1318, 2018. @article{Gruters2018, Interactions between sensory pathways such as the visual and auditory systems are known to occur in the brain, but where they first occur is uncertain. Here, we show a multimodal interaction evident at the eardrum. Ear canal microphone measurements in humans (n = 19 ears in 16 subjects) and monkeys (n = 5 ears in three subjects) performing a saccadic eye movement task to visual targets indicated that the eardrum moves in conjunction with the eye movement. The eardrum motion was oscillatory and began as early as 10 ms before saccade onset in humans or with saccade onset in monkeys. These eardrum movements, which we dub eye movement-related eardrum oscillations (EMREOs), occurred in the absence of a sound stimulus. The amplitude and phase of the EMREOs depended on the direction and horizontal amplitude of the saccade. They lasted throughout the saccade and well into sub-sequent periods of steady fixation. We discuss the possibility that the mechanisms underlying EMREOs create eye movement-related binaural cues that may aid the brain in evaluating the relationship between visual and auditory stimulus locations as the eyes move. |
Maria J. Barraza-Bernal; Katharina Rifai; Siegfried Wahl The retinal locus of fixation in simulations of progressing central scotomas Journal Article In: Journal of Vision, vol. 18, no. 1, pp. 1–12, 2018. @article{BarrazaBernal2018, Patients with central scotoma use a preferred retinal locus (PRL) of fixation to perform visual tasks. Some of the conditions that cause central scotoma are progressive, and as a consequence, the PRL needs to be adjusted throughout the progression. The present study investigates the peripheral locus of fixation in subjects under a simulation of progressive central scotoma. Five normally sighted subjects participated in the study. A foveally centered mask of varying size was presented to simulate the scotoma. Initially, subjects developed a peripheral locus of fixation under simulation of a 68 scotoma, which was used as a baseline. The progression was simulated in two separate conditions: a gradual progression and an abrupt progression. In the gradual progression, the diameter of the scotoma increased by a fixed amount of either 18 or 28 of visual angle, thus scotomas of 88, 108, and 118 of visual angle were simulated. In the abrupt progression, the diameter was adjusted individually to span the area of the visual field used by the current peripheral locus of fixation. Subjects located the peripheral locus of fixation along the same meridian under simulation of scotoma progression. Furthermore, no differences between the fixation stability of the baseline locus of fixation and the incremental progression locus of fixation were found whereas, in abrupt progression, the fixation stability decreased significantly. These results provide first insight into fixation behavior in a progressive scotoma and may contribute to the development of training tools for patients with progressive central maculopathies. |
Abdullah Bin Zahid; Molly E. Hubbard; Julia Lockyer; Olivia E. Podolak; Vikalpa M. Dammavalam; Matthew Grady; Michael Nance; Mitchell Scheiman; Uzma Samadani; Christina L. Master Eye tracking as a biomarker for concussion in children Journal Article In: Clinical Journal of Sport Medicine, pp. 1–11, 2018. @article{BinZahid2018, OBJECTIVE: Concussion is the most common type of brain injury in both pediatric and adult populations and can potentially result in persistent postconcussion symptoms. Objective assessment of physiologic "mild" traumatic brain injury in concussion patients remains challenging. This study evaluates an automated eye-tracking algorithm as a biomarker for concussion as defined by its symptoms and the clinical signs of convergence insufficiency and accommodation dysfunction in a pediatric population. DESIGN: Cross-sectional case-control study. SETTING: Primary care. PATIENTS: Concussed children (N = 56; mean age = 13 years), evaluated at a mean of 22-week post-injury, compared with 83 uninjured controls. INDEPENDENT VARIABLES: Metrics comparing velocity and conjugacy of eye movements over time were obtained and were compared with the correlation between Acute Concussion Evaluation (ACE) scores, convergence, and accommodation dysfunction. MAIN OUTCOME MEASURES: Subjects' eye movements recorded with an automated eye tracker while they watched a 220-second cartoon film clip played continuously while moving within an aperture. RESULTS: Twelve eye-tracking metrics were significantly different between concussed and nonconcussed children. A model to classify concussion as diagnosed by its symptoms assessed using the ACE achieved an area under the curve (AUC) = 0.854 (71.9% sensitivity, 84.4% specificity, a cross-validated AUC = 0.789). An eye-tracking model built to identify near point of convergence (NPC) disability achieved 95.8% specificity and 57.1% sensitivity for an AUC = 0.810. Reduced binocular amplitude of accommodation had a Spearman correlation of 0.752(P value <0.001) with NPC. CONCLUSION: Eye tracking correlated with concussion symptoms and detected convergence and accommodative abnormalities associated with concussion in the pediatric population. It demonstrates utility as a rapid, objective, noninvasive aid in the diagnosis of concussion. |
Paul J. Boon; Silvia Zeni; Jan Theeuwes; Artem V. Belopolsky Rapid updating of spatial working memory across saccades Journal Article In: Scientific Reports, vol. 8, pp. 1072, 2018. @article{Boon2018, Each time we make an eye movement, positions of objects on the retina change. In order to keep track of relevant objects their positions have to be updated. The situation becomes even more complex if the object is no longer present in the world and has to be held in memory. In the present study, we used saccadic curvature to investigate the time-course of updating a memorized location across saccades. Previous studies have shown that a memorized location competes with a saccade target for selection on the oculomotor map, which leads to saccades curving away from it. In our study participants performed a sequence of two saccades while keeping a location in memory. The trajectory of the second saccade was used to measure when the memorized location was updated after the first saccade. The results showed that the memorized location was rapidly updated with the eyes curving away from its spatial coordinates within 130 ms after the first eye movement. The time-course of updating was comparable to the updating of an exogenously attended location, and depended on how well the location was memorized. |
Yehudit Botschko; Merav Yarkoni; Mati Joshua Smooth pursuit eye movement of monkeys naive to laboratory setups with pictures and artificial stimuli Journal Article In: Frontiers in Systems Neuroscience, vol. 12, pp. 15, 2018. @article{Botschko2018, When animal behavior is studied in a laboratory environment, the animals are often extensively trained to shape their behavior. A crucial question is whether the behavior observed after training is part of the natural repertoire of the animal or represents an outlier in the animal's natural capabilities. This can be investigated by assessing the extent to which the target behavior is manifested during the initial stages of training and the time course of learning. We explored this issue by examining smooth pursuit eye movements in monkeys naïve to smooth pursuit tasks. We recorded the eye movements of monkeys from the first days of training on a step-ramp paradigm. We used bright spots, monkey pictures and scrambled versions of the pictures as moving targets. We found that during the initial stages of training, the pursuit initiation was largest for the monkey pictures and in some direction conditions close to target velocity. When the pursuit initiation was large, the monkeys mostly continued to track the target with smooth pursuit movements while correcting for displacement errors with small saccades. Two weeks of training increased the pursuit eye velocity in all stimulus conditions, whereas further extensive training enhanced pursuit slightly more. The training decreased the coefficient of variation of the eye velocity. Anisotropies that grade pursuit across directions were observed from the first day of training and mostly persisted across training. Thus, smooth pursuit in the step-ramp paradigm appears to be part of the natural repertoire of monkeys' behavior and training adjusts monkeys' natural predisposed behavior. |
S. Bouzat; M. L. Freije; A. L. Frapiccini; G. Gasaneo Inertial movements of the iris as the origin of postsaccadic oscillations Journal Article In: Physical Review Letters, vol. 120, pp. 178101, 2018. @article{Bouzat2018, Recent studies on the human eye indicate that the pupil moves inside the eyeball due to deformations of the iris. Here we show that this phenomenon can be originated by inertial forces undergone by the iris during the rotation of the eyeball. Moreover, these forces affect the iris in such a way that the pupil behaves effectively as a massive particle. To show this, we develop a model based on the Newton equation on the noninertial reference frame of the eyeball. The model allows us to reproduce and interpret several important findings of recent eye-tracking experiments on saccadic movements. In particular, we get correct results for the dependence of the amplitude and period of the postsaccadic oscillations on the saccade size and also for the peak velocity. The model developed may serve as a tool for characterizing eye properties of individuals. |
Dinah Chen; Jorge Otero-Millan; Priyanka Kumar; Aasef G. Shaikh; Fatema F. Ghasia Visual search in amblyopia: Abnormal fixational eye movements and suboptimal sampling strategies Journal Article In: Investigative Ophthalmology & Visual Science, vol. 59, no. 11, pp. 4506–4517, 2018. @article{Chen2018a, Purpose: Microsaccades shift the image on the fovea and counteract visual fading. They are also thought to serve as an optimal sampling strategy while viewing complex visual scenes. The goal of our study was to assess visual search in amblyopic children. Methods: Twenty-one amblyopic children with varying severity of amblyopia and 10 healthy controls were recruited. Eye movements were recorded using infrared video-oculography during amblyopic and fellow eye viewing while the subjects performed (1) visual fixation, (2) exploration of a blank scene, and (3) visual search task (spot the difference between two images). The number of correctly identified picture differences and reaction time were recorded. Microsaccade, saccades, and intersaccadic drifts were analyzed in patients without latent nystagmus (LN). Slow phase velocities were computed for patients with LN. Results: Both patients with and without LN were able to spot the same number of differences but took longer during fellow eye viewing compared to controls. The ability to identify differences was diminished during amblyopic eye viewing particularly those with LN and severe amblyopia. We found reduced frequencies of microsaccades and saccades in both amblyopic and fellow eyes during fixation and visual search but not during exploration of blank scene. Across all tasks, amblyopes with LN had increased intersaccadic drifts. Conclusions: Our findings suggest that deficient microsaccade and saccadic activity contributes to poorer sampling strategy in amblyopia, which is seen in both amblyopic and fellow eye. These deficits are more notable among subjects who experienced binocular decorrelation earlier in life, with subsequent development of LN. |
2017 |
Roy Amit; Dekel Abeles; Izhar Bar-Gad; Shlomit Yuval-Greenberg Temporal dynamics of saccades explained by a self-paced process Journal Article In: Scientific Reports, vol. 7, pp. 886, 2017. @article{Amit2017, Sensory organs are thought to sample the environment rhythmically thereby providing periodic perceptual input. Whisking and sniffing are governed by oscillators which impose rhythms on the motor-control of sensory acquisition and consequently on sensory input. Saccadic eye movements are the main visual sampling mechanism in primates, and were suggested to constitute part of such a rhythmic exploration system. In this study we characterized saccadic rhythmicity, and examined whether it is consistent with autonomous oscillatory generator or with self-paced generation. Eye movements were tracked while observers were either free-viewing a movie or fixating a static stimulus. We inspected the temporal dynamics of exploratory and fixational saccades and quantified their first-order and high-order dependencies. Data were analyzed using methods derived from spike-train analysis, and tested against mathematical models and simulations. The findings show that saccade timings are explained by first-order dependencies, specifically by their refractory period. Saccade-timings are inconsistent with an autonomous pace-maker but are consistent with a “self-paced” generator, where each saccade is a link in a chain of neural processes that depend on the outcome of the saccade itself. We propose a mathematical model parsimoniously capturing various facets of saccade-timings, and suggest a possible neural mechanism producing the observed dynamics. |
Chelsea S. Norman; Luke O'Gorman; Jane Gibson; Reuben J. Pengelly; Diana Baralle; J. Arjuna Ratnayaka; Helen Griffiths; Matthew Rose-Zerilli; Megan Ranger; David Bunyan; Helena Lee; Rhiannon Page; Tutte Newall; Fatima Shawkat; Christopher Mattocks; Daniel Ward; Sarah Ennis; Jay E. Self In: Scientific Reports, vol. 7, pp. 4415, 2017. @article{Norman2017, Oculocutaneous albinism (OCA) and ocular albinism (OA) are inherited disorders of melanin biosynthesis, resulting in loss of pigment and severe visual deficits. OCA encompasses a range of subtypes with overlapping, often hypomorphic phenotypes. OCA1 is the most common cause of albinism in European populations and is inherited through autosomal recessive mutations in the Tyrosinase (TYR) gene. However, there is a high level of reported missing heritability, where only a single heterozygous mutation is found in TYR. This is also the case for other OCA subtypes including OCA2 caused by mutations in the OCA2 gene. Here we have interrogated the genetic cause of albinism in a well phenotyped, hypomorphic albinism population by sequencing a broad gene panel and performing segregation studies on phenotyped family members. Of eighteen probands we can confidently diagnose three with OA and OCA2, and one with a PAX6 mutation. Of six probands with only a single heterozygous mutation in TYR, all were found to have the two common variants S192Y and R402Q. Our results suggest that a combination of R402Q and S192Y with a deleterious mutation in a ‘tri-allelic genotype' can account for missing heritability in some hypomorphic OCA1 albinism phenotypes. |
