Search

When intercepting moving targets, people perform slightly better if they follow their natural tendency to pursue the target with their eyes. Is this because the velocity is judged more precisely when pursuing the target? To find out, we compared how well people could determine which of two sequentially presented moving bars was moving faster. There was always also a static bar on the screen. People judged the moving bar's velocity about 10% more precisely when pursuing it than when fixating the static bar.

Smooth pursuit eye movements (SPEM) are essential to guide behaviour in complex visual environments. SPEM accuracy is known to be degraded by the presence of a structured visual background and at higher target velocities. The aim of this preregistered study was to investigate the neural mechanisms of these robust behavioural effects. N = 33 participants performed a SPEM task with two background conditions (present and absent) at two target velocities (0.4 and 0.6 Hz). Eye movement and BOLD data were collected simultaneously. Both the presence of a structured background and faster target velocity decreased pursuit gain and increased catch-up saccade rate. Faster targets additionally increased position error. Higher BOLD response with background was found in extensive clusters in visual, parietal, and frontal areas (including the medial frontal eye fields; FEF) partially overlapping with the known SPEM network. Faster targets were associated with higher BOLD response in visual cortex and left lateral FEF. Task-based functional connectivity analyses (psychophysiological interactions; PPI) largely replicated previous results in the basic SPEM network but did not yield additional information regarding the neural underpinnings of the background and velocity effects. The results show that the presentation of visual background stimuli during SPEM induces activity in a widespread visuo-parieto-frontal network including areas contributing to cognitive aspects of oculomotor control such as medial FEF, whereas the response to higher target velocity involves visual and motor areas such as lateral FEF. Therefore, we were able to propose for the first time different functions of the medial and lateral FEF during SPEM.

Expectations about forthcoming visual motion shaped by observers' experiences are known to induce anticipatory smooth eye movements (ASEMs) and changes in visual perception. Previous studies have demonstrated discrete effects of expectations on the control of ASEM and perception. However, the tasks designed in those studies were not able to segregate the effects of expectations and execution of ASEM itself on perception. In the present study, we attempted to directly examine the effect of ASEM itself on visual speed perception with a two-alternative forced-choice (2AFC) task, in which observers were asked to track a pair of sequentially presented visual motion stimuli with their eyes and to judge whether the second stimulus (test stimulus) was faster or slower than the first (reference stimulus). Our results showed that observers' visual speed perception, quantified by a psychometric function, shifted according to ASEM velocity. This was the case even though there was no difference in the steady-state eye velocity. Further analyses revealed that the observers' perceptual decisions could be explained by a difference in the magnitude of retinal slip velocity in the initial phase of ocular tracking when the reference and test stimuli were presented, rather than in the steady-state phase. Our results provide psychophysical evidence of the importance of initial ocular tracking in visual speed perception and the strong impact of ASEM.

Visual tracking of moving objects requires sustained attention and prediction of the object's trajectory. We tested the hypothesis that measures of eye-head tracking of moving objects are associated to long-term neurodevelopment in very preterm infants.Visual tracking performance was assessed at 4 month's corrected age in 57 infants with gestational age32 weeks. An object moved in front of the infant with sinusoidal or triangular (i.e. abrupt) turns of the direction. Gaze gain, smooth pursuit gain, and timing of gaze to object motion were analyzed. At 6.5 years the Wechsler Intelligence Scale for Children (WISC-IV), the Brown Attention Deficit Disorder (Brown ADD), and visual examination were performed.Gaze gain and smooth pursuit gain at 4 months were strongly related to all WISC-IV parameters at 6.5 years. Gaze gain for the triangular and sinusoidal motion patterns related similarly to the cognitive scores. For the sinusoidal motion pattern, timing related to most Brown ADD parameters. There were no statistically significant differences in associations dependent on motion pattern. Visual function did not influence the results.The ability to attend to and smoothly track a moving object in infancy is an early marker of cognition and attention at 6.5 years.Potential long-term implications of infant visual tracking of moving objects for school-age neurodevelopment has not been previously studied in very preterm infants. Early coordination of eye and head movements in gaze gain, smooth pursuit, and timing of gaze to object motion are closely associated with cognition and attention at 6.5 years. As related functions at 6.5 years include perceptual and verbal skills, working memory, processing speed and attention, predictive elements in gaze tracking of moving objects might be a suitable target for future intervention studies.

A 60-year-old patient had progressive imbalance. Examination revealed saccadic smooth pursuit, downbeat nystagmus, ataxia of stance and gait, and reduced vibration sense. Video head impulse and caloric testing both showed vestibulo-ocular reflex (VOR) deficits (figure). The patient has cerebellar ataxia with neuronopathy and vestibular areflexia syndrome.1,2 Slow head turns while looking at an earth-fixed target produce saccadic rather than smooth compensatory eye movements (Videos 1) due to impairment of both the VOR and smooth pursuit (the visually enhanced VOR): 1 simple bedside test, 2 clinical signs, and 1 precise diagnosis.

In healthy vision, the fovea provides high acuity and serves as the locus for fixation achieved through saccadic eye movements. Bilateral loss of the foveal regions in both eyes causes individuals to adopt an eccentric locus for fixation. This review deals with the eye movement consequences of the loss of the foveal oculomotor reference and the ability of individuals to use an eccentric fixation locus as the new oculomotor reference. Eye movements are an integral part of everyday activities, such as reading, searching for an item of interest, eye–hand coordination, navigation, or tracking an approaching car. We consider how these tasks are impacted by the need to use an eccentric locus for fixation and as a reference for eye movements, specifically saccadic and smooth pursuit eye movements.

During smooth pursuit eye movements, the visual system is faced with the task of telling apart reafferent retinal motion from motion in the world. While an efference copy signal can be used to predict the amount of reafference to subtract from the image, an image-based adaptive mechanism can ensure the continued accuracy of this computation. Indeed, repeatedly exposing observers to background motion with a fixed direction relative to that of the target that is pursued leads to a shift in their point of subjective stationarity (PSS). We asked whether the effect of exposure reflects adaptation to motion contingent on pursuit direction, recalibration of a reference signal or both. A recalibration account predicts a shift in reference signal (i.e. predicted reafference), resulting in a shift of PSS, but no change in sensitivity. Results show that both directional judgements and confidence judgements about them favor a recalibration account, whereby there is an adaptive shift in the reference signal caused by the prevailing retinal motion during pursuit. We also found that the recalibration effect is specific to the exposed visual hemifield.

