Saccades of video head impulse test in Meniere's disease and Vestibular Migraine: What can we learn from?

Background:Saccades are often observed on video head impulse tests(vHIT)in patients with Meniere's Disease(MD)and Vestibular Migraine(VM).However,their saccadic features are not fully described.Objective:This study aims to identify the saccades characteristics of MD and VM.Methods:75 VM patients and 103 definite unilateral MD patients were enrolled in this study.First raw saccades were exported and analyzed.The VM patients were divided into left and right based on their ears,while the MD patients were separated into affected and unaffected subgroups based on their audiograms and symptoms.Results:The MD patients have more saccades on the affected side(85%vs.69%),and saccade velocity is more consistent than the contralateral side(shown by the coefficient of variation).The saccades occurrence rates on both sides are similar in VM(77%vs.76%),as are other saccadic parameters.The MD patients have more significant inter-aural differences than the VM patients,manifested in higher velocity(p-value 0.000),earlier arriving(p-value 0.010),and more time-domain gathered(p-value 0.003)on the affected side.Conclusions:Bilateral saccades are commonly observed in MD and VM.In contrast to MD,saccades on VM are subtle,scattered,and late-arrived.Furthermore,the MD patients showed inconsistent saccadic distribution with more velocity-uniform saccades on the affected side.

AB014.Impaired anti-saccade production in posterior parietal cortex damaged patients

Background:Performing an anti-saccade relies on two mechanisms:(I)inhibiting an automatic saccade to a target,and(II)generating,instead,a voluntary saccade to a location other than this visual target.It remains unclear where and how these two processes are implemented to ensure the production of correct anti-saccades.Previous research in optic ataxia has implicated the posterior parietal cortex(PPC)in anti-pointing,implying a possible role of the PPC in anti-saccade production.Methods:Here,we tested how three patients with unilateral or bilateral damage to the PPC,as well as six neurologically intact controls,perform different types of anti-saccade:classic anti-saccades(180°rotation)or mirror saccades(90°rotation)across and within hemi-fields.Results:We showed that PPC damaged patients were impaired in anti-saccade production for their contralesional visual fields.This was reflected in a longer period of erroneous pro-saccades,longer latencies associated with correct anti-saccades to the contralesional visual field and more imprecise anti-saccades.Conclusions:Our results thus suggest that PPC damage results in delayed and prolonged competing saccade planning processes between two locations(i.e.,visual target and saccade goal location).Taken together,our results provide evidence for a crucial role of the PPC in parallel mechanisms underlying anti-saccade performance.

Analysis of video head impulse test saccades data in patients with vestibular migraine or probable vestibular migraine

Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their utility in diagnosing VM.To better understand clinical features of VM,it is necessary to understand raw saccades data.Methods:Fourteen patients with confirmed VM,45 patients with probable VM(p-VM)and 14 agematched healthy volunteers were included in this study.Clinical findings related to spontaneous nystagmus(SN),positional nystagmus(PN),head-shaking nystagmus(HSN),caloric test and vHIT were recorded.Raw saccades data were exported and numbered by their sequences,and their features analyzed.Results:VM patients showed no SN,PN or HSN,and less than half of them showed unilateral weakness(UW)on caloric test.The first saccades from lateral semicircular canal stimulation were the most predominant for both left and right sides.Neither velocity nor time parameters were significantly different when compared between the two sides.Most VM patients(86%)exhibited small saccades,around 35%of the head peak velocity,with a latency of 200e400 ms.Characteristics of saccades were similar in patients with p-VM.Only four normal subjects showed saccades,all unilateral and seemingly random.Conclusions:Small saccades involving bilateral semicircular canals with a scattered distribution pattern are common in patients with VM and p-VM.