David Aagten-Murphy; Paul M. Bays Automatic and intentional influences on saccade landing Journal Article In: Journal of Neurophysiology, vol. 118, no. 2, pp. 1105–1122, 2017. @article{AagtenMurphy2017, When making an eye movement to a target location, the presence of a nearby distractor can cause the saccade to unintentionally terminate at the distractor itself or the average position in between stimuli. With probabilistic mixture models, we quantified how both unavoidable capture and goal-directed targeting were influenced by changing the task and the target-distractor separation. Using this novel technique, we could extract the time course over which automatic and intentional processes compete for control of saccades. |
Deanna J. Taylor; Nicholas D. Smith; David P. Crabb Searching for Objects in Everyday Scenes: Measuring Performance in People With Dry Age-Related Macular Degeneration Journal Article In: Investigative Ophthalmology & Visual Science, vol. 58, no. 3, pp. 1887, 2017. @article{Taylor2017a, Purpose: Treatment success in clinical trials for AMD would ideally be aligned to measurable performance in visual tasks rather than imperceptible changes on clinical charts. We test the hypothesis that patients with dry AMD perform worse than visually healthy peers on computer-based surrogates of "real-world" visual search tasks. Methods: A prospective case-control study was conducted in which patients with dry AMD performed a computer-based "real-world" visual search task. Participants searched for targets within images of everyday scenes while eye movements were recorded. Average search times across the images were recorded as a primary outcome measure. Comparisons were made against a 90% normative limit established in peers with healthy vision (controls). Eye movement parameters were examined as a secondary outcome measure. Results: Thirty-one patients and 33 controls with median (interquartile range) age of 75 (70-79) and 71 (66-75) years and logMAR binocular visual acuity 0.2 (0.18-0.31) and -0.06 (-0.12 to 0), respectively, were examined. Four, 18, and 9 patients were categorized as having early, intermediate, and late AMD, respectively. Nineteen (61%) patients exceeded the 90% normative limits for average search time; this was statistically significant (Fisher's exact test, P < 0.0001). On average, patients made smaller saccades than controls (P < 0.001). Conclusions: People with dry AMD, certainly those with advanced disease, are likely to have measurable difficulties beyond those observed in visually healthy peers on "real-world" search tasks. Further work might establish this type of task as a useful outcome measure for clinical trials. |
Stefano Targher; Rocco Micciolo; Valeria Occelli; Massimiliano Zampini The role of temporal disparity on audiovisual integration in low-vision individuals Journal Article In: Perception, vol. 46, no. 12, pp. 1356–1370, 2017. @article{Targher2017, Recent findings have shown that sounds improve visual detection in low vision individuals when the audiovisual stimuli pairs of stimuli are presented simultaneously and from the same spatial position. The present study purports to investigate the temporal aspects of the audiovisual enhancement effect previously reported. Low vision participants were asked to detect the presence of a visual stimulus (yes/no task) presented either alone or together with an auditory stimulus at different stimulus onset asynchronies (SOAs). In the first experiment, the sound was presented either simultaneously or before the visual stimulus (i.e., SOAs 0, 100, 250, 400 ms). The results show that the presence of a task-irrelevant auditory stimulus produced a significant visual detection enhancement in all the conditions. In the second experiment, the sound was either synchronized with, or randomly preceded/lagged behind the visual stimulus (i.e., SOAs 0, ?250,?400 ms). The visual detection enhancement was reduced in magnitude and limited only to the synchronous condition and to the condition in which the sound stimulus was presented 250 ms before the visual stimulus. Taken together, the evidence of the present study seems to suggest that audiovisual interaction in low vision individuals is highly modulated by top-down mechanisms. |
Mervyn G. Thomas; Gail D. E. Maconachie; Viral Sheth; Rebecca J. McLean; Irene Gottlob Development and clinical utility of a novel diagnostic nystagmus gene panel using targeted next-generation sequencing Journal Article In: European Journal of Human Genetics, vol. 25, no. 6, pp. 725–734, 2017. @article{Thomas2017, Infantile nystagmus (IN) is a genetically heterogeneous disorder arising from variants of genes expressed within the developing retina and brain. IN presents a diagnostic challenge and patients often undergo numerous investigations. We aimed to develop and assess the utility of a next-generation sequencing (NGS) panel to enhance the diagnosis of IN. We identified 336 genes associated with IN from the literature and OMIM. NimbleGen Human custom array was used to enrich the target genes and sequencing was performed using HiSeq2000. Using reference genome material (NA12878), we show the sensitivity (98.5%) and specificity (99.9%) of the panel. Fifteen patients with familial IN were sequenced using the panel. Two authors were masked to the clinical diagnosis. We identified variants in 12/15 patients in the following genes: FRMD7 (n=3), CACNA1F (n=2), TYR (n=5), CRYBA1 (n=1) and TYRP1 (n=1). In 9/12 patients, the clinical diagnosis was consistent with the genetic diagnosis. In 3/12 patients, the results from the genetic diagnoses (TYR, CRYBA1 and TYRP1 variants) enabled revision of clinical diagnoses. In 3/15 patients, we were unable to determine a genetic diagnosis. In one patient, copy number variation analysis revealed a FRMD7 deletion. This is the first study establishing the clinical utility of a diagnostic NGS panel for IN. We show that the panel has high sensitivity and specificity. The genetic information from the panel will lead to personalised diagnosis and management of IN and enable accurate genetic counselling. This will allow development of a new clinical care pathway for IN. |
Wei Lin Toh; David J. Castle; Susan Lee Rossell Attentional biases in body dysmorphic disorder (BDD): Eye-tracking using the emotional Stroop task Journal Article In: Comprehensive Psychiatry, vol. 74, pp. 151–161, 2017. @article{Toh2017, Objective: Body dysmorphic disorder (BDD) is characterised by repetitive behaviours and/or mental acts occurring in response to preoccupations with perceived defects or flaws in physical appearance. This study aimed to examine attentional biases in BDD via the emotional Stroop task with two modifications: i) incorporating an eye-tracking paradigm, and ii) employing an obsessive–compulsive disorder (OCD) control group. Method: Twenty-one BDD, 19 OCD and 21 HC participants, who were age-, sex-, and IQ-matched, were included. A card version of the emotional Stroop task was employed based on seven 10-word lists: (i) BDD-positive, (ii) BDD-negative, (iii) OCD-checking, (iv) OCD-washing, (v) general positive, (vi) general threat, and (vii) neutral (as baseline). Participants were asked to read aloud words and word colours consecutively, thereby yielding accuracy and latency scores. Eye-tracking parameters were also measured. Results: Participants with BDD exhibited significant Stroop interference for BDD-negative words relative to HC participants, as shown by extended colour-naming latencies. In contrast, the OCD group did not exhibit Stroop interference for OCD-related nor general threat words. Only mild eye-tracking anomalies were uncovered in clinical groups. Inspection of individual scanning styles and fixation heat maps however revealed that viewing strategies adopted by clinical groups were generally disorganised, with avoidance of certain disorder-relevant words and considerable visual attention devoted to non-salient card regions. Conclusion: The operation of attentional biases to negative disorder-specific words was corroborated in BDD. Future replication studies using other paradigms are vital, given potential ambiguities inherent in emotional Stroop task interpretation. |
Travis H. Turner; Jenna B. Renfroe; Amy Duppstadt-Delambo; Vanessa K. Hinson Validation of a behavioral approach for measuring saccades in Parkinson's disease Journal Article In: Journal of Motor Behavior, vol. 49, no. 6, pp. 657–667, 2017. @article{Turner2017, Speed and control of saccades are related to disease progression and cognitive functioning in Parkinson's disease (PD). Traditional eye-tracking complexities encumber application for individual evaluations and clinical trials. The authors examined psychometric properties of standalone tasks for reflexive prosaccade latency, volitional saccade initiation, and saccade inhibition (antisaccade) in a heterogeneous sample of 65 PD patients. Demographics had minimal impact on task performance. Thirty-day test-retest reliability estimates for behavioral tasks were acceptable and similar to traditional eye tracking. Behavioral tasks demonstrated concurrent validity with traditional eye-tracking measures; discriminant validity was less clear. Saccade initiation and inhibition discriminated PD patients with cognitive impairment. The present findings support further development and use of the behavioral tasks for assessing latency and control of saccades in PD. |
Olga Vintonyak; Martin Gorges; Hans Peter Müller; Elmar H. Pinkhardt; Albert C. Ludolph; Hans Jürgen Huppertz; Jan Kassubek Patterns of eye movement impairment correlate with regional brain atrophy in neurodegenerative Parkinsonism Journal Article In: Neurodegenerative Diseases, vol. 17, no. 4-5, pp. 117–126, 2017. @article{Vintonyak2017, Background: One common feature of neurodegenerative parkinsonism including Parkinson's disease (PD), multisys- tem atrophy (MSA), and progressive supranuclear palsy (PSP) is altered eye movement control. Characteristic regional structural atrophy patterns in MRI can be observed in PD, MSA, and PSP. Objective: To investigate the association be- tween eye movement disturbances and regional brain atro- phy in patients with PD, MSA, and PSP. Methods: High-reso lution 3-dimensional T1-weighted MRI images and video- oculographic recordings (EyeLink ® ) were obtained from 39 PD, 32 PSP, and 18 MSA patients and 24 matched healthy control subjects. Automatic regional volumetric assessment was performed using atlas-based volumetry (ABV). Results: The prevalence of saccadic intrusions as a measure of inhib- itory control was significantly increased in PD patients com- pared to controls ( p < 0.001) and negatively correlated with whole brain volume, cerebral brain volume, and occipital lobe volume ( p = 0.0057 |
Gabriel Wainstein; D. Rojas-Líbano; N. A. Crossley; X. Carrasco; F. Aboitiz; Tomás Ossandón Pupil size tracks attentional performance in attention-deficit/hyperactivity disorder Journal Article In: Scientific Reports, vol. 7, pp. 8228, 2017. @article{Wainstein2017, Attention-deficit/hyperactivity disorder (ADHD) diagnosis is based on reported symptoms, which carries the potential risk of over- or under-diagnosis. A biological marker that helps to objectively define the disorder, providing information about its pathophysiology, is needed. A promising marker of cognitive states in humans is pupil size, which reflects the activity of an ‘arousal' network, related to the norepinephrine system. We monitored pupil size from ADHD and control subjects, during a visuo-spatial working memory task. A sub group of ADHD children performed the task twice, with and without methylphenidate, a norepinephrine–dopamine reuptake inhibitor. Off-medication patients showed a decreased pupil diameter during the task. This difference was no longer present when patients were on-medication. Pupil size correlated with the subjects' performance and reaction time variability, two vastly studied indicators of attention. Furthermore, this effect was modulated by medication. Through pupil size, we provide evidence of an involvement of the noradrenergic system during an attentional task. Our results suggest that pupil size could serve as a biomarker in ADHD. |
Julian M. Wallace; Susana T. L. Chung; Bosco S. Tjan Object crowding in age-related macular degeneration Journal Article In: Journal of Vision, vol. 17, no. 1, pp. 33, 2017. @article{Wallace2017, Crowding, the phenomenon of impeded object identification due to clutter, is believed to be a key limiting factor of form vision in the peripheral visual field. The present study provides a characterization of object crowding in age-related macular degeneration (AMD) measured at the participants' respective preferred retinal loci with binocular viewing. Crowding was also measured in young and age-matched controls at the same retinal locations, using a fixation-contingent display paradigm to allow unlimited stimulus duration. With objects, the critical spacing of crowding for AMD participants was not substantially different from controls. However, baseline contrast energy thresholds in the noncrowded condition were four times that of the controls. Crowding further exacerbated deficits in contrast sensitivity to three times the normal crowding-induced contrast energy threshold elevation. These findings indicate that contrast-sensitivity deficit is a major limiting factor of object recognition for individuals with AMD, in addition to crowding. Focusing on this more tractable deficit of AMD may lead to more effective remediation and technological assistance. |