Athletes exhibit better dynamic visual acuity (DVA) compared with nonathletes, whereas action video game players (VGPs) perform more similarly to controls despite having similar static visual acuity and refractive errors. The differences in DVA between groups were not related to differences in static visual acuity, refractive error, or smooth pursuit gain.The purpose of the study was to examine whether athletes and VGPs have superior DVA than controls (nonathletes, nongamers).Forty-six participants (15 athletes, 11 VGPs, 20 controls) aged 21.7 years (standard deviation, 2.8 years) were recruited. Participants were emmetropic with equivalent monocular and binocular static visual acuity between groups. Dynamic visual acuity was assessed using predictable (horizontal) and unpredictable (random) motion targets at velocities of 5, 10, 20, and 30°/s. Smooth pursuit eye movements were assessed using a horizontal motion step-ramp stimulus at the same speeds. This study was pre-registered with the Center for Open Science (https://osf.io/eu7qc).At 30°/s, there were significant main effects of group (F = 4.762, P = .01) and motion type (F = 9.538, P = .004). Tukey post hoc analysis for groups indicated that athletes performed better than did the control group (t = -2.919, P.02). An omnibus (group × motion type × speed) repeated measures ANOVA showed a main effect of speed (F = 110.137, P.001) and a speed × motion-type interaction (F = 27.825, P.001). Dynamic visual acuity decreased as speed increased, and the slope of the change was greater for random than for horizontal motion. Smooth pursuit gains were not significantly different between groups (P.05).Athletes have superior dynamic visual acuity performance compared with controls at 30°/s. This between-group difference cannot be fully explained by differences in smooth pursuit eye movements and therefore may reflect other differences between the groups.

As a tribute to Masao Ito, we propose a model of cerebellar learning that incorporates and extends his original model. We suggest four principles that align well with conclusions from multiple cerebellar learning systems. (1) Climbing fiber inputs to the cerebellum drive early, fast, poorly-retained learning in the parallel fiber to Purkinje cell synapse. (2) Learned Purkinje cell outputs drive late, slow, well-retained learning in non-Purkinje cell inputs to neurons in the cerebellar nucleus, transferring learning from the cortex to the nucleus. (3) Recurrent feedback from Purkinje cells to the inferior olive, through interneurons in the cerebellar nucleus, limits the magnitude of fast, early learning in the cerebellar cortex. (4) Functionally different inputs are subjected to plasticity in the cerebellar cortex versus the cerebellar nucleus. A computational neural circuit model that is based on these principles mimics a large amount of neural and behavioral data obtained from the smooth pursuit eye movements of monkeys.

Virtual reality (VR) head mounted displays (HMDs) require both high spatial resolution and fast temporal response. However, methods to quantify the VR image quality in the spatiotemporal domain when motion exists are not yet standardized. In this study, we characterize the spatiotemporal capabilities of three VR devices: the HTC VIVE, VIVE Pro, and VIVE Pro 2 during smooth pursuit. A spatiotemporal model for VR HMDs is presented using measured spatial and temporal characteristics. Among the three evaluated headsets, the VIVE Pro 2 improves the display temporal performance using a fast 120 Hz refresh rate and pulsed emission with a small duty cycle of 5%. In combination with a high pixel resolution beyond 2 k $$\times$$ × 2 k per eye, the VIVE Pro 2 achieves an improved spatiotemporal performance compared to the VIVE and VIVE Pro in the high spatial frequency range above 8 cycles per degree during smooth pursuit. The result demonstrates that reducing the display emission duty cycle to less than 20% is beneficial to mitigate motion blur in VR HMDs. Frame rate reduction (e.g., to below 60 Hz) of the input signal compared to the display refresh rate of 120 Hz yields replicated shadow images that can affect the image quality under motion. This work supports the regulatory science research efforts in development of testing methods to characterize the spatiotemporal performance of VR devices for medical use.

Upright postural control is regulated by afferent and efferent/reafferent visual mechanisms. There are two types of efferent and conjugate eye movements: saccades and smooth pursuits. Although postural control is improved by saccades, the effects of smooth pursuits on postural control are still debated, because the difficulties of postural and visual tasks differ in the previous research. Additionally, the mechanisms that interfere with postural control and smooth pursuit are not fully understood. To address these issues, we examined the effects of different patterns of smooth-pursuit eye movement on the path length of the center of pressure (COP) displacement under bipedal and unipedal standing conditions. The relative frequency and amplitude of the COP displacement were remarkably increased when uniform linear visual targets were presented during unipedal standing. In addition, dynamic time warping analysis demonstrated that the similarity between the displacement of the COP and eye movements was increased by the presentation of uniform linear visual targets with orientation selectivity during unipedal standing but not during bipedal standing. In contrast, the attenuation of similarity between the displacement of the COP and eye movements significantly decreased the path length, relative frequency, and amplitude of the COP displacement. Our results indicate that postural stability is deteriorated by the increase of similarity between the displacement of the COP and smooth-pursuit eye movements under unstable conditions.

In the evaluation of smooth pursuit eye movements (SPEMs), recording the stimulus onset time is mandatory. In the laboratory, the stimulus onset time is recorded by electrical signal or programming, and video-oculography (VOG) and the visual stimulus are synchronized. Nevertheless, because the examiner must manually move the fixation target, recording the stimulus onset time is challenging in daily clinical practice. Thus, this study aimed to develop an algorithm for evaluating SPEMs while testing the nine-direction eye movements without recording the stimulus onset time using VOG and deep learning–based object detection (single-shot multibox detector), which can predict the location and types of objects in a single image. The algorithm of peak fitting–based detection correctly classified the directions of target orientation and calculated the latencies and gains within the normal range while testing the nine-direction eye movements in healthy individuals. These findings suggest that the algorithm of peak fitting–based detection has sufficient accuracy for the automatic evaluation of SPEM in clinical settings.

Our nervous systems can learn optimal control policies in response to changes to our bodies, tasks, and movement contexts. For example, humans can learn to adapt their control policy in walking contexts where the energy-optimal policy is shifted along variables such as step frequency or step width. However, it is unclear how the nervous system determines which ways to adapt its control policy. Here, we asked how human participants explore through variations in their control policy to identify more optimal policies in new contexts. We created new contexts using exoskeletons that apply assistive torques to each ankle at each walking step. We analyzed four variables that spanned the levels of the whole movement, the joint, and the muscle: step frequency, ankle angle range, total soleus activity, and total medial gastrocnemius activity. We found that, across all of these analyzed variables, variability increased upon initial exposure to new contexts and then decreased with experience. This led to adaptive changes in the magnitude of specific variables, and these changes were correlated with reduced energetic cost. The timescales by which adaptive changes progressed and variability decreased were faster for some variables than others, suggesting a reduced search space within which the nervous system continues to optimize its policy. These collective findings support the principle that exploration through general variability leads to specific adaptation toward optimal movement policies.

