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2022 |
Elham Azizi; Joanne Fielding; Larry A. Abel Video game training in traumatic brain injury patients: an exploratory case report study using eye tracking Journal Article In: Journal of Eye Movement Research, vol. 15, no. 1, pp. 1–14, 2022. @article{Azizi2022, Remediation of attentional impairments is an essential component of cognitive rehabilitation after traumatic brain injury (TBI). Evidence from healthy participants has demonstrated attentional improvement following playing an action video game. This exploratory study investigated its application in TBI participants in a multiple baselines single case experimental design (SCED). Saccadic eye movements, recognized as the visible indicators of visual attention, were assessed to evaluate the effectiveness of the game training. Three severe TBI participants were trained in an action game for 10 hours. Saccadic eye movements during a self-paced saccade and an abstract visual search task were investigated during baseline, mid training and post-training. Using Percentage of Non-overlapping Data (PND), analysis showed consistent increase in the rate of the self-paced saccades in participants 1 (PND=80%) and 2 (PND=70%). In abstract search, fixation duration showed a minimally effective decrease for participant 2 (PND= 60%) and a moderately effective reduction in participant 3 (PND= 80%). Search time showed a highly effective reduction in participant 2 (PND = 100%) and moderately effective decrease in participant 3 (PND=70%). Overall, video game training might modify allocation of attention in eye movements. More evidence is required to validate the usefulness of this novel method of the cognitive training |
Daniela Balslev; Alexandra G. Mitchell; Patrick J. M. Faria; Lukasz Priba; Jennifer A. Macfarlane Proprioceptive contribution to oculomotor control in humans Journal Article In: Human Brain Mapping, vol. 43, no. 16, pp. 5081–5090, 2022. @article{Balslev2022, Stretch receptors in the extraocular muscles (EOMs) inform the central nervous system about the rotation of one's own eyes in the orbits. Whereas fine control of the skeletal muscles hinges critically on proprioceptive feedback, the role of proprioception in oculomotor control remains unclear. Human behavioural studies provide evidence for EOM proprioception in oculomotor control, however, behavioural and electrophysiological studies in the macaque do not. Unlike macaques, humans possess numerous muscle spindles in their EOMs. To find out whether the human oculomotor nuclei respond to proprioceptive feedback we used functional magnetic resonance imaging (fMRI). With their eyes closed, participants placed their right index finger on the eyelid at the outer corner of the right eye. When prompted by a sound, they pushed the eyeball gently and briefly towards the nose. Control conditions separated out motor and tactile task components. The stretch of the right lateral rectus muscle was associated with activation of the left oculomotor nucleus and subthreshold activation of the left abducens nucleus. Because these nuclei control the horizontal movements of the left eye, we hypothesized that proprioceptive stimulation of the right EOM triggered left eye movement. To test this, we followed up with an eye-tracking experiment in complete darkness using the same behavioural task as in the fMRI study. The left eye moved actively in the direction of the passive displacement of the right eye, albeit with a smaller amplitude. Eye tracking corroborated neuroimaging findings to suggest a proprioceptive contribution to ocular alignment. |
Sinem B. Beylergil; Camilla Kilbane; Aasef G. Shaikh; Fatema F. Ghasia Eye movements in Parkinson's disease during visual search Journal Article In: Journal of the Neurological Sciences, vol. 440, pp. 1–16, 2022. @article{Beylergil2022, Visual spatial dysfunction is not uncommon in Parkinson's disease. We hypothesized that visual search behavior is impaired in Parkinson's disease and the deficits correlate with changes in the amplitudes and frequency of fixational and non-fixational rapid eye movements. We measured eye movements, the horizontal and vertical angular position vectors of the right and left eye using high-resolution video oculography, in the Parkinsonian cohort who viewed a blank scene and pictures with real-life scene. Latter was associated with a task of searching an object hidden in a clutter, either at an expected or an unexpected location. Parkinsonian cohort took longer initial time to reach the region of interest. The ultimate response time was comparable in both Parkinson's disease and their healthy peers. The fixation duration was comparable in two cohorts but there was a trend wise decline for the ones located at unexpected locations. Parkinson's disease participants made more fixational saccades with significantly larger amplitude and less non-fixational saccades with significantly smaller amplitude during blank scene viewing. However, overall scanned area of the blank scene was not affected in Parkinson's disease. The Parkinson's disease participants made less non-fixational saccades with amplitudes comparable to healthy control during the visual search of a target object. Fixational saccades during visual search were larger in Parkinson's disease particularly when target was placed at an unexpected location, but the frequency was unchanged. |
Sinem Balta Beylergil; Jordan Murray; Angela M. Noecker; Palak Gupta; Camilla Kilbane; Cameron C. McIntyre; Fatema F. Ghasia; Aasef G. Shaikh Temporal patterns of spontaneous fixational eye movements: The influence of basal ganglia Journal Article In: Journal of Neuro-Ophthalmology, vol. 42, no. 1, pp. 45–55, 2022. @article{Beylergil2022a, Background:Spontaneity is a unique feature of the nervous system. One of the fundamentally critical and recognized forms of spontaneous motor activity is witnessed in the visuomotor system. Microsaccades, the miniature spontaneous eye movements, are critical for the visual perception. We hypothesized that microsaccades follow specific temporal patterns that are modulated by the basal ganglia output.Methods:We used high-resolution video-oculography to capture microsaccades in 48 subjects (31 healthy and 17 with Parkinson's disease) when subjects were asked to hold their gaze on a straight-ahead target projected on white background. We analyzed spontaneous discharge patterns of microsaccades.Results:The first analysis considering coefficient of variation in intersaccadic interval distribution demonstrated that microsaccades in Parkinson's disease are more dispersed than the control group. The second analysis scrutinized microsaccades' temporal variability and revealed 3 distinct occurrence patterns: regular rhythmic, clustered, and randomly occurring following a Poisson-like process. The regular pattern was relatively more common in Parkinson's disease. Subthalamic DBS modulated this temporal pattern. The amount of change in the temporal variability depended on the DBS-induced volume of tissue activation and its overlap with the subthalamic nucleus. The third analysis determined the autocorrelations of microsaccades within 2-second time windows. We found that Parkinson's disease altered local temporal organization in microsaccade generation, and DBS had a modulatory effect.Conclusion:The microsaccades occur in 3 temporal patterns. The basal ganglia are one of the modulators of the microsaccade spontaneity. |
Olivia G. Calancie; Donald C. Brien; Jeff Huang; Brian C. Coe; Linda Booij; Sarosh Khalid-Khan; Douglas P. Munoz Maturation of temporal saccade prediction from childhood to adulthood: Predictive saccades, reduced pupil size, and blink synchronization Journal Article In: Journal of Neuroscience, vol. 42, no. 1, pp. 69–80, 2022. @article{Calancie2022, When presented with a periodic stimulus, humans spontaneously adjust their movements from reacting to predicting the timing of its arrival, but little is known about how this sensorimotor adaptation changes across development. To investigate this, we analyzed saccade behavior in 114 healthy humans (ages 6–24 years) performing the visual metronome task, who were instructed to move their eyes in time with a visual target that alternated between two known locations at a fixed rate, and we compared their behavior to per- formance in a random task, where target onsets were randomized across five interstimulus intervals (ISIs) and thus the timing of appearance was unknown. Saccades initiated before registration of the visual target, thus in anticipation of its appearance, were la- beled predictive [saccade reaction time (SRT),90ms] and saccades that were made in reaction to its appearance were labeled reac- tive (SRT.90ms). Eye-tracking behavior including saccadic metrics (e.g., peak velocity, amplitude), pupil size following saccade to target, and blink behavior all varied as a function of predicting or reacting to periodic targets. Compared with reactive saccades, pre- dictive saccades had a lower peak velocity, a hypometric amplitude, smaller pupil size, and a reduced probability of blink occurrence before target appearance. The percentage of predictive and reactive saccades changed inversely from ages 8–16, at which they reached adult-levels of behavior. Differences in predictive saccades for fast and slow target rates are interpreted by differential maturation of cerebellar-thalamic-striatal pathways. |
Daniel Ernst; Jeremy M. Wolfe How fixation durations are affected by search difficulty manipulations Journal Article In: Visual Cognition, vol. 30, pp. 339–353, 2022. @article{Ernst2022, Many eye tracking studies of visual search have focused on the role of the number of fixations and the nature of scan paths. Less attention has been paid to fixation durations and to how those durations are affected by stimulus features. Previous studies have shown that fixation durations can be as important as the number of fixations in explaining search times with complex stimuli (e.g., in search for specific faces). In the present study, simple stimuli were used in a search experiment where participants searched for a closed ring among rings with a gap. We manipulated distractor heterogeneity (DH), target-distractor similarity (TDS), and stimulus density (SDY, set size within a constant search window), and estimated the contributions of these factors to gaze behaviour and trial search time. The results show that fixation durations contribute less to variation in overall search time with simple search stimuli as compared to previous studies with more complex stimuli. However, fixation durations still increased with DH, TDS, and SDY. These effects were mainly additive, and we did not find an interaction between DH and closer element spacing at high levels of SDY that might have been expected since both DH and SDY influence distractor grouping. |
Peter Essig; Jonas Müller; Siegfried Wahl Parameters of optokinetic nystagmus are influenced by the nature of a visual stimulus Journal Article In: Applied Sciences, vol. 12, pp. 1–13, 2022. @article{Essig2022, Studies on contrast sensitivity (CS) testing using optokinetic nystagmus (OKN) proposed adjusting the stimulus presentation duration based on its contrast, to increase the time efficiency of such measurement. Furthermore, stimulus-specific limits of the least OKN gain might reduce false negatives in OKN detection procedures. Therefore, we aimed to test the effects of various stimulus characteristics on OKN and to propose the stimulus-specific limits for the OKN gain and stimulus presentation duration. We tested the effect of contrast (C), spatial frequency ((Formula presented.)), and color on selected parameters of robust OKN response, namely its onset and offset time, amplitude, and gain. The right eyes of fifteen emmetropes were tracked with an infrared eye tracker during monocular observations of sinusoidal gratings moving over the horizontal plane with a velocity of ((Formula presented.)). The available contrast levels were C: 0.5%, 2.0%, 8.2%, 16.5%, 33.0%, and 55.5% presented in a random order for ten times in all measurements of (Formula presented.) : 0.12, 0.25, 0.5, and 1.00 cycles per degree and grating type: luminance, red-green, and blue-yellow. This study showed a significant effect of the stimulus characteristics on the OKN onset, offset and gain. The effect of (Formula presented.) was insignificant in OKN amplitude; however, it indicated significance for the C and grating type. Furthermore, the OKN gain and offset limits were proposed as functions of contrast for the luminance and chromatic gratings. This study concludes the characteristics of a visual stimulus have an effect on the OKN gain and onset and offset time, yet do not affect the eye-movement amplitude considerably. Moreover, the proposed limits are expected to improve the time efficiency and eye-movement detection in OKN-based contrast sensitivity measurements. |
Peter Essig; Yannick Sauer; Siegfried Wahl Reflexive saccades used for objective and automated measurements of contrast sensitivity in selected areas of visual field Journal Article In: Translational Vision Science & Technology, vol. 11, no. 5, pp. 1–12, 2022. @article{Essig2022a, Purpose: This study proposes a novel approach for objective and automated peripheral contrast sensitivity (CS) testing using reflexive saccades. Here the CS was examined in various areas the of visual field (VF) using a live analysis of gaze data. For validation of the new test, we examined CS with an established procedure of identifying the orientation of a contrast stimulus. Methods: To perform and validate the saccade-based testing, two separate measurement events were performed. In the first, participants were asked to execute a saccade toward a newly-appeared stimulus in their VF. After the saccade execution or stimulus expiry, reporting the target orientation was required in a four-alternatives forced choice (4AFC). Therefore the first measurement yields two outcomes (objective and subjec-tive). In the second measurement, only the identification of the stimulus orientation was requested, while fixating a central mark. Stimulus contrast was controlled by an adaptive psychometric procedure in both measurements. Results: The study found strong correlations (all r ≥ 0.79) of CS values for all three possible testing methods (saccade-based responding in saccadic measurements, keyboard-based responding in saccadic measurements, keyboard-based responding in non-saccadic measurements), showing the feasibility of employment of reflexive saccades in such testing. Second, this study shows a significant influence of eccentricity and direction of the stimulus on the CS function. Conclusions: CS measured with reflexive saccades is comparable to other testing methods over several areas of the participant's VF. Hence, we propose it as a novel and objective testing procedure for CS measurements. |
Marzieh Salehi Fadardi; Javad Salehi Fadardi; Monireh Mahjoob; Hassan Doosti Post-saccadic eye movement indices under cognitive load: A path analysis to determine visual performance Journal Article In: Journal of Ophthalmic and Vision Research, vol. 17, no. 3, pp. 397–404, 2022. @article{Fadardi2022, Purpose: The evidence on the linear relationship between cognitive load, saccade, fixation, and task performance was uncertain. We tested pathway models for degraded task performance resulting from changes in saccadic and post-saccadic fixation under cognitive load. Methods: Participants' (n = 38) eye movements were recorded using a post-saccadic discrimination task with and without arithmetic operations to impose cognitive load, validated through recording heart rate variability and subjective measurement. Results: Results showed that cognitive load led to longer latencies of saccade and fixation; more inaccurate responses and fewer secondary saccades (P < 0.001). Longer saccade latencies influenced task performance indirectly via increases in fixation latency, therefore, longer reaction times and higher response errors were observed due to limited fixation duration on desired target. Conclusion: We suggest that latency and duration of fixation indicate efficiency of information processing and can predict the speed and accuracy of task performance under cognitive load. |
Cecilia E. García Cena; David Gómez-Andrés; Irene Pulido-Valdeolivas; Victoria Galán Sánchez-Seco; Angela Domingo-Santos; Sara Moreno-García; Julián Benito-León Toward an automatic assessment of cognitive dysfunction in relapsing–remitting multiple sclerosis patients using eye movement analysis Journal Article In: Sensors, vol. 22, pp. 1–18, 2022. @article{GarciaCena2022, Despite the importance of cognitive function in multiple sclerosis, it is poorly represented in the Expanded Disability Status Scale (EDSS), the commonly used clinical measure to assess disability, suggesting that an analysis of eye movement, which is generated by an extensive and well-coordinated functional network that is engaged in cognitive function, could have the potential to extend and complement this more conventional measure. We aimed to measure the eye movement of a case series of MS patients with relapsing–remitting MS to assess their cognitive status using a conventional gaze tracker. A total of 41 relapsing–remitting MS patients and 43 age-matched healthy controls were recruited for this study. Overall, we could not find a clear common pattern in the eye motor abnormalities. Vertical eye movement was more impaired in MS patients than horizontal movement. Increased latencies were found in the prosaccades and reflexive saccades of antisaccade tests. The smooth pursuit was impaired with more corrections (backup and catchup movements, p<0.01). No correlation was found between eye movement variables and EDSS or disease duration. Despite significant alterations in the behavior of the eye movements in MS patients, which are compatible with altered cognitive status, there is no common pattern of these alterations. We interpret this as a consequence of the patchy, heterogeneous distribution of white matter involvement in MS that provokes multiple combinations of impairment at different points in the different networks involved in eye motor control. Further studies are therefore required. |
Nora Geiser; Brigitte Charlotte Kaufmann; Henrik Rühe; Noortje Maaijwee; Tobias Nef; Dario Cazzoli; Thomas Nyffeler Visual neglect after PICA stroke—A case study Journal Article In: Brain Sciences, vol. 12, pp. 1–10, 2022. @article{Geiser2022, After cerebellar stroke, cognition can be impaired, as described within the framework of the so-called Cerebellar Cognitive Affective Syndrome (CCAS). However, it remains unclear whether visual neglect can also be part of CCAS. We describe the case of a patient with a subacute cerebellar stroke after thrombosis of the left posterior inferior cerebellar artery (PICA), who showed a left-sided visual neglect, indicating that the cerebellum also has a modulatory function on visual attention. The neglect, however, was mild and only detectable when using the sensitive neuro-psychological Five-Point Test as well as video-oculography assessment, yet remained unnoticed when evaluated with common neglect-specific paper-pencil tests. Three weeks later, follow-up assessments revealed an amelioration of neglect symptoms. Therefore, these findings suggest that visual neglect may be a part of CCAS, but that the choice of neglect assessments and the time delay since stroke onset may be crucial. Although the exact underlying pathophysiological mechanisms remain unclear, we propose cerebellar–cerebral diaschisis as a possible explanation of why neglect can occur on the ipsilateral side. Further research applying sensitive assessment tools at different post-stroke stages is needed to investigate the incidence, lesion correlates, and pathophysiology of neglect after cerebellar lesions. |
Amirhossein Ghaderi; Matthias Niemeier; John Douglas Crawford Linear vector models of time perception account for saccade and stimulus novelty interactions Journal Article In: Heliyon, vol. 8, pp. 1–13, 2022. @article{Ghaderi2022, Various models (e.g., scalar, state-dependent network, and vector models) have been proposed to explain the global aspects of time perception, but they have not been tested against specific visual phenomena like perisaccadic time compression and novel stimulus time dilation. Here, in two separate experiments (N = 31), we tested how the perceived duration of a novel stimulus is influenced by 1) a simultaneous saccade, in combination with 2) a prior series of repeated stimuli in human participants. This yielded a novel behavioral interaction: pre-saccadic stimulus repetition neutralizes perisaccadic time compression. We then tested these results against simulations of the above models. Our data yielded low correlations against scalar model simulations, high but non-specific correlations for our feedforward neural network, and correlations that were both high and specific for a vector model based on identity of objective and subjective time. These results demonstrate the power of global time perception models in explaining disparate empirical phenomena and suggest that subjective time has a similar essence to time's physical vector. |