Alexandra Hoffmann; Ulrich Ettinger; Gustavo A. Reyes del Paso; Stefan Duschek Executive function and cardiac autonomic regulation in depressive disorders Journal Article In: Brain and Cognition, vol. 118, pp. 108–117, 2017. @article{Hoffmann2017, Executive function impairments have been frequently observed in depressive disorders. Moreover, reduced heart rate variability (HRV) has repeatedly been described, especially in the high frequency band (i.e., respiratory sinus arrhythmia, RSA), suggesting lower vagal cardiac outflow. The study tested the hypothesis of involvement of low vagal tone in executive dysfunction in depression. In addition to RSA, HRV in the low frequency (LF) band was assessed. In 36 patients with depression and 36 healthy subjects, electrocardiography recordings were accomplished at rest and during performance of five executive function tasks (number-letter task, n-back task, continuous performance test, flanker task, and antisaccade task). Patients displayed increased error rates and longer reaction times in the task-switching condition of the number-letter task, in addition to increased error rates in the n-back task and the final of two blocks of the antisaccade task. In patients, both HRV parameters were lower during all experimental phases. RSA correlated negatively with reaction time during task-switching. This finding confirms reduced performance across different executive functions in depression and suggests that, in addition to RSA, LF HRV is also diminished. However, the hypothesis of involvement of low parasympathetic tone in executive dysfunction related to depression received only limited support. |
Jaakko Hotta; Jukka Saari; Miika Koskinen; Yevhen Hlushchuk; Nina Forss; Riitta Hari Abnormal brain responses to action observation in complex regional pain syndrome Journal Article In: Journal of Pain, vol. 18, no. 3, pp. 255–265, 2017. @article{Hotta2017, Patients with complex regional pain syndrome (CRPS) display various abnormalities in central motor function, and their pain is intensified when they perform or just observe motor actions. In this study, we examined the abnormalities of brain responses to action observation in CRPS. We analyzed 3-T functional magnetic resonance images from 13 upper limb CRPS patients (all female, ages 31–58 years) and 13 healthy, age- and sex-matched control subjects. The functional magnetic resonance imaging data were acquired while the subjects viewed brief videos of hand actions shown in the first-person perspective. A pattern-classification analysis was applied to characterize brain areas where the activation pattern differed between CRPS patients and healthy subjects. Brain areas with statistically significant group differences (q < .05, false discovery rate-corrected) included the hand representation area in the sensorimotor cortex, inferior frontal gyrus, secondary somatosensory cortex, inferior parietal lobule, orbitofrontal cortex, and thalamus. Our findings indicate that CRPS impairs action observation by affecting brain areas related to pain processing and motor control. Perspective This article shows that in CRPS, the observation of others' motor actions induces abnormal neural activity in brain areas essential for sensorimotor functions and pain. These results build the cerebral basis for action-observation impairments in CRPS. |
Philippa L. Howard; Simon P. Liversedge; Valerie Benson Investigating the use of world knowledge during on-line comprehension in adults with Autism Spectrum Disorder Journal Article In: Journal of Autism and Developmental Disorders, vol. 47, no. 7, pp. 2039–2053, 2017. @article{Howard2017a, The on-line use of world knowledge during reading was examined in adults with autism spectrum disorder (ASD). Both ASD and typically developed adults read sentences that included plausible, implausible and anomalous thematic relations, as their eye movements were monitored. No group differences in the speed of detection of the anomalous violations were found, but the ASD group showed a delay in detection of implausible thematic relations. These findings suggest that there are subtle differences in the speed of world knowledge processing during reading in ASD. |
Philippa L. Howard; Simon P. Liversedge; Valerie Benson Benchmark eye movement effects during natural reading in autism spectrum disorder Journal Article In: Journal of Experimental Psychology: Learning, Memory, and Cognition, vol. 43, no. 1, pp. 109–127, 2017. @article{Howard2017b, In 2 experiments, eye tracking methodology was used to assess on-line lexical, syntactic and semantic processing in autism spectrum disorder (ASD). In Experiment 1, lexical identification was examined by manipulating the frequency of target words. Both typically developed (TD) and ASD readers showed normal frequency effects, suggesting that the processes TD and ASD readers engage in to identify words are comparable. In Experiment 2, syntactic parsing and semantic interpretation requiring the on-line use of world knowledge were examined, by having participants read garden path sentences containing an ambiguous prepositional phrase. Both groups showed normal garden path effects when reading low-attached sentences and the time course of reading disruption was comparable between groups. This suggests that not only do ASD readers hold similar syntactic preferences to TD readers, but also that they use world knowledge on-line during reading. Together, these experiments demonstrate that the initial construction of sentence interpretation appears to be intact in ASD. However, the finding that ASD readers skip target words less often in Experiment 2, and take longer to read sentences during second pass for both experiments, suggests that they adopt a more cautious reading strategy and take longer to evaluate their sentence interpretation prior to making a manual response. |
Anneline Huck; Robin L. Thompson; Madeline Cruice; Jane Marshall The influence of sense-contingent argument structure frequencies on ambiguity resolution in aphasia Journal Article In: Neuropsychologia, vol. 100, pp. 171–194, 2017. @article{Huck2017a, Verbs with multiple senses can show varying argument structure frequencies, depending on the underlying sense. When acknowledge is used to mean ‘recognise', it takes a direct object (DO), but when it is used to mean ‘admit' it prefers a sentence complement (SC). The purpose of this study was to investigate whether people with aphasia (PWA) can exploit such meaning-structure probabilities during the reading of temporarily ambiguous sentences, as demonstrated for neurologically healthy individuals (NHI) in a self-paced reading study (Hare et al., 2003). Eleven people with mild or moderate aphasia and eleven neurologically healthy control participants read sentences while their eyes were tracked. Using adapted materials from the study by Hare et al. target sentences containing an SC structure (e.g. He acknowledged (that) his friends would probably help him a lot) were presented following a context prime that biased either a direct object (DO-bias) or sentence complement (SC-bias) reading of the verbs. Half of the stimuli sentences did not contain that so made the post verbal noun phrase (his friends) structurally ambiguous. Both groups of participants were influenced by structural ambiguity as well as by the context bias, indicating that PWA can, like NHI, use their knowledge of a verb's sense-based argument structure frequency during online sentence reading. However, the individuals with aphasia showed delayed reading patterns and some individual differences in their sensitivity to context and ambiguity cues. These differences compared to the NHI may contribute to difficulties in sentence comprehension in aphasia. |
Anneline Huck; Robin L. Thompson; Madeline Cruice; Jane Marshall Effects of word frequency and contextual predictability on sentence reading in aphasia: An eye movement analysis Journal Article In: Aphasiology, vol. 31, no. 11, pp. 1307–1332, 2017. @article{Huck2017, Background: Mild reading difficulties are a pervasive symptom of aphasia. While much research in aphasia has been devoted to the study of single word reading, little is known about the process of (silent) sentence reading. Reading research in the non-brain-damaged population has benefited from the use of eye-tracking methodology, allowing inferences on cognitive processing without participants making an articulatory response. This body of research identified two factors, which strongly influence reading at the sentence level: word frequency and contextual predictability (influence of context).Aims: The main aim of this study was to investigate whether word frequency and contextual predictability influence sentence reading by people with aphasia (PWA), in parallel to that of neurologically healthy individuals (NHI). A second aim was to examine whether readers with aphasia show individual differences in the effects, and whether these are related to their underlying language profile. Methods & Procedures: Seventeen PWA and associated mild reading difficulties and 20 NHI took part in this study. Individuals with aphasia completed a range of language assessments. For the eye-tracking experiment, participants silently read sentences that included target words varying in word frequency and predictability while their eye movements were recorded. Comprehension accuracy, fixation durations, and the probability of first-pass fixations and first-pass regressions were measured. Outcomes & Results: Eye movements by both groups were significantly influenced by word frequency and predictability, but the predictability effect was stronger for the PWA than the neurologically healthy participants. Additionally, effects of word frequency and predictability were independent for the NHI, but the individuals with aphasia showed a more interactive pattern. Correlational analyses revealed (i) a significant relationship between lexical-semantic impairments and the word frequency effect score and (ii) a marginally significant association between the sentence comprehension skills and the predictability effect score. Conclusions: Consistent with compensatory processing theories, these findings indicate that decreased reading efficiency may trigger a more interactive reading strategy that aims to compensate for poorer reading by putting more emphasis on a sentence context, particularly for low-frequency words. For those individuals who have difficulties applying the strategy automatically, using a sentence context could be a beneficial strategy to focus on in reading intervention. |
Jaime S. Ide; Hsiang C. Tung; Cheng-Ta Yang; Yuan-Chi Tseng; Chiang-Shan R. Li In: Frontiers in Human Neuroscience, vol. 11, pp. 222, 2017. @article{Ide2017, Impulsivity is a personality trait of clinical importance. Extant research focuses on frontostriatal mechanisms of impulsivity and how executive functions are compromised in impulsive individuals. Imaging studies employing voxel based morphometry highlighted impulsivity-related changes in gray matter concentrations in a wide array of cerebral structures. In particular, whereas prefrontal cortical areas appear to show structural alterations in individuals with a neuropsychiatric condition, the findings are less than consistent in the healthy population. Here, in a sample (n = 113) of young adults assessed for Barratt impulsivity, we controlled for age, gender and alcohol use, and showed that higher impulsivity score is associated with increased gray matter volume (GMV) in bilateral medial parietal and occipital cortices known to represent the peripheral visual field. When impulsivity components were assessed, we observed that this increase in parieto-occipital cortical volume is correlated with inattention and non-planning but not motor subscore. In a separate behavioral experiment of 10 young adults, we demonstrated that impulsive individuals are more vulnerable to the influence of a distractor on target detection in an attention task. If replicated, these findings together suggest aberrant visual attention as a neural correlate of an impulsive personality trait in neurotypical individuals and need to be reconciled with the literature that focuses on frontal dysfunctions. |
Krista R. Kelly; Reed M. Jost; Angie De La Cruz; Lori Dao; Cynthia L. Beauchamp; David R. Stager; Eileen E. Birch Slow reading in children with anisometropic amblyopia is associated with fixation instability and increased saccades Journal Article In: Journal of AAPOS, vol. 21, no. 6, pp. 447–451, 2017. @article{Kelly2017, Background: Previous studies show slow reading in strabismic amblyopia. We recently identified amblyopia, not strabismus, as the key factor in slow reading in children. No studies have focused on reading in amblyopic children without strabismus. We examined reading in anisometropic children and evaluated whether slow reading was associated with ocular motor dysfunction in children with amblyopia. Methods: Anisometropic children (7-12 years) with or without amblyopia were compared to age-similar normal controls. Children silently read a grade-appropriate paragraph during binocular viewing. Reading rate (words/min), number of forward and regressive saccades (per 100 words) and fixation duration were recorded with the ReadAlyzer. Binocular fixation instability was also evaluated (EyeLink 1000). Results: Amblyopic anisometropic children read more slowly (n = 25; mean with standard deviation, 149 ± 42 words/min) than nonamblyopic anisometropic children (n = 15; 196 ± 80 words/min; P = 0.024) and controls (n = 25; 191 ± 65 words/min; P = 0.020). Nonamblyopic anisometropic children read at a comparable rate to controls (P = 0.81). Slow reading in amblyopic anisometropic children was correlated with increased forward saccades (r = −0.84, P < 0.001), increased regressive saccades (r = −0.85, P < 0.001), and fellow eye instability during binocular viewing (r = −0.52 |