AB055.Eye movements in the dark:saccades to non-visual targets

Background:Saccades are rapid and abrupt eye movements that allow us to change the point of fixation very quickly.Saccades are generally made to visual points of interest,but we can also saccade to non-visual objects that attract our attention.While there is a plethora of studies investigating saccadic eye movements to visual targets,there is very little evidence of how eye movement planning occurs when individuals are performing eye movements to non-visual targets across different sensory modalities.Methods:Fifteen adults with normal,or corrected to normal,vision made saccades to either visual,auditory,tactile or proprioceptive targets.In the auditory condition a speaker was positioned at one of eight locations along a circle surrounding a central fixation point.In the proprioceptive condition the participant’s finger was placed at one of the eight locations.In the tactile condition participants were touched on their right forearm in one of four eccentric location,left and right of a central point.Eye movements were made in complete darkness.Results:We compared the precision and accuracy of the eye movements to tactile,proprioceptive,and auditory targets in the dark.Overall,both precision and accuracy of movements to non-visual targets were significantly lower compared to visual targets.Conclusions:These differences emphasize the central role of the visual system in saccade planning.

Motion Control in Saccade and Smooth Pursuit for Bionic Eye Based on Three-dimensional Coordinates

Saccade and smooth pursuit are two important functions of human eye. In order to enable bionic eye to imitate the two functions, a control method that implements saccade and smooth pursuit based on the three-dimensional coordinates of target is proposed. An optimal observation position is defined for bionic eye based on three-dimensional coordinates. A kind of motion planning method with high accuracy is developed. The motion parameters of stepper motor consisting of angle acceleration and turning time are computed according to the position deviation, the target＇s angular velocity and the stepper motor＇s current angular velocity in motion planning. The motors are controlled with the motion parameters moving to given position with desired angular velocity in schedule time. The experimental results show that the bionic eye can move to optimal observation positions in 0.6 s from initial location and the accuracy of 3D coordinates is improved. In addition, the bionic eye can track a target within the error of less than 20 pixels based on three-dimensional coordinates. It is verified that saccade and smooth pursuit of bionic eye based on three-dimensional coordinates are feasible.

Modulation of Neuronal Activity and Saccades at Theta Rhythm During Visual Search in Non-human Primates

Active exploratory behaviors have often been associated with theta oscillations in rodents,while theta oscillations during active exploration in non-human primates are still not well understood.We recorded neural activities in the frontal eye field(FEF)and V4 simultaneously when monkeys performed a free-gaze visual search task.Saccades were strongly phase-locked to theta oscillations of V4 and FEF local field potentials,and the phase-locking was dependent on saccade direction.The spiking probability of V4 and FEF units was significantly modulated by the theta phase in addition to the time-locked modulation associated with the evoked response.V4 and FEF units showed significantly stronger responses following saccades initiated at their preferred phases.Granger causality and ridge regression analysis showed modulatory effects of theta oscillations on saccade timing.Together,our study suggests phase-locking of saccades to the theta modulation of neural activity in visual and oculomotor cortical areas,in addition to the theta phase locking caused by saccade-triggered responses.

Modeling perisaccadic time perception

There is an impressive scarcity of quantitative models of the clock patterns in the brain. We propose a mesoscopic approach, i.e. neither a description at single neuron level, nor at systemic level/too coarse granularity, of the time perception at the time of the saccade. This model uses functional pathway knowledge and is inspired by, and integrates, recent findings in both psychophysics and neurophysiology. Perceived time delays in the perisaccadic window are shown numerically consistent with recent experimental measures. Our model provides explanation for several experimental outcomes on saccades, estimates popu-lation variance of the error in time perception and represent a meaningful example for bridging psychophysics and neurophysiology. Finally we found that the insights into information processing during saccadic events lead to considerations on engineering exploitation of the underlying phenomena.

Distortion of Space and Time during Saccadic Eye Movements

The space-time distortion perceived subjectively during saccadic eye movements is an associative phenomenon of a transient shift of observer’s visual frame of reference from one position to another. Here we report that the lines of subjective simultaneity defined as two spatially separated flashes perceived during saccades were nearly uniformly tilted along the physical time-course. The causality of the resulting space-time compression may be explained by the Minkowski space-time diagram in physics.

