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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.

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.

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.

© 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

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.

Neck torsion manoeuvre is thought to affect eye movement control via afferent sensory drive in neck pain disorders patients. Literature reports inconsistencies regarding the angle of neck torsion most commonly used across the studies.The goal of this study was to determine the level of agreement in oculomotor performance between two most commonly used neck torsion angles during smooth pursuit neck torsion test (SPNT).A cross-sectional design was used in thirty-two neck pain patients and thirty-two healthy individuals.Gain and SPNTSmall to medium correlations and wide bias confidence intervals suggest medium level of agreement in gain or SPNTLevel of agreement between the two angles in SPNT test depends on the amplitude and velocity of the moving target. In cases when subjects within the same study are not able to perform 45° of neck torsion, 50° amplitude and 20°s

Motor sequence learning involves predictive processing that results in the anticipation of each component of a sequence of actions. In smooth pursuit, this predictive processing is required to decrease tracking errors between the eye and the stimulus. Current models for motor sequence learning suggest parallel mechanisms in the brain for acquiring sequences of differing complexity. We examined this model by comparing shorter versus longer sequences of pursuit eye movements during fMRI. In this way we were able to identify overlapping and distinct brain areas involved in simple versus more complex oculomotor learning. Participants revealed predictive pursuit eye movements from the second presentation of the stimulus in both short and long sequences. Brain imaging results indicated activation of parallel brain areas for the different sequence lengths that consisted of the Inferior Occipital Gyrus and the Cingulate as areas in common. In addition, distinct activation was found in more working memory related brain regions for the shorter sequences (e.g. the middle frontal cortex and dorsolateral prefrontal cortex), and higher activation in the frontal eye fields, supplementary motor cortex and motor cortex for the longer sequences, independent on the number of repetitions. These findings provide new evidence that there are parallel brain areas that involve working memory circuitry for short sequences, and more motoric areas when the sequence is longer and more cognitively demanding. Additionally, our findings are the first to show that the parallel brain regions involved in sequence learning in pursuit are independent of the number of repetitions, but contingent on sequence complexity.

Electrooculography is useful in detecting smooth pursuit neck torsion (SPNT) abnormalities in patients with neck pain, however, a validated, clinically relevant measure is lacking.To explore the validity of visual assessment of formal and clinical videotaped SPNT tests in comparison to electrooculography.Cross-sectional observational study.Twenty patients with idiopathic neck pain (INP) and twenty healthy controls performed the electrooculography SPNT test: first in neutral, then 45° trunk-under-head torsion to the left then right. The formal video test involved the participant following a horizontal laser stimulus simultaneous to electrooculography. The clinical video test was then performed where the participant followed the clinician's finger in the horizontal direction. One blinded investigator interpreted and analysed the electrooculography trace and two others interpreted the videos.Patients with INP had a significantly (p 0.05) greater SPNT difference than healthy controls. Visual observation of the formal test had 82.5% agreement with electrooculography and showed fair sensitivity (63.5%) and good specificity (89.6) whilst the clinical test had 65% agreement with electrooculography and showed poor sensitivity (27.3%) and good specificity (79.3%). There was an 82.5% agreement between investigators for the formal video taped measure.Visual analysis of assessment of SPNT is sufficient for detecting SPNT abnormalities in patients with INP. Accuracy of the clinical method could be improved by, altering how the visual stimulus is presented and including subjective reporting of symptoms to aid diagnosis resulting in implications for future research.

Macular degeneration results in heterogeneous central field loss (CFL) and often has asymmetrical effects in the two eyes. As such, it is not clear to what degree the movements of the two eyes are coordinated. To address this issue, we examined smooth pursuit quantitatively in CFL participants during binocular viewing and compared it to the monocular viewing case. We also examined coordination of the two eyes during smooth pursuit and how this coordination was affected by interocular ratios of acuity and contrast, as well as CFL-specific interocular differences, such as scotoma sizes and degree of binocular overlap. We hypothesized that the coordination of eye movements would depend on the binocularity of the two eyes. To test our hypotheses, we used a modified step-ramp paradigm, and measured pursuit in both eyes while viewing was binocular, or monocular with the dominant or non-dominant eye. Data for CFL participants and age-matched controls were examined at the group, within-group, and individual levels. We found that CFL participants had a broader range of smooth pursuit gains and a significantly lower correlation between the two eyes, as compared to controls. Across both CFL and control groups, smooth pursuit gain and correlation between the eyes are best predicted by the ratio of contrast sensitivity between the eyes. For the subgroup of participants with measurable stereopsis, both smooth pursuit gain and correlation are best predicted by stereoacuity. Therefore, our results suggest that coordination between the eyes during smooth pursuit depends on binocular cooperation between the eyes.

To successfully navigate throughout the world, observers must rapidly recover depth information. One depth cue that is especially important for a moving observer is motion parallax. To perceive unambiguous depth from motion parallax, the visual system must integrate information from two different proximal signals, retinal image motion and a pursuit eye movement. Previous research has shown that aging affects both of these necessary components for motion parallax depth perception, but no research has yet investigated how aging affects the mechanism for integrating motion and pursuit information to recover depth from motion parallax. The goal of the current experiment was to assess the integration time required by older adults to process depth information. In four psychophysical conditions, younger and older observers made motion and depth judgments about stationary or translating random-dot stimuli. Stimulus presentations in all four psychophysical conditions were followed by a high-contrast pattern mask, and minimum stimulus presentation durations (stimulus-to-mask onset asynchrony, or SOA) were measured. These SOAs reflect the minimum neural processing time required to make motion and motion parallax depth judgments. Pursuit latency was also measured. The results revealed that, after accounting for age-related delays in motion processing and pursuit onset, older and younger adults required similar temporal intervals to combine retinal image motion with an internal pursuit signal for the perception of depth. These results suggest that the mechanism for motion and pursuit integration is not affected by age.