Alma Gharib; Barbara L. Thompson Analysis and novel methods for capture of normative eye-tracking data in 2.5-month old infants Journal Article In: PloS ONE, vol. 17, pp. 1–22, 2022. @article{Gharib2022, Development of attention systems is essential for both cognitive and social behavior maturation. Visual behavior has been used to assess development of these attention systems. Yet, given its importance, there is a notable lack of literature detailing successful methods and procedures for using eye-tracking in early infancy to assess oculomotor and attention dynamics. Here we show that eye-tracking technology can be used to automatically record and assess visual behavior in infants as young as 2.5 months, and present normative data describing fixation and saccade behavior at this age. Features of oculomotor dynamics were analyzed from 2.5-month old infants who viewed videos depicting live action, cartoons, geometric shapes, social and non-social scenes. Of the 54 infants enrolled, 50 infants successfully completed the eye-tracking task and high-quality data was collected for 32 of those infants. We demonstrate that modifications specifically tailored for the infant population allowed for consistent tracking of pupil and corneal reflection and minimal data loss. Additionally, we found consistent fixation and saccade behaviors across the entire six-minute duration of the videos, indicating that this is a feasible task for 2.5-month old infants. Moreover, normative oculomotor metrics for a free-viewing task in 2.5-month old infants are documented for the first time as a result of this high-quality data collection. |
Hanbin Go; James Danckert; Britt Anderson Saccadic eye movement metrics reflect surprise and mental model updating Journal Article In: Attention, Perception, and Psychophysics, vol. 84, no. 5, pp. 1553–1565, 2022. @article{Go2022, Two experiments investigated what eye movements can reveal about how we process surprising information and how we update mental models in dynamic and unstructured environments. Participants made saccades to visual targets presented one at a time, radially, around an invisible perimeter. Target locations were normally distributed and shifted at an unannounced point during the task. Trials following the shift were considered surprising and unexpected. These unexpected and surprising events prompted the need to update. Slower saccadic latencies were observed for surprising/unexpected events, perhaps indicative of the need to reorient attention to the unexpected target location. Longer dwell times were observed for events that signaled a change in the distribution. These data show that eye movement metrics provide a reliable indicator of mental model updating when contingencies change even in the absence of explicit change signals. |
Alexander Goettker; Emma E. M. Stewart Serial dependence for oculomotor control depends on early sensory signals Journal Article In: Current Biology, vol. 32, pp. 2956–2961, 2022. @article{Goettker2022, To create an accurate percept of the world, the visual system relies on past experience and prior assumptions.1 For example, although the retinal projection of an object moving in depth changes drastically, we still perceive the object at a constant size and velocity.2,3 Consequently, if we see the same object with a constant retinal size at two different depth levels, the perceived size differs (illustrated by the Ponzo illusion). Past experience also directly influences perceptual judgments, an effect known as serial dependence.4,5 Such sequential effects have also been reported for oculomotor behavior, even on the trial-by-trial level.6–10 An integration of past experiences seems like a smart and sophisticated mechanism to reduce uncertainty and improve behavior in a world full of statistical regularities. By leveraging the Ponzo illusion to dissociate perceived size and speed from retinal signals, we show that serial-dependence effects for oculomotor control are mediated by retinal error signals. These sequential effects likely take place in early sensory processing because they transfer to different visual stimuli. In contrast to recently reported history effects for perceptual decisions,11 sequential effects for oculomotor control deviate from perceptual mechanisms by not integrating spatial context and by ignoring size and velocity constancy. Although this dissociation might appear suboptimal, we argue that this effect reveals the different goals of the oculomotor and perceptual systems. The oculomotor system tries to reduce retinal error signals to bring and keep the target close to the fovea, whereas the visual system interprets retinal input to achieve an accurate representation of the world.12 |
A. Grillini; L. H. Koens; G. Lizaitiene; F. Lange; F. W. Cornelissen; M. A. J. Tijssen In: Clinical Parkinsonism and Related Disorders, vol. 7, pp. 1–6, 2022. @article{Grillini2022, Introduction: Vertical supranuclear gaze palsy is a key feature of Niemann-Pick type C (NP-C) and is commonly quantified using video-oculography (VOG). VOG requires sitting still for long times and performing specific tasks, thus it can be challenging or impossible for patients severely affected by movement disorders or cognitive impairment. To overcome this limitation, we measure saccades of NP-C patients using a fast eye tracking test based on continuous psychophysics and compare it to VOG. Methods: Saccades of six NP-C patients and six age-matched controls were assessed using VOG and Standardized Oculomotor and Neuro-ophthalmic Disorders Assessment (SONDA). In SONDA, participants continuously track a semi-randomly moving dot on a computer screen while their gaze is being tracked. For both assessments, sac- cades were quantified using four conventional measures: amplitude, gain, latency, and peak velocity. Further- more, SONDA's continuous measures were quantified with several novel spatio-temporal properties. Results: In the NP-C patients, both methods revealed reduced amplitude, gain, peak velocity, and increased la- tency of vertical saccades compared to horizontal saccades and compared to healthy controls. Effect sizes ob- tained with SONDA were overall larger than those for VOG. SONDA's spatio-temporal properties showed similar trends. Conclusion: SONDA reveals a deterioration of vertical saccades in NP-C patients that is consistent with VOG. SONDA's measures based on continuous psychophysics are consistent with traditional saccadic parameters and can potentially provide complementary information. SONDA shows larger effect sizes than VOG, suggesting that it provides robust and clinically relevant outcomes with a more intuitive task and shorter testing time. |
Scott N. Grossman; Rachel Calix; Todd Hudson; John Ross Rizzo; Ivan Selesnick; Steven Frucht; Steven L. Galetta; Laura J. Balcer; Janet C. Rucker Accuracy of clinical versus oculographic detection of pathological saccadic slowing Journal Article In: Journal of the Neurological Sciences, vol. 442, pp. 1–8, 2022. @article{Grossman2022, Saccadic slowing as a component of supranuclear saccadic gaze palsy is an important diagnostic sign in multiple neurologic conditions, including degenerative, inflammatory, genetic, or ischemic lesions affecting brainstem structures responsible for saccadic generation. Little attention has been given to the accuracy with which clinicians correctly identify saccadic slowing. We compared clinician (n = 19) judgements of horizontal and vertical saccade speed on video recordings of saccades (from 9 patients with slow saccades, 3 healthy controls) to objective saccade peak velocity measurements from infrared oculographic recordings. Clinician groups included neurology residents, general neurologists, and fellowship-trained neuro-ophthalmologists. Saccades with normal peak velocities on infrared recordings were correctly identified as normal in 57% (91/171; 171 = 9 videos × 19 clinicians) of clinician decisions; saccades determined to be slow on infrared recordings were correctly identified as slow in 84% (224/266; 266 = 14 videos × 19 clinicians) of clinician decisions. Vertical saccades were correctly identified as slow more often than horizontal saccades (94% versus 74% of decisions). No significant differences were identified between clinician training levels. Reliable differentiation between normal and slow saccades is clinically challenging; clinical performance is most accurate for detection of vertical saccade slowing. Quantitative analysis of saccade peak velocities enhances accurate detection and is likely to be especially useful for detection of mild saccadic slowing. |
Amy Chow; Rajkumar Nallour Raveendran; Ian Erkelens; Raiju Babu; Benjamin Thompson Increased saccadic latency in Amblyopia: Oculomotor and attentional factors Journal Article In: Vision Research, vol. 197, pp. 1–11, 2022. @article{Chow2022, Amblyopia is a neurodevelopmental disorder of vision that arises from disrupted binocular vision during early childhood. Delayed initiation of saccadic eye movements is an established feature of amblyopia. The present study investigated whether oculomotor and/or attentional factors contribute to increased amblyopic eye saccadic latencies. Participants with normal vision (n = 10) and amblyopia (n = 10; 4 anisometropia, 6 strabismic/mixed) performed visually-guided saccades to targets presented via a mirror haploscope. Eye movements were recorded for both eyes even under monocular viewing conditions. In Experiment 1, we measured the latency, amplitude gain and peak velocity of saccades as targets were presented binocularly, or monocularly. Saccadic latencies were significantly longer for both eyes when targets were presented to only the amblyopic eye compared to all other conditions. Saccade gain and main sequence rate constants were similar across groups for all viewing conditions. In Experiment 2, we tested the hypothesis that shifts of overt attention may be deficient when viewing with the amblyopic eye. We presented the fixation target to one eye and the subsequent peripheral target (saccadic error signal) to the other eye. Shifting saccadic targets between the eyes expedited saccadic latencies irrespective of which eye viewed the target in the amblyopia group. These findings indicate that oculomotor factors related to saccade generation are unlikely to be responsible for amblyopic eye saccadic latency delays. We propose that an impairment in the ability to disengage attention from a fixation target and orient to a peripheral target when both targets are seen by the amblyopic eye may contribute to increased saccadic latency. |
Alessio D'Aquino; Cornelia Frank; John Elvis Hagan; Thomas Schack Imagining interceptions: Eye movements as an online indicator of covert motor processes during motor imagery Journal Article In: Frontiers in Neuroscience, vol. 16, pp. 1–15, 2022. @article{DAquino2022, The analysis of eye movements during motor imagery has been used to understand the influence of covert motor processes on visual-perceptual activity. There is evidence showing that gaze metrics seem to be affected by motor planning often dependent on the spatial and temporal characteristics of a task. However, previous research has focused on simulated actions toward static targets with limited empirical evidence of how eye movements change in more dynamic environments. The study examined the characteristics of eye movements during motor imagery for an interception task. Twenty-four participants were asked to track a moving target over a computer display and either mentally simulate an interception or rest. The results showed that smooth pursuit variables, such as duration and gain, were lower during motor imagery when compared to passive observation. These findings indicate that motor plans integrate visual-perceptual information based on task demands and that eye movements during imagery reflect such constraint. |
Bertrand Degos; Pierre Pouget; Marcus Missal From anticipation to impulsivity in Parkinson's disease Journal Article In: npj Parkinson's Disease, vol. 8, pp. 1–12, 2022. @article{Degos2022, Anticipatory actions require to keep track of elapsed time and inhibitory control. These cognitive functions could be impacted in Parkinson's disease (iPD). To test this hypothesis, a saccadic reaction time task was used where a visual warning stimulus (WS) predicted the occurrence of an imperative one (IS) appearing after a short delay. In the implicit condition, subjects were not informed about the duration of the delay, disfavoring anticipatory behavior but leaving inhibitory control unaltered. In the explicit condition, delay duration was cued. This should favor anticipatory behavior and perhaps alter inhibitory control. This hypothesis was tested in controls (N = 18) and age-matched iPD patients (N = 20; ON and OFF L-DOPA). We found that the latency distribution of saccades before the IS was bimodal. The 1st mode weakly depended on temporal information and was more prominent in iPD. Saccades in this mode were premature and could result of a lack of inhibition. The 2nd mode covaried with cued duration suggesting that these movements were genuine anticipatory saccades. The explicit condition increased the probability of anticipatory saccades before the IS in controls and iPDON but not iPDOFF patients. Furthermore, in iPD patients the probability of sequences of 1st mode premature responses increased. In conclusion, the triggering of a premature saccade or the initiation of a controlled anticipatory one could be conceptualized as the output of two independent stochastic processes. Altered time perception and increased motor impulsivity could alter the balance between these two processes in favor of the latter in iPD, particularly OFF L-Dopa. |
Dominika Drcażyk; Marcus Missal The oculomotor signature of expected surprise Journal Article In: Scientific Reports, vol. 12, no. 1, pp. 1–14, 2022. @article{Dra̧zyk2022, Expected surprise, defined as the anticipation of uncertainty associated with the occurrence of a future event, plays a major role in gaze shifting and spatial attention. In the present study, we analyzed its impact on oculomotor behavior. We hypothesized that the occurrence of anticipatory saccades could decrease with increasing expected surprise and that its influence on visually-guided responses could be different given the presence of sensory information and perhaps competitive attentional effects. This hypothesis was tested in humans using a saccadic reaction time task in which a cue indicated the future stimulus position. In the ‘no expected surprise' condition, the visual target could appear only at one previously cued location. In other conditions, more likely future positions were cued with increasing expected surprise. Anticipation was more frequent and pupil size was larger in the ‘no expected surprise' condition compared with all other conditions, probably due to increased arousal. The latency of visually-guided saccades increased linearly with the logarithm of surprise (following Hick's law) but their maximum velocity repeated the arousal-related pattern. Therefore, expected surprise affects anticipatory and visually-guided responses differently. Moreover, these observations suggest a causal chain linking surprise, attention and saccades that could be disrupted in attentional or impulse control disorders. |
Matt J. Dunn; J. Margaret Woodhouse Voluntary flutter presenting during ophthalmoscopy: A case report Journal Article In: Case Reports in Ophthalmology, pp. 286–291, 2022. @article{Dunn2022a, Voluntary flutter (sometimes known as “voluntary nystagmus”) is a conjugate saccadic oscillation of the eyes that occurs in some healthy individuals. It has no relation to pathological nystagmus, which can manifest in infancy or become acquired later in life. This report presents an unusual case of voluntary flutter that presented in a 20-year-old male with autism spectrum disorder during ocular examination via direct ophthalmoscopy. Refraction and ocular motor balance were normal, and visual acuity was good in each eye (−0.10 logMAR). During direct ophthalmoscopy, a fine intermittent tremor was initiated. The patient was referred for further assessment, and eye movements were recorded at 1,000 Hz with an EyeLink 1000 eye tracker. Upon request, the patient could manifest voluntary flutter again and sustain the eye movements with effort during convergence. The voluntary flutter consisted of back-to-back saccadic oscillations in a predominantly horizontal direction, with an average frequency of 13 Hz and an amplitude of ∼8°, both reducing over time. We speculate that the discomfort induced by the proximity of the clinician during direct ophthalmoscopy examination may have triggered the eye oscillations. Although the oscillations typically manifest during convergence, atypical forms of voluntary flutter can also occur during divergence. Voluntary flutter can be a useful differential diagnosis in patients with a recently onset apparent “nystagmus,” and no other neurological signs and symptoms. |
Marcel Linka; Maximilian Davide Broda; Tamara Alsheimer; Benjamin Haas; Meike Ramon Characteristic fixation biases in Super-Recognizers Journal Article In: Journal of Vision, vol. 22, no. 8, pp. 1–15, 2022. @article{Linka2022, Neurotypical observers show large and reliable individual differences in gaze behavior along several semantic object dimensions. Individual gaze behavior toward faces has been linked to face identity processing, including that of neurotypical observers. Here, we investigated potential gaze biases in Super-Recognizers (SRs), individuals with exceptional face identity processing skills. Ten SRs, identified with a novel conservative diagnostic framework, and 43 controls freely viewed 700 complex scenes depicting more than 5000 objects. First, we tested whether SRs and controls differ in fixation biases along four semantic dimensions: faces, text, objects being touched, and bodies. Second, we tested potential group differences in fixation biases toward eyes and mouths. Finally, we tested whether SRs fixate closer to the theoretical optimal fixation point for face identification. SRs showed a stronger gaze bias toward faces and away from text and touched objects, starting from the first fixation onward. Further, SRs spent a significantly smaller proportion of first fixations and dwell time toward faces on mouths but did not differ in dwell time or first fixations devoted to eyes. Face fixation of SRs also fell significantly closer to the theoretical optimal fixation point for identification, just below the eyes. Our findings suggest that reliable superiority for face identity processing is accompanied by early fixation biases toward faces and preferred saccadic landing positions close to the theoretical optimum for face identification.We discuss future directions to investigate the functional basis of individual fixation behavior and face identity processing ability. |
Matteo Lisi; Michael J. Morgan; Joshua A. Solomon Perceptual decisions and oculomotor responses rely on temporally distinct streams of evidence Journal Article In: Communications Biology, vol. 5, pp. 1–8, 2022. @article{Lisi2022, Perceptual decisions often require the integration of noisy sensory evidence over time. This process is formalized with sequential sampling models, where evidence is accumulated up to a decision threshold before a choice is made. Although intuition suggests that decision formation must precede the preparation of a motor response (i.e., the action used to communicate the choice), neurophysiological findings have suggested that these two processes might be one and the same. To test this idea, we developed a reverse-correlation protocol in which the visual stimuli that influence decisions can be distinguished from those guiding motor responses. In three experiments, we found that the temporal weighting function of oculomotor responses did not overlap with the relatively early weighting function of stimulus properties having an impact on decision formation. These results support a timeline in which perceptual decisions are formed, at least in part, prior to the preparation of a motor response. |
Baiwei Liu; Anna C. Nobre; Freek Ede Functional but not obligatory link between microsaccades and neural modulation by covert spatial attention Journal Article In: Nature Communications, vol. 13, pp. 1–10, 2022. @article{Liu2022, Covert spatial attention is associated with spatial modulation of neural activity as well as with directional biases in fixational eye movements known as microsaccades. We studied how these two ‘fingerprints' of attention are interrelated in humans. We investigated spatial modulation of 8-12 Hz EEG alpha activity and microsaccades when attention is directed internally within the spatial layout of visual working memory. Consistent with a common origin, spatial modulations of alpha activity and microsaccades co-vary: alpha lateralisation is stronger in trials with microsaccades toward versus away from the memorised location of the to-be-attended item and occurs earlier in trials with earlier microsaccades toward this item. Critically, however, trials without attention-driven microsaccades nevertheless show clear spatial modulation of alpha activity – comparable to trials with attention-driven microsaccades. Thus, directional biases in microsaccades correlate with neural signatures of spatial attention, but they are not necessary for neural modulation by spatial attention to be manifest. |
