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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.
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.
Daniela Canu; Chara Ioannou; Katarina Müller; Berthold Martin; Christian Fleischhaker; Monica Biscaldi; André Beauducel; Nikolaos Smyrnis; Ludger Tebartz Elst; Christoph Klein
Evidence towards a continuum of impairment across neurodevelopmental disorders from basic ocular-motor tasks Journal Article
In: Scientific Reports, vol. 12, no. 1, pp. 1–17, 2022.
Findings of genetic overlap between Schizophrenia, Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) contributed to a renewed conceptualization of these disorders as laying on a continuum based on aetiological, pathophysiological and neurodevelopmental features. Given that cognitive impairments are core to their pathophysiology, we compared patients with schizophrenia, ADHD, ASD, and controls on ocular-motor and manual-motor tasks, challenging crucial cognitive processes. Group comparisons revealed inhibition deficits common to all disorders, increased intra-subject variability in schizophrenia and, to a lesser extent, ADHD as well as slowed processing in schizophrenia. Patterns of deviancies from controls exhibited strong correlations, along with differences that posited schizophrenia as the most impaired group, followed by ASD and ADHD. While vector correlations point towards a common neurodevelopmental continuum of impairment, vector levels suggest differences in the severity of such impairment. These findings argue towards a dimensional approach to Neurodevelopmental Disorders' pathophysiological mechanisms.
Daniela Canu; Chara Ioannou; Katarina Müller; Berthold Martin; Christian Fleischhaker; Monica Biscaldi; André Beauducel; Nikolaos Smyrnis; Ludger Tebartz Elst; Christoph Klein
Visual search in neurodevelopmental disorders: Evidence towards a continuum of impairment Journal Article
In: European Child and Adolescent Psychiatry, vol. 31, no. 8, pp. 1–18, 2022.
Disorders with neurodevelopmental aetiology such as Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD) and Schizophrenia share commonalities at many levels of investigation despite phenotypic differences. Evidence of genetic overlap has led to the concept of a continuum of neurodevelopmental impairment along which these disorders can be positioned in aetiological, pathophysiological and developmental features. This concept requires their simultaneous comparison at different levels, which has not been accomplished so far. Given that cognitive impairments are core to the pathophysiology of these disorders, we provide for the first time differentiated head-to-head comparisons in a complex cognitive function, visual search, decomposing the task with eye movement-based process analyses. N = 103 late-adolescents with schizophrenia, ADHD, ASD and healthy controls took a serial visual search task, while their eye movements were recorded. Patients with schizophrenia presented the greatest level of impairment across different phases of search, followed by patients with ADHD, who shared with patients with schizophrenia elevated intra-subject variability in the pre-search stage. ASD was the least impaired group, but similar to schizophrenia in post-search processes and to schizophrenia and ADHD in pre-search processes and fixation duration while scanning the items. Importantly, the profiles of deviancy from controls were highly correlated between all three clinical groups, in line with the continuum idea. Findings suggest the existence of one common neurodevelopmental continuum of performance for the three disorders, while quantitative differences appear in the level of impairment. Given the relevance of cognitive impairments in these three disorders, we argue in favour of overlapping pathophysiological mechanisms.
Matthew R. Cavanaugh; Duje Tadin; Marisa Carrasco; Krystel R. Huxlin
Benefits of endogenous spatial attention during visual double-training in cortically-blinded fields Journal Article
In: Frontiers in Neuroscience, vol. 16, pp. 1–14, 2022.