Visual sensitivity is dynamically modulated by eye movements. During saccadic eye movements, sensitivity is reduced selectively for low-spatial frequency luminance stimuli and largely unaffected for high-spatial frequency luminance and chromatic stimuli (Nature 371 (1994), 511-513). During smooth pursuit eye movements, sensitivity for low-spatial frequency luminance stimuli is moderately reduced while sensitivity for chromatic and high-spatial frequency luminance stimuli is even increased (Nature Neuroscience, 11 (2008), 1211-1216). Since these effects are at least partly of different polarity, we investigated the combined effects of saccades and smooth pursuit on visual sensitivity. For the time course of chromatic sensitivity, we found that detection rates increased slightly around pursuit onset. During saccades to static and moving targets, detection rates dropped briefly before the saccade and reached a minimum at saccade onset. This reduction of chromatic sensitivity was present whenever a saccade was executed and it was not modified by subsequent pursuit. We also measured contrast sensitivity for flashed high- and low-spatial frequency luminance and chromatic stimuli during saccades and pursuit. During saccades, the reduction of contrast sensitivity was strongest for low-spatial frequency luminance stimuli (about 90%). However, a significant reduction was also present for chromatic stimuli (about 58%). Chromatic sensitivity was increased during smooth pursuit (about 12%). These results suggest that the modulation of visual sensitivity during saccades and smooth pursuit is more complex than previously assumed.

Introduction Nicotine and methylphenidate are putative cognitive enhancers in healthy and patient populations. Although they stimulate different neurotransmitter systems, they have been shown to enhance performance on overlapping measures of attention. So far, there has been no direct comparison of the effects of these two stimulants on behavioural performance or brain function in healthy humans. Here, we directly compare the two compounds using a well-established oculomotor biomarker in order to explore common and distinct behavioural and neural effects. Methods Eighty-two healthy male non-smokers performed a smooth pursuit eye movement task while lying in an fMRI scanner. In a between-subjects, double-blind design, subjects either received placebo (placebo patch and capsule), nicotine (7 mg nicotine patch and placebo capsule), or methylphenidate (placebo patch and 40 mg methylphenidate capsule). Results There were no significant drug effects on behavioural measures. At the neural level, methylphenidate elicited higher activation in left frontal eye field compared to nicotine, with an intermediate response under placebo. Discussion The reduced activation of task-related regions under nicotine could be associated with more efficient neural processing, while increased hemodynamic response under methylphenidate is interpretable as enhanced processing of task-relevant networks. Together, these findings suggest dissociable neural effects of these putative cognitive enhancers.

Current study attempted to determine whether repeated smooth pursuit trials using theta motion, in which the directions of retinal image-motion and object-motion are opposed, yield pursuit adaptation. Adaptation trials consisted of 350 step-ramp trials using theta motion, and pre- and post-trials using first-order motion were conducted. As a result, initial acceleration in post-adaptation increased significantly than pre-adaptation trials. This was the case even though there was no adaptive change throughout adaptation (350 trials) using theta motion. Our results suggest that smooth pursuit could adapt to theta motion even with challenges associated with opposite retinal slip.

We report here a case with unidirectional abnormalities of smooth eye movements without gaze nystagmus. Abnormalities of eye movements were confined to unidirectional (leftward) horizontal pursuit and slow phase of OKN; however, horizontal VOR (slow phase of caloric nystagmus) and saccade were normal, and vertical eye movements were also normal. No lesions were detected in the central nervous system, and any history of drug intake was denied. Although the cause of the unidirectional abnormality in eye movement of this case is still not clear, a congenital origin seems to be the most probable.

Eye movement behavior can be determined by bottom-up factors like visual salience and by top-down factors like expected value. These different types of signals have to be combined for the control of eye movements. In this study we investigated how smooth pursuit eye movements integrate salience and value information. Observers were asked to track a random-dot kinematogram containing two coherent motion directions. To manipulate salience, the coherence or the density of one of the motion signals was varied. To manipulate value, observers won or lost money in a separate experiment if they were tracking one or the other motion direction. Our results show that pursuit direction was initially determined only by salience. 300–400 ms after target motion onset, pursuit steered towards the rewarded direction and the salience effects disappeared. The time course of this effect depended crucially on the difficulty to segment the two signal directions. These results indicate that salience determines early pursuit responses in the same way as saccades with short latencies. Value information is processed slower and dominates pursuit after several 100 ms.

Motion direction discrimination in humans is worse for oblique directions than for the cardinal directions (the oblique effect). For some unknown reason, the human visual system makes systematic errors in the estimation of particular motion directions; a direction displacement near a cardinal axis appears larger than it really is whereas the same displacement near an oblique axis appears to be smaller. Although the perceptual effects are robust and are clearly measurable in smooth pursuit eye movements, all attempts to identify the neural underpinnings for the oblique effect have failed. Here we show that a model of image velocity estimation based on the known properties of neurons in primary visual cortex (V1) and the middle temporal (MT) visual area of the primate brain produces the oblique effect. We also provide an explanation for the unusual asymmetric patterns of inhibition that have been found surrounding MT neurons. These patterns are consistent with a mechanism within the visual system that prevents redundant velocity signals from being passed onto the next motion-integration stage, (dorsal Medial superior temporal, MSTd). We show that model redundancy-reduction mechanisms within the MT-MSTd pathway produce the oblique effect.