Jia Liu; Jinsheng Hu; Qi Li; Xiaoning Zhao; Ying Liu; Shuqing Liu Atypical processing pattern of gaze cues in dynamic situations in autism spectrum disorders Journal Article In: Scientific Reports, vol. 12, pp. 1–11, 2022. @article{Liu2022b, Psychological studies have generally shown that individuals with Autism Spectrum Disorder (ASD) have particularity in the processing of social information by using static or abstract images. Yet, a recent study showed that there was no difference in their use of social or non-social cues in dynamic interactive situations. To establish the cause of the inconsistent results, we added gaze cues in different directions to the chase detection paradigm to explore whether they would affect the performance of participants with ASD. Meanwhile, eye-tracking methodology was used to investigate whether the processing patterns of gaze cues were different between individuals with ASD and TD. In this study, unlike typical controls, participants with ASD showed no detection advantage when the direction of gaze was consistent with the direction of movement (oriented condition). The results suggested that individuals with ASD may utilize an atypical processing pattern, which makes it difficult for them to use social information contained in oriented gaze cues in dynamic interactive situations. |
Vanessa M. Loaiza; Alessandra S. Souza The eyes don't have it: Eye movements are unlikely to reflect refreshing in working memory Journal Article In: PLoS ONE, vol. 17, no. 7, pp. 1–18, 2022. @article{Loaiza2022, There is a growing interest in specifying the mechanisms underlying refreshing, i.e., the use of attention to keep working memory (WM) contents accessible. Here, we examined whether participants' visual fixations during the retention interval of a WM task indicate the current focus of internal attention, thereby serving as an online measure of refreshing. Eye movements were recorded while participants studied and maintained an array of colored dots followed by probed recall of one (Experiments 1A and 1B) or all (Experiment 2) of the memoranda via a continuous color wheel. Experiments 1A and 2 entailed an unfilled retention interval in which refreshing is assumed to occur spontaneously, and Experiment 1B entailed a retention interval embedded with cues prompting the sequential refreshment of a subset of the memoranda. During the retention interval, fixations revisited the locations occupied by the memoranda, consistent with a looking-at-nothing phenomenon in WM, but the pattern was only evident when placeholders were onscreen in Experiment 2, indicating that most of these fixations may largely reflect random gaze. Furthermore, spontaneous fixations did not predict recall precision (Experiments 1A and 2), even when ensuring that they did not reflect random gaze (Experiment 2). In Experiment 1B, refreshing cues increased fixations to the eventually tested target and predicted better recall precision, which interacted with an overall benefit of target fixations, such that the benefit of fixations decreased as the number of refreshing cues increased. Thus, fixations under spontaneous conditions had no credible effect on recall precision, whereas the beneficial effect of fixations under instructed refreshing conditions may indicate situations in which cues were disregarded. Consequently, we conclude that eye movements do not seem suitable as an online measure of refreshing. |
Dillon Lohr; Henry Griffith; Oleg V. Komogortsev Eye know you: Metric learning for end-to-end biometric authentication using eye movements from a longitudinal dataset Journal Article In: IEEE Transactions on Biometrics, Behavior, and Identity Science, vol. 4, no. 2, pp. 276–288, 2022. @article{Lohr2022, The permanence of eye movements as a biometric modality remains largely unexplored in the literature. The present study addresses this limitation by evaluating a novel exponentially-dilated convolutional neural network for eye movement authentication using a recently proposed longitudinal dataset known as GazeBase. The network is trained using multi-similarity loss, which directly enables the enrollment and authentication of out-of-sample users. In addition, this study includes an exhaustive analysis of the effects of evaluating on various tasks and downsampling from 1000 Hz to several lower sampling rates. Our results reveal that reasonable authentication accuracy may be achieved even during both a low-cognitive-load task and at low sampling rates. Moreover, we find that eye movements are quite resilient against template aging after as long as 3 years. |
Floor C. Loonstra; Lodewijk R. J. De Ruiter; Djoeke Doesburg; Ka-Hoo Lam; Zoe Y. G. J. Van Lierop; Bastiaan Moraal; Eva M. M. Strijbis; Joep Killestein; Bernard M. J. Uitdehaag Project Y: The search for clues explaining phenotype variability in MS Journal Article In: Multiple Sclerosis and Related Disorders, vol. 57, pp. 1–8, 2022. @article{Loonstra2022, Background: To study phenotypic variability in MS patients, well-defined unbiased cohort studies are necessary. The most common and probably most important confounding factor when studying disease phenotype in MS is age. Objective: To describe study design and subject characteristics of a unique birth cohort (Project Y). The overall aim of Project Y is to identify determinants associated with phenotypic variability in MS, eliminating the possibility of confounding by age. Methods: Project Y is a population-based cross-sectional study of all people with MS born in the Netherlands in 1966. Patients and healthy controls were subjected to comprehensive examinations: functional and static imaging, physical and cognitive measurements, and lifestyle factors early and later in life. In addition body fluids were collected and stored for future biomarker research. Results: 452 eligible MS patients were identified. Between December 2017 and January 2021, 367 MS patients and 125 healthy controls participated. The total number of identified cases results in a current prevalence of at least 189/100.000 for people born in the year 1966 in The Netherlands. Conclusion: Project Y is a unique cohort designed to identify factors associated with phenotypic variability in MS patients without the confounding effects of age. This first description of the Project Y cohort indicates that the prevalence of MS in the Netherlands might be higher than previously presumed. Various studies using Project Y data are ongoing and results will be published in upcoming years. |
Kaleb A. Lowe; Wolf Zinke; Joshua D. Cosman; Jeffrey D. Schall Frontal eye fields in macaque monkeys: Prefrontal and premotor contributions to visually guided saccades Journal Article In: Cerebral Cortex, vol. 32, pp. 5083–5107, 2022. @article{Lowe2022, Neuronal spiking was sampled from the frontal eye field (FEF) and from the rostral part of area 6 that reaches to the superior limb of the arcuate sulcus, dorsal to the arcuate spur when present (F2vr) in macaque monkeys performing memory-guided saccades and visually guided saccades for visual search. Neuronal spiking modulation in F2vr resembled that in FEF in many but not all respects. A new consensus clustering algorithm of neuronal modulation patterns revealed that F2vr and FEF contain a greater variety of modulation patterns than previously reported. The areas differ in the proportions of visuomotor neuron types, the proportions of neurons discriminating a target from distractors during visual search, and the consistency of modulation patterns across tasks. However, between F2vr and FEF we found no difference in the magnitude of delay period activity, the timing of the peak discharge rate relative to saccades, or the time of search target selection. The observed similarities and differences between the 2 cortical regions contribute to other work establishing the organization of eye fields in the frontal lobe and may help explain why FEF in monkeys is identified within granular prefrontal area 8 but in humans is identified within agranular premotor area 6. |
Yun-Jhen Lu; I. -Chun Kuo; Ming-Chou Ho The effects of emotional films and subtitle types on eye movement patterns Journal Article In: Acta Psychologica, vol. 230, no. 110, pp. 1–7, 2022. @article{Lu2022, Background: In Taiwan, the use of subtitle is common in TV programs and movies. However, studies on subtitles mostly focus on foreign language learning and film subtitle translation. Few studies address how subtitle types and emotion-laden films affect the viewers' eye movement patterns. Purpose: We aim to examine how the emotion type of film (happy, sad, angry, fear, or neutral) and subtitle type (meaningful subtitle, no subtitle, or meaningless subtitle) affect the dwell times and fixation counts in the subtitle area. Methods: This study is a 5 (emotion type of film) × 3 (subtitle type) between-participants design. There were 15 participants per condition, resulting in a total of 225 participants. After watching a film, participants filled out a self-reported questionnaire regarding this film. Results: The subtitled films have more fixation counts and dwell time for the meaningful subtitle compared to meaningless subtitle and no subtitle. The dwell time was longer on the subtitle area for the sad film than the neutral and happy films. Also, the dwell time was longer on the subtitle area for the fear film than the happy film. There were more fixation counts on the subtitle area for the sad film than the angry and happy films. Conclusions: The subtitle meaning is critical in directing overt attention. Also, overt attention directed to the subtitle area is affected by the different emotion types of films. |
Malte Lüken; Šimon Kucharský; Ingmar Visser Characterising eye movement events with an unsupervised hidden markov model Journal Article In: Journal of Eye Movement Research, vol. 15, no. 1, pp. 1–29, 2022. @article{Lueken2022, Eye-tracking allows researchers to infer cognitive processes from eye movements that are classified into distinct events. Parsing the events is typically done by algorithms. Here we aim at developing an unsupervised, generative model that can be fitted to eye-movement data using maximum likelihood estimation. This approach allows hypothesis testing about fitted models, next to being a method for classification. We developed gazeHMM, an algorithm that uses a hidden Markov model as a generative model, has few critical parameters to be set by users, and does not require human coded data as input. The algorithm classifies gaze data into fixations, saccades, and optionally postsaccadic oscillations and smooth pursuits. We evaluated gazeHMM's performance in a simulation study, showing that it successfully recovered hidden Markov model parameters and hidden states. Parameters were less well recovered when we included a smooth pursuit state and/or added even small noise to simulated data. We applied generative models with different numbers of events to benchmark data. Comparing them indicated that hidden Markov models with more events than expected had most likely generated the data. We also applied the full algorithm to benchmark data and assessed its similarity to human coding and other algorithms. For static stimuli, gazeHMM showed high similarity and outperformed other algorithms in this regard. For dynamic stimuli, gazeHMM tended to rapidly switch between fixations and smooth pursuits but still displayed higher similarity than most other algorithms. Concluding that gazeHMM can be used in practice, we recommend parsing smooth pursuits only for exploratory purposes. Future hidden Markov model algorithms could use covariates to better capture eye movement processes and explicitly model event durations to classify smooth pursuits more accurately. |
Xiaoxiao Luo; Jiayan Gu; Yueyuan Zheng; Xiaolin Zhou Making a saccade enhances Stroop and Simon conflict control Journal Article In: Attention, Perception, and Psychophysics, vol. 84, no. 3, pp. 795–814, 2022. @article{Luo2022, Cognitive control is an important ability instantiated in many situations such as conflict control (e.g., Stroop/Simon task) and the control of eye movements (e.g., saccades). However, it is unclear whether eye movement control shares a common cognitive control system with the conflict control. In Experiment 1, we asked participants to make a prosaccade or antisaccade and then to identify the color of a lateralized color word (i.e., a Stroop–Simon stimulus). The stimulus onset asynchrony (SOA) between the saccadic cue and the Stroop–Simon stimulus was manipulated to be either short (200 ms) or long (600 ms). Results showed that the Stroop effect at the response level and the (negative) Simon effect were smaller when the SOA was short than long, demonstrating a decline of response control over time after making a saccade. Moreover, this temporal change of the Simon effect was more pronounced in the antisaccade session than in the prosaccade session. Furthermore, individuals who had better performance in the antisaccade task performed better in the response control of Stroop interference. When the saccade task was removed in Experiment 2, the temporal declines of the response control observed in Experiment 1 were absent. Experiment 3 replicated the key results of Experiment 1 by replacing the Stroop–Simon task with a typical Simon task and separately testing the typical Stroop and Simon tasks. Overall, our findings suggest that a common system is shared between the control of eye movements and the conflict control at the response level. |
Xinyu Lv; Suping Cheng; Zhiguo Wang; Jianrong Jia The dynamics of microsaccade amplitude reflect shifting of covert attention Journal Article In: Consciousness and Cognition, vol. 101, pp. 1–10, 2022. @article{Lv2022, Attention flexibly shifts between spatial locations to accommodate task demands. The present study examined if the dynamics of attentional shifting are seen in microsaccades whose direction has been shown to accompany the shifts of covert attention. In a spatial cueing task, the cue predicted the target location on 100%, 75%, or 50% of the trials. The results revealed that microsaccade rate and amplitude were both reduced following cue onset and then rebounded. Both microsaccade rate and amplitude were biased towards the opposite direction of the cue and then returned to the cued direction. Importantly, the cue validity modulated the temporal profile of microsaccade amplitude but had little impact on the temporal profile of microsaccade rate. In line with this, the cueing effect measured with target response accuracy was correlated with the microsaccade amplitude only. These results indicate that the temporal dynamics of microsaccade amplitude reflect shifting of covert attention. |
Wenbo Ma; Min Li; Junru Wu; Zhihao Zhang; Fangfang Jia; Mingsha Zhang; Hagai Bergman; Xuemei Li; Zhipei Ling; Xin Xu Multiple step saccades in simply reactive saccades could serve as a complementary biomarker for the early diagnosis of Parkinson's disease Journal Article In: Frontiers in Aging Neuroscience, vol. 14, pp. 1–14, 2022. @article{Ma2022a, Objective: It has been argued that the incidence of multiple step saccades (MSS) in voluntary saccades could serve as a complementary biomarker for diagnosing Parkinson's disease (PD). However, voluntary saccadic tasks are usually difficult for elderly subjects to complete. Therefore, task difficulties restrict the application of MSS measurements for the diagnosis of PD. The primary objective of the present study is to assess whether the incidence of MSS in simply reactive saccades could serve as a complementary biomarker for the early diagnosis of PD. Materials and methods: There were four groups of human subjects: PD patients, mild cognitive impairment (MCI) patients, elderly healthy controls (EHCs), and young healthy controls (YHCs). There were four monkeys with subclinical hemi-PD induced by injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) through the unilateral internal carotid artery and three healthy control monkeys. The behavioral task was a visually guided reactive saccade. Results: In a human study, the incidence of MSS was significantly higher in PD than in YHC, EHC, and MCI groups. In addition, receiver operating characteristic (ROC) analysis could discriminate PD from the EHC and MCI groups, with areas under the ROC curve (AUCs) of 0.76 and 0.69, respectively. In a monkey study, while typical PD symptoms were absent, subclinical hemi-PD monkeys showed a significantly higher incidence of MSS than control monkeys when the dose of MPTP was greater than 0.4 mg/kg. Conclusion: The incidence of MSS in simply reactive saccades could be a complementary biomarker for the early diagnosis of PD. |
Wenbo Ma; Mingsha Zhang The effects of age and sex on the incidence of multiple step saccades and corrective saccades Journal Article In: Frontiers in Aging Neuroscience, vol. 14, pp. 1–11, 2022. @article{Ma2022b, Objective: Although multiple step saccades (MSS) is occasionally observed in healthy subjects, it is more pronounced in patients with aging-related neurodegenerative diseases, particularly Parkinson's disease (PD). Thus, MSS has been treated as a complementary biomarker for diagnosing PD. Despite the aforementioned knowledge, several questions remain unexplored: (1) How does aging affect MSS? (2) Is there a sex difference in MSS? (3) Are there differences in MSS between vertical and horizontal saccades? (4) Are MSS and corrective saccade (CS) the same behavior? (5) How do age and sex affect CS? The objectives of the present study are to address these questions. Method: Four hundred eighty healthy participants were recruited to perform a visually guided reactive saccade task. Participants were divided into six groups according to their ages. Each group consisted of 40 male and 40 female participants. Eye movements were recorded with infrared eye trackers. Results: The incidence of MSS increased as a function of age, whereas the incidence of CS first increased with age 20–49 and then decreased with age 50–79. The incidences of both MSS and CS did not show sex differences. The incidence of MSS in vertical saccades was significantly higher than that in horizontal saccades, and their difference increased with increasing age, whereas the incidence of CS showed a reversed pattern. Conclusion: Age and saccadic direction affect the occurrences of MSS and CS differently, indicating that MSS and CS are different saccadic behaviors. In addition, measuring saccades could reliably reflect the function of human's brain which is affected by aging. |
Walker S. McKinney; Shannon E. Kelly; Kathryn E. Unruh; Robin L. Shafer; John A. Sweeney; Martin Styner; Matthew W. Mosconi Cerebellar volumes and sensorimotor behavior in autism spectrum disorder Journal Article In: Frontiers in Integrative Neuroscience, vol. 16, pp. 1–16, 2022. @article{McKinney2022, Background: Sensorimotor issues are common in autism spectrum disorder (ASD), though their neural bases are not well understood. The cerebellum is vital to sensorimotor control and reduced cerebellar volumes in ASD have been documented. Our study examined the extent to which cerebellar volumes are associated with multiple sensorimotor behaviors in ASD. Materials and Methods: Fifty-eight participants with ASD and 34 typically developing (TD) controls (8–30 years) completed a structural MRI scan and precision grip testing, oculomotor testing, or both. Force variability during precision gripping as well as absolute error and trial-to-trial error variability of visually guided saccades were examined. Volumes of cerebellar lobules, vermis, and white matter were quantified. The relationships between each cerebellar region of interest (ROI) and force variability, saccade error, and saccade error variability were examined. Results: Relative to TD controls, individuals with ASD showed increased force variability. Individuals with ASD showed a reduced volume of cerebellar vermis VI-VII relative to TD controls. Relative to TD females, females with ASD showed a reduced volume of bilateral cerebellar Crus II/lobule VIIB. Increased volume of Crus I was associated with increased force variability. Increased volume of vermal lobules VI-VII was associated with reduced saccade error for TD controls but not individuals with ASD. Increased right lobule VIII and cerebellar white matter volumes as well as reduced right lobule VI and right lobule X volumes were associated with greater ASD symptom severity. Reduced volumes of right Crus II/lobule VIIB were associated with greater ASD symptom severity in only males, while reduced volumes of right Crus I were associated with more severe restricted and repetitive behaviors only in females. Conclusion: Our finding that increased force variability in ASD is associated with greater cerebellar Crus I volumes indicates that disruption of sensory feedback processing supported by Crus I may contribute to skeletomotor differences in ASD. Results showing that volumes of vermal lobules VI-VII are associated with saccade precision in TD but not ASD implicates atypical organization of the brain systems supporting oculomotor control in ASD. Associations between volumes of cerebellar subregions and ASD symptom severity suggest cerebellar pathological processes may contribute to multiple developmental challenges in ASD. |
Ómar I. Jóhannesson; Árni Kristjánsson; Jérôme Tagu Contrasting attentional biases in a saccadic choice task Journal Article In: Experimental Brain Research, vol. 240, no. 1, pp. 173–187, 2022. @article{Johannesson2022, To gain insight into how human observers select items in the visual field we pitted two attentional biases against one another in a single free choice design. The first bias is the nasal-temporal asymmetry during free choice tasks, where observers tend to choose targets that appear in their temporal hemifield over targets appearing in their nasal hemifield. The second is the choice bias found in studies of attentional priming. When observers have to select between a stimulus that shares features with a preceding target and a stimulus sharing features with previous distractors, they have a strong tendency to choose the preceding search target and this bias increases the more often the same search is repeated. Our results show that both biases affect saccadic choice, but they also show that the nasal-temporal bias can modulate the strength of the priming effects, but not vice versa. The priming effect was stronger for stimuli appearing in the temporal than in the nasal hemifield, but the nasal-temporal bias was similar for primed and unprimed targets. Additionally, our findings are the first to show how search repetition leads to faster saccades. The observed difference between the effects of the NTA and priming biases may reflect the difference in neural mechanisms thought to be behind these biases and that biases at lower levels may outrank higher-level biases, at least in their effect on visual attention. |