Abnormal eye movements are often associated with psychiatric disorders. Eye movements are sensorimotor functions of the brain, and aging and sex would affect their characteristics. A precise understanding of normal eye movements is required to distinguish disease‐related abnormalities from natural differences associated with aging or sex. To date, there is no multicohort study examining age‐related dependency and sex effects of eye movements in healthy, normal individuals using large samples to ensure the robustness and reproducibility of the results. In this study, we aimed to provide findings showing the impact of age and sex on eye movement measures. The present study used eye movement measures of more than seven hundred healthy individuals from three large independent cohorts. We herein evaluated eye movement measures quantified by using a set of standard eye movement tests that have been utilized for the examination of patients with schizophrenia. We assessed the statistical significance of the effects of age and sex and its reproducibility across cohorts. We found that 4‐18 out of 35 eye movement measures were significantly correlated with age, depending on the cohort, and that 10 of those, which are related to the fixation and motor control of smooth pursuit and saccades, showed high reproducibility. On the other hand, the effects of sex, if any, were less reproducible. The present results suggest that we should take age into account when we evaluate abnormalities in eye movements., In this study, we aimed to provide findings showing the impact of age and sex on eye movement measures. We found significant effects of age on the eye movement measures related to the fixation and motor control of smooth pursuit and saccades, with high reproducibility. Thus, we should take age into account when we evaluate abnormalities in eye movements.

International audience; When tracking targets moving in various directions with one's eyes, horizontal components of pursuit are more precise than vertical ones. Is this because horizontal target motion is predicted better or because horizontal movements of the eyes are controlled more precisely? When tracking a visual target with the hand, the eyes also track the target. We investigated whether the directional asymmetries that have been found during isolated eye movements are also present during such manual tracking, and if so, whether individual participants' asymmetry in eye movements is accompanied by a similar asymmetry in hand movements. We examined the data of 62 participants who used a joystick to track a visual target with a cursor. The target followed a smooth but unpredictable trajectory in two dimensions. Both the mean gaze-target distance and the mean cursor-target distance were about 20% larger in the vertical direction than in the horizontal direction. Gaze and cursor both followed the target with a slightly longer delay in the vertical than in the horizontal direction, irrespective of the target's trajectory. The delays of gaze and cursor were correlated, as were their errors in tracking the target. Gaze clearly followed the target rather than the cursor, so the asymmetry in both eye and hand movements presumably results from better predictions of the target's horizontal than of its vertical motion. Altogether this study speaks for the presence of anisotropic predictive processes that are shared across effectors.

Key points Oculomotor behaviours are commonly used to evaluate sensorimotor disruption due to ethanol (EtOH).The current study demonstrates the dose‐dependent impairment in oculomotor and ocular behaviours across a range of ultra‐low BACs (

Smooth pursuit eye movements (SPEM) hold the image of a slowly moving stimulus on the fovea. The neural system underlying SPEM primarily includes visual, parietal, and frontal areas. In the present study, we investigated how these areas are functionally coupled and how these couplings are influenced by target motion frequency. To this end, healthy participants (n = 57) were instructed to follow a sinusoidal target stimulus moving horizontally at two different frequencies (0.2 Hz, 0.4 Hz). Eye movements and blood oxygen level-dependent (BOLD) activity were recorded simultaneously. Functional connectivity of the key areas of the SPEM network was investigated with a psychophysiological interaction (PPI) approach. How activity in five eye movement-related seed regions (lateral geniculate nucleus, V1, V5, posterior parietal cortex, frontal eye fields) relates to activity in other parts of the brain during SPEM was analyzed. The behavioral results showed clear deterioration of SPEM performance at higher target frequency. BOLD activity during SPEM versus fixation occurred in a geniculo-occipito-parieto-frontal network, replicating previous findings. PPI analysis yielded widespread, partially overlapping networks. In particular, frontal eye fields and posterior parietal cortex showed task-dependent connectivity to large parts of the entire cortex, whereas other seed regions demonstrated more regionally focused connectivity. Higher target frequency was associated with stronger activations in visual areas but had no effect on functional connectivity. In summary, the results confirm and extend previous knowledge regarding the neural mechanisms underlying SPEM and provide a valuable basis for further investigations such as in patients with SPEM impairments and known alterations in brain connectivity.NEW & NOTEWORTHY This study provides a comprehensive investigation of blood oxygen level-dependent (BOLD) functional connectivity during smooth pursuit eye movements. Results from a large sample of healthy participants suggest that key oculomotor regions interact closely with each other but also with regions not primarily associated with eye movements. Understanding functional connectivity during smooth pursuit is important, given its potential role as an endophenotype of psychoses.

Subjective visual complaints are commonly reported in patients with neck pain, but their relation to objectively measured oculomotor functions during smooth pursuit neck torsion tests (SPNTs) has not yet been investigated. The aim of the study was to analyse classification accuracy of visual symptom intensity and frequency based on SPNT results. Forty-three patients with neck pain were referred by orthopaedic outpatient clinics where they were required to fill out 16-item proformas of visual complaints. Infrared video-oculography was used to measure smooth pursuit eye movements during neutral and neck torsion positions. Parameters of gain and SPNT difference (SPNTdiff) were taken into the Naïve Bayes model as classifiers, while intensity and frequency of visual symptoms were taken as predicted class. Intensity and, to a lesser degree, frequency of visual symptoms previously associated with neck pain or focal vision disorders (computer vision syndrome) showed better classification accuracy using gain at neck torsion position, indicating cervical driven visual disturbances. Moreover, SPNTdiff presented with slightly lower classification accuracy as compared to gain at neck torsion position. Our study confirmed the relationship between cervical driven oculomotor deficits and some visual complaints (concentrating to read, words moving on page, blurred vision, difficulty judging distance, sore eyes, heavy eyes, red eyes, and eyes strain).