Objective To review the scientific literature about the relationship between impairment on smooth pursuit eye movements and schizophrenia. Methods Narrative review that includes historical articles, reports about basic and clinical investigation, systematic reviews, and meta-analysis on the topic. Results Up to 80% of schizophrenic patients have impairment of smooth pursuit eye movements. Despite the diversity of test protocols, 65% of patients and controls are correctly classified by their overall performance during this pursuit. The smooth pursuit eye movements depend on the ability to anticipate the target's velocity and the visual feedback, as well as on learning and attention. The neuroanatomy implicated in smooth pursuit overlaps to some extent with certain frontal cortex zones associated with some clinical and neuropsychological characteristics of the schizophrenia, therefore some specific components of smooth pursuit anomalies could serve as biomarkers of the disease. Due to their sedative effect, antipsychotics have a deleterious effect on smooth pursuit eye movements, thus these movements cannot be used to evaluate the efficacy of the currently available treatments. Conclusion Standardized evaluation of smooth pursuit eye movements on schizophrenia will allow to use specific aspects of that pursuit as biomarkers for the study of its genetics, psychopathology, or neuropsychology.

Intravitreal injections and drug-loaded implants are current approaches to treat diseases of the posterior eye. To investigate the release of active agents and their distribution in the vitreous body, a new test system was developed that enables a realistic simulation of eye motions. It is called the eye movement system (EyeMoS). In combination with a previously developed model containing a polyacrylamide gel as a substitute for the vitreous body, this new system enables the characterization of the influence of eye motions on drug distribution within the vitreous body. In the presented work, the distribution of fluorescence-tagged model drugs of different molecular weight within the simulated vitreous was examined under movement with the EyeMoS and without movement. By replacing a part of the gel in the simulated vitreous body with buffer, the influence of the progress of posterior vitreous detachment (PVD) on the distribution of these model substances was also studied. The results indicate that convective forces may be of predominate influence on initial drug distribution. The impact of these forces on drug transport increases with simulated progression of PVD. Using the EyeMoS, the investigation of release and distribution from intravitreal drug delivery systems becomes feasible under biorelevant conditions. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:517–526, 2014

Background and purpose Unilateral saccadic pursuit is reported to be suggestive of a pontine lesion in sensory stroke patients. We attempted to verify this eye sign in just-hospitalized pontine sensory stroke patients. Methods Horizontal smooth pursuit eye movements were evaluated upon hospital arrival in 4 pontine sensory stroke patients and were compared with those in 6 thalamic sensory stroke patients. Eye movements were evaluated with the patient lying down on the emergency room or stroke care unit bed by means of a newly developed video-oculography-based eye movement recording system equipped to project a moving laser pointer onto the ceiling. Results Laterality of horizontal smooth pursuit gain in pontine sensory stroke patients was evident upon arrival; in thalamic sensory stroke patients, horizontal smooth pursuit gain was equal in both directions. These characteristics were easily detected at bedside. Conclusion Unilateral saccadic pursuit in pontine sensory stroke patients may be a practical diagnostic sign that can be detected even in the emergency room. The video-oculography-based recording system equipped to project a moving laser pointer onto the ceiling may be useful for detecting this eye sign.

The extent of perceived blur produced by a moving retinal image is less when the image motion occurs during pursuit eye movements compared to fixation. This study examined the effect of this reduced perception of motion blur during pursuit on spatial-interval acuity. Observers judged during pursuit at 4 or 8deg/s whether the horizontal separation between two stationary lines was larger or smaller than a standard. Three different line separations were tested for each pursuit velocity. Each observer performed these judgments also during fixation, for spatial-interval stimuli that moved with the same mean and standard deviation of speeds as the distribution of eye velocities during pursuit. Spatial-interval acuity was better during pursuit than fixation for small or intermediate line separations. The results indicate that a reduction of perceived motion blur during pursuit eye movements can lead to improved visual performance.

Pursuit and saccades almost always select the same target. Is this the results of a common selection process or does smooth pursuit obligatorily follow the stimulus targeted by saccades? To address this question, we used microstimulation of the primate superior colliculus (SC) to redirect the eyes from a selected pursuit target to a distracter moving in the opposite direction. During each trial, monkeys pursued a horizontally moving array of colored target stimuli. In half of the trials, this target array was accompanied by a distracter array moving horizontally in the opposite direction, offset by the vertical amplitude of the stimulation-evoked saccade. We stimulated the SC during maintained pursuit on half of the trials, and measured pursuit eye velocity during the 50-ms interval immediately following the stimulation-evoked saccade to the distracter array. Saccades evoked by SC stimulation did not alter pursuit target selection. Pursuit velocity on average changed by less than 10% of that expected if the monkey had completely switched targets. Moreover, the same changes in velocity occurred when there was no distracter, indicating that even these small changes in pursuit velocity were a direct effect of the evoked saccade, not partial selection of the distracter. These results show that motor execution of saccades is not sufficient to select a pursuit target, and support the idea that the coordination of pursuit and saccades is accomplished by a shared target selection process.

Haptic guidance by a robot is a recent technology to support motor learning. Its mechanisms and effects are not yet well understood. One of the hypotheses is that learning of temporal characteristics is particularly susceptible to the beneficial effects of robotic guidance. In this study we investigate the influence of robotic guidance on the production of spatio-temporal patterns. Participants practiced to draw circles with the velocity profile of ellipses. Performance during the practice phase, when participants were assisted by a robotic device, as well as during the test phase, when assistance was switched off, was compared to a control group. During practice participants with robotic assistance performed better on all three dependent measures, shape, timing of the velocity modulation, and modulation amplitude. However, these differences between groups largely disappeared in the test phase. Only the difference in the amplitude of the velocity modulation remained, which was more accurate in the robot-guidance group than in the control group. This remaining difference likely results from a secondary effect of robotic guidance, namely the experience of smaller visual errors and weaker velocity modulations during practice.