Recovery of visual discrimination thresholds inside cortically-blinded (CB) fields is most commonly attained at a single, trained location at a time, with iterative progress deeper into the blind field as performance improves over several months. As such, training is slow, inefficient, burdensome, and often frustrating for patients. Here, we investigated whether double-location training, coupled with a covert spatial-attention (SA) pre-cue, could improve the efficiency of training. Nine CB participants completed a randomized, training assignment with either a spatial attention or neutral pre-cue. All trained for a similar length of time on a fine direction discrimination task at two blind field locations simultaneously. Training stimuli and tasks for both cohorts were identical, save for the presence of a central pre-cue, to manipulate endogenous (voluntary) SA, or a Neutral pre-cue. Participants in the SA training cohort demonstrated marked improvements in direction discrimination thresholds, albeit not to normal/intact-field levels; participants in the Neutral training cohort remained impaired. Thus, double-training within cortically blind fields, when coupled with SA pre-cues can significantly improve direction discrimination thresholds at two locations simultaneously, offering a new method to improve performance and reduce the training burden for CB patients. Double-training without SA pre-cues revealed a hitherto unrecognized limitation of cortically-blind visual systems' ability to improve while processing two stimuli simultaneously. These data could potentially explain why exposure to the typically complex visual environments encountered in everyday life is insufficient to induce visual recovery in CB patients. It is hoped that these new insights will direct both research and therapeutic developments toward methods that can attain better, faster recovery of vision in CB fields.
Alexis Cheviet; Jana Masselink; Eric Koun; Roméo Salemme; Markus Lappe; Caroline Froment-Tilikete; Denis Pélisson
Cerebellar signals drive motor adjustments and visual perceptual changes during forward and backward adaptation of reactive saccades Journal Article
In: Cerebral Cortex, vol. 32, no. 18, pp. 3896–3916, 2022.
Saccadic adaptation (SA) is a cerebellar-dependent learning of motor commands (MC), which aims at preserving saccade accuracy. Since SA alters visual localization during fixation and even more so across saccades, it could also involve changes of target and/or saccade visuospatial representations, the latter (CDv) resulting from a motor-to-visual transformation (forward dynamics model) of the corollary discharge of the MC. In the present study, we investigated if, in addition to its established role in adaptive adjustment of MC, the cerebellum could contribute to the adaptation-associated perceptual changes. Transfer of backward and forward adaptation to spatial perceptual performance (during ocular fixation and trans-saccadically) was assessed in eight cerebellar patients and eight healthy volunteers. In healthy participants, both types of SA altered MC as well as internal representations of the saccade target and of the saccadic eye displacement. In patients, adaptation-related adjustments of MC and adaptation transfer to localization were strongly reduced relative to healthy participants, unraveling abnormal adaptation-related changes of target and CDv. Importantly, the estimated changes of CDv were totally abolished following forward session but mainly preserved in backward session, suggesting that an internal model ensuring trans-saccadic localization could be located in the adaptation-related cerebellar networks or in downstream networks, respectively.
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.
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.
Francesco Cimminella; Giorgia D'Innocenzo; Sergio Della Sala; Alessandro Iavarone; Caterina Musella; Moreno I. Coco
Preserved extra-foveal processing of object semantics in Alzheimer's disease Journal Article
In: Journal of Geriatric Psychiatry and Neurology, vol. 35, no. 3, pp. 418–433, 2022.
Alzheimer's disease (AD) patients underperform on a range of tasks requiring semantic processing, but it is unclear whether this impairment is due to a generalised loss of semantic knowledge or to issues in accessing and selecting such information from memory. The objective of this eye-tracking visual search study was to determine whether semantic expectancy mechanisms known to support object recognition in healthy adults are preserved in AD patients. Furthermore, as AD patients are often reported to be impaired in accessing information in extra-foveal vision, we investigated whether that was also the case in our study. Twenty AD patients and 20 age-matched controls searched for a target object among an array of distractors presented extra-foveally. The distractors were either semantically related or unrelated to the target (e.g., a car in an array with other vehicles or kitchen items). Results showed that semantically related objects were detected with more difficulty than semantically unrelated objects by both groups, but more markedly by the AD group. Participants looked earlier and for longer at the critical objects when these were semantically unrelated to the distractors. Our findings show that AD patients can process the semantics of objects and access it in extra-foveal vision. This suggests that their impairments in semantic processing may reflect difficulties in accessing semantic information rather than a generalised loss of semantic memory.
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.
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.
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.
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.