Jessica Klusek; Joseph Schmidt; Amanda J. Fairchild; Anna Porter; Jane E. Roberts Altered sensitivity to social gaze in the FMR1 premutation and pragmatic language competence Journal Article In: Journal of Neurodevelopmental Disorders, vol. 9, no. 1, pp. 1–10, 2017. @article{Klusek2017, Background: The FMR1 premutation affects 1:291 women and is associated with a range of cognitive, affective, and physical health complications, including deficits in pragmatic language (i.e., social language). This study investigated attention to eye gaze as a fundamental social-cognitive skill that may be impaired in the FMR1 premutation and could underlie pragmatic deficits. Given the high prevalence of the FMR1 premutation, efforts to define its phenotype and mechanistic underpinnings have significant public health implications. Methods: Thirty-five women with the FMR1 premutation and 20 control women completed an eye-tracking paradigm that recorded time spent dwelling within the eye region in response to a face displaying either direct or averted gaze. Pragmatic language ability was coded from a conversational sample using the Pragmatic Rating Scale. Results: Women with the FMR1 premutation failed to show attentional preference to direct gaze and spent more time dwelling on the averted eyes relative to controls. While dwelling on the eyes was associated with better pragmatic language performance in controls, these variables were unrelated in the women with the FMR1 premutation. Conclusions: Altered sensitivity to social gaze, characterized by increased salience of averted gaze, was observed among womenwiththe FMR1 premutation. Furthermore, women with the FMR1 premutation wereunabletocapitalizeon information conveyed through the eyes to enhance social-communicative engagement, which differed from patterns seen in controls. These findings contribute to the growing characterization of social and communication phenotypes associated with the FMR1 premutation. |
Catarina C. Kordsachia; Izelle Labuschagne; Julie C. Stout Abnormal visual scanning of emotionally evocative natural scenes in Huntington's disease Journal Article In: Frontiers in Psychology, vol. 8, pp. 405, 2017. @article{Kordsachia2017, Abstract Huntington's disease (HD) is a neurodegenerative movement disorder associated with deficits in the processing of emotional stimuli, including alterations in the self-reported subjective experience of emotion when presented with pictures of emotional scenes. The aim of this study was to determine whether individuals with HD, compared to unaffected controls, display abnormal visual scanning of emotionally-evocative natural scenes. Using eye-tracking, we recorded eye-movements of 25 HD participants (advanced pre-symptomatic and early symptomatic) and 25 age-matched unaffected control participants during a picture viewing task. Participants viewed pictures of natural scenes associated with different emotions: anger, disgust, happiness, or neutral, and evaluated those pictures on a valence rating scale. Individuals with HD displayed abnormal visual scanning patterns, but did not differ from controls with respect to their valence ratings. Specifically, compared to controls, HD participants spent less time fixating on the pictures and made longer scan paths. This finding highlights the importance of taking visual scanning behavior into account when investigating emotion processing in HD. The visual scanning patterns displayed by HD participants could reflect a heightened, but possibly unfocussed, search for information, and might be linked to attentional deficits or to altered subjective emotional experiences in HD. Another possibility is that HD participants may have found it more difficult than controls to evaluate the emotional valence of the scenes, and the heightened search for information was employed as a compensatory strategy. |
Angelina Paolozza; Sarah Treit; Christian Beaulieu; James N. Reynolds In: Human Brain Mapping, vol. 38, no. 1, pp. 444–456, 2017. @article{Paolozza2017, Prenatal alcohol exposure (PAE) can cause central nervous system dysfunction and widespread structural anomalies as detected by magnetic resonance imaging (MRI). This study focused on diffusion tensor imaging (DTI) of white matter in a large sample of PAE participants that allowed us to examine correlations with behavioral outcomes. Participants were confirmed PAE (n = 69, mean age = 12.5 ± 3.2 years) or typically developing control children (n = 67, mean age = 12.1 ± 3.2 years) who underwent brain MRI, eye movement tasks, and psychometric tests. A semi‐automated tractography method extracted fractional anisotropy (FA) and mean diffusivity (MD) values from 15 white matter tracts. The PAE group displayed decreased FA compared with controls in multiple tracts including 3 corpus callosum regions, right corticospinal tract, and 3 left hemisphere tracts connecting to the frontal lobe (cingulum, uncinate fasciculus, and superior longitudinal fasciculus). Significant group by sex interactions were found for the genu, left superior longitudinal fasciculus, and the left uncinate, with females in the PAE group exhibiting lower FA compared with control females. Correlations were found between DTI and eye movement measures in the control group, but these same relationships were absent in the PAE group. In contrast, no correlations were found between DTI and any of the psychometric tests used in this study. These findings support the hypothesis that measures of eye movement control may be valuable functional biomarkers of the brain injury induced by PAE as these tasks reveal group differences that appear to be linked to deficits in white matter integrity in the brain. |
Ivanna M. Pavisic; Nicholas C. Firth; Samuel Parsons; David Martinez Rego; Timothy J. Shakespeare; Keir X. X. Yong; Catherine F. Slattery; Ross W. Paterson; Andrew J. Foulkes; Kirsty Macpherson; Amelia M. Carton; Daniel C. Alexander; John Shawe-Taylor; Nick C. Fox; Jonathan M. Schott; Sebastian J. Crutch; Silvia Primativo Eyetracking metrics in young onset alzheimer's disease: A window into cognitive visual functions Journal Article In: Frontiers in Neurology, vol. 8, pp. 377, 2017. @article{Pavisic2017, Young onset Alzheimer's disease (YOAD) is defined as symptom onset before the age of 65 years and is particularly associated with phenotypic heterogeneity. Atypical presentations, such as the clinic-radiological visual syndrome posterior cortical atrophy (PCA), often lead to delays in accurate diagnosis. Eyetracking has been used to demonstrate basic oculomotor impairments in individuals with dementia. In the present study, we aim to explore the relationship between eyetracking metrics and standard tests of visual cognition in individuals with YOAD. Fifty-seven participants were included: 36 individuals with YOAD (n = 26 typical AD; n = 10 PCA) and 21 age-matched healthy controls. Participants completed three eyetracking experiments: fixation, pro-saccade, and smooth pursuit tasks. Summary metrics were used as outcome measures and their predictive value explored looking at correlations with visuoperceptual and visuospatial metrics. Significant correlations between eyetracking metrics and standard visual cognitive estimates are reported. A machine-learning approach using a classification method based on the smooth pursuit raw eyetracking data discriminates with approximately 95% accuracy patients and controls in cross-validation tests. Results suggest that the eyetracking paradigms of a relatively simple and specific nature provide measures not only reflecting basic oculomotor characteristics but also predicting higher order visuospatial and visuoperceptual impairments. Eyetracking measures can represent extremely useful markers during the diagnostic phase and may be exploited as potential outcome measures for clinical trials. |
Melanie Perron; Annie Roy-Charland; Joël Dickinson; Christian LaForge; Randal Joseph Ryan; Annalie Pelot The use of the Duchenne marker and symmetry of the expression in the judgment of smiles in schizophrenia Journal Article In: Psychiatry Research, vol. 252, pp. 126–133, 2017. @article{Perron2017, Research has recurrently shown that individuals with schizophrenia have impairments in emotional facial recognition and this deficit has been associated with aberrant visual scanning of the face. Because human beings have the ability to control the expression of emotion, the communication process becomes more complex. The goal of the current study was to conduct a systematic examination of the response pattern and perceptual-attentional processing in distinguishing smiles with the presence and absence of the Duchenne marker and symmetry and asymmetry of the activation in individuals with schizophrenia. Sixteen individuals diagnosed with schizophrenia and 16 control individuals were asked to judge whether the smiles were really happy or not. Individuals with schizophrenia produced fewer expected responses than controls in judging the symmetric non-Duchenne smile as not really happy. In addition, like their healthy counterparts, individuals with schizophrenia showed difficulty with the judgement of asymmetric Duchenne smiles. In addition to not being as sensitive to the cues, individuals with schizophrenia show differences in their viewing patterns. While the current study does not provide clear links between these viewing patterns and judgment responses, future research should explore other explanations, such as explicit knowledge, for the differences in results. |
Laura Piccardi; M. De Luca; Antonella Di Vita; Liana Palermo; Antonio Tanzilli; Claudia Dacquino; M. R. Pizzamiglio Evidence of taxonomy for developmental topographical disorientation: Developmental landmark agnosia case 1 Journal Article In: Applied Neuropsychology: Child, vol. 2965, pp. 1–12, 2017. @article{Piccardi2017, We report Developmental Landmark Agnosia (DLA) in a 6-year-old boy (L.G.) who was referred to us for congenital prosopagnosia (see Pizzamiglio et al., 2017 , in which both testing and rehabilitation of Congenital Prosopagnosia are reported). We investigated his performance using a neuropsychological battery and eye movement recordings. The assessment showed the presence of deficits in recognizing familiar places (along with Congenital Prosopagnosia), but not common objects. Eye movement recordings confirmed his problems in recognizing familiar landmarks and misrecognition of unfamiliar places. L.G. is the first evidence of a DLA, suggesting identification of taxonomy of navigational disorders in Developmental Topographical Disorientation is possible, as in the Acquired Topographical Disorientation. |
Pilar Piñar; Matthew T. Carlson; Jill P. Morford; Paola E. Dussias Bilingual deaf readers' use of semantic and syntactic cues in the processing of English relative clauses Journal Article In: Bilingualism: Language and Cognition, vol. 20, no. 5, pp. 980–998, 2017. @article{Pinar2017, Eye fixation measures were used to examine English relative clause processing by adult ASL-English bilingual deaf readers. Participants processed subject relative clauses faster than object relative clauses, but expected animacy cues eliminated processing difficulty in object relative clauses. This brings into question previous claims that deaf readers' sentence processing strategies are qualitatively different from those of hearing English native speakers. Measures of English comprehension predicted reading speed, but not differences in syntactic processing. However, a trend for ASL self-ratings to predict the ability to handle syntactic complexity approached significance. Results suggest a need to explore how objective ASL proficiency measures might provide insights into deaf readers' ability to exploit syntactic cues in English. |
M. R. Pizzamiglio; M. De Luca; Antonella Di Vita; Liana Palermo; Antonio Tanzilli; Claudia Dacquino; Laura Piccardi Congenital prosopagnosia in a child: Neuropsychological assessment, eye movement recordings and training Journal Article In: Neuropsychological Rehabilitation, vol. 27, no. 3, pp. 369–408, 2017. @article{Pizzamiglio2017, Here we report the assessment and treatment of a 6-year-old boy (L.G.) who was referred to us for congenital prosopagnosia (CP). We investigated his performance using a test battery and eye movement recordings pre- and post-training. L.G. showed deficits in recognising relatives and learning new faces, and misrecognition of unfamiliar people. Eye movement recordings showed that L.G. focused on the lower part of stimuli in naming tasks based on familiar or unfamiliar incomplete or complete faces. The training focused on improving his ability to explore internal features of faces, to discriminate specific facial features of familiar and unfamiliar faces, and to provide his family with strategies to use in the future. At the end of the training programme L.G. no longer failed to recognise close and distant relatives and classmates and did not falsely recognise unknown people. |
Barbara Poletti; Laura Carelli; Federica Solca; Annalisa Lafronza; Elisa Pedroli; Andrea Faini; Nicola Ticozzi; Andrea Ciammola; Paolo Meriggi; Pietro Cipresso; Dorothée Lulé; Albert C. Ludolph; Giuseppe Riva; Vincenzo Silani An eye-tracker controlled cognitive battery: Overcoming verbal-motor limitations in ALS Journal Article In: Journal of Neurology, vol. 264, no. 6, pp. 1136–1145, 2017. @article{Poletti2017, We assessed language, attention, executive, and social cognition abilities in a sample of patients with Amyotrophic Lateral Sclerosis (ALS) by means of a recently developed cognitive battery based on oculomotor control with eye-tracking (ET) technology. Twenty-one ALS patients and 21 age- and education-matched healthy subjects underwent the ET-based cognitive assessment, together with the standard cognitive screening tools [Frontal Assessment Battery (FAB); Montreal Cognitive Assessment (MoCA); and Digit Sequencing Task]. Psychological measures of anxiety (State-Trait Anxiety Inventory-Y) and depression (Beck Depression Inventory) were also collected, and an ET usability questionnaire was administered. For patients, clinical and respiratory examinations were also performed, together with behavioural assessment (Frontal Behavioural Inventory). The developed battery discriminated among patients and controls with regard to measures of verbal fluency, frontal abilities, and social cognition. Measures of diagnostic utility confirmed a higher diagnostic accuracy of such ET-based tests with respect to FAB; similar diagnostic accuracy emerged when comparing them to the other standard cognitive tools (MoCA, WM). Usability ratings about the ET tests were comparable among the two groups. The ET-based neuropsychological battery demonstrated good levels of diagnostic accuracy and usability in a clinical population of non-demented ALS patients, compared to matched healthy controls. Future studies will be aimed at further investigate validity and usability components by recruiting larger sample of patients, both in moderate-to-severe stages of the disease and affected by more severe cognitive impairment. |