Fixation nystagmus refers to the nystagmus that appears or markedly increases with fixation. While relatively common in infantile (congenital) nystagmus, acquired fixation nystagmus is unusual and has been ascribed to lesions involving the cerebellar nuclei or the fibers projecting from the cerebellum to the brainstem. We aimed to report the clinical features of patients with acquired fixation nystagmus and discuss possible mechanisms using a model simulation and diagnostic significance. We describe four patients with acquired fixation nystagmus that appears or markedly increases with visual fixation. All patients had lesions involving the cerebellum or dorsal medulla. All patients showed direction-changing gaze-evoked nystagmus, impaired smooth pursuit, and decreased vestibular responses on head-impulse tests. The clinical implication of fixation nystagmus is that it may occur in central lesions that impair both smooth pursuit and the vestibulo-ocular reflex (VOR) but without creating a spontaneous nystagmus in the dark. We develop a mathematical model that hypothesizes that fixation nystagmus reflects a central tone imbalance due to abnormal function in cerebellar circuits that normally optimize the interaction between visual following (pursuit) and VOR during attempted fixation. Patients with fixation nystagmus have central lesions involving the cerebellar circuits that are involved in visual-vestibular interactions and normally eliminate biases that cause a spontaneous nystagmus.

Eye movements are disrupted in many neurodegenerative diseases and are frequent and early features in conditions affecting the cerebellum. Characterizing eye movements is important for diagnosis and may be useful for tracking disease progression and response to therapies. Assessments are limited as they require an in-person evaluation by a neurology subspecialist or specialized and expensive equipment. We tested the hypothesis that important eye movement abnormalities in cerebellar disorders (i.e., ataxias) could be captured from iPhone video. Videos of the face were collected from individuals with ataxia (n = 102) and from a comparative population (Parkinson’s disease or healthy participants, n = 61). Computer vision algorithms were used to track the position of the eye which was transformed into high temporal resolution spectral features. Machine learning models trained on eye movement features were able to identify abnormalities in smooth pursuit (a key eye behavior) and accurately distinguish individuals with abnormal pursuit from controls (sensitivity = 0.84, specificity = 0.77). A novel machine learning approach generated severity estimates that correlated well with the clinician scores. We demonstrate the feasibility of capturing eye movement information using an inexpensive and widely accessible technology. This may be a useful approach for disease screening and for measuring severity in clinical trials.

When the eyes are fixated on a spot, fixation neurons in the frontal eye field (FEF) show an increase in activity. Our previous study suggested that fixation neurons in the FEF contribute to the suppression of saccades and smooth pursuit eye movements to maintain active fixation. The present study examined the role of the FEF in the suppressive control of reflexive eye movements, optokinetic and vestibular nystagmus, in trained monkeys. Electrical stimulation in the FEF suppressed the quick and slow phases of optokinetic and vestibular nystagmus at an intensity lower than the threshold for eliciting electrically evoked saccades. Relatively weak suppression influenced the slow phase of vestibular nystagmus. During optokinetic or vestibular nystagmus, presentation of a stationary small spot to the eyes followed by fixation is known to suppress both the quick and slow phases of eye movements. We recorded the activity of fixation neurons in the FEF and found that fixation neurons usually showed a decrease in activity during optokinetic and vestibular nystagmus and an increase in activity during the suppression of nystagmus by visual fixation. The present results show that the activity of fixation neurons in the FEF is related to the suppressive control of optokinetic and vestibular nystagmus for maintaining active fixation. We discuss the role of a generalized visual fixation system that can maintain visual attention on an interesting object.

Tracking of eye movements is an established measurement for many types of experimental paradigms. More complex and more prolonged visual stimuli have made algorithmic approaches to eye movement event classification the most pragmatic option. A recent analysis revealed that many current algorithms are lackluster when it comes to data from viewing dynamic stimuli such as video sequences. Here we present an event classification algorithm—built on an existing velocity-based approach—that is suitable for both static and dynamic stimulation, and is capable of classifying saccades, post-saccadic oscillations, fixations, and smooth pursuit events. We validated classification performance and robustness on three public datasets: 1) manually annotated, trial-based gaze trajectories for viewing static images, moving dots, and short video sequences, 2) lab-quality gaze recordings for a feature length movie, and 3) gaze recordings acquired under suboptimal lighting conditions inside the bore of a magnetic resonance imaging (MRI) scanner for the same full-length movie. We found that the proposed algorithm performs on par or better compared to state-of-the-art alternatives for static stimulation. Moreover, it yields eye movement events with biologically plausible characteristics on prolonged dynamic recordings. Lastly, algorithm performance is robust on data acquired under suboptimal conditions that exhibit a temporally varying noise level. These results indicate that the proposed algorithm is a robust tool with improved classification accuracy across a range of use cases. The algorithm is cross-platform compatible, implemented using the Python programming language, and readily available as free and open source software from public sources.

Macular degeneration (MD) often leads to the loss of the fovea and surrounding central visual field. This type of visual loss is very common and can present particular challenges for oculomotor tasks that may rely on the fovea. For certain tasks, individuals develop a new, eccentric fixational locus. Our previous work has shown that smooth pursuit is impaired in MD. However, extent of retinal lesion size and eccentricity of fixation do not directly contribute to changes in smooth pursuit gain. Oculomotor limitations due to eccentric eye position in the orbit may be another culprit. Here we test the hypothesis that deficits in smooth pursuit in MD would be reduced under head-unrestrained conditions. To that end, we examined eye, head, and gaze movements in eight individuals with MD and seven age-matched controls in response to a step-ramp pursuit stimulus. We found that despite variability across participants, both groups had similar smooth pursuit head movements (P = 0.76), while both had significantly higher pursuit gains in the head-restrained condition (P < 0.0001), suggesting that in older populations, head movements may lead to a decrease in pursuit gain. Furthermore, we did not find a correlation between eccentricity of fixation and amount of head displacement during the trial (P = 0.25), suggesting that eccentric eye position does not lead to higher reliance on head movements in smooth pursuit. Our finding that individuals with MD have lower pursuit gains, despite similar head movements as controls, suggests a difference in how MD affects mechanisms underlying eye versus head movements in smooth pursuit. NEW & NOTEWORTHY This article is the first to look at eye and head movements in observers with macular degeneration. It is the first to show that in older individuals, regardless of central field defect, freedom of head movement may reduce pursuit gain. Despite oculomotor limitations due to eccentric fixation, individuals with macular degeneration do not rely on head movements more than age-matched controls, with both groups having a similarly heterogenous eye and head movement strategy for pursuit.