Ryohei Nakayama; Jean Baptiste Bardin; Ai Koizumi; Isamu Motoyoshi; Kaoru Amano
Building a decoder of perceptual decisions from microsaccades and pupil size Journal Article
In: Frontiers in Psychology, vol. 13, pp. 1–14, 2022.
Many studies have reported neural correlates of visual awareness across several brain regions, including the sensory, parietal, and frontal areas. In most of these studies, participants were instructed to explicitly report their perceptual experience through a button press or verbal report. It is conceivable, however, that explicit reporting itself may trigger specific neural responses that can confound the direct examination of the neural correlates of visual awareness. This suggests the need to assess visual awareness without explicit reporting. One way to achieve this is to develop a technique to predict the visual awareness of participants based on their peripheral responses. Here, we used eye movements and pupil sizes to decode trial-by-trial changes in the awareness of a stimulus whose visibility was deteriorated due to adaptation-induced blindness (AIB). In the experiment, participants judged whether they perceived a target stimulus and rated the confidence they had in their perceptual judgment, while their eye movements and pupil sizes were recorded. We found that not only perceptual decision but also perceptual confidence can be separately decoded from the eye movement and pupil size. We discuss the potential of this technique with regard to assessing visual awareness in future neuroimaging experiments.
Kien Trong Nguyen; Wei-Kuang Liang; Chi-Hung Juan; Chin-An Wang
Time-frequency analysis of pupil size modulated by global luminance, arousal, and saccade preparation signals using Hilbert-Huang transform Journal Article
In: International Journal of Psychophysiology, vol. 176, pp. 89–99, 2022.
Pupil size changes constantly and is mainly determined by global luminance signals. In addition, the pupil responds to various cognitive and arousal processes, with larger pupil dilation observed in higher levels of cognitive or arousal processing. Although these task-evoked pupillary responses are extensively used in the pupil research, pupil analysis focusing on the frequency domain, particularly in the context of arousal and cognitive modulations, is less established. Fourier Transform method (FFT) has been used to understand the modulation of task difficulty on pupil oscillations. However, physiological signals are often characterized as non-linear and non-stationary waves, and the conventional spectral analytical method with linearity presumption is less appropriate to reveal modulation dynamics between time and frequency. Here, we used Hilbert-Huang Transform (HHT) to examine the time-frequency modulations on pupil size regulated by arousal, cognitive, and global luminance signals. Consistent with previous research, using FFT, higher spectral densities were obtained with lower luminance background. Moreover, higher spectral densities were found in the high emotional arousal condition. With HHT, we further demonstrated temporal changes on amplitude spectrum and inter-trial phase coherence (ITPC) in each intrinsic mode function (IMF), with stronger amplitudes in higher IMFs (i.e., low frequencies). Moreover, although global luminance, arousal and saccade preparation modulated pupil oscillatory responses, the modulation pattern in different IMFs was different. Together, our results demonstrated dynamics between the time and frequency domain on pupil oscillatory responses, highlighting the importance of examining the time-frequency interactions in the context of various pupil modulations.
James E. Niemeyer; Seth Akers-Campbell; Aaron Gregoire; Michael A. Paradiso
Perceptual enhancement and suppression correlate with V1 neural activity during active sensing Journal Article
In: Current Biology, vol. 32, pp. 2654–2667, 2022.