Barbara Poletti; Laura Carelli; Federica Solca; Annalisa Lafronza; Elisa Pedroli; Andrea Faini; Stefano Zago; Nicola Ticozzi; Andrea Ciammola; Claudia Morelli; Paolo Meriggi; Pietro Cipresso; Dorothée Lulé; Albert C. Ludolph; Giuseppe Riva; Vincenzo Silani An eye-tracking controlled neuropsychological battery for cognitive assessment in neurological diseases Journal Article In: Neurological Sciences, vol. 38, no. 4, pp. 595–603, 2017. @article{Poletti2017a, Traditional cognitive assessment in neurological conditions involving physical disability is often prevented by the presence of verbal-motor impairment; to date, an extensive motor-verbal-free neuropsychological battery is not available for such purposes. We adapted a set of neuropsychological tests, assessing language, attentional abilities, executive functions and social cognition, for eye-tracking (ET) control, and explored its feasibility in a sample of healthy participants. Thirty healthy subjects performed a neuropsychological assessment, using an ET-based neuropsychological battery, together with standard "paper and pencil" cognitive measures for frontal (Frontal Assessment Battery-FAB) and working memory abilities (Digit Sequencing Task) and for global cognitive efficiency (Montreal Cognitive Assessment-MoCA). Psychological measures of anxiety (State-Trait Anxiety Inventory-Y-STAI-Y) and depression (Beck Depression Inventory-BDI) were also collected, and a usability questionnaire was administered. Significant correlations were observed between the "paper and pencil" screening of working memory abilities and the ET-based neuropsychological measures. The ET-based battery also correlated with the MoCA, while poor correlations were observed with the FAB. Usability aspects were found to be influenced by both working memory abilities and psychological components. The ET-based neuropsychological battery developed could provide an extensive assessment of cognitive functions, allowing participants to perform tasks independently from the integrity of motor or verbal channels. Further studies will be aimed at investigating validity and usability components in neurological populations with motor-verbal impairments. |
Joshua D. Pratt; Scott B. Stevenson; Harold E. Bedell Scotoma visibility and reading rate with bilateral central scotomas Journal Article In: Optometry and Vision Science, vol. 94, no. 3, pp. 279–284, 2017. @article{Pratt2017, PURPOSE: In this experiment, we tested whether perceptually delineating the scotoma location and border with a gaze contingent polygon overlay improves reading speed and reading eye movements in patients with bilateral central scotomas. METHODS: Eight patients with age-related macular degeneration and bilateral central scotomas read aloud MNRead style sentences with their preferred eye. Eye movement signals from an EyeLink II eyetracker were used to create a gaze contingent display in which a polygon overlay delineating the area of the patient's scotoma was superimposed on the text during 18 of the 42 trials. Blocks of six trials with the superimposed polygon were alternated with blocks of six trials without the polygon. Reading speed and reading eye movements were assessed before and after the subjects practiced reading with the polygon overlay. RESULTS: All of the subjects but one showed an increase in reading speed. A paired-samples t-test for the group as a whole revealed a statistically significant increase in reading speed of 0.075 ± 0.060 (SD) log wpm after reading with the superimposed polygon. Individual subjects demonstrated significant changes in reading eye movements, with the greatest number of subjects demonstrating a shift in the average vertical fixation locus. Across subjects, there was no significant difference between the initial and final reading eye movements in terms of saccades per second, average fixation duration, average amplitude of saccades, or proportion of non-horizontal saccades. CONCLUSIONS: The improvement in reading speed (0.075 log wpm or 19%) over the short experimental session for the majority of subjects indicates that making the scotoma location more visible is potentially beneficial for improving reading speed in patients with bilateral central scotomas. Additional research to examine the efficacy of more extended training with this paradigm is warranted. |
Silvia Primativo; Camilla Clark; Keir X. X. Yong; Nicholas C. Firth; Jennifer M. Nicholas; Daniel C. Alexander; Jason D. Warren; Jonathan D. Rohrer; Sebastian J. Crutch Eyetracking metrics reveal impaired spatial anticipation in behavioural variant frontotemporal dementia Journal Article In: Neuropsychologia, vol. 106, pp. 328–340, 2017. @article{Primativo2017, Eyetracking technology has had limited application in the dementia field to date, with most studies attempting to discriminate syndrome subgroups on the basis of basic oculomotor functions rather than higher-order cognitive abilities. Eyetracking-based tasks may also offer opportunities to reduce or ameliorate problems associated with standard paper-and-pencil cognitive tests such as the complexity and linguistic demands of verbal test instructions, and the problems of tiredness and attention associated with lengthy tasks that generate few data points at a slow rate. In the present paper we adapted the Brixton spatial anticipation test to a computerized instruction-less version where oculomotor metrics, rather than overt verbal responses, were taken into account as indicators of high level cognitive functions. Twelve bvFTD (in whom spatial anticipation deficits were expected), six SD patients (in whom deficits were predicted to be less frequent) and 38 healthy controls were presented with a 10 × 7 matrix of white circles. During each trial (N = 24) a black dot moved across seven positions on the screen, following 12 different patterns. Participants' eye movements were recorded. Frequentist statistical analysis of standard eye movement metrics were complemented by a Bayesian machine learning (ML) approach in which raw eyetracking time series datasets were examined to explore the ability to discriminate diagnostic group performance not only on the overall performance but also on individual trials. The original pen and paper Brixton test identified a spatial anticipation deficit in 7/12 (58%) of bvFTD and in 2/6 (33%) of SD patients. The eyetracking frequentist approach reported the deficit in 11/12 (92%) of bvFTD and in none (0%) of the SD patients. The machine learning approach had the main advantage of identifying significant differences from controls in 24/24 individual trials for bvFTD patients and in only 12/24 for SD patients. Results indicate that the fine grained rich datasets obtained from eyetracking metrics can inform us about high level cognitive functions in dementia, such as spatial anticipation. The ML approach can help identify conditions where subtle deficits are present and, potentially, contribute to test optimisation and the reduction of testing times. The absence of instructions also favoured a better distinction between different clinical groups of patients and can help provide valuable disease-specific markers. |
Malcolm Proudfoot; Gustavo Rohenkohl; Andrew Quinn; Giles L. Colclough; Joanne Wuu; Kevin Talbot; Mark W. Woolrich; Michael Benatar; Anna C. Nobre; Martin R. Turner Altered cortical beta-band oscillations reflect motor system degeneration in amyotrophic lateral sclerosis Journal Article In: Human Brain Mapping, vol. 38, pp. 237–254, 2017. @article{Proudfoot2017, Continuous rhythmic neuronal oscillations underpin local and regional cortical communication. The impact of the motor system neurodegenerative syndrome amyotrophic lateral sclerosis (ALS) on the neuronal oscillations subserving movement might therefore serve as a sensitive marker of disease activity. Movement preparation and execution are consistently associated with modulations to neuronal oscillation beta (15–30 Hz) power. Cortical beta-band oscillations were measured using magnetoencephalography (MEG) during preparation for, execution, and completion of a visually cued, lateralized motor task that included movement inhibition trials. Eleven “classical” ALS patients, 9 with the primary lateral sclerosis (PLS) phenotype, and 12 asymptomatic carriers of ALS-associated gene mutations were compared with age-similar healthy control groups. Augmented beta desynchronization was observed in both contra- and ipsilateral motor cortices of ALS patients during motor preparation. Movement execution coincided with excess beta desynchronization in asymptomatic mutation carriers. Movement completion was followed by a slowed rebound of beta power in all symptomatic patients, further reflected in delayed hemispheric lateralization for beta rebound in the PLS group. This may correspond to the particular involvement of interhemispheric fibers of the corpus callosum previously demonstrated in diffusion tensor imaging studies. We conclude that the ALS spectrum is characterized by intensified cortical beta desynchronization followed by delayed rebound, concordant with a broader concept of cortical hyperexcitability, possibly through loss of inhibitory interneuronal influences. MEG may potentially detect cortical dysfunction prior to the development of overt symptoms, and thus be able to contribute to the assessment of future neuroprotective strategies. |
Ileana Ratiu; Tamiko Azuma Language control in bilingual adults with and without history of mild traumatic brain injury Journal Article In: Brain and Language, vol. 166, pp. 29–39, 2017. @article{Ratiu2017a, Adults with a history of traumatic brain injury often show deficits in executive functioning (EF), including the ability to inhibit, switch, and attend to tasks. These abilities are critical for language processing in bilinguals. This study examined the effect of mild traumatic brain injury (mTBI) on EF and language processing in bilinguals using behavioral and eye-tracking measures. Twenty-two bilinguals with a history of mTBI and twenty healthy control bilinguals were administered executive function and language processing tasks. Bilinguals with a history of mTBI showed deficits in specific EFs and had higher rates of language processing errors than healthy control bilinguals. Additionally, individuals with a history of mTBI have different patterns of eye movements during reading than healthy control bilinguals. These data suggest that language processing deficits are related to underlying EF abilities. The findings provide important information regarding specific EF and language control deficits in bilinguals with a history mTBI. |
Amanda L. Rodrigue; Benjamin P. Austin; Jennifer E. McDowell; Amanda L. Rodrigue Plasticity of prefrontal cortex connectivity in schizophrenia in response to antisaccade practice Journal Article In: Psychiatry Research: Neuroimaging, vol. 265, pp. 77–86, 2017. @article{Rodrigue2017, People with schizophrenia exhibit difficulties in cognitive control that are often attributed to deficits in prefrontal cortex (PFC) circuitry. Practice paradigms have been used to improve these PFC-mediated deficits. The neural consequences of practice on task-based PFC activation have been addressed. Effects on task-based PFC connectivity, however, are largely unknown. We recruited people with schizophrenia and controls to practice antisaccades, a measure of PFC-mediated cognitive control that is disrupted in people with schizophrenia. Subjects performed antisaccades during functional magnetic resonance imaging (fMRI) before and after eight days of antisaccade practice. A group (schizophrenia, controls) × time (pre-, post-test) repeated measures ANOVA on the results of a psychophysiological interaction (PPI) analysis was used to evaluate changes in PFC connectivity; a similar model was used to evaluate changes in antisaccade behavior. After practice, antisaccade behavior improved and PFC connectivity with insular/temporal regions (involved in bottom-up orienting processes) increased in the schizophrenia group. The level of connectivity at post-test in the schizophrenia group was similar to that seen at pre-test in controls and positively correlated with antisaccade performance. Increases in connectivity between bottom-up and top-down regions may underlie behavioral improvements in people with schizophrenia after cognitive control practice. |
Johannes Rosskopf; Martin Gorges; Hans Peter Müller; Dorothée Lulé; Ingo Uttner; Albert C. Ludolph; Elmar H. Pinkhardt; Freimut D. Juengling; Jan Kassubek In: Movement Disorders, vol. 32, no. 7, pp. 1006–1015, 2017. @article{Rosskopf2017, BACKGROUND: The topography of functional network changes in progressive supranuclear palsy can be mapped by intrinsic functional connectivity MRI. The objective of this study was to study functional connectivity and its clinical and behavioral correlates in dedicated networks comprising the cognition-related default mode and the motor and midbrain functional networks in patients with PSP. METHODS: Whole-brain-based "resting-state" functional MRI and high-resolution T1-weighted magnetic resonance imaging data together with neuropsychological and video-oculographic data from 34 PSP patients (22 with Richardson subtype and 12 with parkinsonian subtype) and 35 matched healthy controls were subjected to network-based functional connectivity and voxel-based morphometry analysis. RESULTS: After correction for global patterns of brain atrophy, the group comparison between PSP patients and controls revealed significantly decreased functional connectivity (P < 0.05, corrected) in the prefrontal cortex, which was significantly correlated with cognitive performance (P = 0.006). Of note, midbrain network connectivity in PSP patients showed increased connectivity with the thalamus, on the one hand, whereas, on the other hand, lower functional connectivity within the midbrain was significantly correlated with vertical gaze impairment, as quantified by video-oculography (P = 0.004). PSP Richardson subtype showed significantly increased functional motor network connectivity with the medial prefrontal gyrus. CONCLUSIONS: PSP-associated neurodegeneration was attributed to both decreased and increased functional connectivity. Decreasing functional connectivity was associated with worse behavioral performance (ie, dementia severity and gaze palsy), whereas the pattern of increased functional connectivity may be a potential adaptive mechanism. |