Eye Tracking and Learning Predictability

Eye-tracking is a unique research method in education to help understand learners’attention to learning materials,reading struggles,learning strategies,and learning behaviors within the context of multimedia.This study overviews the empirical studies in this field,examines the role of eye-tracking in learning predictability,and discusses the ways that eye-tracking can be used for early intervention.

AB073.Correlations between control of saccadic eye movements and performance in other cognitive tasks in younger adults,older adults and patients with Parkinson’s disease

Background:Cognitive control is defined as the ability to act flexibly in the environment by either behaving automatically or inhibiting said automatic behaviour and it can be measured using an interleaved pro/anti-saccade task.Decline in cognitive control has been attributed to normal aging and neurological illnesses such as Parkinson’s disease(PD)as well as decline in other cognitive abilities.This parallel might highlight the role played by cognitive control in information processing and working memory.However,little is known about the relationship between cognitive control and other cognitive processes such as visual memory,decision making,and visual search.We thus propose to correlate the incidence of impaired cognitive control with deficits in visual memory,decision making and visual search in three groups:younger adults,older adults and patients with idiopathic PD.Methods:Seventy-one participants,namely 34 adults(M=22.75,SD=3.8),22 older adults(M=67.4,SD=8.3),and 20 PD patients(M=65.59,SD=8.2)performed four tasks:interleaved pro/anti-saccade,visual memory,decision making,and serial and pop-out visual search.Results:Results show that within each group,anti-saccade error rate(ER)were significantly and negatively correlated with visual memory ER(ryounger=−0.378,P=0.036;rolder=−0.440,Polder=0.046;rPD=−0.609,P=0.016).On the other hand,correct decision-making reaction times(RT)were significantly correlated with anti-saccade ER,and RTs only in older adults(rER=0.529,P=0.014;rRT=0.512,P=0.018)and PD patients(rER=0.727,P=0.012;rRT=0.769,P=0.001).For visual search,PD patients showed a significant relationship between RTs for correct pro-saccades and pop-out(r=0.665,P=0.007),and serial(r=0.641,P=0.010)search RTs.Furthermore,there was a significant correlation between MoCA scores and anti-saccade RTs(r=−0.559,P=0.030)and ER(r=−0.562,P=0.029)in PD patients.Taken together,these results support the hypothesis of PD patients’reliance on bottom-up processes as top-down processes decline.For younger adults,there was a significant correlation between serial search performance and both anti-saccade ER(r=0.488,P=0.005),and correct pro-saccade ER(r=0.413,P=0.021).In older adults,this relationship was absent,but anti-saccade ER significantly correlated with pop-out search times(r=0.473,P=0.030).Conclusions:We found significant relationships between cognitive tasks and cognitive control as measured through the interleaved pro/anti-saccade task across and within participant groups,providing evidence of the appropriateness of the use of the interleaved pro/anti-saccade task as a measure of overall cognitive control.

Exploration of Arabic reading, in terms of the vocalization of the text form by registering the eyes movements of pupils

The intrinsic factors such as the visual constraints, extrinsic such as biomechanics, interface such as the support: the writing, the linguistics, the typography, the sense of progress of the language, have their impact on the habit, and the fittest and particularly the efficiency in reading. We suspect that circuits and zones involved in horizontal orientation “right to the left” are not the same the other way around hanging the linguistic collection. Reading Arabic provided with a specific difference in vocalization proves to be a valuable model verification two major issues which arouse language perception: [lexical processing: is it instantaneous (visual memory) or delayed (memory-tampon)? ···]. And a comparison with other models of language detection mechanisms and brain areas mnemonics which is involved in making information. Results are significatively: children vocalized mode is best seen. It must extend the duration of the mode without vowels. In our opinion, our study is original, and we introduced what a valuable tool in the diagnosis of visual and cognitive strategy by the biotechnology technical based on variations in terms of reading. This opens a horizon of opportunity for the application of the method to the Arabic language to determine the differences in eye size reflecting the effects of task variables in reading and a comparative study of other languages.