Perception in multiple sensory modalities is an active process that involves exploratory behaviors. In humans and other primates, vision results from sensory sampling guided by saccadic eye movements. Saccades are known to modulate visual perception, and a corollary discharge signal associated with saccades appears to establish a sense of visual stability. Neural recordings have shown that saccades also modulate activity widely across the brain. To investigate the neural basis of saccadic effects on perception, simultaneous recordings from multiple neurons in area V1 were made as animals performed a contrast detection task. Perceptual and neural measures were compared when the animal made real saccades that brought a stimulus into V1 receptive fields and when simulated saccades were made (identical retinal stimulation but no eye movement). When real saccades were made and low spatial frequency stimuli were presented, we observed a reduction in both perceptual sensitivity and neural activity compared with simulated saccades; conversely, with higher spatial frequency stimuli, saccades increased visual sensitivity and neural activity. The performance of neural decoders, which used the activity of the population of simultaneously recorded neurons, showed saccade effects on sensitivity that mirrored the frequency-dependent perceptual changes, suggesting that the V1 population activity could support the perceptual effects. A minority of V1 neurons had significant choice probabilities, and the saccades decreased both average choice probability and pairwise noise correlations. Taken together, the findings suggest that a signal related to saccadic eye movements alters V1 spiking to increase the independence of spiking neurons and bias the system toward processing higher spatial frequencies, presumably to enhance object recognition. The effects of saccades on visual perception and noise correlations appear to parallel effects observed in other sensory modalities, suggesting a general principle of active sensory processing.
Valentina Vencato; Mark Harwood; Laurent Madelain
Saccadic initiation biased by fixational activity Journal Article
In: Vision Research, vol. 201, pp. 1–15, 2022.
Both the gap and overlap paradigm may reveal the interaction between fixating and moving the eyes, but the effects of the overlap paradigm have not been fully characterized yet. Here we present a series of experiments probing how an overlap paradigm, combined with the manipulation of stimuli durations, saliency and transient changes might modulate saccadic reaction time distributions. We recorded saccadic reaction time in four participants in six experiments in which a saccade-target appeared at a pseudo-random amplitude after a fixation period. First, we parametrically manipulated the duration of the overlap using a range of intervals (from 0 to 200 ms). In a second experiment we probed the interaction of various foreperiod intervals (i.e. the duration of the fixation period prior to saccade-target onset) and overlap using two overlap intervals (20 or 140 ms). In two additional experiments we manipulated either the stimuli sizes or their contrast ratio in overlap paradigms (20 or 140 ms). Lastly, we introduced a visual transient during the overlap interval via two manipulations (both with a range of SOA): either a distractor ring appeared around the fixation-target, or a dynamic random noise patch replaced the fixation-target. Results show reliable modifications in the latency distributions depending on the overlap interval as well as idiosyncratic differences. Additional experimental manipulations also affected the latency distributions revealing strong interacting inhibitory processes. We conclude that the effects of overlap intervals may combine with the influence of other stimuli properties affecting decision process.
Jason E. Vice; Mandy K. Biles; Marcello Maniglia; Kristina M. Visscher
Oculomotor changes following learned use of an eccentric retinal locus Journal Article
In: Vision Research, vol. 201, pp. 1–9, 2022.
People with bilateral central vision loss sometimes develop a new point of oculomotor reference called a preferred retinal locus (PRL) that is used for fixating and planning saccadic eye movements. How individuals develop and learn to effectively use a PRL is still debated; in particular, the time course of learning to plan saccades using a PRL and learning to stabilize peripheral fixation at the desired location. Here we address knowledge limitations through research describing how eye movements change as a person learns to adopt an eccentric retinal locus. Using a gaze-contingent, eye tracking-guided paradigm to simulate central vision loss, 40 participants developed a PRL by engaging in an oculomotor and visual recognition task. After 12 training sessions, significant improvements were observed in six eye movement metrics addressing different aspects involved in learning to use a PRL: first saccade landing dispersion, saccadic re-referencing, saccadic precision, saccadic latency, percentage of useful trials, and fixation stability. Importantly, our analyses allowed separate examination of the stability of target fixation separately from the dispersion and precision of the landing location of saccades. These measures explained 50% of the across-subject variance in accuracy. Fixation stability and saccadic precision showed a strong, positive correlation. Although there was no statistically significant difference in rate of learning, individuals did tend to learn saccadic precision faster than fixation stability. Saccadic precision was also more associated with accuracy than fixation stability for the behavioral task. This suggests effective intervention strategies in low vision should address both fixation stability and saccadic precision.