© 2020 The Authors. In recent years there has been a surge of interest and corresponding accumulation of knowledge about the role of sleep disturbance in schizophrenia. In this review, we provide an update on the current status of experimentally controlled sleep deprivation (SD) as an experimental medicine model of psychosis, and also consider, given the complexity and heterogeneity of schizophrenia, whether this (state) model can be usefully combined with other state or trait model systems to more powerfully model the pathophysiology of psychosis. We present evidence of dose-dependent aberrations that qualitatively resemble positive, negative and cognitive symptoms of schizophrenia as well as deficits in a range of translational biomarkers for schizophrenia, including prepulse inhibition, smooth pursuit and antisaccades, following experimentally controlled SD, relative to standard sleep, in healthy volunteers. Studies examining the combination of SD and schizotypy, a trait model of schizophrenia, revealed only occasional, task-dependent superiority of the combination model, relative to either of the two models alone. Overall, we argue that experimentally controlled SD is a valuable experimental medicine model of schizophrenia to advance our understanding of the pathophysiology of the clinical disorder and discovery of more effective or novel treatments. Future studies are needed to test its utility in combination with other, especially state, model systems of psychosis such as ketamine. The Humboldt Foundation

Background Schizophrenia is a multifactorial neurodevelopmental disorder associated with cognitive dysfunction and changes in primary sensory processing. This article aims to explore the current insights into the relationship between schizophrenia and different visual disturbances. Methods To provide a literature review of visual impairments in schizophrenia, we performed a PubMed/MEDLINE and Scopus search to identify all articles in English on the topic up to the end of 2018. Results Multiple retinal functional and structural abnormalities are found in patients with schizophrenia. Wider retinal venules suggest chronically insufficient brain supply of oxygen and this could contribute to the occurrence of psychotic symptoms. Optical coherence tomography studies showed that retinal nerve fiber layer, macular thickness, and macular volume were significantly lowered in the chronic phase of schizophrenia. Results from electroretinogram recordings have demonstrated different declinations such as abnormalities of a - wave activity in the photoreceptors or b - wave activity in the bipolar and Muller cells. Abnormalities in eye movements, such as a notable decrease in saccades and smooth pursuit eye movements, are one of the most reliable and reproducible impairments associated with schizophrenia. Disrupted visual processing of the magnocellular pathway may result in a decrease of contrast sensitivity, sensory processing, orientation discrimination, visual integration, trajectory and spatial localization, backward masking and motion tracking. Visual perceptual abnormalities occur in more than 60% of schizophrenic patients and these are visual hallucinations, perceptual distortion of colors, shapes and light intensity, decrease in contour integration and surround suppression. Other, frequently present eye disorders include impaired visual acuity, strabismus and nystagmus. Conclusion Visual impairments are one of the most important features of schizophrenia, which could help in defining the disease state and assigning appropriate treatment.

The cerebellum exhibits both motor and reward-related signals. However, it remains unclear whether reward is processed independently from the motor command or might reflect the motor consequences of the reward drive. To test how reward-related signals interact with sensorimotor processing in the cerebellum, we recorded Purkinje cell simple spike activity in the cerebellar floccular complex while monkeys were engaged in smooth pursuit eye movement tasks. The color of the target signaled the size of the reward the monkeys would receive at the end of the target motion. When the tracking task presented a single target, both pursuit and neural activity were only slightly modulated by the reward size. The reward modulations in single cells were rarely large enough to be detected. These modulations were only significant in the population analysis when we averaged across many neurons. In two-target tasks where the monkey learned to select based on the size of the reward outcome, both behavior and neural activity adapted rapidly. In both the single- and two-target tasks, the size of the reward-related modulation matched the size of the effect of reward on behavior. Thus, unlike cortical activity in eye movement structures, the reward-related signals could not be dissociated from the motor command. These results suggest that reward information is integrated with the eye movement command upstream of the Purkinje cells in the floccular complex. Thus reward-related modulations of the simple spikes are akin to modulations found in motor behavior and not to the central processing of the reward value. NEW & NOTEWORTHY Disentangling sensorimotor and reward signals is only possible if these signals do not completely overlap. We recorded activity in the floccular complex of the cerebellum while monkeys performed tasks designed to separate representations of reward from those of movement. Activity modulation by reward could be accounted for by the coding of eye movement parameters, suggesting that reward information is already integrated into motor commands upstream of the floccular complex.

Smooth pursuit eye movements (SPEMs) and saccadic eye movements are both commonly impaired following sport-related concussion (SRC). Typical oculomotor assessments measure individual eye movements in a series of restrictive tests designed to isolate features such as response times. These measures lack ecological validity for athletes because athletes are adept at simple tasks designed for the general population. Yet, because eye movement metrics are sensitive and well-characterized neuroanatomically, it would be valuable to test whether athletes exhibit abnormal eye movements with more challenging tasks. To address this gap in knowledge, we collected eye-tracking data during a sport-like task to gain insight on gaze behavior during active self-motion. SPEMs and saccadic eye movements were recorded during a sport-like visual task within 24–48 h following SRC. Thirty-six Division I student-athletes were divided into SRC and control (CON) groups. All participants completed two blocks of the Wii Fit(©) soccer heading game (WF) while wearing a monocular infrared eye tracker. Eye movement classification systems quantified saccadic amplitude (SA), velocity (SV), and count (SC); as well as SPEM velocity (SPV) and amplitude (SPA). Separate Mann-Whitney U tests evaluated SPA and SC and found no significant effects (SPA, p = 0.11; SC, p = 0.10). A multi-variate analysis of variance (MANOVA) for remaining variables revealed SPV was significantly greater in CON (p

Optokinetic responses in several species are compared, describing differences in afoveate and foveate animals, and the effects of visual testing conditions, including directions of stimulus motion. Smooth pursuit contributes to responses to full-field visual motion in foveate species; in the latter, measurement of optokinetic after-nystagmus in darkness allows investigation of the optokinetic system. The concept of optokinetic-vestibular symbiosis and velocity storage are discussed, pertinent electrophysiological studies (such as vestibular nucleus neurons that respond to both optokinetic and vestibular stimuli) are reviewed and a model is developed. The different purposes and properties of optokinetic responses (to maintain clear vision during self-rotation) and smooth pursuit (to visually track a moving target) are clarified.