Richard Johnston; Adam C. Snyder; Sanjeev B. Khanna; Deepa Issar; Matthew A. Smith The eyes reflect an internal cognitive state hidden in the activity of the neurons Journal Article In: Cerebral Cortex, vol. 32, pp. 3331–3346, 2022. @article{Johnston2022, Decades of research have shown that global brain states such as arousal can be indexed by measuring the properties of the eyes. The spiking responses of neurons throughout the brain have been associated with the pupil, small fixational saccades, and vigor in eye movements, but it has been difficult to isolate how internal states affect the eyes, and vice versa. While recording from populations of neurons in the visual and prefrontal cortex (PFC), we recently identified a latent dimension of neural activity called “slow drift,” which appears to reflect a shift in a global brain state. Here, we asked if slow drift is correlated with the action of the eyes in distinct behavioral tasks. We recorded from visual cortex (V4) while monkeys performed a change detection task, and PFC, while they performed a memory-guided saccade task. In both tasks, slow drift was associated with the size of the pupil and the microsaccade rate, two external indicators of the internal state of the animal. These results show that metrics related to the action of the eyes are associated with a dominant and task-independent mode of neural activity that can be accessed in the population activity of neurons across the cortex. |
Oren Kadosh; Yoram Bonneh Face familiarity revealed by fixational eye movements and fixation-related potentials in free viewing Journal Article In: Scientific Reports, vol. 12, no. 1, pp. 1–13, 2022. @article{Kadosh2022a, Event-related potentials (ERPs) and the oculomotor inhibition (OMI) in response to visual transients are known to be sensitive to stimulus properties, attention, and expectation. We have recently found that the OMI is also sensitive to face familiarity. In natural vision, stimulation of the visual cortex is generated primarily by saccades, and it has been recently suggested that fixation-related potentials (FRPs) share similar components with the ERPs. Here, we investigated whether FRPs and microsaccade inhibition (OMI) in free viewing are sensitive to face familiarity. Observers freely watched a slideshow of seven unfamiliar and one familiar facial images presented randomly for 4-s periods, with multiple images per identity. We measured the occipital fixation-related N1 relative to the P1 magnitude as well as the associated fixation-triggered OMI. We found that the average N1-P1 was significantly smaller and the OMI was shorter for the familiar face, compared with any of the seven unfamiliar faces. Moreover, the P1 was suppressed across saccades for the familiar but not for the unfamiliar faces. Our results highlight the sensitivity of the occipital FRPs to stimulus properties such as face familiarity and advance our understanding of the integration process across successive saccades in natural vision. |
Oren Kadosh; Yoram S. Bonneh Fixation-related saccadic inhibition in free viewing in response to stimulus saliency Journal Article In: Scientific Reports, vol. 12, pp. 1–12, 2022. @article{Kadosh2022b, Microsaccades that occur during fixation were studied extensively in response to transient stimuli, showing a typical inhibition (Oculomotor Inhibition, OMI), and a later release with a latency that depends on stimulus saliency, attention, and expectations. Here, we investigated the hypothesis that in free viewing every saccade provides a new transient stimulation that should result in a stimulus-dependent OMI like a flashed presentation during fixation. Participants (N = 16) freely inspected static displays of randomly oriented Gabor texture images, with varied contrast and spatial frequency (SF) for periods of 10 s each. Eye tracking recordings were divided into epochs triggered by saccade landing (> 1 dva), and microsaccade latency relative to fixation onset was computed (msRT). We found that the msRT in free viewing was shorter for more salient stimuli (higher contrast or lower SF), as previously found for flashed stimuli. It increased with saccade size and decreased across successive saccades, but only for higher contrast, suggesting contrast-dependent repetition enhancement in free viewing. Our results indicate that visual stimulus-dependent inhibition of microsaccades also applies to free viewing. These findings are in agreement with the similarity found between event-related and fixation-related potentials and open the way for studies combining both approaches to study natural vision. |
Oren Kadosh; Yoram S. Bonneh Involuntary oculomotor inhibition markers of saliency and deviance in response to auditory sequences Journal Article In: Journal of Vision, vol. 22, no. 5, pp. 1–19, 2022. @article{Kadosh2022, Our eyes move constantly but are often inhibited momentarily in response to external stimuli (oculomotor inhibition [OMI]), depending on the stimulus saliency, anticipation, and attention. Previous studies have shown prolonged OMI for auditory oddballs; however, they required counting the oddballs, possibly reflecting voluntary attention. Here, we investigated whether the “passive” OMI response to auditory deviants can provide a quantitative measure of deviance strength (pitch difference) and studied its dependence on the inter-trial interval (ITI). Participants fixated centrally and passively listened to repeated short sequences of pure tones that contained a deviant tone either regularly or with 20% probability (oddballs). In an “active” control experiment, participants counted the deviant or the standard. As in previous studies, the results showed prolonged microsaccade inhibition and increased pupil dilation following the rare deviant tone. Earlier inhibition onset was found in proportion to the pitch deviance (the saliency effect), and a later release was found for oddballs, but only for ITI <2.5 seconds. The active control experiment showed similar results when counting the deviant but longer OMI for the standard when counting it. Taken together, these results suggest that OMI provides involuntary markers of saliency and deviance, which can be obtained without the participant's response. |
Tatiana Karpouzian-Rogers; Rob Hurley; Mustafa Seckin; Stacey Moeller; Nathan Gill; Hui Zhang; Christina Coventry; Matthew Nelson; Sandra Weintraub; Emily Rogalski; M. Marsel Mesulam Eye movements as a measure of word comprehension deficits in primary progressive aphasia Journal Article In: Brain and Language, vol. 232, pp. 1–5, 2022. @article{KarpouzianRogers2022, Introduction: Eye movement studies can uncover subtle aspects of language processing impairment in individuals with primary progressive aphasia (PPA), who may have difficulty understanding words. This study examined eye movement patterns on a word-object matching task in response to varying levels of word-knowledge in PPA. Methods: Participants with semantic and non-semantic PPA completed an object-matching task, where a word was presented and participants then selected the corresponding pictured object from an array. Afterwards, participants defined words for trials to which they incorrectly pointed. Linear mixed-effects analyses examined fixation differences on targets and related and unrelated foils. Results: On incorrectly-pointed trials, participants demonstrated greater fixation duration on related foils, demonstrating intra-category blurring. For words that could not be defined, there was similar fixation duration on related and unrelated foils, demonstrating inter-category semantic blurring. Discussion: This study demonstrated that fixation patterns reflect varying levels of word knowledge in PPA. |
Chaim N. Katz; Andrea G. P. Schjetnan; Kramay Patel; Victoria Barkley; Kari L. Hoffman; Suneil K. Kalia; Katherine D. Duncan; Taufik A. Valiante A corollary discharge mediates saccade-related inhibition of single units in mnemonic structures of the human brain Journal Article In: Current Biology, vol. 32, no. 14, pp. 3082–3094, 2022. @article{Katz2022, Despite the critical link between visual exploration and memory, little is known about how neuronal activity in the human mesial temporal lobe (MTL) is modulated by saccades. Here, we characterize saccade-associated neuronal modulations, unit-by-unit, and contrast them to image onset and to occipital lobe neurons. We reveal evidence for a corollary discharge (CD)-like modulatory signal that accompanies saccades, inhibiting/exciting a unique population of broad-/narrow-spiking units, respectively, before and during saccades and with directional selectivity. These findings comport well with the timing, directional nature, and inhibitory circuit implementation of a CD. Additionally, by linking neuronal activity to event-related potentials (ERPs), which are directionally modulated following saccades, we recontextualize the ERP associated with saccades as a proxy for both the strength of inhibition and saccade direction, providing a mechanistic underpinning for the more commonly recorded saccade-related ERP in the human brain. |
Johannes Kirchner; Tamara Watson; Niko A. Busch; Markus Lappe Timing and kinematics of horizontal within-blink saccades measured by EOG Journal Article In: Journal of Neurophysiology, vol. 127, no. 6, pp. 1655–1668, 2022. @article{Kirchner2022, Eyeblinks are the brief closures of the lid. They are accompanied by a cocontraction of the eye muscles that temporarily pulls the whole eyeball back into its socket. When blinks occur together with execution of saccadic gaze shifts, they interfere with the saccadic premotor circuit, causing these within-blink saccades to be slower than normal and also time-locked to blinks. To analyze the trajectory of within-blink saccades, subtraction of the entangled blink-related eye movement is required. Here we propose a combination of principal component analysis (PCA) and a regression model to subtract the blink-related component of the eye movement based on the respective blink metrics. We used electrooculography (EOG) to measure eye and lid movements of 12 participants who performed saccades with and without blinks. We found that within-blink saccades are slower than without-blink saccades and are tightly coupled in time to blink onset. Surprisingly, in some participants we observed large dynamic overshoots of up to 15° for saccades of only 5° amplitude. The finding of dynamic overshoots was independently confirmed by dynamic MRI for two of the participants and challenges the current view that within-blink saccades are programmed as slow, but straight, saccades. We hypothesize that the dynamic overshoots could be attributed to inhibition of omnipause neurons during blinks, the simultaneous cocontraction of extraocular muscles, or a combination of both. |
Colin C. Korbisch; Daniel R. Apuan; Reza Shadmehr; Alaa A. Ahmed Saccade vigor reflects the rise of decision variables during deliberation Journal Article In: Current Biology, vol. 32, pp. 5374–5381, 2022. @article{Korbisch2022, During deliberation, as we quietly consider our options, the neural activities representing the decision variables that reflect the goodness of each option rise in various regions of the cerebral cortex.1,2,3,4,5,6,7 If the options are depicted visually, we make saccades, focusing gaze on each option. Do the kinematics of these saccades reflect the state of the decision variables? To test this idea, we engaged human participants in a decision-making task in which they considered two effortful options that required walking across various distances and inclines. As they deliberated, they made saccades between the symbolic representations of their options. These deliberation period saccades had no bearing on the effort they would later expend, yet saccade velocities increased gradually and differentially: the rate of rise was faster for saccades toward the option that they later indicated as their choice. Indeed, the rate of rise encoded the difference in the subjective value of the two options. Importantly, the participants did not reveal their choice at the conclusion of deliberation, but rather waited during a delay period, and finally expressed their choice by making another saccade. Remarkably, vigor for this saccade dropped to baseline and no longer encoded subjective value. Thus, saccade vigor appeared to provide a real-time window to the otherwise hidden process of option evaluation during deliberation. |
Lisa M. Kroell; Martin Rolfs Foveal vision anticipates defining features of eye movement targets Journal Article In: eLife, vol. 11, pp. 1–38, 2022. @article{Kroell2022, High-acuity foveal processing is vital for human vision. Nonetheless, little is known about how the preparation of large-scale rapid eye movements (saccades) affects visual sensitivity in the center of gaze. Based on findings from passive fixation tasks, we hypothesized that during saccade preparation, foveal processing anticipates soon-to-be fixated visual features. Using a dynamic large-field noise paradigm, we indeed demonstrate that defining features of an eye movement target are enhanced in the pre-saccadic center of gaze. Enhancement manifested as higher Hit Rates for foveal probes with target-congruent orientation and a sensitization to incidental, target-like orientation information in foveally presented noise. Enhancement was spatially confined to the center of gaze and its immediate vicinity, even after parafoveal task performance had been raised to a foveal level. Moreover, foveal enhancement during saccade preparation was more pronounced and developed faster than enhancement during passive fixation. Based on these findings, we suggest a crucial contribution of foveal processing to trans-saccadic visual continuity: Foveal processing of saccade targets commences before the movement is executed and thereby enables a seamless transition once the center of gaze reaches the target. |
Sunwoo Kwon; Berkeley K. Fahrenthold; Matthew R. Cavanaugh; Krystel R. Huxlin; Jude F. Mitchell Perceptual restoration fails to recover unconscious processing for smooth eye movements after occipital stroke Journal Article In: eLife, vol. 11, pp. 1–23, 2022. @article{Kwon2022, The visual pathways that guide actions do not necessarily mediate conscious perception. Patients with primary visual cortex (V1) damage lose conscious perception but often retain unconscious abilities (e.g. blindsight). Here, we asked if saccade accuracy and post-saccadic following responses (PFRs) that automatically track target motion upon saccade landing are retained when conscious perception is lost. We contrasted these behaviors in the blind and intact fields of 11 chronic V1-stroke patients, and in 8 visually intact controls. Saccade accuracy was relatively normal in all cases. Stroke patients also had normal PFR in their intact fields, but no PFR in their blind fields. Thus, V1 damage did not spare the unconscious visual processing necessary for automatic, postsaccadic smooth eye movements. Importantly, visual training that recovered motion perception in the blind field did not restore the PFR, suggesting a clear dissociation between pathways mediating perceptual restoration and automatic actions in the V1-damaged visual system. |
Natalia Ladyka-Wojcik; Zhong-Xu Liu; Jennifer D. Ryan Unrestricted eye movements strengthen effective connectivity from hippocampal to oculomotor regions during scene construction Journal Article In: NeuroImage, vol. 260, pp. 1–15, 2022. @article{LadykaWojcik2022, Scene construction is a key component of memory recall, navigation, and future imagining, and relies on the medial temporal lobes (MTL). A parallel body of work suggests that eye movements may enable the imagination and construction of scenes, even in the absence of external visual input. There are vast structural and functional connections between regions of the MTL and those of the oculomotor system. However, the directionality of connections between the MTL and oculomotor control regions, and how it relates to scene construction, has not been studied directly in human neuroimaging. In the current study, we used dynamic causal modeling (DCM) to interrogate effective connectivity between the MTL and oculomotor regions using a scene construction task in which participants' eye movements were either restricted (fixed-viewing) or unrestricted (free-viewing). By omitting external visual input, and by contrasting free- versus fixed- viewing, the directionality of neural connectivity during scene construction could be determined. As opposed to when eye movements were restricted, allowing free-viewing during construction of scenes strengthened top-down connections from the MTL to the frontal eye fields, and to lower-level cortical visual processing regions, suppressed bottom-up connections along the visual stream, and enhanced vividness of the constructed scenes. Taken together, these findings provide novel, non-invasive evidence for the underlying, directional, connectivity between the MTL memory system and oculomotor system associated with constructing vivid mental representations of scenes. |
Christian Wolf; Artem V. Belopolsky; Markus Lappe Current foveal inspection and previous peripheral preview influence subsequent eye movement decisions Journal Article In: iScience, vol. 25, no. 9, pp. 1–16, 2022. @article{Wolf2022, Humans visually inspect the world with their fovea and select new parts of the scene using saccadic eye movements. Foveal inspection and the decision of where and when to look next proceed simultaneously, but there is mixed evidence concerning their independence. Here, we tested their interdependence using drift-diffusion modeling. Participants first made a saccade to a predetermined inspection target and subsequently decided between two selection targets. We found that the inspected target's meaningfulness and the opportunity to preview it peripherally affects fixation durations and the upcoming saccadic selection. Drift-diffusion modeling showed that meaningfulness and the absence of peripheral preview can both delay the subsequent saccadic decision process and affect the rate at which peripheral information is accumulated. Our results thus show that foveal inspection and peripheral selection are dependent on each other and that peripheral information can be maintained across the saccade to influence subsequent eye movement decisions. |
Xiuyun Wu; Miriam Spering Tracking and perceiving diverse motion signals: Directional biases in human smooth pursuit and perception Journal Article In: PLoS ONE, vol. 17, no. 9, pp. 1–22, 2022. @article{Wu2022a, Human smooth pursuit eye movements and motion perception behave similarly when observers track and judge the motion of simple objects, such as dots. But moving objects in our natural environment are complex and contain internal motion. We ask how pursuit and perception integrate the motion of objects with motion that is internal to the object. Observers (n = 20) tracked a moving random-dot kinematogram with their eyes and reported the object's perceived direction. Objects moved horizontally with vertical shifts of 0, ±3, ±6, or ±9° and contained internal dots that were static or moved ±90° up/down. Results show that whereas pursuit direction was consistently biased in the direction of the internal dot motion, perceptual biases differed between observers. Interestingly, the perceptual bias was related to the magnitude of the pursuit bias (r = 0.75): perceptual and pursuit biases were directionally aligned in observers that showed a large pursuit bias, but went in opposite directions in observers with a smaller pursuit bias. Dissociations between perception and pursuit might reflect different functional demands of the two systems. Pursuit integrates all available motion signals in order to maximize the ability to monitor and collect information from the whole scene. Perception needs to recognize and classify visual information, thus segregating the target from its context. Ambiguity in whether internal motion is part of the scene or contributes to object motion might have resulted in individual differences in perception. The perception-pursuit correlation suggests shared early-stage motion processing or perception- pursuit interactions. |
Jin Xie; Ting Yan; Jie Zhang; Zhengyu Ma; Huihui Zhou Modulation of neuronal activity and saccades at theta rhythm during visual search in non-human primates Journal Article In: Neuroscience Bulletin, vol. 38, no. 10, pp. 1183–1198, 2022. @article{Xie2022, 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. |