Manuel Vidal; Françoise Vitu
Multisensory temporal binding induces an illusory gap/overlap that reduces the expected audiovisual interactions on saccades but not manual responses Journal Article
In: PLoS ONE, vol. 17, no. 4, pp. 1–30, 2022.
Throughout the day, humans react to multisensory events conveying both visual and auditory signals by rapidly reorienting their gaze. Several studies showed that sounds can impact the latency of visually guided saccades depending on when and where they are delivered. We found that unlocalized beeps delivered near the onset time of a visual target reduce latencies, more for early beeps and less for late beeps, however, this modulation is far weaker than for perceptual temporal judgments. Here we tested our previous assumption that beeps shift the perceived timing of target onset and result in two competing effects on saccade latencies: a multisensory modulation in line with the expected perceptual effect and an illusory gap/overlap effect, resulting from target appearance being perceived later/closer in time than fixation offset and shortening/lengthening saccade latencies. Gap/overlap effects involve an oculomotor component associated with neuronal activity in the superior colliculus (SC), a multisensory subcortical structure devoted to sensory-motor transformation. We therefore predicted that the interfering illusory gap/overlap effect would be weaker for manual responses, which involve distinct multisensory areas. In three experiments we manipulated the delay between target onset and an irrelevant auditory beep (stimulus onset asynchrony; SOA) and between target onset and fixation offset (real gap/overlap). Targets appeared left/right of fixation and participants were instructed to make quick saccades or button presses towards the targets. Adding a real overlap/gap (50% of SOA) compensated for the illusory gap/overlap by increasing the beep-related modulation of saccade latencies across the entire SOA range, whereas it barely affected manual responses. However, although auditory and gap/overlap effects modulated saccade latencies in similar ways, these were additive and could saturate, suggesting that they reflect independent mechanisms. Therefore, multisensory temporal binding affects perception and oculomotor control differently, likely due to the implication of the SC in saccade programming and multisensory integration.
Chin-an Wang; Brian White; Douglas P. Munoz
Pupil-linked arousal signals in the midbrain superior colliculus Journal Article
In: Journal of Cognitive Neuroscience, vol. 34, no. 8, pp. 1340–1354, 2022.
The orienting response evoked by the appearance of a salient stimulus is modulated by arousal; however, neural under- pinnings for the interplay between orienting and arousal are not well understood. The superior colliculus (SC), causally involved in multiple components of the orienting response including gaze and attention shifts, receives not only multisensory and cognitive inputs but also arousal-regulated inputs from various cortical and subcortical structures. To investigate the impact of moment-by-moment fluctuations in arousal on orienting saccade responses, we used microstimulation of the monkey SC to trigger saccade responses, and we used pupil size and velocity to index the level ofarousal at stimulation onset because these measures correlate with changes in brain states and locus coeruleus activity. Saccades induced by SC microstimulation correlated with prestimulation pupil velocity, with higher pupil velocities on trials without evoked saccades than with evoked saccades. In contrast, prestimulation absolute pupil size did not correlate with saccade behavior. Moreover, pupil velocity correlated with evoked saccade latency and metrics. Together, our results demonstrated that small fluctuations in arousal, indexed by pupil velocity, can modulate the saccade response evoked by SC microstimulation in awake behaving monkeys.
Abigail L. M. Webb; Jordi M. Asher; Paul B. Hibbard
Saccadic eye movements are deployed faster for salient facial stimuli, but are relatively indifferent to their emotional content Journal Article
In: Vision Research, vol. 198, pp. 1–11, 2022.
The present study explores the threat bias for fearful facial expressions using saccadic latency, with a particular focus on the role of low-level facial information, including spatial frequency and contrast. In a simple localisation task, participants were presented with spatially-filtered versions of neutral, fearful, angry and happy faces. Together, our findings show that saccadic responses are not biased toward fearful expressions compared to neutral, angry or happy counterparts, regardless of their spatial frequency content. Saccadic response times are, however, significantly influenced by the spatial frequency and contrast of facial stimuli. We discuss the implications of these findings for the threat bias literature, and the extent to which image processing can be expected to influence behavioural responses to socially-relevant facial stimuli.