This chapter summarizes early electrophysiological and lesion studies to elucidate cortical, subcortical and cerebellar mechanisms for extracting visual target motion and programming a smooth-pursuit response. The importance of a descending pursuit pathway from the middle temporal (MT) cortical visual area, which extracts the speed and direction of a moving target, the projections to dorsolateral pontine nuclei, and onto the cerebellum are outlined. Contributions of the cerebellum to pursuit are discussed and models are presented to account for the ways in which floccular gaze Purkinje cells behave during smooth pursuit, combined eye-head tracking, and during head rotation while viewing a stationary target.

This chapter deals with mathematical models for smooth-pursuit eye movements, starting with simple negative-feedback schemes. After pointing out their deficiencies, Robinson developed models that account for specific dynamic properties of pursuit behavior, such as the transient ocular oscillations that may occur at onset, and the adaptive properties of pursuit. The challenges posed by the inherent latency of visual responses to target motion-specifically the instability of a negative feedback model-are resolved by including an efference copy internal positive feedback loop, and distributing system delays throughout the model's pathways. A model for smooth combined eye-head tracking is presented in which the brain sends an efference copy of the planned head movement to null out the vestibular signal expected.

This chapter summarizes how visual feedback could be used to stabilize the line of sight and optimize vision during attempted fixation of a stationary target. Quantitative features of oculomotor noise that causes drifts of the eye away from the target are analyzed. The sources of such noise, including the ripples in eye position due to muscle fiber twitches, and drifts of the eye away from the visual target due to vestibular imbalance, are examined. Evidence for a promptly responding stabilization system, distinct from optokinetic or pursuit eye movements is reviewed. Smooth eye movements that negate drifts of the eyes, which are discussed here, are distinct from microsaccades, which are discussed in chapter "Behavior of the saccadic system: Metrics of timing and accuracy" by Robinson.

This chapter describes dynamic properties of smooth pursuit, visual and non-visual stimuli for pursuit, smooth eye-head tracking movements, and plastic-adaptive properties of pursuit. Step-ramp visual stimulus motion has revealed important properties of pursuit, including the latency to onset, initial acceleration, accuracy, and transient oscillations-all features that have been used to develop models of the pursuit system, discussed in the chapter "Models of pursuit" by Robinson. The role of predictive neural mechanisms in generating pursuit movements that anticipate target motion, and that enable near-perfect tracking of sinusoidal target motion, are examined. Smooth pursuit can be generated in response to targets that do not move, such as stroboscopic lights and images stabilized in the periphery of vision. The view that, during combined eye-head pursuit, the pursuit signal is used to cancel the vestibulo-ocular reflex is an incomplete hypothesis, contradicted by behavioral and electrophysiological findings. Smooth pursuit shows adaptive capabilities, evident in individuals who develop extraocular muscle palsies.

Gaze behavior during visual tracking consists of a combination of pursuit and saccadic movements. When the tracked object is intermittently occluded, the role of smooth pursuit is reduced, with a corresponding increase in the role of saccades. However, studies of visual tracking during occlusion have focused only on the first few saccades, usually with occlusion periods of less than 1 second in duration. We investigated tracking on a circular trajectory with random occlusions and found that an occluded object can be tracked reliably for up to several seconds with mainly anticipatory saccades and very little smooth pursuit. Furthermore, we investigated the accumulation of uncertainty in prediction and found that prediction errors seem to accumulate faster when an absolute reference frame is not available during tracking. We suggest that the observed saccadic tracking reflects the use of a time-based internal estimate of object position that is anchored to the environment via fixations.

Aims Abnormalities in the oculomotor system may represent an early sign of diabetic neuropathy and are currently poorly studied. We designed an eye-tracking-based test to evaluate oculomotor function in patients with type 1 diabetes. Methods We used the SRLab—Tobii TX300 Eye tracker®, an eye-tracking device, coupled with software that we developed to test abnormalities in the oculomotor system. The software consists of a series of eye-tracking tasks divided into 4 classes of parameters (Resistance, Wideness, Pursuit and Velocity) to evaluate both smooth and saccadic movement in different directions. We analyzed the oculomotor system in 34 healthy volunteers and in 34 patients with long-standing type 1 diabetes. Results Among the 474 parameters analyzed with the eye-tracking-based system, 11% were significantly altered in patients with type 1 diabetes (p p = 0.02). The classes of Velocity and Pursuit were less frequently altered in patients with type 1 diabetes as compared to healthy subjects, with anomalous measurements mainly observed in patients with diabetic neuropathy. Conclusions Abnormalities in oculomotor system function can be detected in patients with type 1 diabetes using a novel eye-tracking-based test. A larger cohort study may further determine thresholds of normality and validate whether eye-tracking can be used to non-invasively characterize early signs of diabetic neuropathy. Trial: NCT04608890.

Deficits in smooth-pursuit eye movements (SPEM) are often associated with mild traumatic brain injury(TBI). Eye tracking tests serve as a quick objective clinical tool to assess such predictive visual tracking. In this study, SPEM was assessed along circular, horizontal and vertical trajectories in adolescents with concussion and age-matched controls.Ninety-one young adolescents with concussion and 140 visually healthy age-matched controls with a mean age of 14 years performed a computerized test of circular, horizontal and vertical tracking task using an eye tracker. Oculomotor tracking was assessed by computing the rate of fixation, saccades and SPEM made while performing the tasks.The predictive visual tracking task was able to differentiate the TBI group from the non-TBI group. The TBI group showed a significant difference in the fixation, saccades and SPEM percentages for circular tracking movement compared to the controls. There was a significant difference in fixation and SPEM % for horizontal and vertical tracking.Predictive visual tracking, assessed using eye tracking technology, is able to differentiate deficits in oculomotor functions in individuals with and without concussion. The eye tracking technology may serve as a quick objective tool to detect and monitor neural deficits due to TBI.

Saccades during smooth pursuit can help bring the fovea on target, particularly in cases of low pursuit gain. Individuals with macular degeneration often suffer damage to the central retina including the fovea, which impacts oculomotor function such as fixation, saccadic and smooth pursuit eye movements. We hypothesized that these oculomotor changes in macular degeneration (MD) would make saccades less appropriately directed (even if more numerous). To investigate saccades during pursuit in MD, we conducted a quantitative analysis of smooth pursuit eye movement data from a prior study, Vision Research 141 (2017) 181-190. Here we examined saccade frequency, magnitude, and direction across viewing conditions for MD and control participants during pursuit of a target moving in a modified step-ramp paradigm. Individuals with MD had more variability in saccade directions that included directions orthogonal to the target trajectory. PRL eccentricity significantly correlated with increases in saccades in non-target directions during smooth pursuit. These results suggest that a large number of saccades during pursuit in MD participants are unlikely to be catch-up saccades that serve to keep the eye on the target.