Simulate Human Saccadic Scan-Paths in Target Searching

Human saccade is a dynamic process of information pursuit. There are many methods using either global context or local context cues to model human saccadic scan-paths. In contrast to them, this paper introduces a model for gaze movement control using both global and local cues. To test the performance of this model, an experiment is done to collect human eye movement data by using an SMI iVIEW X Hi-Speed eye tracker with a sampling rate of 1250 Hz. The experiment used a two-by-four mixed design with the location of the targets and the four initial positions. We compare the saccadic scan-paths generated by the proposed model against human eye movement data on a face benchmark dataset. Experimental results demonstrate that the simulated scan-paths by the proposed model are similar to human saccades in term of the fixation order, Hausdorff distance, and prediction accuracy for both static fixation locations and dynamic scan-paths.

AB048.Pre-saccadic attentional facilitation is influenced by irrelevant post-saccadic changes

Background:Many studies have shown that attention is shifted toward the goal of the upcoming saccade.It has been suggested that the purpose of this attentional shift is to aid in trans-saccadic integration by acting as a‘pointer’(Cavanagh,Hunt,Afraz&Rolfs,2010)for remembering,processing and updating objects across saccadic eye movements(Rolfs,Jonikaitis,Deubel&Cavanagh,2011).We tested this hypothesis that pre-saccadic attentional facilitation acts as a pointer for trans-saccadic integration by investigating how irrelevant post-saccadic changes influenced pre-saccadic attentional discrimination.On one hand,if pre-saccadic attentional facilitation is an independent process involved only in enhancing peripheral information before the saccade,then manipulating visual information(absence or shift)after the saccade should have no influence on discrimination.On the other hand,if pre-saccadic attentional facilitation is involved in trans-saccadic integration,changes in visual information should influence discrimination of the pre-saccadic information.Methods:We tested different conditions involving different post-saccadic changes.In the baseline condition,participants made a saccade at the appearance of an arrow and discriminated a symbol(DS)that was presented briefly before the saccade at one of six peripheral locations.The symbol was masked thereafter with a figure 8,which remained till the end of the trial.Importantly,the DS was always presented while participants were fixating at center,and only the figure 8 was present at the end of the saccade.Participants were instructed to make the saccade then report the identity of the DS(4AFC).We then tested how blanking post-saccadic information[blanking of the saccade goal(SG)location,DSOff condition;of the entire visual scene including or excluding the SG location,AllOff and DSOnly conditions]and how displacement of the figure 8s after the saccade would affect performance.Results:We observed that discrimination performance was significantly lower when the SG location disappeared during the saccade and was no longer present when the saccade was completed(DSOff,-6.9%).This decrease in performance cannot be attributed to changes in the visual scene that may have drawn attention,as this was the case for all conditions;performance was not different when the entire visual scene was blanked(AllOff,-0.0%)or when only the DS remained(DSOnly,-1.6%).We also found that the performance decreased as a function of the displacement of the figure 8 from the SG location,particularly if it was displaced outside of the saccade landing zone.Conclusions:Based on these pattern of results,we suggest that pre-saccadic attentional facilitation is indeed involved in trans-saccadic integration by acting as a location marker or pointer.The lack of a visual target at the saccade goal,even if it is irrelevant to the pre-saccadic discrimination task,disrupted performance.