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.
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.
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.
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.
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.
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.
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.
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 Book
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.
Mislocalization in saccadic suppression of displacement Journal Article
In: Vision Research, vol. 196, pp. 1–6, 2022.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Jens Kürten; Tim Raettig; Julian Gutzeit; Lynn Huestegge
Dual-action benefits: Global (action-inherent) and local (transient) sources of action prepotency underlying inhibition failures in multiple action control Journal Article
In: Psychological Research, pp. 1–15, 2022.
Previous research has shown that the simultaneous execution of two actions (instead of only one) is not necessarily more difficult but can actually be easier (less error-prone), in particular when executing one action requires the simultaneous inhibition of another action. Corresponding inhibitory demands are particularly challenging when the to-be-inhibited action is highly prepotent (i.e., characterized by a strong urge to be executed). Here, we study a range of important potential sources of such prepotency. Building on a previously established paradigm to elicit dual-action benefits, participants responded to stimuli with single actions (either manual button press or saccade) or dual actions (button press and saccade). Crucially, we compared blocks in which these response demands were randomly intermixed (mixed blocks) with pure blocks involving only one type of response demand. The results highlight the impact of global (action-inherent) sources of action prepotency, as reflected in more pronounced inhibitory failures in saccade vs. manual control, but also more local (transient) sources of influence, as reflected in a greater probability of inhibition failures following trials that required the to-be-inhibited type of action. In addition, sequential analyses revealed that inhibitory control (including its failure) is exerted at the level of response modality representations, not at the level of fully specified response representations. In sum, the study highlights important preconditions and mechanisms underlying the observation of dual-action benefits.
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.
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.
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.
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.
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.
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.
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.
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.
Zoe Loh; Elizabeth H. Hall; Deborah Cronin; John M. Henderson
Working memory control predicts fixation duration in scene-viewing Journal Article
In: Psychological Research, pp. 1–12, 2022.
When viewing scenes, observers differ in how long they linger at each fixation location and how far they move their eyes between fixations. What factors drive these differences in eye-movement behaviors? Previous work suggests individual differences in working memory capacity may influence fixation durations and saccade amplitudes. In the present study, participants (N = 98) performed two scene-viewing tasks, aesthetic judgment and memorization, while viewing 100 photographs of real-world scenes. Working memory capacity, working memory processing ability, and fluid intelligence were assessed with an operation span task, a memory updating task, and Raven's Advanced Progressive Matrices, respectively. Across participants, we found significant effects of task on both fixation durations and saccade amplitudes. At the level of each individual participant, we also found a significant relationship between memory updating task performance and participants' fixation duration distributions. However, we found no effect of fluid intelligence and no effect of working memory capacity on fixation duration or saccade amplitude distributions, inconsistent with previous findings. These results suggest that the ability to flexibly maintain and update working memory is strongly related to fixation duration behavior.
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.
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.
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.
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.
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.
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.
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.
Yingyi Luo; Dixiao Tan; Ming Yan
Morphological structure influences saccade generation in Chinese reading Journal Article
In: Reading and Writing, pp. 1–17, 2022.
Recent studies have demonstrated that saccadic programming in reading is not only determined by low-level visual factors. High-level morphological effects on saccade have been shown in two morphologically rich languages. In the present study, we examined the underlying mechanism of such morphological influences by comparing the processes of reading three-character Chinese compound words that differ in their structures in terms of morphological decomposition. Consistent with earlier reports, our results showed an effect of morphological structure on saccade. The readers' first-fixation location shifted further away from the beginning of the word, when the last two characters were more morphologically bounded and thus formed a [1 + 2] structure, than when the first two characters were more bounded (i.e., a [2 + 1] structure). The results are not accountable by a processing difficulty hypothesis, which proposes that saccade amplitude is determined by morphological complexity; rather, they suggest that Chinese readers parafoveally decompose a word and spontaneously target its longer stem, thus reflecting parafoveal access to words' stems.