For Listing’s law to be obeyed during eye movements, the “half-angle rule” must be satisfied: the eye velocity axis must tilt away from Listing’s plane by half the angle of eye position eccentricity from primary position. We aimed to determine if this rule is satisfied during horizontal and vertical pursuit compared with saccades. Three-dimensional (3-d) eye rotation data were acquired from five normal head-fixed humans using the search coil technique. Saccades were recorded in response to 40° horizontal or vertical steps in target position, at different elevations and azimuths. Pursuit was recorded while tracking a target moving horizontally or vertically at 20°/s, with peak-to-peak amplitude of 40°, at the same elevations and azimuths. First- and second-order surfaces were fitted to 3-d eye position data from periods of fixation. In all subjects, eye positions did not lie on a planar surface, but on a twisted surface in 3-d space. The tilt-angle coefficient (TAC) during saccades and pursuit was calculated as the ratio of the angle of eye velocity axis tilt to the angle of eye position eccentricity. During horizontal saccades and pursuit, mean TACs were 0.58 and 0.64, respectively. During vertical saccades and pursuit, mean TACs were 0.35 and 0.43, respectively, and lower than their horizontal counterparts (p

The perception of depth from relative motion is believed to be a slow process that “builds-up” over a period of observation. However, in the case of motion parallax, the potential accuracy of the depth estimate suffers as the observer translates during the viewing period. Our recent quantitative model for the perception of depth from motion parallax proposes that relative object depth (d) can be determined from retinal image motion (dθ/dt), pursuit eye movement (dα/dt), and fixation distance (f) by the formula: d/f ≈ dθ/dα. Given the model’s dynamics, it is important to know the integration time required by the visual system to recover dα and dθ, and then estimate d. Knowing the minimum integration time reveals the incumbent error in this process. A depth-phase discrimination task was used to determine the time necessary to perceive depth-sign from motion parallax. Observers remained stationary and viewed a briefly translating random-dot motion parallax stimulus. Stimulus duration varied between trials. Fixation on the translating stimulus was monitored and enforced with an eye-tracker. The study found that relative depth discrimination can be performed with presentations as brief as 16.6 msec, with only two stimulus frames providing both retinal image motion and the stimulus window motion for pursuit (mean range = 16.6–33.2 msec). This was found for conditions in which, prior to stimulus presentation, the eye was engaged in ongoing pursuit or the eye was stationary. A large high-contrast masking stimulus disrupted depth-discrimination for stimulus presentations less than 70-75 msec in both pursuit and stationary conditions. This interval might be linked to ocular-following response eye-movement latencies. We conclude that neural mechanisms serving depth from motion parallax generate a depth estimate much more quickly than previously believed. We propose that additional sluggishness might be due to the visual system’s attempt to determine the maximum dθ/dα ratio for a selection of points on a complicated stimulus.

To pursue a small target moving in front of a drifting background, motion vectors from the target need to be integrated and segmented from those belonging to the background. Smooth pursuit eye movements typically integrate target and background directions initially and after some time shift towards the veridical target direction. The perceived target direction on the other hand is generally stable over time: the target is perceived to move in the same direction as long as the motion information maintains the same properties over time. If illusory target motion is observed, this tends to be shifted away from the background. Here we investigated how initial motion integration and segmentation of such stimuli are modulated by direction cues. We presented a small pursuit target moving along a straight path, in front of a background moving in a different direction. Without a direction cue, initial pursuit was biased towards the background direction before shifting towards the veridical target direction. The target’s perceived direction on the other hand was near veridical. A cue in the background direction increased initial pursuit integration but also caused perception to behave in a similar way: the target initially had an illusory motion component in the background direction and after about 200ms it was perceived to curve towards its veridical direction. This illusion shows that during the initial process of segmenting the direction of a pursuit target from irrelevant background motion, both pursuit and perception can be erroneously influenced by a direction cue and integrate the cued background motion. Both modalities corrected this initial integration error as more information about the target became available.

Pursuit eye movements are smooth rotations of the eye aimed at tracking moving objects. During pursuit, the visual system “compensates” for the eye movements, and transforms image movements captured by the eye from retinal to extra-retinal coordinates, for world-centered perception and action. When this function is impaired such as in schizophrenia, subjects misattribute retinal movements generated by their own eye movements to external sources. Surprisingly, even in healthy subjects pursuit compensation is incomplete, and results in illusory perception of motion. Neurophysiological, psychophysical and imaging studies elucidated many aspects of the neural substrates of visual processing during pursuit, including where and how in the cortex visual and non-visual signals interact to produce extra-retinal perception of motion. Here we review current understanding of motion processing in the visual cortex during pursuit and its relation to perception, from a broad perspective drawing from electrophysiology, fMRI, psychophysics and computational modeling. We discuss the experimental findings in the context of theories of pursuit compensation, and review some of the open questions in the field.

Simultaneously adapting to retinal motion and non-collinear pursuit eye movement produces a motion aftereffect (MAE) that moves in a different direction to either of the individual adapting motions. Mack, Hill and Kahn (1989, Perception, 18, 649–655) suggested that the MAE was determined by the perceived motion experienced during adaptation. We tested the perceived-motion hypothesis by having observers report perceived direction during simultaneous adaptation. For both central and peripheral retinal motion adaptation, perceived direction did not predict the direction of subsequent MAE. To explain the findings we propose that the MAE is based on the vector sum of two components, one corresponding to a retinal MAE opposite to the adapting retinal motion and the other corresponding to an extra-retina MAE opposite to the eye movement. A vector model of this component hypothesis showed that the MAE directions reported in our experiments were the result of an extra-retinal component that was substantially larger in magnitude than the retinal component when the adapting retinal motion was positioned centrally. However, when retinal adaptation was peripheral, the model suggested the magnitude of the components should be about the same. These predictions were tested in a final experiment that used a magnitude estimation technique. Contrary to the predictions, the results showed no interaction between type of adaptation (retinal or pursuit) and the location of adapting retinal motion. Possible reasons for the failure of component hypothesis to fully explain the data are discussed.