Aasef G. Shaikh; Fatema F. Ghasia Novel eye movement disorders in Whipple's disease-staircase horizontal saccades, gaze-evoked nystagmus, and esotropia Journal Article In: Frontiers in Neurology, vol. 8, pp. 321, 2017. @article{Shaikh2017, Whipple's disease, a rare systemic infectious disorder, is complicated by the involvement of the central nervous system in about 5% of cases. Oscillations of the eyes and the jaw, called oculo-masticatory myorhythmia, are pathognomonic of the central nervous system involvement but are often absent. Typical manifestations of the central nervous system Whipple's disease are cognitive impairment, parkinsonism mimicking progressive supranuclear palsy with vertical saccade slowing, and upgaze range limitation. We describe a unique patient with the central nervous system Whipple's disease who had typical features including parkinsonism, cognitive impairment, and upgaze limitation; but also had diplopia, esotropia with mild horizontal (abduction more than adduction) limitation, and vertigo. The patient also had gaze-evoked nystagmus and staircase horizontal saccades. Latter were thought to be due to mal-programmed small saccades followed by a series of corrective saccades. The saccades were disconjugate due to the concurrent strabismus. Also, we noted disconjugacy in the slow phase of gaze-evoked nystagmus. The disconjugacy of the slow phase of gaze-evoked nystagmus was larger during monocular viewing condition. We propose that interaction of the strabismic drifts of the covered eyes and the nystagmus drift, putatively at the final common pathway might lead to such disconjugacy. |
Annie L. Shelton; Kim M. Cornish; Meaghan Clough; Sanuji Gajamange; Scott Kolbe; Joanne Fielding Disassociation between brain activation and executive function in fragile X premutation females Journal Article In: Human Brain Mapping, vol. 38, no. 2, pp. 1056–1067, 2017. @article{Shelton2017, Executive dysfunction has been demonstrated among premutation (PM) carriers (55-199 CGG repeats) of the Fragile X mental retardation 1 (FMR1) gene. Further, alterations to neural activation patterns have been reported during memory and comparison based functional magnetic resonance imaging (fMRI) tasks in these carriers. For the first time, the relationships between fMRI neural activation during an interleaved ocular motor prosaccade/antisaccade paradigm, and concurrent task performance (saccade measures of latency, accuracy and error rate) in PM females were examined. Although no differences were found in whole brain activation patterns, regions of interest (ROI) analyses revealed reduced activation in the right ventrolateral prefrontal cortex (VLPFC) during antisaccade trials for PM females. Further, a series of divergent and group specific relationships were found between ROI activation and saccade measures. Specifically, for control females, activation within the right VLPFC and supramarginal gyrus correlated negatively with antisaccade latencies, while for PM females, activation within these regions was found to negatively correlate with antisaccade accuracy and error rate (right VLPFC only). For control females, activation within frontal and supplementary eye fields and bilateral intraparietal sulci correlated with prosaccade latency and accuracy; however, no significant prosaccade correlations were found for PM females. This exploratory study extends previous reports of altered prefrontal neural engagement in PM carriers, and clearly demonstrates dissociation between control and PM females in the transformation of neural activation into overt measures of executive dysfunction. |
Martha M. Shiell; Robert J. Zatorre White matter structure in the right planum temporale region correlates with visual motion detection thresholds in deaf people Journal Article In: Hearing Research, vol. 343, pp. 64–71, 2017. @article{Shiell2017, The right planum temporale region is typically involved in higher-order auditory processing. After deafness, this area reorganizes to become sensitive to visual motion. This plasticity is thought to support compensatory enhancements to visual ability. In earlier work we showed that enhanced visual motion detection abilities in early-deaf people correlate with cortical thickness in a subregion of the right planum temporale. In the current study, we build on this earlier result by examining the relationship between enhanced visual motion detection ability and white matter structure in this area in the same sample. We used diffusion-weighted magnetic resonance imaging and extracted the measures of white matter structure from a region-of-interest just below the grey matter surface where cortical thickness correlates with visual motion detection ability. We also tested control regions-of-interest in the auditory and visual cortices where we did not expect to find a relationship between visual motion detection ability and white matter. We found that in the right planum temporale subregion, and in no other tested regions, fractional anisotropy, radial diffusivity, and mean diffusivity correlated with visual motion detection thresholds. We interpret this change as further evidence of a structural correlate of cross-modal reorganization after deafness. |
Tarkeshwar Singh; Julius Fridriksson; Christopher M. Perry; Sarah C. Tryon; Angela Ross; Stacy L. Fritz; Troy M. Herter A novel computational model to probe visual search deficits during motor performance Journal Article In: Journal of Neurophysiology, vol. 117, no. 1, pp. 79–92, 2017. @article{Singh2017, Successful execution of many motor skills relies on well-organized visual search (voluntary eye movements that actively scan the environment for task-relevant information). Although impairments of visual search that result from brain injuries are linked to diminished motor performance, the neural processes that guide visual search within this context remain largely unknown. The first objective of this study was to examine how visual search in healthy adults and stroke survivors is used to guide hand movements during the Trail Making Test (TMT), a neuropsychological task that is a strong predictor of visuomotor and cognitive deficits. Our second objective was to develop a novel computational model to investigate combinatorial interactions between three underlying processes of visual search (spatial planning, working memory and peripheral visual processing). We predicted that stroke survivors would exhibit deficits in integrating the three underlying processes, resulting in deteriorated overall task performance. We found that normal TMT performance is associated with patterns of visual search that primarily rely on spatial planning and/or working memory (but not peripheral visual processing). Our computational model suggested that abnormal TMT performance following stroke is associated with impairments of visual search that are characterized by deficits integrating spatial planning and working memory. This innovative methodology provides a novel framework for studying how the neural processes underlying visual search interact combinatorially to guide motor performance. |
Ingmar Sperling; Sabrina Baldofski; Patrick Lüthold; Anja Hilbert Cognitive food processing in binge-eating disorder: An eye-tracking study Journal Article In: Nutrients, vol. 9, pp. 1–13, 2017. @article{Sperling2017, Studies indicate an attentional bias towards food in binge-eating disorder (BED); however, more evidence on attentional engagement and disengagement and processing of multiple attention-competing stimuli is needed. This study aimed to examine visual attention to food and non-food stimuli in BED. In n = 23 participants with full-syndrome and subsyndromal BED and n = 23 individually matched healthy controls, eye-tracking was used to assess attention to food and non-food stimuli during a free exploration paradigm and a visual search task. In the free exploration paradigm, groups did not differ in their initial fixation position. While both groups fixated non-food stimuli significantly longer than food stimuli, the BED group allocated significantly more attention towards food than controls. In the visual search task, groups did not differ in detection times. However, a significant detection bias for food was found in full-syndrome BED, but not in controls. An increased initial attention towards food was related to greater BED symptomatology and lower body mass index (BMI) only in full-syndrome BED, while a greater maintained attention to food was associated with lower BMI in controls. The results suggest food-biased visual attentional processing in adults with BED. Further studies should clarify the implications of attentional processes for the etiology and maintenance of BED. |
Daniel Fiset; Caroline Blais; Jessica Royer; Anne Raphäelle Richoz; Gabrielle Dugas; Roberto Caldara Mapping the impairment in decoding static facial expressions of emotion in prosopagnosia Journal Article In: Social Cognitive and Affective Neuroscience, vol. 12, no. 8, pp. 1334–1341, 2017. @article{Fiset2017, Acquired prosopagnosia is characterized by a deficit in face recognition due to diverse brain lesions, but interestingly most prosopagnosic patients suffering from posterior lesions use the mouth instead of the eyes for face identification. Whether this bias is present for the recognition of facial expressions of emotion has not yet been addressed.We tested PS, a pure case of acquired prosopagnosia with bilateral occipitotemporal lesions anatomically sparing the regions dedicated for facial expression recognition. PS used mostly the mouth to recognize facial expressions even when the eye area was the most diagnostic. Moreover, PS directed most of her fixations towards the mouth. Her impairment was still largely present when she was instructed to look at the eyes, or when she was forced to look at them. Control participants showed a performance comparable to PS when only the lower part of the face was available. These observations suggest that the deficits observed in PS with static images are not solely attentional, but are rooted at the level of facial information use. This study corroborates neuroimaging findings suggesting that the Occipital Face Area might play a critical role in extracting facial features that are integrated for both face identification and facial expression recognition in static images. |
Anna C. Geuzebroek; Albert V. Berg Impaired visual competition in patients with homonymous visual field defects Journal Article In: Neuropsychologia, vol. 97, pp. 152–162, 2017. @article{Geuzebroek2017, Intense visual training can lead to partial recovery of visual field defects caused by lesions of the primary visual cortex. However, the standard visual detection and discrimination tasks, used to assess this recovery process tend to ignore the complexity of the natural visual environment, where multiple stimuli continuously interact. Visual competition is an essential component for natural search tasks and detecting unexpected events. Our study focused on visual decision-making and to what extent the recovered visual field can compete for attention with the ‘intact' visual field. Nine patients with visual field defects who had previously received visual discrimination training, were compared to healthy age-matched controls using a saccade target-selection paradigm, in which participants actively make a saccade towards the brighter of two flashed targets. To further investigate the nature of competition (feed-forward or feedback inhibition), we presented two flashes that reversed their intensity difference during the flash. Both competition between recovered visual field and intact visual field, as well as competition within the intact visual field, were assessed. Healthy controls showed the expected primacy effect; they preferred the initially brighter target. Surprisingly, choice behaviour, even in the patients' supposedly ‘intact' visual field, was significantly different from the control group for all but one. In the latter patient, competition was comparable to the controls. All other patients showed a significantly reduced preference to the brighter target, but still showed a small hint of primacy in the reversal conditions. The present results indicate that patients and controls have similar decision-making mechanisms but patients' choices are affected by a strong tendency to guess, even in the intact visual field. This tendency likely reveals slower integration of information, paired with a lower threshold. Current rehabilitation should therefore also include training focused on improving visual decision-making of the defective and the intact visual field. |
Steven M. Gillespie; Pia Rotshtein; Anthony R. Beech; Ian J. Mitchell Boldness psychopathic traits predict reduced gaze toward fearful eyes in men with a history of violence Journal Article In: Biological Psychology, vol. 128, pp. 29–38, 2017. @article{Gillespie2017, Research with developmental and adult samples has shown a relationship of psychopathic traits with reduced eye gaze. However, these relationships remained to be investigated among forensic samples. Here we examined the eye movements of male violent offenders during an emotion recognition task. Violent offenders performed similar to non-offending controls, and their eye movements varied with the emotion and intensity of the facial expression. In the violent offender group Boldness psychopathic traits, but not Meanness or Disinhibition, were associated with reduced dwell time and fixation counts, and slower first fixation latencies, on the eyes compared with the mouth. These results are the first to show a relationship of psychopathic traits with reduced attention to the eyes in a forensic sample, and suggest that Boldness is associated with difficulties in orienting attention toward emotionally salient aspects of the face. |