Jinghui Yin; Jiande Sun; Jing Li; Ke Liu An effective gaze-based authentication method with the spatiotemporal feature of eye movement Journal Article In: Sensors, vol. 22, no. 3002, pp. 1–18, 2022. @article{Yin2022, Eye movement has become a new behavioral feature for biometric authentication. In the eye movement-based authentication methods that use temporal features and artificial design features, the required duration of eye movement recordings are too long to be applied. Therefore, this study aims at using eye movement recordings with shorter duration to realize authentication. And we give out a reasonable eye movement recording duration that should be less than 12 s, referring to the changing pattern of the deviation degree between the gaze point and the stimulus point on the screen. In this study, the temporal motion features of the gaze points and the spatial distribution features of the saccade are using to represent the personal identity. Two datasets are constructed for the experiments, including 5 s and 12 s of eye movement recordings. On the datasets constructed in this paper, the open-set authentication results show that the Equal Error Rate of our proposed methods can reach 10.62% when recording duration is 12 s and 12.48% when recording duration is 5 s. The closed-set authentication results show that the Equal Error Rate of our proposed methods can reach 5.25% when recording duration is 12 s and 7.82% when recording duration is 5 s. It demonstrates that the proposed method provides a reference for the eye movements data-based identity authentication. |
Gongchen Yu; James P. Herman; Leor N. Katz; Richard J. Krauzlis Microsaccades as a marker not a cause for attention-related modulation Journal Article In: eLife, vol. 11, pp. 1–14, 2022. @article{Yu2022, Recent evidence suggests that microsaccades are causally linked to the attentionrelated modulation of neurons—specifically, that microsaccades toward the attended location are required for the subsequent changes in firing rate. These findings have raised questions about whether attention-related modulation is due to different states of attention as traditionally assumed or might instead be a secondary effect of microsaccades. Here, in two rhesus macaques, we tested the relationship between microsaccades and attention-related modulation in the superior colliculus (SC), a brain structure crucial for allocating attention. We found that attention-related modulation emerged even in the absence of microsaccades, was already present prior to microsaccades toward the cued stimulus, and persisted through the suppression of activity that accompanied all microsaccades. Nonetheless, consistent with previous findings, we also found significant attention-related modulation when microsaccades were directed toward, rather than away from, the cued location. Thus, despite the clear links between microsaccades and attention, microsaccades are not necessary for attention-related modulation, at least not in the SC. They do, however, provide an additional marker for the state of attention, especially at times when attention is shifting from one location to another. |
Haojue Yu; Foroogh Shamsi; MiYoung Kwon Altered eye movements during reading under degraded viewing conditions: Background luminance, text blur, and text contrast Journal Article In: Journal of Vision, vol. 22, no. 10, pp. 1–20, 2022. @article{Yu2022a, Degraded viewing conditions caused by either natural environments or visual disorders lead to slow reading. Here, we systematically investigated how eye movement patterns during reading are affected by degraded viewing conditions in terms of spatial resolution, contrast, and background luminance. Using a high-speed eye tracker, binocular eye movements were obtained from 14 young normally sighted adults. Images of text passages were manipulated with varying degrees of background luminance (1.3–265 cd/m2), text blur (severe blur to no blur), or text contrast (2.6%–100%). We analyzed changes in key eye movement features, such as saccades, microsaccades, regressive saccades, fixations, and return-sweeps across different viewing conditions. No significant changes were observed for the range of tested background luminance values. However, with increasing text blur and decreasing text contrast, we observed a significant decrease in saccade amplitude and velocity, as well as a significant increase in fixation duration, number of fixations, proportion of regressive saccades, microsaccade rate, and duration of return-sweeps. Among all, saccade amplitude, fixation duration, and proportion of regressive saccades turned out to be the most significant contributors to reading speed, together accounting for 90% of variance in reading speed. Our results together showed that, when presented with degraded viewing conditions, the patterns of eye movements during reading were altered accordingly. These findings may suggest that the seemingly deviated eye movements observed in individuals with visual impairments may be in part resulting from active and optimal information acquisition strategies operated when visual sensory input becomes substantially deprived. |
Dan Zhang; Qian Guo; Lihua Xu; Xu Liu; Tian Hong Zhang; Xiaohua Liu; Haiying Chen; Guanjun Li; Jijun Wang The impact of COVID-19 pandemic on individuals at clinical high-risk for psychosis: Evidence from eye-tracking measures Journal Article In: Progress in Neuro-Psychopharmacology and Biological Psychiatry, vol. 118, pp. 1–8, 2022. @article{Zhang2022b, Emerging evidence suggested that people with severe mental disorders were more vulnerable to the negative effects of the COVID-19 pandemic. However, few researches investigated the influence of global pandemics on people at clinical high risk (CHR) for psychosis. This study aimed to investigate the impact of the COVID-19 pandemic on clinical symptoms, psychological distress, and eye-tracking characteristics in CHR individuals and healthy participants. Forty-nine CHR individuals and 50 healthy controls (HC) were assessed by PTSD Checklist for DSM-5 (PCL-5), Perceived Stress Scale, 10-item version (PSS-10), and Coronavirus Impact Scale (CIS). Eye movement performances were measured by the tests of fixation stability, free-viewing, and anti-saccade. According to the mean score of CIS, participants were stratified into high-impact (n = 35) and low-impact (n = 64) subgroups. Compared with the HC group, CHR participants reported significantly higher levels of post-traumatic symptoms caused by the COVID-19 pandemic and showed abnormalities in most of the eye movement indexes. Among the altered indexes, the saccade amplitude of fixation stability test (far distractor), the scan path length of free-viewing test, and the accuracy of anti-saccade test were negatively affected by the severity of impact level in the CHR group. Moreover, the altered eye movement indexes were significantly associated with the total scores of CIS, PCL-5, and subscales of the Scale of Prodromal Syndromes (SOPS) among CHR individuals. Overall, our findings suggested the negative impact of the COVID-19 pandemic on the eye movement characteristics of CHR individuals. The present study provides valuable information on physiological distress related to the COVID-19 pandemic and sensitive neuropsychological biomarkers that interacted with social and environment stress in the CHR population. |
Dan Zhang; Xu Liu; Lihua Xu; Yu Li; Yangyang Xu; Mengqing Xia; Zhenying Qian; Yingying Tang; Zhi Liu; Tao Chen; HaiChun Liu; TianHong Zhang; Jijun Wang Effective differentiation between depressed patients and controls using discriminative eye movement features Journal Article In: Journal of Affective Disorders, vol. 307, pp. 237–243, 2022. @article{Zhang2022c, Background: Depression is a common debilitating mental disorder caused by various factors. Identifying and diagnosing depression are challenging because the clinical evaluation of depression is mainly subjective, lacking objective and quantitative indicators. The present study investigated the value and significance of eye movement measurements in distinguishing depressed patients from controls. Methods: Ninety-five depressed patients and sixty-nine healthy controls performed three eye movement tests, including fixation stability, free-viewing, and anti-saccade tests, and eleven eye movement indexes were obtained from these tests. The independent t-test was adopted for group comparisons, and multiple logistic regression analysis was employed to identify diagnostic biomarkers. Support vector machine (SVM), quadratic discriminant analysis (QDA), and Bayesian (BYS) algorithms were applied to build the classification models. Results: Depressed patients exhibited eye movement anomalies, characterized by increased saccade amplitude in the fixation stability test; diminished saccade velocity in the anti-saccade test; and reduced saccade amplitude, shorter scan path length, lower saccade velocity, decreased dynamic range of pupil size, and lower pupil size ratio in the free-viewing test. Four features mentioned above entered the logistic regression equation. The classification accuracies of SVM, QDA, and BYS models reached 86.0%, 81.1%, and 83.5%, respectively. Conclusions: Depressed patients exhibited abnormalities across multiple tests of eye movements, assisting in differentiating depressed patients from healthy controls in a cost-effective and non-invasive manner. |
Mengmi Zhang; Marcelo Armendariz; Will Xiao; Olivia Rose; Katarina Bendtz; Margaret Livingstone; Carlos Ponce; Gabriel Kreiman Look twice: A generalist computational model predicts return fixations across tasks and species Journal Article In: PLoS Computational Biology, vol. 18, no. 11, pp. 1–38, 2022. @article{Zhang2022i, Primates constantly explore their surroundings via saccadic eye movements that bring different parts of an image into high resolution. In addition to exploring new regions in the visual field, primates also make frequent return fixations, revisiting previously foveated locations. We systematically studied a total of 44,328 return fixations out of 217,440 fixations. Return fixations were ubiquitous across different behavioral tasks, in monkeys and humans, both when subjects viewed static images and when subjects performed natural behaviors. Return fixations locations were consistent across subjects, tended to occur within short temporal offsets, and typically followed a 180-degree turn in saccadic direction. To understand the origin of return fixations, we propose a proof-of-principle, biologically-inspired and image-computable neural network model. The model combines five key modules: an image feature extractor, bottom-up saliency cues, task-relevant visual features, finite inhibition-of-return, and saccade size constraints. Even though there are no free parameters that are fine-tuned for each specific task, species, or condition, the model produces fixation sequences resembling the universal properties of return fixations. These results provide initial steps towards a mechanistic understanding of the trade-off between rapid foveal recognition and the need to scrutinize previous fixation locations. |
Eckart Zimmermann Mislocalization in saccadic suppression of displacement Journal Article In: Vision Research, vol. 196, pp. 1–6, 2022. @article{Zimmermann2022, Visual stability across saccades requires us to discriminate self-generated motion by eye movements from motion occurring in the external world. In the laboratory visual stability is often studied by asking observers to discriminate the direction of trans-saccadic target displacements. It is a well established finding that in this paradigm performance is usually very poor. If observers are insensitive to the intra-saccadic motion and see the pre- and the post-saccadic target in one location, one of both targets should be reported as shifted when observers would localize them. Here, I asked participants to perform a saccade to a target. During saccade execution the target was displaced either in backward or forward direction. After finishing the saccade, subjects had to report the position of either the pre-or the post-saccadic target. I found that subjects mislocalized the pre-saccadic target to the physical position of the post-saccadic target. This mislocalization occurred only after backward but not after forward displacements. |
Trevor Meyer; Laureano Moro-Velazquez; Seneca Motley; Ankur Butala; Ashley Paul; Quincy M. Samus; Pedro Irazoqui; Najim Dehak; Esther S. Oh Automatic extraction of oculographic signals as digital biomarkers for Alzheimer's Disease Journal Article In: Alzheimer's Association International Conference, vol. 18, pp. 1–4, 2022. @article{Meyer2022, Background: Similar to other neurological diseases, subtle early neurological changes that occur in Alzheimer's Disease (AD) are difficult to quantify and track objectively. One relevant bio-signal is eyemovement, as it presents a unique window into cognitive processes as a direct measure of real-time inputs to the brain. Eye-tracking allows us to estimate timestamped activity of neural function and begin to infer and quantify atten- tion, reprocessing (eg. word revisits), andmany other aspects relevant to assessing AD. The goal of this study was to investigate the saccadic movements and trial progress during administration of the Stroop test in AD compared to normal controls. Method: 5 AD subjects and 12 age-matched cognitively normal controls were recruited from the Johns Hopkins Memory and Alzheimer's Treatment Center and the Movement Disorders Clinic at the Johns Hopkins University School of Medicine. An Eyelink Portable Duo in head-free-to-move mode was used to track eye move- ments. Movement of the eyes were analyzed by automatically segmenting saccade movements throughout a trial. We then analyzed the eye movements in the context of cognitive performance, by identifying when subjects progress to each word in the Stroop test. We compared the performance of each group using a Wilcoxon RankSum test with the SciPy package using Python. Result: |
K. A. Mitchnick; Z. Ahmad; S. D. Mitchnick; J. D. Ryan; R. S. Rosenbaum; E. Freud Damage to the human dentate gyrus impairs the perceptual discrimination of complex, novel objects Journal Article In: Neuropsychologia, vol. 172, pp. 1–12, 2022. @article{Mitchnick2022, The hippocampus (HPC), and the dentate gyrus (DG) subregion in particular, is purported to be a pattern separator, orthogonally representing similar information so that distinct memories may be formed. The HPC may also be involved in complex perceptual discrimination. It is unclear if this role is limited to spatial/scene stimuli or extends to the discrimination of objects. Also unclear is whether the DG itself contributes to pattern separation beyond memory. BL, an individual with bilateral DG lesions, was previously shown to have poor discrimination of similar, everyday objects in memory. Here, we demonstrate that BL's deficit extends to complex perceptual discrimination of novel objects. Specifically, BL was presented with closely matched possible and impossible objects, which give rise to fundamentally different 3D perceptual representations despite being visually similar. BL performed significantly worse than controls when asked to select an odd object (e.g., impossible) amongst three identical counterpart objects (e.g., possible) presented at different rotations. His deficit was also evident in an atypical eye fixation pattern during this task. In contrast, BL's performance was indistinguishable from that of controls on other tasks involving the same objects, indicating that he could visually differentiate the object pairs, that he perceived the objects holistically in 3D, and that he has only a mild weakness in categorizing object possibility. Furthermore, his performance on standardized neuropsychological measures indicated intact mental rotation, visual-spatial attention, and working memory (visual and auditory). Collectively, these results provide evidence that the DG is necessary for complex perceptual discrimination of novel objects, indicating that the DG might function as a generic pattern separator of a wide range of stimuli within high-level perception, and that its role is not limited to memory. |
Miranda J. Munoz; Lisa C. Goelz; Gian D. Pal; Jessica A. Karl; Leo Verhagen Metman; Sepehr Sani; Joshua M. Rosenow; Jody D. Ciolino; Ajay S. Kurani; Daniel M. Corcos; Fabian J. David Increased subthalamic nucleus deep brain stimulation amplitude impairs inhibitory control of eye movements in Parkinson's disease Journal Article In: Neuromodulation: Technology at the Neural Interface, vol. 25, no. 6, pp. 866–876, 2022. @article{Munoz2022a, Background and Objectives: Bilateral subthalamic nucleus deep brain stimulation (STN DBS) in Parkinson's disease (PD) can have detrimental effects on eye movement inhibitory control. To investigate this detrimental effect of bilateral STN DBS, we examined the effects of manipulating STN DBS amplitude on inhibitory control during the antisaccade task. The prosaccade error rate during the antisaccade task, that is, directional errors, was indicative of impaired inhibitory control. We hypothesized that as stimulation amplitude increased, the prosaccade error rate would increase. Materials and Methods: Ten participants with bilateral STN DBS completed the antisaccade task on six different stimulation amplitudes (including zero amplitude) after a 12-hour overnight withdrawal from antiparkinsonian medication. Results: We found that the prosaccade error rate increased as stimulation amplitude increased (p < 0.01). Additionally, prosaccade error rate increased as the modeled volume of tissue activated (VTA) and STN overlap decreased, but this relationship depended on stimulation amplitude (p = 0.04). Conclusions: Our findings suggest that higher stimulation amplitude settings can be modulatory for inhibitory control. Some individual variability in the effect of stimulation amplitude can be explained by active contact location and VTA-STN overlap. Higher stimulation amplitudes are more deleterious if the active contacts fall outside of the STN resulting in a smaller VTA-STN overlap. This is clinically significant as it can inform clinical optimization of STN DBS parameters. Further studies are needed to determine stimulation amplitude effects on other aspects of cognition and whether inhibitory control deficits on the antisaccade task result in a meaningful impact on the quality of life. |
Jordan Murray; Palak Gupta; Cody Dulaney; Kiran Garg; Aasef G. Shaikh; Fatema F. Ghasia Effect of viewing conditions on fixation eye movements and eye alignment in amblyopia Journal Article In: Investigative Ophthalmology & Visual Science, vol. 63, no. 2, pp. 1–16, 2022. @article{Murray2022, PURPOSE. Patients with amblyopia are known to have fixation instability, which arises from alteration of physiologic fixation eye movements (FEMs) and nystagmus. We assessed the effects of monocular, binocular, and dichoptic viewing on FEMs and eye alignment in patients with and without fusion maldevelopment nystagmus (FMN). METHODS. Thirty-four patients with amblyopia and seven healthy controls were recruited for this study. Eye movements were recorded using infrared video-oculography during (1) fellow eye viewing (FEV), (2) amblyopic eye viewing (AEV), (3) both eye viewing (BEV), and (4) dichoptic viewing (DcV) at varying fellow eye (FE) contrasts. The patients were classified per the clinical type of amblyopia and FEM waveforms into those without nystagmus, those with nystagmus with and without FMN. Fixational saccades and intersaccadic drifts, quick and slow phases of nystagmus, and bivariate contour ellipse area were analyzed in the FE and amblyopic eye (AE). RESULTS. We found that FEMs are differentially affected with increased amplitude of quick phases of FMN observed during AEV than BEV and during DcV at lower FE contrasts. Increased fixation instability was seen in anisometropic patients at lower FE contrasts. Incomitance of eye misalignment was seen with the greatest increase during FEV. Strabismic/mixed amblyopia patients without FMN were more likely to demonstrate a fixation switch where the AE attends to the target during DcV than patients with FMN. CONCLUSIONS. Our findings suggest that FEM abnormalities modulate with different viewing conditions as used in various amblyopia therapies. Increased FEM abnormalities could affect the visual function deficits and may have treatment implications. |
Stuart B. Murray; Tomislav D. Zbozinek; Michelle Craske; Reza Tadayonnejad; Michael Strober; Ausaf A. Bari; John P. O'Doherty; Jamie D. Feusner Neural, physiological, and psychological markers of appetitive conditioning in anorexia nervosa: a study protocol Journal Article In: Journal of Eating Disorders, vol. 10, no. 1, pp. 1–11, 2022. @article{Murray2022b, Background: Anorexia nervosa (AN) is a chronic and disabling psychiatric condition characterized by low hedonic drive towards food, and is thought to be inclusive of altered dimensions of reward processing. Whether there exists a fundamental aberrancy in the capacity to acquire and maintain de novo hedonic associations—a critical component of hedonic responding—has never been studied in AN. Methods: This multi-modal study will employ a 2-day Pavlovian appetitive conditioning paradigm to interrogate the (1) acquisition, (2) extinction, (3) spontaneous recovery and (4) reinstatement of appetitive learning in adolescents and young adults with AN. Participants will be 30 currently ill, underweight individuals with AN; 30 weight-restored individuals with AN; and 30 age-matched healthy controls, all aged 12–22 years. All subjects will undergo clinical assessment, followed by the 2-day appetitive conditioning task during which fMRI, pupillometry, heart rate deceleration, and subjective ratings will be acquired. Discussion: This study will be the first to interrogate appetitive conditioning in AN—a disorder characterized by altered hedonic responding to food. Results will help establish objective biomarkers of appetitive conditioning in AN and lay the groundwork for developing novel lines of treatment for AN and other psychiatric disorders involving diminished ability to experience pleasure and reward. Trial registration: Pending. Intended registry: Clinicaltrials.gov. |