In mild traumatic brain injury (mTBI), the fiber tracts that connect the frontal cortex with the cerebellum may suffer shear damage, leading to attention deficits and performance variability. This damage also disrupts the enhancement of eye-target synchronization that can be affected by cognitive load when subjects are tested using a concurrent eye-tracking test and word-recall test. We investigated the effect of cognitive load on eye-target synchronization in normal and mTBI patients using the nonlinear dynamical technique of stochastic phase synchronization. Results demonstrate that eye-target synchronization was negatively affected by cognitive load in mTBI subjects. In contrast, eye-target synchronization improved under intermediate cognitive load in young (≤40years old) normal subjects.

Many neurophysiological studies in monkeys have indicated that visual motion information for the guidance of perception and smooth pursuit eye movements is – at an early stage – processed in the same visual pathway in the brain, crucially involving the middle temporal area (MT). However, these studies left some questions unanswered: Are perception and pursuit driven by the same or independent neuronal signals within this pathway? Are the perceptual interpretation of visual motion information and the motor response to visual signals limited by the same source of neuronal noise? Here, we review psychophysical studies that were motivated by these questions and compared perception and pursuit behaviorally in healthy human observers. We further review studies that focused on the interaction between perception and pursuit. The majority of results point to similarities between perception and pursuit, but dissociations were also reported. We discuss recent developments in this research area and conclude with suggestions for common and separate principles for the guidance of perceptual and motor responses to visual motion information.

Self-motion perception and vestibulo-ocular reflex (VOR) were studied during whole body yaw rotation in the dark at different static head positions. Rotations consisted of four cycles of symmetric sinusoidal and asymmetric oscillations. Self-motion perception was evaluated by measuring the ability of subjects to manually track a static remembered target. VOR was recorded separately and the slow phase eye position (SPEP) was computed. Three different head static yaw deviations (active and passive) relative to the trunk (0°, 45° to right and 45° to left) were examined. Active head deviations had a significant effect during asymmetric oscillation: the movement perception was enhanced when the head was kept turned toward the side of body rotation and decreased in the opposite direction. Conversely, passive head deviations had no effect on movement perception. Further, vibration (100 Hz) of the neck muscles splenius capitis and sternocleidomastoideus remarkably influenced perceived rotation during asymmetric oscillation. On the other hand, SPEP of VOR was modulated by active head deviation, but was not influenced by neck muscle vibration. Through its effects on motion perception and reflex gain, head position improved gaze stability and enhanced self-motion perception in the direction of the head deviation.

Spatial perception is modulated by eye movements. During smooth pursuit, perceived locations are shifted in the direction of the eye movement. During active fixation, visual space is perceptually compressed towards the fovea. In our present study, we were interested to determine the time course of spatial localization during pursuit initiation, i.e. the transition period from fixation to steady-state pursuit. Human observers had to localize briefly flashed targets around the time of pursuit initiation. Our data clearly show that pursuit-like mislocalization starts well before the onset of the eye movement. Our results point towards corollary-discharge as neural source for the observed perceptual effect.

Humans use smooth pursuit eye movements to track moving objects of interest. In order to track an object accurately, motion signals from the target have to be integrated and segmented from motion signals in the visual context. Most studies on pursuit eye movements used small visual targets against a featureless background, disregarding the requirements of our natural visual environment. Here, we tested the ability of the pursuit and the perceptual system to integrate motion signals across larger areas of the visual field. Stimuli were random-dot kinematograms containing a horizontal motion signal, which was perturbed by a spatially localized, peripheral motion signal. Perturbations appeared in a gaze-contingent coordinate system and had a different direction than the main motion including a vertical component. We measured pursuit and perceptual direction discrimination decisions and found that both steady-state pursuit and perception were influenced most by perturbation angles close to that of the main motion signal and only in regions close to the center of gaze. The narrow direction bandwidth (26 angular degrees full width at half height) and small spatial extent (8 degrees of visual angle standard deviation) correspond closely to tuning parameters of neurons in the middle temporal area (MT).

When different interceptive skills are considered, humans tend not to pursuit track the approaching object along its entire trajectory to the point of interception. Previous research of cricket batsmen facing medium paced deliveries reported pursuit visual tracking of the ball for the first 100-150 ms of flight followed by a saccade to the predicted ball bounce location. The aim of this study was to examine eye movements of batsmen while facing a range of slow to medium pace delivery speeds. Thirteen sub-elite batsmen faced 36 deliveries from a ball machine in which the projection speed was randomly varied across a range of 17-25 ms(-1). The foveal gaze of the batsmen was recorded with a monocular eye movement registration system. Gaze strategies differed between participants in several ways, i.e., in the initial location of gaze prior to delivery (on the outlet of the ball machine or "parked" at a location on the predicted flight trajectory), the behavior immediately after ball release (pursuit tracking or saccade), and the behavior in mid-late flight (predictive saccade to the bounce point or "parafoveal" pursuit tracking). Across the range of delivery speeds used in the current study, it was possible to pursuit track the ball from release to bounce point but it was also possible to choose to make saccades along the trajectory. Depending on the spatio-temporal demands of the task and the intentions of the batsman a range of visual search strategies can be employed to support their actions.