Lisa C. Goelz; Fabian J. David; John A. Sweeney; David E. Vaillancourt; Howard Poizner; Leonard Verhagen Metman; Daniel M. Corcos The effects of unilateral versus bilateral subthalamic nucleus deep brain stimulation on prosaccades and antisaccades in Parkinson's disease Journal Article In: Experimental Brain Research, vol. 235, no. 2, pp. 615–626, 2017. @article{Goelz2017, Unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients with Parkinson's disease improves skeletomotor function assessed clinically, and bilateral STN DBS improves motor function to a significantly greater extent. It is unknown whether unilateral STN DBS improves oculomotor function and whether bilateral STN DBS improves it to a greater extent. Further, it has also been shown that bilateral, but not unilateral, STN DBS is associated with some impaired cognitive-motor functions. The current study compared the effect of unilateral and bilateral STN DBS on sensorimotor and cognitive aspects of oculomotor control. Patients performed prosaccade and antisaccade tasks during no stimulation, unilateral stimulation, and bilateral stimulation. There were three sets of findings. First, for the prosaccade task, unilateral STN DBS had no effect on prosaccade latency and it reduced prosaccade gain; bilateral STN DBS reduced prosaccade latency and increased prosaccade gain. Second, for the antisaccade task, neither unilateral nor bilateral stimulation had an effect on antisaccade latency, unilateral STN DBS increased antisaccade gain, and bilateral STN DBS increased antisaccade gain to a greater extent. Third, bilateral STN DBS induced an increase in prosaccade errors in the antisaccade task. These findings suggest that while bilateral STN DBS benefits spatiotemporal aspects of oculomotor control, it may not be as beneficial for more complex cognitive aspects of oculomotor control. Our findings are discussed considering the strategic role the STN plays in modulating information in the basal ganglia oculomotor circuit. |
Piril Hepsomali; Julie A. Hadwin; Simon P. Liversedge; Matthew Garner Pupillometric and saccadic measures of affective and executive processing in anxiety Journal Article In: Biological Psychology, vol. 127, pp. 173–179, 2017. @article{Hepsomali2017, Anxious individuals report hyper-arousal and sensitivity to environmental stimuli, difficulties concentrating, performing tasks efficiently and inhibiting unwanted thoughts and distraction. We used pupillometry and eye-movement measures to compare high vs. low anxious individuals hyper-reactivity to emotional stimuli (facial expressions) and subsequent attentional biases in a memory-guided pro- and antisaccade task during conditions of low and high cognitive load (short vs. long delay). High anxious individuals produced larger and slower pupillary responses to face stimuli, and more erroneous eye-movements, particularly following long delay. Low anxious individuals' pupillary responses were sensitive to task demand (reduced during short delay), whereas high anxious individuals' were not. These findings provide evidence in anxiety of enhanced, sustained and inflexible patterns of pupil responding during affective stimulus processing and cognitive load that precede deficits in task performance. |
Jianglan Wang; Jiao Zhao; Shoujing Wang; Rui Gong; Zhong Zheng; Longqian Liu Cognitive processing of orientation discrimination in anisometropic amblyopia Journal Article In: PLoS ONE, vol. 12, no. 10, pp. e0186221, 2017. @article{Wang2017f, Cognition is very important in our daily life. However, amblyopia has abnormal visual cogni- tion. Physiological changes of the brain during processes of cognition could be reflected with ERPs. So the purpose of this study was to investigate the speed and the capacity of resource allocation in visual cognitive processing in orientation discrimination task during monocular and binocular viewing conditions of amblyopia and normal control as well as the corresponding eyes of the two groups with ERPs. We also sought to investigate whether the speed and the capacity of resource allocation in visual cognitive processing vary with target stimuli at different spatial frequencies (3, 6 and 9 cpd) in amblyopia and normal control as well as between the corresponding eyes of the two groups. Fifteen mild to moderate aniso- metropic amblyopes and ten normal controls were recruited. Three-stimulus oddball para- digms of three different spatial frequency orientation discrimination tasks were used in monocular and binocular conditions in amblyopes and normal controls to elicit event-related potentials (ERPs). Accuracy (ACC), reaction time (RT), the latency of novelty P300 and P3b, and the amplitude of novelty P300 and P3b were measured. Results showed that RT was longer in the amblyopic eye than in both eyes of amblyopia and non-dominant eye in control. Novelty P300 amplitude was largest in the amblyopic eye, followed by the fellow eye, and smallest in both eyes of amblyopia. Novelty P300 amplitude was larger in the amblyopic eye than non-dominant eye and was larger in fellow eye than dominant eye. P3b latency was longer in the amblyopic eye than in the fellow eye, both eyes of amblyopia and non-dominant eye of control. P3b latency was not associated with RT in amblyopia. Neural responses of the amblyopic eye are abnormal at the middle and late stages of cognitive pro- cessing, indicating that the amblyopic eye needs to spend more time or integrate more resources to process the same visual task. Fellow eye and both eyes in amblyopia are slightly different from the dominant eye and both eyes in normal control at the middle and late stages of cognitive processing. Meanwhile, abnormal extents of amblyopic eye do not vary with three different spatial frequencies used in our study. |
Thomas Welton; Sarim Ather; Frank A. Proudlock; Irene Gottlob; Robert A. Dineen Altered whole-brain connectivity in albinism Journal Article In: Human Brain Mapping, vol. 38, no. 2, pp. 740–752, 2017. @article{Welton2017, Albinism is a group of congenital disorders of the melanin synthesis pathway. Multiple ocular, white matter and cortical abnormalities occur in albinism, including a greater decussation of nerve fibres at the optic chiasm, foveal hypoplasia and nystagmus. Despite this, visual perception is largely preserved. It was proposed that this may be attributable to reorganisation among cerebral networks, including an increased interhemispheric connectivity of the primary visual areas. A graph-theoretic model was applied to explore brain connectivity networks derived from resting-state functional and diffusion-tensor magnetic resonance imaging data in 23 people with albinism and 20 controls. They tested for group differences in connectivity between primary visual areas and in summary network organisation descriptors. Main findings were supplemented with analyses of control regions, brain volumes and white matter microstructure. Significant functional interhemispheric hyperconnectivity of the primary visual areas in the albinism group were found (P = 0.012). Tests of interhemispheric connectivity based on the diffusion-tensor data showed no significant group difference (P = 0.713). Second, it was found that a range of functional whole-brain network metrics were abnormal in people with albinism, including the clustering coefficient (P = 0.005), although this may have been driven partly by overall differences in connectivity, rather than reorganisation. Based on the results, it was suggested that changes occur in albinism at the whole-brain level, and not just within the visual processing pathways. It was proposed that their findings may reflect compensatory adaptations to increased chiasmic decussation, foveal hypoplasia and nystagmus. |
Ivan Koychev; Dan Joyce; E. Barkus; Ulrich Ettinger; Anne Schmechtig; Colin T. Dourish; G. R. Dawson; Kevin J. Craig; J. F. William Deakin In: Cognitive Neuropsychiatry, vol. 22, no. 3, pp. 213–232, 2017. @article{Koychev2017, Introduction: Body dysmorphic disorder (BDD) is characterised by repetitive behaviours and/or mental acts occurring in response to preoccupations with perceived flaws in physical appearance. Based on an eye-tracking paradigm, this study aimed to examine how individuals with BDD processed their own face. Methods: Participants were 21 BDD patients, 19 obsessive– compulsive disorder patients and 21 healthy controls (HC), who were age-, sex-, and IQ-matched. Stimuli were photographs of participants' own faces as well as those from the Pictures of Facial Affect battery. Outcome measures were affect recognition accuracy as well as spatial and temporal scanpath parameters. Results: The BDD group exhibited significantly decreased recognition accuracy for their own face relative to the HC group, and this was most pronounced for those who had a key concern centred on their face. Individual qualitative scanpath analysis revealed restricted and extensive scanning behaviours in BDD participants with a facial preoccupation. Persons with severe BDD also exhibited more marked scanpath deficits. Conclusions: Future research should be directed at extending the current work by incorporating neuroimaging techniques, and investigations of eye-tracking focused on affected body parts in BDD. These could yield fruitful therapeutic applications via incorporation with existing treatment approaches. |
Mariska E. Kret; Jeroen J. Stekelenburg; Beatrice Gelder; Karin Roelofs From face to hand: Attentional bias towards expressive hands in social anxiety Journal Article In: Biological Psychology, vol. 122, pp. 42–50, 2017. @article{Kret2017a, The eye-region conveys important emotional information that we spontaneously attend to. Socially submissive individuals avoid other's gaze which is regarded as avoidance of others' emotional face expressions. But this interpretation ignores the fact that there are other sources of emotional information besides the face. Here we investigate whether gaze-aversion is associated with increased attention to emotional signals from the hands. We used eye-tracking to compare eye-fixations of pre-selected high and low socially anxious students when labeling bodily expressions (Experiment 1) with (non)-matching facial expressions (Experiment 2) and passively viewed (Experiment 3). High compared to low socially anxious individuals attended more to hand-regions. Our findings demonstrate that socially anxious individuals do attend to emotions, albeit to different signals than the eyes and the face. Our findings call for a closer investigation of alternative viewing patterns explaining gaze-avoidance and underscore that other signals besides the eyes and face must be considered to reach conclusions about social anxiety. |
Jiyeon Lee Time course of lexicalization during sentence production in Parkinson's Disease: Eye-tracking while speaking Journal Article In: Journal of Speech, Language, and Hearing Research, vol. 60, no. 4, pp. 924–936, 2017. @article{Lee2017b, Purpose: Growing evidence suggests that sentence formulation is affected in Parkinson's disease (PD); however, how speakers with PD coordinate sentence planning and speaking remains unclear. Within 2 competing models of sentence production, this study examined whether speakers with PD show advanced buffering of words to minimize disfluencies and increased demands during speech or whether they plan one word at a time, compromising accuracy and fluency of speech. Method: Participants described 3 computer-displayed pictures using the sentence "the A and the B are above the C." Name agreement (codability) was varied to be high (clock) or low (sofa/couch) for each object position (A, B, C), affecting difficulty of lexical selection. Participants' gaze durations to each object were recorded. Results: Speakers with PD showed incremental word-by-word planning, retrieving only the first lexical item (A) before speech onset, similar to controls. However, they produced greater word-finding errors and disfluencies compared to controls for the low-codable pictures, but not for high-codable pictures. Conclusions: These findings suggest that by following word-by-word incremental production, speakers with PD compromise fluency and accuracy of speech to a greater extent than healthy older speakers and that PD is associated with impaired inhibitory control during lexical selection. |
Amelia K. Lewis; Melanie A. Porter; Tracey A. Williams; Samantha Bzishvili; Kathryn N. North; Jonathan M. Payne Facial emotion recognition, face scan paths, and face perception in children with neurofibromatosis type Journal Article In: Neuropsychology, vol. 31, no. 4, pp. 361–370, 2017. @article{Lewis2017, OBJECTIVE: This study aimed to investigate face scan paths and face perception abilities in children with Neurofibromatosis Type 1 (NF1) and how these might relate to emotion recognition abilities in this population. METHOD: The authors investigated facial emotion recognition, face scan paths, and face perception in 29 children with NF1 compared to 29 chronological age-matched typically developing controls. Correlations between facial emotion recognition, face scan paths, and face perception in children with NF1 were examined. RESULTS: Children with NF1 displayed significantly poorer recognition of fearful expressions compared to controls, as well as a nonsignificant trend toward poorer recognition of anger. Athough there was no significant difference between groups in time spent viewing individual core facial features (eyes, nose, mouth, and nonfeature regions), children with NF1 spent significantly less time than controls viewing the face as a whole. Children with NF1 also displayed significantly poorer face perception abilities than typically developing controls. Facial emotion recognition deficits were not significantly associated with aberrant face scan paths or face perception abilities in the NF1 group. CONCLUSIONS: These results suggest that impairments in the perception, identification, and interpretation of information from faces are important aspects of the social-cognitive phenotype of NF1. |