The sensory mismatch commonly observed in patients with neck pain disorders could alter intra-trial reliability in simple implicit smooth pursuit eye movement tasks. This could be more pronounced when neck is in torsioned position (SPNT). The aim of this study was to explore the effects of neck torsion, target movement velocity and amplitude on intra-trial reliability of smooth pursuit eye movements in patients with neck pain disorders and healthy individuals. SPNT test was evaluated in 32 chronic neck pain patients and 32 healthy controls. Ten cycles were performed using video-oculography at three different velocities (20° s

It is more challenging to plan eye movements during perceptual tasks performed in dynamic displays than in static displays. Decisions about the timing of saccades become more critical, and decisions must also involve smooth eye movements, as well as saccades. The present study examined eye movements when judging which of two moving discs would arrive first, or collide, at a common meeting point. Perceptual discrimination after training was precise (Weber fractions < 6%). Strategies reflected a combined contribution of saccades and smooth eye movements. The preferred strategy was to look near the meeting point when strategies were freely chosen. When strategies were assigned, looking near the meeting point produced better performance than switching between the discs. Smooth eye movements were engaged in two ways: (a) low-velocity smooth eye movements correlated with the motion of each disc (micropursuit) were found while the line of sight remained between the discs; and (b) spontaneous smooth pursuit of the pair of discs occurred after the perceptual report, when the discs moved as a pair along a common path. The results show clear preferences and advantages for those eye movement strategies during dynamic perceptual tasks that require minimal management or effort. In addition, smooth eye movements, whose involvement during perceptual tasks within dynamic displays may have previously escaped notice, provide useful indictors of the strategies used to select information and distribute attention during the performance of dynamic perceptual tasks.

Idiopathic neck pain patients frequently experience oculomotor disfunctions with deficits in eye movement control between neutral and neck torsion position (SPNT test) being commonly investigated in clinical and research settings.The aim of the study was to determine accuracy of SPNT test in classifying idiopathic neck pain patients.a datamining based diagnostic accuracy study.The study was conducted on a referred sample of 38 chronic neck pain patients from orthopaedic outpatient clinic and 40 healthy controls. Video-oculography was used to study gain and SPNTGain during two target movement profiles at velocities of 30°sSPNT test provides useful diagnostic tool for classifying neck pain patients when using single or combination of two target movement profiles. Neck torsion of 45° as opposed to 30° should be used during SPNT test when investigating patients with neck pain disorders.

International audience; The study showed that smooth pursuit eye movement produces a bias in tactile motion perception. This phenomenon is modulated by the reliability of the tactile estimate and by the presence of a visual background, in line with the predictions of the Bayesian framework of motion perception. Overall, these results support the hypothesis of shared representations for motion perception.

The pursuit system has the ability to perform predictive control of eye movements. Even when the target motion is unpredictable due to velocity or direction changes, preceding changes in eye velocity are generated based on weighted averaging of past stimulus timing. However, it is still uncertain whether behavioral history influences the control of predictive pursuit. Thus, we attempted to clarify the influences of stimulus and behavioral histories on predictive pursuit to randomized target velocity. We used alternating-ramp stimuli, where the rightward velocity was fixed while the leftward velocity was either fixed (predictable) or randomized (unpredictable). Predictive eye deceleration was observed regardless of whether the target velocity was predictable or not. In particular, the predictable condition showed that the predictive pursuit responses corresponded to future target velocity. The linear mixed-effects model showed that both stimulus and behavioral histories of the previous two or three trials had influences on the predictive pursuit responses to the unpredictable target velocity. Our results suggest that the predictive pursuit system allows to track randomized target motion using the information from previous several trials, and the information of sensory input (stimulus) and motor output (behavior) in the past time sequences have partially different influences on predictive pursuit.

Purpose To accurately record the movements of a hand-held target together with the smooth pursuit eye movements (SPEMs) elicited with video-oculography (VOG) combined with deep learning-based object detection using a single-shot multibox detector (SSD). Methods The SPEMs of 11 healthy volunteers (21.3 ± 0.9 years) were recorded using VOG. The subjects fixated on a moving target that was manually moved at a distance of 1 m by the examiner. An automatic recording system was developed using SSD to predict the type and location of objects in a single image. The 400 images that were taken of one subject using a VOG scene camera were distributed into 2 groups (300 and 100) for training and validation. The testing data included 1100 images of all subjects (100 images/subject). The method achieved 75% average precision (AP75) for the relationship between the location of the fixated target (as calculated by SSD) and the position of each eye (as recorded by VOG). Results The AP75 for all subjects was 99.7% ± 0.6%. The horizontal and vertical target locations were significantly and positively correlated with each eye position in the horizontal and vertical directions (adjusted R2 ≥ 0.955, P < 0.001). Conclusions The addition of SSD-driven recording of hand-held target positions with VOG allows for quantitative assessment of SPEMs following a target during an SPEM test. Translational Relevance The combined methods of VOG and SSD can be used to detect SPEMs with greater accuracy, which can improve the outcome of clinical evaluations.

Due to the close relationship between oculomotor behavior and visual processing, eye movements have been studied in many different areas of research over the last few decades. While these studies have brought interesting insights, specialization within each research area comes at the potential cost of a narrow and isolated view of the oculomotor system. In this review, we want to expand this perspective by looking at the interactions between the two most important types of voluntary eye movements: saccades and pursuit. Recent evidence indicates multiple interactions and shared signals at the behavioral and neurophysiological level for oculomotor control and for visual perception during pursuit and saccades. Oculomotor control seems to be based on shared position- and velocity-related information, which leads to multiple behavioral interactions and synergies. The distinction between position- and velocity-related information seems to be also present at the neurophysiological level. In addition, visual perception seems to be based on shared efferent signals about upcoming eye positions and velocities, which are to some degree independent of the actual oculomotor response. This review suggests an interactive perspective on the oculomotor system, based mainly on different types of sensory input, and less so on separate subsystems for saccadic or pursuit eye movements.