Dinavahi V. P. S. Murty; Keerthana Manikandan; Wupadrasta Santosh Kumar; Ranjini Garani Ramesh; Simran Purokayastha; Bhargavi Nagendra; M. L. Abhishek; Aditi Balakrishnan; Mahendra Javali; Naren Prahalada Rao; Supratim Ray Stimulus-induced gamma rhythms are weaker in human elderly with mild cognitive impairment and Alzheimer's disease Journal Article In: Bio-protocol, vol. 12, no. 7, pp. 1–13, 2022. @article{Murty2022, Stimulus-induced narrow-band gamma oscillations (20–70 Hz) are induced in the visual areas of the brain when particular visual stimuli, such as bars, gratings, or full-screen hue, are shown to the subject. Such oscillations are modulated by higher cognitive functions, like attention, and working memory, and have been shown to be abnormal in certain neuropsychiatric disorders, such as schizophrenia, autism, and Alzheimer's disease. However, although electroencephalogram (EEG) remains one of the most non-invasive, inexpensive, and accessible methods to record brain signals, some studies have failed to observe discernable gamma oscillations in human EEG. In this manuscript, we have described in detail a protocol to elicit robust gamma oscillations in human EEG. We believe that our protocol could help in developing non-invasive gamma-based biomarkers in human EEG, for the early detection of neuropsychiatric disorders. |
Krishnaveni Nagarajan; Gang Luo; Monika Narasimhan; PremNandhini Satgunam Children with amblyopia make more saccadic fixations when doing the visual search task Journal Article In: Investigative Ophthalmology & Visual Science, vol. 63, no. 13, pp. 1–7, 2022. @article{Nagarajan2022, Purpose: Individuals with amblyopia are known to have functional vision deficits (e.g., reduced reading speed) in spite of good visual acuity in the nonamblyopic eye. We studied and compared eye movements in children with and without amblyopia to examine how a visual scene is explored during visual search. Methods: Children (six to 16 years of age) in the control group (n = 14) and cases group with anisometropic amblyopia (n = 23) participated in a visual search study, in which they looked for targets in real-world images displayed on a computer monitor. Eyelink 1000 Plus was used to track the eye movements. Three viewing conditions were randomized: dominant/fellow eye, nondominant/amblyopic eye, and binocular viewing. Visual search performance was measured by combining search time and accuracy. Results: As expected, poorer visual search performance was observed in the amblyopic eye when compared to the controls and fellow eye (P < 0.005). However, the reaction time was longer even in binocular and fellow eye viewing conditions than the controls (P < 0.028). Children with amblyopia made more saccades (17 vs. 12 |
Adam J. Naples; Jennifer H. Foss-Feig; Julie M. Wolf; Vinod H. Srihari; James C. McPartland Predictability modulates neural response to eye contact in ASD Journal Article In: Molecular Autism, vol. 13, no. 42, pp. 1–12, 2022. @article{Naples2022, Background: Deficits in establishing and maintaining eye-contact are early and persistent vulnerabilities of autism spectrum disorder (ASD), and the neural bases of these deficits remain elusive. A promising hypothesis is that social features of autism may reflect difficulties in making predictions about the social world under conditions of uncertainty. However, no research in ASD has examined how predictability impacts the neural processing of eye-contact in naturalistic interpersonal interactions. Method: We used eye tracking to facilitate an interactive social simulation wherein onscreen faces would establish eye-contact when the participant looked at them. In Experiment One, receipt of eye-contact was unpredictable; in Experiment Two, receipt of eye-contact was predictable. Neural response to eye-contact was measured via the N170 and P300 event-related potentials (ERPs). Experiment One included 23 ASD and 46 typically developing (TD) adult participants. Experiment Two included 25 ASD and 43 TD adult participants. Results: When receipt of eye-contact was unpredictable, individuals with ASD showed increased N170 and increased, but non-specific, P300 responses. The magnitude of the N170 responses correlated with measures of sensory and anxiety symptomology, such that increased response to eye-contact was associated with increased symptomology. However, when receipt of eye-contact was predictable, individuals with ASD, relative to controls, exhibited slower N170s and no differences in the amplitude of N170 or P300. Limitations: Our ASD sample was composed of adults with IQ > 70 and included only four autistic women. Thus, further research is needed to evaluate how these results generalize across the spectrum of age, sex, and cognitive ability. Additionally, as analyses were exploratory, some findings failed to survive false-discovery rate adjustment. Conclusions: Neural response to eye-contact in ASD ranged from attenuated to hypersensitive depending on the predictability of the social context. These findings suggest that the vulnerabilities in eye-contact during social interactions in ASD may arise from differences in anticipation and expectation of eye-contact in addition to the perception of gaze alone. |
Sergio Navas-León; Milagrosa Sánchez-Martín; Ana Tajadura-Jiménez; Lize De Coster; Mercedes Borda-Más; Luis Morales In: Journal of Eating Disorders, vol. 10, no. 47, pp. 1–8, 2022. @article{NavasLeon2022, Background: Recent research indicates that patients with anorexia (AN) show specific eye movement abnormalities such as shorter prosaccade latencies, more saccade inhibition errors, and increased rate of saccadic intrusions compared to participants without AN. However, it remains unknown whether these abnormal eye movement patterns, which may serve as potential biomarkers and endophenotypes for an early diagnosis and preventive clinical treatments, start to manifest also in people with subclinical eating disorders (ED) symptomatology. Therefore, we propose a protocol for an exploratory experimental study to investigate whether participants with subclinical ED symptomatology and control participants differ in their performance on several eye movement tasks. Methods: The sample will be recruited through convenience sampling. The Eating Disorder Examination Questionnaire will be administered as a screening tool to split the sample into participants with subclinical ED symptomatology and control participants. A fixation task, prosaccade/antisaccade task, and memory-guided task will be administered to both groups. Additionally, we will measure anxiety and premorbid intelligence as confounding variables. Means comparison, exploratory Pearson's correlations and discriminant analysis will be performed. Discussion: This study will be the first to elucidate the presence of specific eye movement abnormalities in participants with subclinical ED symptomatology. The results may open opportunities for developing novel diagnostic tools/therapies being helpful to the EDs research community and allied fields. |
Andrea L. Nelson; Leanne Quigley; Jonathan Carriere; Elizabeth Kalles; Daniel Smilek; Christine Purdon Avoidance of mild threat observed in generalized anxiety disorder (GAD) using eye tracking Journal Article In: Journal of Anxiety Disorders, vol. 88, pp. 1–10, 2022. @article{Nelson2022, Attentional biases towards threat are assumed to be a causal factor in the development of anxiety disorders, including generalized anxiety disorder (GAD). However, findings have been inconsistent, and studies often examine single time-point bias during threat exposure, instead of across time. Attention to threat may shift throughout exposure (e.g., from initial engagement to avoidance), and research suggests that threat intensity and state anxiety influence attentional biases. No studies to our knowledge have examined biases across time and with varying threat intensity and state anxiety. Participants with GAD (n=38) and non-anxious controls (n=25) viewed emotional (high threat, mild threat, and positive) and neutral image pairs under calm and anxious mood states while their eye movements were tracked. Participants showed an initial orientation to emotional images, and, under the anxious mood induction, demonstrated a bias towards threatening images at first fixation and over time. Results suggest it may be normative to attend to threat cues over other stimuli while in an anxious state. Individuals with GAD uniquely showed a bias away from mild (but not high) threat images over time relative to controls. Implications for theories of attentional biases to threat and clinical implications for GAD and anxiety disorders broadly are discussed. |
Suhyun Park; Louis Wiliams; Rebecca Chamberlain Global saccadic eye movements characterise artists' visual ttention while drawing Journal Article In: Empirical Studies of the Arts, vol. 40, no. 2, pp. 228–244, 2022. @article{Park2022a, Previous research has shown that artists employ flexible attentional strategies during offline perceptual tasks. The current study explored visual processing online, by tracking the eye movements of artists and non-artists (n=65) while they produced representational drawings of photographic stimuli. The findings revealed that it is possible to differentiate artists from non-artists on the basis of the relative amount of global-to-local saccadic eye movements they make when looking at the target stimulus while drawing, but not in a preparatory free viewing phase. Results indicated that these differences in eye movements are not specifically related to representational drawing ability, and may be a feature of artistic ability more broadly. This eye movement analysis technique may be used in future research to characterise the dynamics of attentional shifts in eye movements while artists are carrying out a range of artistic tasks. |
Mattia Pietrelli; Jason Samaha; Bradley R. Postle Spectral distribution dynamics across different attentional priority states Journal Article In: Journal of Neuroscience, vol. 42, no. 19, pp. 4026–4041, 2022. @article{Pietrelli2022, Anticipatory covert spatial attention improves performance on tests of visual detection and discrimination, and shifts are accompanied by decreases and increases of a band power at electroencephalography (EEG) electrodes corresponding to the attended and unattended location, respectively. Although the increase at the unattended location is often interpreted as an active mechanism (e.g., inhibiting processing at the unattended location), most experiments cannot rule out the alternative possibility that it is a secondary consequence of selection elsewhere. To adjudicate between these accounts, we designed a Posner- style visual cueing task in which male and female human participants made orientation judgments of targets appearing at one of four locations: up, down, right, or left. Critically, trials were blocked such that within a block the locations along one meridian alternated in status between attended and unattended, and targets never appeared at the other two, making them irrelevant. Analyses of the concurrently measured EEG signal were conducted on “traditional” narrowband a (8–14 Hz), as well as on two components resulting from the decomposition of this signal: “periodic” a;and the slope of the aperiodic 1/f-like component. Although data from right-left blocks replicated the familiar pattern of lateralized asymmetry in narrowband a power, with neither a signal couldwe findevidence for any difference inthe time course at unattended versus irrelevant locations, an outcome consistent with the secondary-consequence interpretation of attention- related dynamics in the a band. Additionally, 1/f slope was shallower at attended and unattended locations, relative to irrelevant, suggesting a tonic adjustment of physiological state. |
Alessandro Piras; Aurelio Trofè; Andrea Meoni; Milena Raffi Influence of radial optic flow stimulation on static postural balance in Parkinson's disease: A preliminary study Journal Article In: Human Movement Science, vol. 81, pp. 1–11, 2022. @article{Piras2022, The role of optic flow in the control of balance in persons with Parkinson's disease (PD) has yet to be studied. Since basal ganglia are understood to have a role in controlling ocular fixation, we have hypothesized that persons with PD would exhibit impaired performance in fixation tasks, i.e., altered postural balance due to the possible relationships between postural disorders and visual perception. The aim of this preliminary study was to investigate how people affected by PD respond to optic flow stimuli presented with radial expanding motion, with the intention to see how the stimulation of different retinal portions may alter the static postural sway. We measured the body sway using center of pressure parameters recorded from two force platforms during the presentation of the foveal, peripheral and full field radial optic flow stimuli. Persons with PD had different visual responses in terms of fixational eye movement characteristics, with greater postural alteration in the sway area and in the medio-lateral direction than the age-matched control group. Balance impairment in the medio-lateral oscillation is often observed in persons with atypical Parkinsonism, but not in Parkinson's disease. Persons with PD are more dependent on visual feedback with respect to age-matched control subjects, and this could be due to their impaired peripheral kinesthetic feedback. Visual stimulation of standing posture would provide reliable signs in the differential diagnosis of Parkinsonism. |
Milena Raffi; Aurelio Trofè; Andrea Meoni; Luca Gallelli; Alessandro Piras Optic flow speed and retinal stimulation influence microsaccades Journal Article In: International Journal of Environmental Research and Public Health, vol. 19, pp. 1–10, 2022. @article{Raffi2022, Microsaccades are linked with extraretinal mechanisms that significantly alter spatial perception before the onset of eye movements. We sought to investigate whether microsaccadic activity is modulated by the speed of radial optic flow stimuli. Experiments were performed in the dark on 19 subjects who stood in front of a screen covering 135 × 107◦ of the visual field. Subjects were instructed to fixate on a central fixation point while optic flow stimuli were presented in full field, in the foveal, and in the peripheral visual field at different dot speeds (8, 11, 14, 17, and 20◦/s). Fixation in the dark was used as a control stimulus. For almost all tested speeds, the stimulation of the peripheral retina evoked the highest microsaccade rate. We also found combined effects of optic flow speed and the stimulated retinal region (foveal, peripheral, and full field) for microsaccade latency. These results show that optic flow speed modulates microsaccadic activity when presented in specific retinal portions, suggesting that eye movement generation is strictly dependent on the stimulated retinal regions. |
Hamidreza Ramezanpour; Shawn Blizzard; Devin Heinze Kehoe; Mazyar Fallah Oculomotor system can differentially process red and green colors during saccade programming in the presence of a competing distractor Journal Article In: Experimental Brain Research, vol. 240, no. 11, pp. 2847–2860, 2022. @article{Ramezanpour2022, Selective attention filters irrelevant information entering our brain to allow for fine-tuning of the relevant information processing. In the visual domain, shifts of attention are most often followed by a saccadic eye movement to objects and places of high relevance. Recent studies have shown that the stimulus color can affect saccade target selection and saccade trajectories. While those saccade modulations are based on perceptual color space, the level in the visual processing hierarchy at which color selection biases saccade programming remains unclear. As color has also been shown to influence manual response inhibition which is a key function of the prefrontal cortex, we hypothesized that the effects of color on executive functions would also inherently affect saccade programming. To test this hypothesis, we measured behavioral performance and saccade metrics during a modified saccadic Stroop task which reflects competition between color words (“RED” and “GREEN”) and their color at the level of the prefrontal cortex. Our results revealed that the oculomotor system can differentially process red and green colors when planning a saccade in the presence of a competing distractor. |
Lukas Recker; Rebecca M. Foerster; Werner X. Schneider; Christian H. Poth In: PLoS ONE, vol. 17, pp. 1–19, 2022. @article{Recker2022, The Trail-Making-Test (TMT) is one of the most widely used neuropsychological tests for assessing executive functions, the brain functions underlying cognitively controlled thought and action. Obtaining a number of test scores at once, the TMT allows to characterize an assortment of executive functions efficiently. Critically, however, as most test scores are derived from test completion times, the scores only provide a summary measure of various cognitive control processes. To address this problem, we extended the TMT in two ways. First, using a computerized eye-tracking version of the TMT, we added specific eye movement measures that deliver a richer set of data with a higher degree of cognitive process specificity. Second, we included an experimental manipulation of a fundamental executive function, namely participants' ability to emphasize speed or accuracy in task performance. Our study of healthy participants showed that eye movement measures differed between TMT conditions that are usually compared to assess the cognitive control process of alternating between task sets for action control. This demonstrates that eye movement measures are indeed sensitive to executive functions implicated in the TMT. Crucially, comparing performance under cognitive control sets of speed vs. accuracy emphasis revealed which test scores primarily varied due to this manipulation (e.g., trial duration, number of fixations), and which were still more sensitive to other differences between individuals (e.g., fixation duration, saccade amplitude). This provided an experimental construct validation of the test scores by distinguishing scores primarily reflecting the executive function of emphasizing speed vs. accuracy and those independent from it. In sum, both the inclusion of eye movement measures and of the experimental manipulation of executive functions in the TMT enabled a more specific interpretation of the TMT in terms of cognitive functions and mechanisms, which offers more precise diagnoses in clinical applications and basic research. |
Oded Rock; Andrea Albonico; Farnaz Javadian; Mohammad Ashkanani; Alisdair J. G. Taylor; Michael Dreyer; Jason J. S. Barton Oblique saccades in internuclear ophthalmoplegia Journal Article In: Experimental Brain Research, vol. 240, no. 3, pp. 861–869, 2022. @article{Rock2022, Purpose: Oblique saccades often display component stretching, in which the shorter vector in one cardinal direction is slowed so that its duration matches that of the longer vector in the orthogonal direction, resulting in a straighter trajectory. In internuclear ophthalmoplegia, adducting saccades are typically slowed while vertical saccades are unaffected. It is not known whether these slowed adducting movements are accompanied by adaptive component stretching of the vertical vector during oblique saccades. This was a cross-sectional study. We recorded the saccadic eye movement in 5 patients with right or bilateral internuclear ophthalmoplegia from multiple sclerosis and 17 healthy controls, using an EyeLink 1000 machine. The target stimulus was located at varying angles (0–360) and amplitudes (4, 8, 12 degrees). For each saccade we have calculated the curvature index as the main outcome measure, which is the area between the actual and ideal straight trajectory for oblique saccadic eye movements, divided by the square of the length of the straight trajectory, to give a unit-less metric for curvature. In the 17 control subjects, curvature showed a strong positive correlation between adducting saccades and the yoked abducting saccades of the other eye. In internuclear ophthalmoplegia, adducting saccades showed a strong curvature concave to the horizontal meridian, indicating inadequate component stretching, while abducting saccades did not differ from controls. This new sign of oblique saccadic curvature in internuclear ophthalmoplegia indicates a limitation of the range of central adaptive changes in response to distal lesions affecting transmission of the saccadic command. |