Qingxiao Liu; Bo Tan; Jing Zhou; Zhong Zheng; Ling Li; Yanchun Yang Pathophysiology of refractory obsessive-compulsive disorder Journal Article In: Medicine, pp. 1–11, 2017. @article{Liu2017d, Based on both functional and structural studies of excessive activity, fronto-striatal-thalamic-cortical and cortico-striatal circuits have been hypothesized to underlie the pathophysiology of obsessive-compulsive disorder (OCD). However, the neurobiological underpinnings of OCD refractory to medication and therapy remain controversial. This study aimed to evaluate neuroanatomical abnormalities of the whole brain and to evaluate visual processing in patients with refractory OCD. This study was comprised of 2 experiments. The neuroanatomical abnormalities of the whole brain were evaluated using a visual search in combination with overactive performance monitoring (Experiment I), and visual processing was evaluated using event- related potentials recorded from subjects during performance of a visual search task. We also examined the amplitudes and latency of the error-related negativity (ERN) using a modified flanker task (Experiment II). Standard low-resolution electromagnetic tomography analysis was applied to determine the special areas. Patients with refractory OCD had a significantly greater number of saccades and prolonged latencies relative to the healthy controls. Scalp map topography confirmed that visual cognitive and executive dysfunction was localized to the fusiform gyrus. Furthermore, we found that during a modified flanker task, ERNs had a greater amplitude and a prolonged latency relative to those of the healthy controls. Further data analysis suggested that cognitive dysfunction and compulsive behavior in OCD patients were linked to abnormalities within the dorsolateral prefrontal cortex (DLPFC). We identified abnormal activities within the fusiform gyrus and DLPFC that likely play important roles in the pathophysiology of OCD. |
Barbara C. Y. Lo; Jeffrey C. C. Liu Executive control in depressive rumination: Backward inhibition and non-inhibitory switching performance in a modified mixed antisaccade task Journal Article In: Frontiers in Psychology, vol. 8, pp. 136, 2017. @article{Lo2017, BACKGROUND AND OBJECTIVES: The present study examines backward inhibition (BI) and non-inhibitory switching performance among depressed and healthy participants in a modified mixed antisaccade task. Specifically, sad and neutral faces were incorporated in the design to examine executive control difficulties associated with brooding trait. METHODS: Thirty-nine participants took part in the study, including 19 depressed patients and 20 healthy control subjects. Participants completed a diagnostic interview and self-report questionnaires, including the Beck Depression Inventory and Ruminative Response Scale-Brooding Subscale. They were then instructed to complete prosaccade and antisaccade trials in the pure and mixed blocks whereby eye gazes were tracked to assess inhibition and switching efficiency. RESULTS: For the switching effects, a significant group x brooding x task type interaction was found as hypothesized when multilevel modeling analysis was employed. Switching deficits associated with brooding was found to be greatest when sad faces were presented to depressed group. No significant results in BI or error rates were observed. CONCLUSION: The patterns observed suggest that as opposed to BI, set shifting difficulty associated with brooding trait may be modulated by negative mood and cognition. In future research, emotional faces other than sad faces may be used to further explore if the observations could be generalized to other affective conditions. |
Masoumeh Mahmoodi-Aghdam; Mohsen Dehghani; Mehrnoosh Ahmadi; Anahita Khorrami Banaraki; Ali Khatibi Chronic pain and selective attention to pain arousing daily activity pictures: Evidence from an eye tracking study Journal Article In: Basic and Clinical Neuroscience, vol. 8, no. 6, pp. 467–478, 2017. @article{MahmoodiAghdam2017, Introduction: According to the pain research literature, attentional bias for pain is the mechanism responsible for the development and maintenance of fear of pain in patients with chronic pain. However, there is still some debate about the exact mechanism and the role of faster engagement versus difficulty in disengagement in the development of attentional bias. Methods: To investigate attentional bias in patients with chronic pain, we used an eye-tracker with the pictures of pain-provoking activities and compared the results with an age-and gender-matched group of pain-free participants. In addition, other measures of pain-related cognition and pain severity ratings were included to assess their contribution to the attentional bias toward pain-related information. Results: Calculating the frequency of the first fixations showed that both groups fixated initially on pain-provoking pictures compared to neutral one. Calculating the speed of fixations showed that control participants were faster in fixating on neutral stimuli, but patients with pain were faster in fixating on pain-provoking pictures, indicating a relative vigilance for the pain-related stimuli among them. These patients reported that the intensity of pain in the previous week was positively correlated with the speed of their fixation on the painful stimuli. Conclusion: Although these results did not provide unequivocal support for the vigilance-avoidance hypothesis, they are generally consistent with the results of studies using eye tracking technology. Furthermore, our findings put a question over characterization of attentional biases in patients with chronic pain by simply relating that to difficulty in disengaging from pain-related stimuli. |
Manuela Malaspina; Andrea Albonico; Carlo Toneatto; Roberta Daini What do eye movements tell us about the visual perception of individuals with congenital prosopagnosia? Journal Article In: Neuropsychology, vol. 31, no. 5, pp. 546–563, 2017. @article{Malaspina2017, Objective: The lack of inversion effect for face recognition in congenital prosopagnosia (CP) is consistent with the hypothesis of a failure in holistic processing. However, although CPs' abnormal gaze behavior for upright faces has already been demonstrated, neither their scanning strategy for inverted faces, nor the possibility that their abnormal gaze behavior with upright faces is because of reasons other than the holistic deficit have been investigated yet. Method: We recorded the eye movements of a congenital prosopagnosic and a control group during the encoding of unknown faces, objects, and flowers. Two types of stimuli (faces and objects) were presented upright and inverted. Results: CPs explored upright and inverted faces in the same way (i.e., similar number of fixations of the same duration and similarly distributed), whereas controls increased the number of fixations and their duration during the presentation of inverted faces. By contrast, the 2 groups showed a similar inversion effect during the encoding of objects. Finally, CPs showed anomalous exploration of within-class objects (i.e., flowers) and impairment in subordinate-level object discrimination. Conclusions: Our results demonstrate that: (a) CPs use the same part-based strategy in encoding both upright and inverted faces, suggesting a possible interpretation of the lack of inversion effect in this population; (b) CPs' lack of inversion effect is face-specific and does not affect objects; (c) however, CPs' deficit seems not to be limited to faces, and to extend to individual-item recognition within a class. |
Jun Maruta; Lisa A. Spielman; Irene D. Tseretopoulos; Adrienne Hezghia; Jamshid Ghajar Possible medication-resistant deficits in adult ADHD Journal Article In: Journal of Attention Disorders, vol. 21, no. 14, pp. 1169–1179, 2017. @article{Maruta2017b, OBJECTIVE: The nature of ADHD, especially in adulthood, is not well-understood. Therefore, we explored subcomponents of attention in adult ADHD. METHOD: Twenty-three adults with ADHD were tested on neurocognitive and visual tracking performance both while on their regular prescription stimulant medication and while abstaining from the medication for 1 day. Pairwise comparisons to 46 two-for-one matched normal controls were made to detect medication-resistant effects of ADHD, and within-participant comparisons were made to detect medication-sensitive effects in patients. RESULTS: Even when on medication, patients performed more poorly than controls on a spatial working memory task, and on visual tracking and simple reaction time tasks immediately following other attention-demanding tasks. Patients' visual tracking performance degraded while off-medication in a manner consistent with reduced vigilance. CONCLUSION: There may be persistent cognitive impairments in adult ADHD despite medication. In addition, the benefit of stimulants seems reduced under cognitive fatigue. |
Eliana Mastrantuono; David Saldaña; Isabel R. Rodríguez-Ortiz An eye tracking study on the perception and comprehension of unimodal and bimodal linguistic inputs by deaf adolescents Journal Article In: Frontiers in Psychology, vol. 8, pp. 1044, 2017. @article{Mastrantuono2017, An eye tracking experiment explored the gaze behaviour of deaf individuals when perceiving language in spoken and sign language only, and in sign-supported speech. Participants were deaf (n = 25) and hearing (n = 25) Spanish adolescents. Deaf students were prelingually profoundly deaf individuals with cochlear implants used by age 5 or earlier, or prelingually profoundly deaf native signers with deaf parents. The effectiveness of sign-supported speech has rarely been tested within the same group of children at discourse-level comprehension. Here, video-recorded texts, including spatial descriptions, were alternately transmitted in spoken language, sign language and sign-supported speech. The capacity of these communicative systems to equalise comprehension in deaf participants with that of spoken language in hearing participants was tested. Within-group analyses of deaf participants tested if the bimodal linguistic input of sign-supported speech favoured discourse comprehension compared to unimodal languages. Deaf participants with cochlear implants achieved equal comprehension to hearing controls in all communicative systems while deaf native signers with no cochlear implants achieved equal comprehension to hearing participants if tested in their native sign language. Comprehension of sign-supported speech was not increased compared to spoken language, even when spatial information was communicated. Eye movements of deaf and hearing participants were tracked and data of dwell times spent looking at the face or body area of the sign model were analysed. Within-group analyses focused on differences between native and non-native signers. Dwell times of hearing participants were equally distributed across upper and lower areas of the face while deaf participants mainly looked at the mouth area; this could enable information to be obtained from mouthings in sign language and from lipreading in sign-supported speech and spoken language. Few fixations were directed towards the signs, although these were more frequent when spatial language was transmitted. Both native and non-native signers looked mainly at the face when perceiving sign language, although non-native signers looked significantly more at the body than native signers. This distribution of gaze fixations suggested that deaf individuals – particularly native signers – mainly perceived signs through peripheral vision. |
Bob McMurray; Ashley Farris-Trimble; Hannah Rigler Waiting for lexical access: Cochlear implants or severely degraded input lead listeners to process speech less incrementally Journal Article In: Cognition, vol. 169, pp. 147–164, 2017. @article{McMurray2017, Spoken language unfolds over time. Consequently, there are brief periods of ambiguity, when incomplete input can match many possible words. Typical listeners solve this problem by immediately activating multiple candidates which compete for recognition. In two experiments using the visual world paradigm, we examined real-time lexical competition in prelingually deaf cochlear implant (CI) users, and normal hearing (NH) adults listening to severely degraded speech. In Experiment 1, adolescent CI users and NH controls matched spoken words to arrays of pictures including pictures of the target word and phonological competitors. Eye-movements to each referent were monitored as a measure of how strongly that candidate was considered over time. Relative to NH controls, CI users showed a large delay in fixating any object, less competition from onset competitors (e.g., sandwich after hearing sandal), and increased competition from rhyme competitors (e.g., candle after hearing sandal). Experiment 2 observed the same pattern with NH listeners hearing highly degraded speech. These studies suggests that in contrast to all prior studies of word recognition in typical listeners, listeners recognizing words in severely degraded conditions can exhibit a substantively different pattern of dynamics, waiting to begin lexical access until substantial information has accumulated. |
Jenny A. Nij Bijvank; L. J. Balk; H. S. Tan; Bernard M. J. Uitdehaag; L. J. Rijn; A. Petzold A rare cause for visual symptoms in multiple sclerosis: Posterior internuclear ophthalmoplegia of Lutz, a historical misnomer Journal Article In: Journal of Neurology, vol. 264, no. 3, pp. 600–602, 2017. @article{NijBijvank2017, A 22-year-old female patient with a 1 year history of relapsing remitting multiple sclerosis (MS) complained of difficulties focusing and brief episodes of horizontal gaze evoked diplopia. Symptoms occurred intermittently in rest, and increased whilst walking or cycling in busy environ- ments. Her past medical and family history was unre- markable and she was not taking any medication. On examination extraocular eye movements were full and convergence was normal. There was no abducting or adducting nystagmus, and no convincingly reproducible slowing of saccades on repeated testing and no oscillopsia. The reminder of her cranial nerve examination was normal. Her vestibulo-ocular reflex was normal. The optokinetic nystagmus was not tested. We thought we had not suffi- ciently excluded the possibility of an internuclear ophthal- moplegia (INO) and recorded the eye movements with high-frequency infrared oculography (Eyelink 1000 plus, SR Research Ltd., Canada). |