Secondary degeneration is a process encompassing damage adjacent to a primary injury, usually involving increased Ca(2+) influx into neurons and glia. Lomerizine dihydrochloride is a calcium channel blocker with relatively selective CNS effects, currently in clinical trials for glaucoma. We have recently demonstrated that, following partial transection of the optic nerve (ON), 1 month of lomerizine treatment protects retinal ganglion cells (RGCs), incompletely preserves visual function and also limits elements of secondary degeneration, including macrophage infiltration. However, under some circumstances macrophages have been shown to have different supportive effects on RGC protection and regeneration, casting doubt on the benefit of longer term therapies that reduce macrophage numbers. Here, we determined whether shorter treatment times (1 day or 1 week) result in improved effects on RGC survival and visual function, and whether benefits are maintained after cessation of treatment. We demonstrate that 1 month of lomerizine is the minimum period required to restore the fast reset phase of the optokinetic nystagmus and maintain it for a further 2 months after cessation of treatment (p>0.05, not different from normal). While 1 week of lomerizine treatment results in temporary recovery of numbers of fast reset phases, the recovery is not maintained after treatment cessation. Similarly, protection of RGC densities requires 1 month of lomerizine treatment, but protection is not maintained after treatment cessation. Importantly, none of the lomerizine treatment protocols resulted in full restoration of visual function, confirming the necessity of combining lomerizine with other treatment modalities.

Background Smooth pursuit deficits are an intermediate phenotype for schizophrenia that may result from disturbances in visual motion perception, sensorimotor transformation, predictive mechanisms, or alterations in basic oculomotor control. Which of these components are the primary causes of smooth pursuit impairments and whether they are impaired similarly across psychotic disorders remain to be established. Methods First-episode psychotic patients with bipolar disorder ( n = 34), unipolar depression ( n = 24), or schizophrenia ( n = 77) and matched healthy participants ( n = 130) performed three smooth pursuit tasks designed to evaluate different components of pursuit tracking. Results On ramp tasks, maintenance pursuit velocity was reduced in all three patients groups with psychotic bipolar patients exhibiting the most severe impairments. Open loop pursuit velocity was reduced in psychotic bipolar and schizophrenia patients. Motion perception during pursuit initiation, as indicated by the accuracy of saccades to moving targets, was not impaired in any patient group. Analyses in 138 participants followed for 6 weeks, during which patients were treated and psychotic symptom severity decreased, and no significant change in performance in any group was revealed. Conclusions Sensorimotor transformation deficits in all patient groups suggest a common alteration in frontostriatal networks that dynamically regulate gain control of pursuit responses using sensory input and feedback about performance. Predictive mechanisms appear to be sufficiently intact to compensate for this deficit across psychotic disorders. The absence of significant changes after acute treatment and symptom reduction suggests that these deficits appear to be stable over time.

One of vision’s most important functions is specification of the layout of objects in the 3D world. While the static optical geometry of retinal disparity explains the perception of depth from binocular stereopsis, we propose a new formula to link the pertinent dynamic geometry to the computation of depth from motion parallax. Mathematically, the ratio of retinal image motion (motion) and smooth pursuit of the eye (pursuit) provides the necessary information for the computation of relative depth from motion parallax. We show that this could have been obtained with the approaches of Nakayama and Loomis [Nakayama, K., & Loomis, J. M. (1974). Optical velocity patterns, velocity-sensitive neurons, and space perception: A hypothesis. Perception, 3, 63–80] or Longuet-Higgens and Prazdny [Longuet-Higgens, H. C., & Prazdny, K. (1980). The interpretation of a moving retinal image. Proceedings of the Royal Society of London Series B, 208, 385–397] by adding pursuit to their treatments. Results of a psychophysical experiment show that changes in the motion/pursuit ratio have a much better relationship to changes in the perception of depth from motion parallax than do changes in motion or pursuit alone. The theoretical framework provided by the motion/pursuit law provides the quantitative foundation necessary to study this fundamental visual depth perception ability.

An evaluation of eye movements is very useful in neurological disorders but is complicated by issues such as maturation and lack of normative data in children. In order to address these issues we studied smooth pursuit eye movements of 65 normal children aged 7-11 years old. The gain of horizontal smooth pursuit (HSP) was higher than the gain of the vertical smooth pursuit (SP) and this difference had a statistical tendency to disappear with aging from 7 to 11 years. These data suggest that, in the cerebral regions involved in the control of SP, i.e. posterior parietal and superior temporal lobe regions, the networks for VSP mature latter than those for HSP.

We used a dual-task paradigm to investigate the spatial allocation of attention during smooth pursuit. Subjects tracked one character in a translating string of characters (block letter 8’s), and during maintained pursuit, one of the characters briefly changed to an E or 3. Based on the ability of subjects to correctly discriminate the probed character, we found that the primary focus of attention during smooth pursuit is centered on the tracked target with no appreciable lead or lag. Spatial cues were only partly effective in directing attention to other locations in our task, and these cueing effects were biased for locations ahead of the tracked target.

The oculomotor system coordinates different types of eye movements in order to orient the visual axis, including saccade and smooth pursuit,. It was traditionally thought that the premotor pathways for these different eye movements are largely separate. In particular, a group of midline cells in the pons called omnipause neurons were considered to be part of only the saccadic system. Recent experimental findings have shown activity modulation of these brainstem premotor neurons during both kinds of eye movements. In this study, we propose a new computational model of the brainstem circuitry underlying the generation of saccades and smooth pursuit eye movements. Similar models have been developed earlier, but mainly looking at pure saccades. Here, we integrated recent neurophysiological findings on omnipause neuron activity during smooth pursuit. Our computational model can mimic some new experimental findings as the similarity of "eye velocity profile" with "omnipause neuron pattern of activity" in pursuit movement. We showed that pursuit neuron activity is augmented during catch-up saccades; this increment depends on the initial pursuit velocity in catch-up saccade onset. We conclude that saccadic and pursuit components of catch-up saccades are added to each other nonlinearly.