Shannon Ross-Sheehy; Bret Eschman; Esther E. Reynolds Seeing and looking: Evidence for developmental and stimulus-dependent changes in infant scanning efficiency Journal Article In: PLoS ONE, vol. 17, no. 9, pp. 1–24, 2022. @article{RossSheehy2022, Though previous work has examined infant attention across a variety of tasks, less is known about the individual saccades and fixations that make up each bout of attention, and how individual differences in saccade and fixation patterns (i.e., scanning efficiency) change with development, scene content and perceptual load. To address this, infants between the ages of 5 and 11 months were assessed longitudinally (Experiment 1) and cross-sectionally (Experiment 2). Scanning efficiency (fixation duration, saccade rate, saccade amplitude, and saccade velocity) was assessed while infants viewed six quasi-naturalistic scenes that varied in content (social or non-social) and scene complexity (3, 6 or 9 people/objects). Results from Experiment 1 revealed moderate to strong stability of individual differences in saccade rate, mean fixation duration, and saccade amplitude, and both experiments revealed 5-month-old infants to make larger, faster, and more frequent saccades than older infants. Scanning efficiency was assessed as the relation between fixation duration and saccade amplitude, and results revealed 11-month-olds to have high scanning efficiency across all scenes. However, scanning efficiency also varied with scene content, such that all infants showing higher scanning efficiency when viewing social scenes, and more complex scenes. These results suggest both developmental and stimulus-dependent changes in scanning efficiency, and further highlight the use of saccade and fixation metrics as a sensitive indicator of cognitive processing. |
Uzma Samadani; Robert J. Spinner; Gerard Dynkowski; Susan Kirelik; Tory Schaaf; Stephen P. Wall; Paul Huang Eye tracking for classification of concussion in adults and pediatrics Journal Article In: Frontiers in Neurology, vol. 13, no. 2, pp. 1–6, 2022. @article{Samadani2022, INTRODUCTION In order to obtain FDA Marketing Authorization for aid in the diagnosis of concussion, an eye tracking study in an intended use population was conducted. METHODS Potentially concussed subjects recruited in emergency department and concussion clinic settings prospectively underwent eye tracking and a subset of the Sport Concussion Assessment Tool 3 at 6 sites. The results of an eye tracking-based classifier model were then validated against a pre-specified algorithm with a cutoff for concussed vs. non-concussed. The sensitivity and specificity of eye tracking were calculated after plotting of the receiver operating characteristic curve and calculation of the AUC (area under curve). RESULTS When concussion is defined by SCAT3 subsets, the sensitivity and specificity of an eye tracking algorithm was 80.4 and 66.1%, The AUC was 0.718. The misclassification rate (n = 282) was 31.6%. CONCLUSION A pre-specified algorithm and cutoff for diagnosis of concussion vs. non-concussion has a sensitivity and specificity that is useful as a baseline-free aid in diagnosis of concussion. Eye tracking has potential to serve as an objective "gold-standard" for detection of neurophysiologic disruption due to brain injury. |
José P. Ossandón; Paul Zerr; Idris Shareef; Ramesh Kekunnaya; Brigitte Röder Active vision in sight recovery individuals with a history of long-lasting congenital blindness Journal Article In: eNeuro, vol. 9, no. 5, pp. 1–17, 2022. @article{Ossandon2022, What we see is intimately linked to how we actively and systematically explore the world through eye movements. However, it is unknown to what degree visual experience during early development is necessary for such systematic visual exploration to emerge. The present study investigated visual exploration behavior in 10 human participants whose sight had been restored only in childhood or adulthood, after a period of congenital blindness because of dense bilateral congenital cataracts. Participants freely explored real-world images while their eye movements were recorded. Despite severe residual visual impairments and gaze instability (nystag-mus), visual exploration patterns were preserved in individuals with reversed congenital cataract. Modeling analyses indicated that, similar to healthy control subjects, visual exploration in individuals with reversed congenital cataract was based on the low-level (luminance contrast) and high-level (object components) visual content of the images. Moreover, participants used visual short-term memory representations for narrowing down the exploration space. More systematic visual exploration in individuals with reversed congenital cataract was associated with better object recognition, suggesting that active vision might be a driving force for visual system development and recovery. The present results argue against a sensitive period for the development of neural mechanisms associated with visual exploration. |
Mehmet N. Agaoglu; Wai Fung; Susana T. L. Chung Oculomotor responses of the visual system to an artificial central scotoma may not represent genuine visuomotor adaptation Journal Article In: Journal of Vision, vol. 22, no. 10, pp. 1–20, 2022. @article{Agaoglu2022, Patients with central vision loss often adopt a location outside their scotoma as the new reference for vision, the preferred retinal locus (PRL). The development of a PRL is important not only for the rehabilitation of patients with central vision loss, but also helps us better understand how the brain adapts to the lack of visual input. Many investigators studied this question using a gaze-contingent display paradigm by imposing an artificial scotoma to simulate central vision loss for normally sighted subjects, with an important assumption that the "PRL" thus developed is the result of visuomotor adaptation, as is the case for people with a real scotoma. In this study, we tested the validity of this assumption. We used a gaze-contingent display combined with an artificial scotoma to first train normally sighted subjects to develop a "PRL" for saccade eye movements. Then, we compared the properties of saccades when the artificial scotoma was randomly turned off or on. When the artificial scotoma was absent, subjects automatically reverted to using their fovea, with a shorter saccade latency. Our findings suggest that the development of a "PRL" in response to an artificial scotoma may represent a strategy, instead of a genuine visuomotor adaptation. |
Svetlana Alexeeva; Vladislav Zubov; Alena Konina The effect of a dyslexia-specific Cyrillic font, LexiaD, on reading speed: further exploration in adolescents with and without dyslexia Journal Article In: Primenjena Psihologija, vol. 15, no. 2, pp. 199–236, 2022. @article{Alexeeva2022, The current study aims to test the assumption that a specially designed Cyrillic font, LexiaD, can assist adolescents with reading problems and facilitate their reading experience. LexiaD was compared with the widely used Arial font. Two groups of adolescents with dyslexia (N = 34) and without dyslexia (N = 28) silently read 144 sentences from the Russian Sentence Corpus (Laurinavichyute et al., 2019), some of which were presented in LexiaD, and others in Arial, while their eye movements were recorded. LexiaD did not show the desired effect for adolescents at the beginning of the experiment: Arial outperformed it in reading speed in both participant groups. However, by the end of the experiment, LexiaD showed a better performance. Although the speed of the higher-level cognitive processing (e.g., lexical access) in both fonts did not differ significantly, the feature extraction was found to be better in LexiaD than in Arial. Thus, we found some positive effect of LexiaD when participants with and without dyslexia got accustomed to it. A follow-up study with an explicit exposure session is needed to confirm this conclusion. |
Iti Arora; Alessio Bellato; Teodora Gliga; Danielle Ropar; Puja Kochhar; Chris Hollis; Madeleine Groom What is the effect of stimulus complexity on attention to repeating and changing information in Autism? Journal Article In: Journal of Autism and Developmental Disorders, vol. 52, no. 2, pp. 600–616, 2022. @article{Arora2022, Slower habituation to repeating stimuli characterises Autism, but it is not known whether this is driven by difficulties with information processing or an attentional bias towards sameness. We conducted eye-tracking and presented looming geometrical shapes, clocks with moving arms and smiling faces, as two separate streams of stimuli (one repeating and one changing), to 7–15 years old children and adolescents (n = 103) with Autism, ADHD or co-occurring Autism+ADHD, and neurotypical children (Study-1); and to neurotypical children (n = 64) with varying levels of autistic traits (Study-2). Across both studies, autistic features were associated with longer looks to the repeating stimulus, and shorter looks to the changing stimulus, but only for more complex stimuli, indicating greater difficulty in processing complex or unpredictable information. |
Jordi M. Asher; Paul B. Hibbard Visual field loss: Integrating overlayed information to increase the effective field of view Journal Article In: Vision, vol. 6, no. 67, pp. 1–12, 2022. @article{Asher2022, Visual field loss is a debilitating impairment that can impact normal daily activities. The advancement of augmented and virtual realities brings opportunities for potential substitutive technologies for visual field loss. Here we outline a conceptual approach to increasing the amount of useful information by overlaying the blind field into the sighted field. In this proof-of-concept experiment, 33 observers were allocated to either a left or right blind condition (with a simulated scotoma). All observers completed a line bisection task in all three conditions (baseline, scotoma, manipulation), with the baseline condition always completed first. The scotoma condition (baseline with the addition of a simulated scotoma) and the manipulated condition (baseline with the addition of a simulated scotoma, and a “minified window overlay”) were randomised in order of presentation. Predictably, our results show that a simulated scotoma impaired performance on the task. However, observers were able to make use the overlay to improve their estimation of the line's midpoint. Our results show that a substitutive augmentation of this type improved accuracy in estimating the midpoint of a line with a (simulated) scotoma. |
Asmara Awada; Shahab Bakhtiari; Catherine Legault; Celine Odier; Christopher C. Pack Training with optic flow stimuli promotes recovery in cortical blindness Journal Article In: Restorative Neurology and Neuroscience, vol. 40, pp. 1–16, 2022. @article{Awada2022, Background: Cortical blindness is a form of severe vision loss that is caused by damage to the primary visual cortex (V1) or its afferents. This condition has devastating effects on quality of life and independence. While there are few treatments currently available, accumulating evidence shows that certain visual functions can be restored with appropriate perceptual training: Stimulus sensitivity can be increased within portions of the blind visual field. However, this increased sensitivity often remains highly specific to the trained stimulus, limiting the overall improvement in visual function. Objective: Recent advances in the field of perceptual learning show that such specificity can be overcome with training paradigms that leverage the properties of higher-level visual cortical structures, which have greater capacity to generalize across stimulus positions and features. This targeting can be accomplished by using more complex training stimuli that elicit robust responses in these visual structures. Methods: We trained cortically blind subjects with a complex optic flow motion stimulus that was presented in a location of their blind field. Participants were instructed to train with the stimulus at home for approximately 30 minutes per day. Once performance plateaued, the stimulus was moved deeper into the blind field. A battery of pre- and post-training measures, with careful eye tracking, was performed to quantify the improvements. Results:We show that 1) optic flow motion discrimination can be relearned in cortically blind fields; 2) training with an optic flow stimulus can lead to improvements that transfer to different tasks and untrained locations; and 3) such training leads to a significant expansion of the visual field. The observed expansion of the visual field was present even when eye movements were carefully controlled. Finally, we show that regular training is critical for improved visual function, as sporadic training reduced the benefits of training, even when the total numbers of training sessions were equated. Conclusions: These findings are consistent with the hypothesis that complex training stimuli can improve outcomes in cortical blindness, provided that patients adhere to a regular training regimen. Nevertheless, such interventions remain limited in their ability |
Omer Azriel; Jennifer C. Britton; Chelsea D. Gober; Daniel S. Pine; Yair Bar-Haim Development and validation of the Attention Bias Questionnaire (ABQ) Journal Article In: International Journal of Methods in Psychiatric Research, vol. 31, no. 2, pp. 1–11, 2022. @article{Azriel2022, Objectives: Various psychopathologies are associated with threat-related attention biases, which are typically measured using mechanized behavioral tasks. While useful and objective, behavioral measures do not capture the subjective experience of biased attention in daily-living. To complement extant behavioral measures, we developed and validated a self-report measure of threat-related attention bias – the Attention Bias Questionnaire (ABQ). Methods: The ABQ consists of nine items reflecting the subjective experience of attention bias towards threats. To enable personalized relevance in threat-content, the general term “threat” was used, and respondents were instructed to refer to specific things that threaten them personally. In a set of five studies, the ABQ was developed and validated. Internal consistency, discriminant validity, test-retest reliability, and convergent validity were tested. Results: The ABQ emerged as a coherent and stable measure with two sub-scales: Engagement with Threat and Difficulty to Disengage from Threat. ABQ scores were positively correlated with trait anxiety, social anxiety, PTSD, and depression, as well as behaviorally measured attention bias. Conclusion: Assessing the subjective experience of threat-related attention bias can enrich existing knowledge about the cognitive mechanisms underlying psychopathology and complement extant behavioral bias measures in research and clinical evaluation. |
Chiara Barattieri di San Pietro; Giovanni Girolamo; Claudio Luzzatti; Marco Marelli Agency of subjects and eye movements in schizophrenia spectrum disorders Journal Article In: Journal of Psycholinguistic Research, vol. 51, no. 6, pp. 1371–1391, 2022. @article{BarattieridiSanPietro2022, People with schizophrenia spectrum disorders (SSD) show anomalies in language processing with respect to “who is doing what” in an action. This linguistic behavior is suggestive of an atypical representation of the formal concepts of “Agent” in the lexical representation of a verb, i.e., its thematic grid. To test this hypothesis, we administered a silent-reading task with sentences including a semantic violation of the animacy trait of the grammatical subject to 30 people with SSD and 30 healthy control participants (HCs). When the anomalous grammatical subject was the Agent of the event, a significant increase of Gaze Duration was observed in HCs, but not in SSDs. Conversely, when the anomalous subject was a Theme, SSDs displayed an increased probability of go-back movements, unlike HCs. These results are suggestive of a higher tolerability for anomalous Agents in SSD compared to the normal population. The fact that SSD participants did not show a similar tolerability for anomalous Themes rules out the issue of an attention deficit. We suggest that general communication abilities in SSD might benefit from explicit training on deep linguistic structures. |
Doug J. K. Barrett; David Souto; Michael Pilling; David M. Baguley An exploratory investigation of pupillometry as a measure of tinnitus intrusiveness on a test of auditory short-term memory Journal Article In: Ear & Hearing, vol. 43, no. 5, pp. 1540–1548, 2022. @article{Barrett2022, Objectives: The purpose of the current study was to investigate the potential of pupillometry to provide an objective measure of competition between tinnitus and external sounds during a test of auditory short-term memory. Design: Twelve participants with chronic tinnitus and twelve control participants without tinnitus took part in the study. Pretest sessions used an adaptive method to estimate listeners' frequency discrimination threshold on a test of delayed pitch discrimination for pure tones. Target and probe tones were presented at 72 dB SPL and centered on 750 Hz±2 semitones with an additional jitter of 5 to 20 Hz. Test sessions recorded baseline pupil diameter and task-related pupillary responses (TEPRs) during three blocks of delayed pitch discrimination trials. The difference between target and probe tones was set to the individual's frequency detection threshold for 80% response-accuracy. Listeners with tinnitus also completed the Tinnitus Handicap Inventory (THI). Linear mixed effects procedures were applied to examine changes in baseline pupil diameter and TEPRs associated with group (tinnitus versus control), block (1 to 3) and their interaction. The association between THI scores and maximum TEPRs was assessed using simple linear regression. Results: Patterns of baseline pupil dilation across trials diverged in listeners with tinnitus and controls. For controls, baseline pupil dilation remained constant across blocks. For listeners with tinnitus, baseline pupil dilation increased on blocks 2 and 3 compared with block 1. TEPR amplitudes were also larger in listeners with tinnitus than controls. Linear mixed effects models yielded a significant group by block interaction for baseline pupil diameter and a significant main effect of group on maximum TEPR amplitudes. Regression analyses yielded a significant association between THI scores and TEPR amplitude in listeners with tinnitus. Conclusions: Our data indicate measures of baseline pupil diameter, and TEPRs are sensitive to competition between tinnitus and external sounds during a test of auditory short-term memory. This result suggests pupillometry can provide an objective measure of intrusion in tinnitus. Future research will be required to establish whether our findings generalize to listeners across a full range of tinnitus severity. |
Dana Basel; Tamar Aviram; Amit Lazarov Lack of an attention bias away from relatively negative faces in dysphoria is not related to biased emotion identification Journal Article In: Behavior Therapy, vol. 53, no. 2, pp. 182–195, 2022. @article{Basel2022, Eye-tracking-based attention research has consistently shown a lack of a normative attentional bias away from dysphoric face stimuli in depression, characterizing the attention system of non-depressed individuals. However, this more equal attention allocation pattern could also be related to biased emotion identification, namely, an inclination of depressed individuals to attribute negative emotions to non-negative stimuli when processing mood-congruent stimuli. Here, we examined emotion identification as a possible mechanism associated with attention allocation when processing emotional faces in depression. Attention allocation and emotion identification of participants with high (HD; n = 30) and low (LD; n = 30) levels of depression symptoms were assessed using two corresponding tasks previously shown to yield significant findings in depression, using the same face stimuli (sad, happy, and neutral faces) across both tasks. We examined group differences on each task and possible between-task associations. Results showed that while LD participants dwelled longer on relatively positive faces compared with relatively negative faces on the attention allocation task, HD participants showed no such bias, dwelling equally on both. Trait anxiety did not affect these results. No group differences were noted for emotion identification, and no between-task associations emerged. Present results suggest that depression is characterized by a lack of a general attention bias toward relatively positive faces over relatively negative faces, which is not related to a corresponding bias in emotion identification. |
Dana Basel; Amit Lazarov Reward functioning from an attentional perspective and obsessive-compulsive symptoms — an eye-tracking study Journal Article In: CNS Spectrums, pp. 1–9, 2022. @article{Basel2022a, Background. Recently, a novel approach to obsessive-compulsive disorder has emerged, implicating altered reward functioning in the disorder. Yet, no study to date has directly examined the attentional aspect of reward functioning in participants with obsessive- compulsive (OC) symptoms, with past research mostly relying on reaction-time-based tasks. Methods. A reward-based value-modulated attentional capture task was completed by a sample of nonclinical student participants—44 with high (HOC) and 48 with low (LOC) levels ofOC symptoms. We measured the extent to which high and low reward-signaling distractors captured attention and impaired performance on the task, resulting in a lower possibility of obtaining a monetary reward. Attentional capture was indexed via fixation data, and further explored using saccade data. Results. Both groups performed more poorly when a high-reward signaling distractor was present, compared to when a low-reward signaling distractor was present. Importantly, this difference was significantly greater in the HOC group, and was found to be driven by the specific effects of reward-signaling distractors. Similar results emerged when exploring saccade data, and remained significant after controlling for both addiction-related compulsivity and depres- sive symptoms. Conclusions. Current findings suggest that attentional reward-related functioning may be associated with OC symptoms. Different aspects of reward functioning, including attention, should be further explored and incorporated into future research and clinical endeavors. |