Electrocortical Activity Differences Related to Saccadic Movements between Bipolar Patients and Healthy Subjects

Objective: The present study aimed to investigate and to compare the electrophysiological changes in bipolar patients and healthy subjects during the execution of a saccade task. Materials and Methods: The subjects had to respond to a fixed visual stimulus presented by a LEDs bar. We executed an ANOVA (one-way) and post hoc Scheffé test to examine the difference of absolute alpha power and reaction time among four groups: control, depression, manic and euthymic. We observed the frontal, parietal and occipital regions. The paired t test was realized on each electrode and group to compare the pre and post moment in the task. Results: We observed a statistical difference among the groups for the behavioral variable—saccade reaction time. For the electrophysiological variable—absolute alpha power, we did not find significant difference between the moments (pre and post stimulus presentation) for none of the electrodes of each bipolar group. However, the results pointed out to a difference between the moments for F3, P3, O1 and O2 electrodes for control group. Conclusion: We cannot affirm that the task influences the cortical activity of the patients. It is possible that the method used to analyze the data is not the adequate. The time-frequency analysis could be better to analyze the present data. We also observed that the absolute alpha power could be considered a marker of bipolar disorder, but not of the different states (i.e., mania, depression, euthymia).

Neuronal Response to Reward and Luminance in Macaque LIP During Saccadic Choice

Recent work in decision neuroscience suggests that visual saliency can interact with reward-based choice,and the lateral intraparietal cortex(LIP)is implicated in this process.In this study,we recorded from LIP neurons while monkeys performed a two alternative choice task in which the reward and luminance associated with each offer were varied independently.We discovered that the animal’s choice was dictated by the reward amount while the luminance had a marginal effect.In the LIP,neuronal activity corresponded well with the animal’s choice pattern,in that a majority of reward-modulated neurons encoded the reward amount in the neuron’s preferred hemifield with a positive slope.In contrast,compared to their responses to low luminance,an approximately equal proportion of luminance-sensitive neurons responded to high luminance with increased or decreased activity,leading to a much weaker population-level response.Meanwhile,in the non-preferred hemifield,the strength of encoding for reward amount and luminance was positively correlated,suggesting the integration of these two factors in the LIP.Moreover,neurons encoding reward and luminance were homogeneously distributed along the anterior-posterior axis of the LIP.Overall,our study provides further evidence supporting the neural instantiation of a priority map in the LIP in reward-based decisions.

Biomimetic Autopilot Based on Minimalistic Motion Vision for Navigating along Corridors Comprising U-shaped and S-shaped Turns

A bioinspired autopilot is presented, in which body saccadic and intersaceadic systems are combined. This autopilot en- ables a simulated hovercraft to travel along corridors comprising L-junctions, U-shaped and S-shaped turns, relying on mini- realistic motion vision cues alone without measuring its speed or distance from walls, in much the same way as flies and bees manage their flight in similar situations. The saccadic system responsible for avoiding frontal collisions triggers yawing body saccades with appropriately quantified angles based simply on a few local optic flow measurements, giving the angle of inci- dence with respect to a frontal wall. The simulated robot negotiates stiff bends by triggering body saccades to realign its tra- jectory, thus traveling parallel with the wall along a corridor comprising sharp turns. Direct comparison shows that the per- formance of this new body saccade-based autopilot closely resembles the behavior of a fly using similar body saccade strategy when flying along a corridor with an S-shaped turn, despite the huge differences in terms of the inertia.

Computational Decision Support System for ADHD Identification

Attention deficit/hyperactivity disorder(ADHD)is a common disorder among children.ADHD often prevails into adulthood,unless proper treatments are facilitated to engage self-regulatory systems.Thus,there is a need for effective and reliable mechanisms for the early identification of ADHD.This paper presents a decision support system for the ADHD identification process.The proposed system uses both functional magnetic resonance imaging(fMRI)data and eye movement data.The classification processes contain enhanced pipelines,and consist of pre-processing,feature extraction,and feature selection mechanisms.fMRI data are processed by extracting seed-based correlation features in default mode network(DMN)and eye movement data using aggregated features of fixations and saccades.For the classification using eye movement data,an ensemble model is obtained with 81%overall accuracy.For the fMRI classification,a convolutional neural network(CNN)is used with 82%accuracy for the ADHD identification.Both ensemble models are proved for overfitting avoidance.