Purpose Children with cerebral visual impairment (CVI) often have abnormal visual orienting behaviors due to impaired or damaged visual cortex. Alternatively, visual-cortical function is intact but visual information is not transformed downstream into an appropriate oculomotor output (visuomotor dysfunction). We examined visual, anatomic, and oculomotor assessments to distinguish visuomotor dysfunction from CVI associated with severely reduced visual-cortical response. Methods We reviewed the medical records from children with CVI having abnormal visual orienting behaviors, normal ocular examinations, and born near term. Relevant data were visual evoked potentials (VEPs), Teller card acuity, eye movements recorded by video-oculography (VOG), and neuroimaging (magnetic resonance imaging [MRI]) including diffusion tensor imaging (DTI) tractography. Results Thirty subjects had visuomotor dysfunction based on a normal VEP; of these 33% had a normal MRI and 67% had white matter abnormalities associated with metabolic disease and/or decreased volume of brain parenchyma. VOG recordings showed smooth pursuit gains were uniformly reduced and saccades were dysmetric but followed the main sequence. Ten subjects had severe CVI based on VEPs at noise levels; visual acuities and MRI findings overlapped those of the visuomotor dysfunction group. Developmental delay, seizures, microcephaly, and hypotonia were common across all groups. All subjects with an abnormal conventional MRI had abnormal metrics on DTI tractography from the occipital lobe. Conclusions A subset of patients with CVI have abnormal visual orienting behaviors despite a normal VEP (visuomotor dysfunction). A majority have abnormal white matter metrics on tractography suggesting a downstream defect in sensorimotor transformation. Clinically, visuomotor dysfunction is indistinguishable from severe CVI.

The purpose of this study was to determine whether smooth pursuit eye movements affect visual motion prediction using a time‐to‐contact task where observers anticipate the exact instant that a partially occluded target would coincide with a stationary object. Moreover, we attempted to clarify the influence of second‐order motion on visual motion prediction during smooth pursuit. One target object moved to another stationary object (6 deg apart) at constant velocity of 3, 4, and 5 deg/s, and then the two objects disappeared 500 ms after the onset of target motion. The observers estimated the moment the moving object would overlap the stationary object and pressed a button. For the pursuit condition, both a Gaussian window and a random dots texture moved in the same direction at the same speed for the first‐order motion, whereas a Gaussian window moved over a static background composed of random dots texture for the second‐order motion. The results showed that the constant error of the time‐to‐contact shifted to a later response for the pursuit condition compared to the fixation condition, regardless of the object velocity. In addition, during smooth pursuit, the constant error for the second‐order motion shifted to an earlier response compared to the first‐order motion when the object velocity was 3 deg/s, whereas no significant difference was found at 4 and 5 deg/s. Therefore, our results suggest that visual motion prediction using a time‐to‐contact task is affected by both eye movements and motion configuration such as second‐order motion., The purpose of this study was to determine whether smooth pursuit eye movements and motion configuration affect visual motion prediction using a time‐to‐contact task where observers anticipate the exact instant that a partially occluded target would coincide with a stationary object. Our results suggest that visual motion prediction using a time‐to‐contact task is affected by both eye movements and motion configuration such as second‐order motion.

In human vision, smooth pursuit eye movement is the basic ability to visually follow a moving object by keeping it at the sight center. In this study, we validate that a human hand has a similar ability to track a midair haptic stimulus, i.e., a human palm exposed to a point vibration by a noncontact ultrasound tactile display can follow the continuous movement of the stimulation point. The experimental results show that the trackable velocity limit is 10 cm/s for motion parallel to the palm, when the initial velocity is zero. This ability of motion tracking by hand can be applied to haptic guidance for visually impaired people or for evacuation navigation, where no devices are needed to be equipped by users.

Vision represents the most important sense of primates. To understand visual processing, various different methods are employed-for example, electrophysiology, psychophysics, or eye-tracking. For the latter method, researchers have recently begun to step outside the artificial environments of laboratory setups toward the more natural conditions we usually face in the real world. To get a better understanding of the advantages and limitations of modern mobile eye-trackers, we quantitatively compared one of the most advanced mobile eye-trackers available, the EyeSeeCam, with a commonly used laboratory eye-tracker, the EyeLink II, serving as a gold standard. We aimed to investigate whether or not fully mobile eye-trackers are capable of providing data that would be adequate for direct comparisons with data recorded by stationary eye-trackers. Therefore, we recorded three different, commonly used eye movements-fixations, saccades, and smooth-pursuit eye movements-with both eye-trackers, in successive standardized paradigms in a laboratory setting with eight human subjects. Despite major technical differences between the devices, most eye movement parameters were not statistically different between the two systems. Differences could only be found in overall gaze accuracy and for time-critical parameters such as saccade duration, for which a higher sample frequency is especially useful. Although the stationary EyeLink II system proved to be superior, especially on a single-subject or even a single-trial basis, the ESC showed similar performance for the averaged parameters across both trials and subjects. We concluded that modern mobile eye-trackers are well-suited to providing reliable oculomotor data at the required spatial and temporal resolutions.

SIGNIFICANCE. Oculomotor tests in concussion commonly show impairment in smooth pursuit and saccadic function. Honing in on the systems likely to be affected by concussion will streamline use of oculomotor function as a supplemental diagnostic and prognostic tool, as well as improve our understanding of the pathophysiology of concussion. PURPOSE. This study investigates oculomotor function between concussed and healthy collegiate athletes, as well as determines measurement test-retest reliability of those tools. METHODS. Eighty-seven healthy athletes were recruited from a US Division 1 sports university and completed a 30-minute vestibular ocular testing battery in an enclosed rotary chair system equipped with 100Hz eye-tracking goggles. Forty-three individuals completed the battery twice. Twenty-eight individuals with a current diagnosis of concussion also completed the battery. All participants were ages 18–24. Bivariate statistical tests examined differences in scores across groups, and intraclass coefficients were computed to test reliability. RESULTS. Concussed individuals had significantly longer saccadic, visual, and dual-task reaction times and reduced saccadic accuracy. There was no difference in optokinetic reflex gain, but few concussed individuals tolerated the task. Reaction time latencies and optokinetic gain show moderate test-retest reliability. Smooth pursuit tasks and saccadic accuracies showed poor test-retest reliability. CONCLUSIONS. Saccadic latency was the most sensitive oculomotor function to change following concussion and was reliable over time. Saccadic accuracy was significantly lower in the concussed group but had poor retest-reliability. Optokinetic gain may warrant more investigation due to its high test-retest reliability and symptom provocation in concussion, despite not showing a significant difference between groups.