Doris Bazzini; Chris Dickinson; Alison N. Cooke; Amanda Pepper; Jessica Udry; Sidney Murray Athletic image type influences women's social physique anxiety and visual attention Journal Article In: Women in Sport and Physical Activity Journal, vol. 30, no. 2, pp. 123–132, 2022. @article{Bazzini2022, Media images depicting idealized female physiques have been shown to heighten body dissatisfaction and body objectification. A potentially buffering factor in media exposure are depictions of female athletes performing their sports, which are associated with reduced objectification. These findings have not been extended to social physique anxiety (SPA), a heightened concern that one's body does not meet comparative standards of physicality and beauty. Sixty-nine college-aged women reported levels of SPA following exposure to images of the same female professional athletes performing their sport, or in a sexualized pose. Visual attention to body parts on the images was measured via an eye tracker to explore whether fixations corresponded with the experience of SPA. Performance images lowered feelings of SPA relative to sexual images, and induced a lesser percentage of time visually fixating on the head/face, and more time fixating on arms and legs, relative to sexual images of the athletes. No differences emerged for fixations on the torso across conditions. Exploratory mediation models were also conducted to explore the influence of visual attention on the relationship between image type and SPA. These findings are considered in light of the nature of objectifying images of women and the importance of promoting empowering images to audiences. |
Annabell Coors; Mohammed Aslam Imtiaz; Meta M. Boenniger; N. Ahmad Aziz; Ulrich Ettinger; Monique M. B. Breteler Associations of genetic liability for Alzheimer's disease with cognition and eye movements in a large, population-based cohort study Journal Article In: Translational Psychiatry, vol. 12, pp. 1–11, 2022. @article{Coors2022a, To identify cognitive measures that may be particularly sensitive to early cognitive decline in preclinical Alzheimer's disease (AD), we investigated the relation between genetic risk for AD and cognitive task performance in a large population-based cohort study. We measured performance on memory, processing speed, executive function, crystallized intelligence and eye movement tasks in 5182 participants of the Rhineland Study, aged 30 to 95 years. We quantified genetic risk for AD by creating three weighted polygenic risk scores (PRS) based on the genome-wide significant single-nucleotide polymorphisms coming from three different genetic association studies. We assessed the relation of AD PRS with cognitive performance using generalized linear models. Three PRS were associated with lower performance on the Corsi forward task, and two PRS were associated with a lower probability of correcting antisaccade errors, but none of these associations remained significant after correction for multiple testing. Associations between age and trail-making test A (TMT-A) performance were modified by AD genetic risk, with individuals at high genetic risk showing the strongest association. We conclude that no single measure of our cognitive test battery robustly captures genetic liability for AD as quantified by current PRS. However, Corsi forward performance and the probability of correcting antisaccade errors may represent promising candidates whose ability to capture genetic liability for AD should be investigated further. Additionally, our finding on TMT-A performance suggests that processing speed represents a sensitive marker of AD genetic risk in old age and supports the processing speed theory of age-related cognitive decline. |
Bing Dai; Kwang Meng Cham; Larry Allen Abel Perception of coherent motion in infantile nystagmus syndrome Journal Article In: Investigative Ophthalmology & Visual Science, vol. 63, no. 1, pp. 1–10, 2022. @article{Dai2022, PURPOSE. Research on infantile nystagmus syndrome (INS) and motion perception is limited. We investigated how individuals with INS perform coherent motion tasks. Particularly, we assessed how the null position affects their performance. METHODS. Subjects with INS and controls identified the direction of coherent motion stimuli (22 subjects with INS and 13 controls) in a two-alternative forced-choice design. For subjects with INS, testing was done at the null position and 15 degrees away from it. If there was no null, testing was done at primary gaze position and 15 degrees away from primary. For controls, testing was done at primary gaze position and 20 degrees away from primary. Horizontal and vertical motion coherence thresholds were determined. RESULTS. Subjects with INS showed significantly higher horizontal and vertical motion coherence thresholds compared with controls at both gaze positions (P < 0.001). Within the INS group, for 12 subjects with INS who had an identified null position, no differences in coherence thresholds were found between their null and 15 degrees away from it (P > 0.05). CONCLUSIONS. Coherent motion perception was impaired in subjects with INS. The null position did not significantly influence motion coherence thresholds for either horizontal or vertical motion. |
Kelly M. Dann; Aaron Veldre; Phillipa Hay; Stephen Touyz; Sally Andrews Assessing cognitive flexibility in anorexia nervosa using eye tracking: A registered report Journal Article In: International Journal of Eating Disorders, vol. 55, no. 10, pp. 1411–1417, 2022. @article{Dann2022, Objective: Cognitive flexibility research in anorexia nervosa (AN) has primarily focused on group differences between clinical and control participants, but research in the general population utilizing the mixed pro- anti-saccade flexibility task has demonstrated individual differences in trait anxiety are a determinant of switching performance, and switching impairments are more pronounced for keypress than saccadic (eye-movement) responses. The aim of the current research is to explore trait anxiety and differences in saccadic and keypress responding as potential determinants of performance on flexibility tasks in AN. Method: We will compare performance on the mixed pro- anti-saccade paradigm between female adult participants with a current diagnosis of AN and matched control participants, observing both saccadic and keypress responses while controlling for trait anxiety (State - Trait Anxiety Inventory) and spatial working memory (Corsi Block Tapping Test). Associations with eating disorder-related symptoms (Eating Disorder Examination Questionnaire), flexibility in everyday life (Eating Disorder Flexibility Index), and the Clinical Perfectionism Questionnaire will also be assessed. Results: Data which controls for individual differences in trait anxiety and assesses flexibility at both the task- and response-set level may be used to more accurately understand differences in performance on cognitive flexibility tasks by participants with AN. Discussion: Clarifying the effects of trait anxiety on flexibility, and differences between task- and response-set switching may advance our understanding of how cognitive flexibility relates to flexibility in everyday life and improve translation to therapeutic approaches. Public significance statement: This research will compare performance on a flexibility task between participants with anorexia nervosa (AN) and controls while observing their eye-movements to examine whether trait anxiety and type of response (eye-movement and keypress) are associated with performance. This data may improve our understanding of why participants with AN perform more poorly on cognitive flexibility tasks, and how poor cognitive flexibility relates to eating disorder-related issues with flexibility in everyday life. |
Daniel G. Dillon; Amit Lazarov; Sarah Dolan; Yair Bar-Haim; Diego A. Pizzagalli; Franklin R. Schneier Fast evidence accumulation in social anxiety disorder enhances decision making in a probabilistic reward task Journal Article In: Emotion, vol. 22, no. 1, pp. 1–18, 2022. @article{Dillon2022, Choices and response times in two-alternative decision-making tasks can be modeled by assuming that individuals steadily accrue evidence in favor of each alternative until a response boundary for one of them is crossed, at which point that alternative is chosen. Prior studies have reported that evidence accumulation during decision-making tasks takes longer in adults with psychopathology than in healthy controls, indicating that slow evidence accumulation may be transdiagnostic. However, few studies have examined perceptual decision making in anxiety disorders, where hypervigilance might enhance performance. Therefore, this study used the Hierarchical Drift Diffusion model to investigate evidence accumulation in adults with social anxiety disorder (SAD) and healthy controls as they performed a probabilistic reward task (PRT), in which social rewards were delivered for correct perceptual judgments. Adults with SAD completed the PRT before and after gaze-contingent music reward therapy (GCMRT), which trains attention allocation and has shown efficacy for SAD. Healthy controls also completed the PRT twice. Results revealed excellent performance in adults with SAD, especially after GCMRT: relative to controls, they showed faster evidence accumulation, better discriminability, and earned more rewards. These data highlight a positive effect of attention training on performance in anxious adults and show how a behavioral trait that is typically problematic-hypervigilance in SAD-can nevertheless confer advantages in certain contexts. The data also indicate that, in contrast to other forms of psychopathology, SAD is not characterized by slow evidence accumulation, at least in the context of the social PRT. |
Mahtab Farahbakhsh; Elaine J. Anderson; Roni O. Maimon-Mor; Andy Rider; John A. Greenwood; Nashila Hirji; Serena Zaman; Pete R. Jones; D. Samuel Schwarzkopf; Geraint Rees; Michel Michaelides; Tessa M. Dekker A demonstration of cone function plasticity after gene therapy in achromatopsia Journal Article In: Brain, vol. 145, pp. 3803–3815, 2022. @article{Farahbakhsh2022, Recent advances in regenerative therapy have placed the treatment of previously incurable eye diseases within arms' reach. Achromatopsia is a severe monogenic heritable retinal disease that disrupts cone function from birth, leaving patients with complete colour blindness, low acuity, photosensitivity and nystagmus. While successful gene-replacement therapy in non-primate models of achromatopsia has raised widespread hopes for clinical treatment, it was yet to be determined if and how these therapies can induce new cone function in the human brain. Using a novel multimodal approach, we demonstrate for the first time that gene therapy can successfully activate dormant cone-mediated pathways in children with achromatopsia (CNGA3- and CNGB3-associated, 10–15 years). To test this, we combined functional MRI population receptive field mapping and psychophysics with stimuli that selectively measure cone photoreceptor signalling. We measured cortical and visual cone function before and after gene therapy in four paediatric patients, evaluating treatment-related change against benchmark data from untreated patients (n = 9) and normal-sighted participants (n = 28). After treatment, two of the four children displayed strong evidence for novel cone-mediated signals in visual cortex, with a retinotopic pattern that was not present in untreated achromatopsia and which is highly unlikely to emerge by chance. Importantly, this change was paired with a significant improvement in psychophysical measures of cone-mediated visual function. These improvements were specific to the treated eye, and provide strong evidence for successful read-out and use of new cone-mediated information. These data show for the first time that gene replacement therapy in achromatopsia within the plastic period of development can awaken dormant cone-signalling pathways after years of deprivation. This reveals unprecedented neural plasticity in the developing human nervous system and offers great promise for emerging regenerative therapies. |
Lisa Feldmann; Carolin Zsigo; Charlotte Piechaczek; Pia Theresa Schröder; Christian Wachinger; Gerd Schulte-Körne; Ellen Greimel Visual attention during cognitive reappraisal in adolescent major depression: Evidence from two eye-tracking studies Journal Article In: Behaviour Research and Therapy, vol. 153, pp. 1–10, 2022. @article{Feldmann2022, Adolescent major depression (MD) is associated with impaired emotion regulation. However, results on cognitive reappraisal (CR) are mixed. Investigation of gaze behavior during CR allows a more thorough understanding of intact and deviant CR processes in MD. These studies examined for the first time the role of visual attention during CR in MD. We applied an established CR paradigm in two separate studies, with each study focusing on a different CR strategy. In Study 1, we investigated “distancing” in 39 adolescents with MD and 44 healthy controls (HCs). In Study 2, we applied “reinterpretation” in an independent sample of 37 HCs and 19 adolescents with MD. In both studies, adolescents either down-regulated negative affect to negative pictures via CR or attended them, while eye-movements were continuously recorded. Results of both studies showed that adolescents with MD and HCs did not differ in self-reported ER success. The groups showed comparable gaze behaviour patterns for emotional interest areas and entire pictures. Findings suggest that adolescents with MD are capable of applying CR when instructed and show intact visual attention processes. Future studies should examine whether repeatedly instructing adolescents with MD to apply CR might lead to improved emotion regulation in daily life. |
Amanda Fernandez; Leanne Quigley; Keith Dobson; Christopher Sears Coherence of attention and memory biases in currently and previously depressed women Journal Article In: Cognition and Emotion, pp. 1–16, 2022. @article{Fernandez2022, Previous research has found that depression is characterised by biased processing of emotional information. Although most studies have examined cognitive biases in isolation, simultaneous examination of multiple biases is required to understand how they may interact and influence one another to produce depression vulnerability. In this study, the attention and memory biases of currently depressed, previously depressed, and never depressed women were examined using the same stimuli and a unified methodology. Participants viewed negative, positive, and neutral words while their eye gaze was tracked and recorded. After a distraction task, participants completed an incidental recognition test that included words from the eye-tracking task and new words. The results supported the hypothesised mediation model for positive words: currently depressed women had a reduced attention bias for positive words and, in turn, had poorer memory for positive words relative to never depressed women. Previously depressed women, however, showed a lack of coherence between attention and memory biases for positive words. The groups did not differ in their attention or memory biases for negative words. The findings provide novel evidence in support of a causal link between the absence of protective attention and memory biases for positive information in clinical depression. |
Julia Fietz; Dorothee Pöhlchen; Florian P. Binder; Michael Czisch; Philipp G. Sämann; Victor I. Spoormaker Pupillometry tracks cognitive load and salience network activity in a working memory functional magnetic resonance imaging task Journal Article In: Human Brain Mapping, vol. 43, no. 2, pp. 665–680, 2022. @article{Fietz2022, The diameter of the human pupil tracks working memory processing and is associated with activity in the frontoparietal network. At the same time, recent neuroimaging research has linked human pupil fluctuations to activity in the salience network. In this combined functional magnetic resonance imaging (fMRI)/pupillometry study, we recorded the pupil size of healthy human participants while they performed a blockwise organized working memory task (N-back) inside an MRI scanner in order to monitor the pupil fluctuations associated neural activity during working memory processing. We first confirmed that mean pupil size closely followed working memory load. Combining this with fMRI data, we focused on blood oxygen level dependent (BOLD) correlates of mean pupil size modeled onto the task blocks as a parametric modulation. Interrogating this modulated task regressor, we were able to retrieve the frontoparietal network. Next, to fully exploit the within-block dynamics, we divided the blocks into 1 s time bins and filled these with corresponding pupil change values (first-order derivative of pupil size). We found that pupil change within N-back blocks was positively correlated with BOLD amplitudes in the areas of the salience network (namely bilateral insula, and anterior cingulate cortex). Taken together, fMRI with simultaneous measurement of pupil parameters constitutes a valuable tool to dissect working memory subprocesses related to both working memory load and salience of the presented stimuli. |
Rebekka Schröder; Eliana Faiola; Maria Fernanda Urquijo; Katharina Bey; Inga Meyhöfer; Maria Steffens; Anna-Maria Kasparbauer; Anne Ruef; Hanna Högenauer; René Hurlemann; Joseph Kambeitz; Alexandra Philipsen; Michael Wagner; Nikolaos Koutsouleris; Ulrich Ettinger Neural correlates of smooth pursuit eye movements in schizotypy and recent onset psychosis: A multivariate pattern classification approach Journal Article In: Schizophrenia Bulletin Open, vol. 3, no. 1, pp. 1–13, 2022. @article{Schroeder2022, Schizotypy refers to a set of personality traits that bear resemblance, at subclinical level, to psychosis. Despite evidence of similarity at multiple levels of analysis, direct comparisons of schizotypy and clinical psychotic disorders are rare. Therefore, we used functional magnetic resonance imaging (fMRI) to examine the neural correlates and task-based functional connectivity (psychophysiological interactions; PPI) of smooth pursuit eye movements (SPEM) in patients with recent onset psychosis (ROP; n = 34), participants with high levels of negative (HNS; n = 46) or positive (HPS; n = 41) schizotypal traits, and low-schizotypy control participants (LS; n = 61) using machine-learning. Despite strong previous evidence that SPEM is a highly reliable marker of psychosis, patients and controls could not be significantly distinguished based on SPEM performance or blood oxygen level dependent (BOLD) signal during SPEM. Classification was, however, significant for the right frontal eye field (FEF) seed region in the PPI analyses but not for seed regions in other key areas of the SPEM network. Applying the right FEF classifier to the schizotypal samples yielded decision scores between the LS and ROP groups, suggesting similarities and dissimilarities of the HNS and HPS samples with the LS and ROP groups. The very small difference between groups is inconsistent with previous studies that showed significant differences between patients with ROP and controls in both SPEM performance and underlying neural mechanisms with large effect sizes. As the current study had sufficient power to detect such differences, other reasons are discussed. |
Rebekka Schröder; Martin Reuter; Kaja Faßbender; Thomas Plieger; Jessie Poulsen; Simon S. Y. Lui; Raymond C. K. Chan; Ulrich Ettinger The role of the SLC6A3 3' UTR VNTR in nicotine effects on cognitive, affective, and motor function Journal Article In: Psychopharmacology, vol. 239, no. 2, pp. 489–507, 2022. @article{Schroeder2022a, Rationale: Nicotine has been widely studied for its pro-dopaminergic effects. However, at the behavioural level, past investigations have yielded heterogeneous results concerning effects on cognitive, affective, and motor outcomes, possibly linked to individual differences at the level of genetics. A candidate polymorphism is the 40-base-pair variable number of tandem repeats polymorphism (rs28363170) in the SLC6A3 gene coding for the dopamine transporter (DAT). The polymorphism has been associated with striatal DAT availability (9R-carriers > 10R-homozygotes), and 9R-carriers have been shown to react more strongly to dopamine agonistic pharmacological challenges than 10R-homozygotes. Objectives: In this preregistered study, we hypothesized that 9R-carriers would be more responsive to nicotine due to genotype-related differences in DAT availability and resulting dopamine activity. Methods: N=194 non-smokers were grouped according to their genotype (9R-carriers, 10R-homozygotes) and received either 2-mg nicotine or placebo gum in a between-subject design. Spontaneous blink rate (SBR) was obtained as an indirect measure of striatal dopamine activity and smooth pursuit, stop signal, simple choice and affective processing tasks were carried out in randomized order. Results: Reaction times were decreased under nicotine compared to placebo in the simple choice and stop signal tasks, but nicotine and genotype had no effects on any of the other task outcomes. Conditional process analyses testing the mediating effect of SBR on performance and how this is affected by genotype yielded no significant results. Conclusions: Overall, we could not confirm our main hypothesis. Individual differences in nicotine response could not be explained by rs28363170 genotype. |