We used passive and active following of a predictable smooth pursuit stimulus in order to establish if predictive eye movement responses are equivalent under both passive and active conditions. The smooth pursuit stimulus was presented in pairs that were either 'predictable' in which both presentations were matched in timing and velocity, or 'randomized' in which each presentation in the pair was varied in both timing and velocity. A visual cue signaled the type of response required from the subject; a green cue indicated the subject should follow both the target presentations (Go-Go), a pink cue indicated that the subject should passively observe the 1st target and follow the 2nd target (NoGo-Go), and finally a green cue with a black cross revealed a randomized (Rnd) trial in which the subject should follow both presentations. The results revealed better prediction in the Go-Go trials than in the NoGo-Go trials, as indicated by higher anticipatory velocity and earlier eye movement onset (latency). We conclude that velocity and timing information stored from passive observation of a moving target is diminished when compared to active following of the target. This study has significant consequences for understanding how visuomotor memory is generated, stored and subsequently released from short-term memory.

What is the main purpose of visual motion processing? One very important aspect of motion processing is definitively the generation of smooth pursuit eye movements. These eye movements avoid motion blur of moving objects which would obstruct the analysis of the objects’ visual details. However, these eye movements can only be executed if there is a moving target. So there is a very close and inseparable relationship between smooth pursuit and motion processing. The hub for visual motion processing is situated in the middle temporal (MT) and medial superior temporal (MST) area. Despite the undoubted importance of these areas for the generation of smooth pursuit or goal-directed behavior in general, it is important to keep in mind that motion processing in addition serves perceptual purposes such as object recognition, structure-from-motion detection, scene segmentation, self-motion estimation and depth perception. This review focuses at the beginning on pursuit-related activity recorded from MT and MST, subsequently extends the view to goal-directed hand movements, and finally addresses the possible contributions of these areas to motion perception.

Smooth pursuit eye movements (SP) are driven by moving objects. The pursuit system processes the visual input signals and transforms this information into an oculomotor output signal. Despite the object's movement on the retina and the eyes' movement in the head, we are able to locate the object in space implying coordinate transformations from retinal to head and space coordinates. To test for the visual and oculomotor components of SP and the possible transformation sites, we investigated three experimental conditions: (I) fixation of a stationary target with a second target moving across the retina (visual), (II) pursuit of the moving target with the second target moving in phase (oculomotor), (III) pursuit of the moving target with the second target remaining stationary (visuo-oculomotor). Precise eye movement data were simultaneously measured with the fMRI data. Visual components of activation during SP were located in the motion-sensitive, temporo-parieto-occipital region MT+ and the right posterior parietal cortex (PPC). Motor components comprised more widespread activation in these regions and additional activations in the frontal and supplementary eye fields (FEF, SEF), the cingulate gyrus and precuneus. The combined visuo-oculomotor stimulus revealed additional activation in the putamen. Possible transformation sites were found in MT+ and PPC. The MT+ activation evoked by the motion of a single visual dot was very localized, while the activation of the same single dot motion driving the eye was rather extended across MT+. The eye movement information appeared to be dispersed across the visual map of MT+. This could be interpreted as a transfer of the one-dimensional eye movement information into the two-dimensional visual map. Potentially, the dispersed information could be used to remap MT+ to space coordinates rather than retinal coordinates and to provide the basis for a motor output control. A similar interpretation holds for our results in the PPC region.

Smooth pursuit eye movements (SPEM) are used to maintain focus upon moving targets. The generation of SPEM velocity is controlled by retinal information and extraretinal signals. Although there is a wealth of studies investigating retinal and extraretinal SPEM control, the main questions regarding the cortical mechanisms involved in the processing of SPEM to different stimulus velocities are still unresolved. We applied an innovative event-related fMRI-design by presenting target ramps at different velocities (5, 10, 15, 20°/s) with both continuous target presentation and intervals of target blanking. The stimulus parameters were integrated into the statistical model and eye movements were registered to confirm SPEM performance. Our results clearly demonstrate that in humans the oculomotor network (V5, frontal and supplementary eye fields, lateral intraparietal area) is engaged in the processing of retinal and extraretinal SPEM velocity. Within this network neural activity increases with increasing target velocity. During extraretinal SPEM, additional engagement of the dorsolateral prefrontal cortex, angular gyrus, parahippocampal gyrus and superior temporal gyrus occurs. These regions encode cognitive functions such as memory, attention and monitoring. The activation of the inferior parietal cortex seems to be related to the interaction between velocity and blanking thereby underlining its relevance for task switching and sensorimotor transformation.

Ten-month-old infants' sensitivity to first-order motion (FOM) defined by luminance and second-order motion (SOM) defined by flickering was measured in an eye-tracking paradigm. We used a small single disc or gratings moving horizontally. Although infants could track the SOM of a small disc, they failed to exhibit smooth pursuit eye movements. They also failed to track SOM gratings with smooth pursuit. However, the gain of tracking based on slow eye movement was influenced by the motion direction of SOM in cases when both FOM and SOM were presented simultaneously, suggesting some sensitivity to SOM.

Introduction Ataxia telangiectasia (AT) is a recessive neurodegenerative disease due to a faulty repair mechanism for breaks in double-stranded DNA ( ATM mutation). Ophthalmic features of AT include conjunctival telangiectasia, strabismus, saccadic dysfunction with head thrusts, and convergence insufficiency. Ataxia telangiectasia–like syndrome (ATLD) is a more recently recognized condition due to homozygous mutation in MRE11 , a gene also involved in the cellular repair response to double-stranded DNA breaks; ophthalmic features of ATLD are not well described. The purpose of this article is to describe the ophthalmic features of ATLD. Methods Full ophthalmologic and orthoptic evaluations were obtained in 13 individuals: 10 previously reported ATLD patients, an additional related ATLD patient, and 3 nonaffected relatives. All individuals were from three unrelated consanguineous Saudi Arabian families harboring an MRE11 mutation (W210C). Age range was from 2 to 40 years of age. Results No affected patient had structural ocular abnormality (eg, conjunctival telangiectasia), manifest strabismus at distance, or duction limitation. All but one (the youngest) had saccadic dysfunction (without head thrusts). Most patients had abnormal convergence. Older patients had nystagmus with abnormalities in smooth pursuit and vestibular ocular reflex. All patients had cerebellar atrophy by neuroimaging and slowly progressive ataxia. The unaffected heterozygous relatives had unremarkable ophthalmic and neurologic examinations. Conclusions Saccadic dysfunction without head thrusts and convergence abnormality are common in ATLD secondary to homozygous W210C MRE11 mutation. Older patients have nystagmus with abnormalities in smooth pursuit and vestibular ocular reflex. Eye movement control systems apparently deteriorate with time in this rare neurological disease. Ophthalmic features of AT that were not observed in any of our ATLD patients include conjunctival telangiectasia, head thrusting, and manifest strabismus at distance.

The role of eye movements in the perception of depth from motion was investigated in esotropia. Elevated motion parallax thresholds have been shown in strabismus [Thompson, A. M., & Nawrot, M. (1999). Abnormal depth perception from motion parallax in amblyopic observers. Vision Research, 39, 1407–1413] suggesting a global deficit in depth perception involving both stereopsis and motion. However, this motion parallax deficit in strabismus might be better explained by the role that eye movements play in motion parallax [Nawrot, M., & Joyce, L. (2006). The pursuit theory of motion parallax. Vision Research, 46, 4709–4725]. Esotropia is associated with asymmetric pursuit and optokinetic response eye movements [Demer, J. L., & von Noorden, G. K. (1988). Optokinetic asymmetry in esotropia. Journal of Pediatric Ophthalmology and Strabismus, 25, 286–292; Schor, C. M., & Levi, D. M. (1980). Disturbances of small-field horizontal and vertical optokinetic nystagmus in amblyopia. Investigative Ophthalmology and Visual Science, 19, 851–864; Tychsen, L., & Lisberger, S. G. (1986). Maldevelopment of visual motion processing in humans who had strabismus with onset in infancy. The Journal of Neuroscience, 6, 2495–2508; [Westall, C. A., Eizenman, M., Kraft, S. P., Panton, C. M., Chatterjee, S., & Sigesmund, D. (1998). Cortical binocularity and monocular optokinetic asymmetry in early-onset esotropia. Investigative Ophthalmology and Visual Science, 39, 1352–1360.]. The first experiment demonstrates that the motion parallax deficit in esotropia mirrors the pursuit eye movement asymmetry: in the direction of normal pursuit, esotropic observers had normal depth from motion parallax. A second set of experiments, conducted in normal observers, demonstrates that this motion parallax deficit is not a secondary problem due to the retinal slip created by inadequate pursuit. These results underscore the role of pursuit eye movements in the perception of depth from motion parallax.

We report a 37-year-old woman with acute disseminated encephalomyelitis (ADEM) who presented with progressive vertigo. A central nervous system disorder was initially suspected because gaze-evoked torsional nystagmus was observed and electrical nystagmography (ENG) revealed abnormal eye movements with saccadic ocular pursuit and pathological optokinetic nystagmus. Finally ADEM was diagnosed by the clinical symptoms and the characteristic patterns of brain MRI. It is rare for otolaryngologists to examine patients with ADEM. ADEM takes an acute course and can present a grave state and therefore needs early diagnosis, early treatment. We have to keep ADEM in mind in the diagnosis of vertigo.

It is well established that elementary motion detectors are only able to code for the movement of a contour perpendicular to its orientation. This shortcoming explains why the initial direction of smooth-pursuit eye movements is directed orthogonal to the orientation of a moving contour independent of its veridical direction of motion. Here, we replicated this finding and asked whether this directional error can be reduced by subjects’ prediction of upcoming target moving direction and whether this directional error also occurs during tracking of an illusory contour. Our results show that prediction did not abolish the directional error, it was only slightly reduced. On the other hand, the directional error was considerably diminished during pursuit initiation towards illusory contours and most likely reflected the amount of real stimulation defining the specific illusory contour. We conclude that pursuit initiation is driven by raw retinal image motion signals, which are not yet processed for figure completion.

A number of studies have shown that stationary backgrounds compromise smooth pursuit eye movements. It has been suggested that poor attentional selection of the pursuit target was responsible for reductions of pursuit gain. To quantify the detrimental effects of attention, we instructed observers to either pay attention to background objects or to ignore them. The to-be-attended object was indicated by peripheral or central cues. Strong reductions of pursuit gain occurred when the following conditions were met: (a) the subject payed attention to the object (b) a salient event was present, for instance the onset of the target or cue and (c) the attended target produced retinal motion. Removing any of the three conditions resulted in no or far smaller decreases of pursuit gain. Further, decreases in pursuit gain were present with perceptual discrimination and simple manual detection.

SummarySmooth-pursuit eye velocity to a moving target is more accurate after an initial catch-up saccade than before, an enhancement that is poorly understood. We present an individual-differences-based method for identifying mechanisms underlying a physiological response and use it to test whether visual motion signals driving pursuit differ pre- and postsaccade. Correlating moment-to-moment measurements of pursuit over time with two psychophysical measures of speed estimation during fixation, we find two independent associations across individuals. Presaccadic pursuit acceleration is predicted by the precision of low-level (motion-energy-based) speed estimation, and postsaccadic pursuit precision is predicted by the precision of high-level (position-tracking) speed estimation. These results provide evidence that a low-level motion signal influences presaccadic acceleration and an independent high-level motion signal influences postsaccadic precision, thus presenting a plausible mechanism for postsaccadic enhancement of pursuit.