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.
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.
Ehsan Sedaghat-Nejad; Jay S. Pi; Paul Hage; Mohammad Amin Fakharian; Reza Shadmehr
Synchronous spiking of cerebellar Purkinje cells during control of movements Journal Article
In: PNAS, vol. 119, no. 14, pp. 1–11, 2022.
The ability of the brain to accurately control a movement depends on the cerebellum. Yet, how the cerebellar neurons encode information relevant for this control remains poorly understood. The computations that are performed in the cerebellar cortex are transmitted to its nuclei via Purkinje cells (P cells), which are inhibitory neurons. How- ever, if the spiking activity within P cell populations were temporally synchronized, that inhibition would entrain nucleus neurons, making them fire. Do P cells transmit information by synchronously timing their spikes? We simultaneously recorded from multiple P cells while marmosets performed saccadic eye movements, and organized the neurons into populations that shared a complex spike response to error. Before move- ment onset, this population ofP cells increased their simple spike activity with a magni- tude that depended on the velocity of the upcoming saccade, and then sharply reduced their activity below baseline at saccade onset. During deceleration, the spikes became temporally aligned within the population. Thus, the P cells relied on disinhibition, combined with spike synchronization, to convey to the nucleus when to decelerate and potentially stop the movement.
Xiaoyu Tang; Mengying Yuan; Zhongyu Shi; Min Gao; Rongxia Ren; Wei Ming; Yulin Gao
Multisensory integration attenuates visually induced oculomotor inhibition of return Journal Article
In: Journal of Vision, vol. 22, no. 4, pp. 1–17, 2022.
Inhibition of return (IOR) is a mechanism of the attention system involving bias toward novel stimuli and delayed generation of responses to targets at previously attended locations. According to the two-component theory, IOR consists of a perceptual component and an oculomotor component (oculomotor IOR [O-IOR]) depending on whether the eye movement system is activated. Previous studies have shown that multisensory integration weakens IOR when paying attention to both visual and auditory modalities. However, it remains unclear whether the O-IOR effect attenuated by multisensory integration also occurs when the oculomotor system is activated. Here, using two eye movement experiments, we investigated the effect of multisensory integration on O-IOR using the exogenous spatial cueing paradigm. In Experiment 1, we found a greater visual O-IOR effect compared with audiovisual and auditory O-IOR in divided modality attention. The relative multisensory response enhancement (rMRE) and violations of Miller's bound showed a greater magnitude of multisensory integration in the cued location compared with the uncued location. In Experiment 2, the magnitude of the audiovisual O-IOR effect was significantly less than that of the visual O-IOR in single visual modality selective attention. Implications for the effect of multisensory integration on O-IOR were discussed under conditions of oculomotor system activation, shedding new light on the two-component theory of IOR.
Susanne M. Veen; Alexander Stamenkovic; James S. Thomas; Peter E. Pidcoe
Skill-related adaptive modifications of gaze stabilization in elite and non-elite athletes Journal Article
In: Frontiers in Sports and Active Living, vol. 4, pp. 1–7, 2022.
The vestibular ocular reflex (VOR) provides gaze stability during head movements by driving eye movements in a direction opposing head motion. Although vestibular-based rehabilitation strategies are available, it is still unclear whether VOR can be modulated by training. By examining adaptations in gaze stabilization mechanisms in a population with distinct visuomotor requirements for task success (i.e., gymnasts), this study was designed to determine whether experience level (as a proxy of training potential) was associated with gaze stabilization modifications during fixed target (VOR promoting) and fixed-to-head-movement target (VOR suppressing) tasks. Thirteen gymnasts of different skill levels participated in VOR and VOR suppression tasks. The gain between head and eye movements was calculated and compared between skill levels using an analysis of covariance. Across experience levels, there was a similar degradation in VOR gain away from −1 at higher movement speeds. However, during the suppression tasks, more experienced participants were able to maintain VOR gain closer to 0 across movement speeds, whereas novice participants showed greater variability in task execution regardless of movement speed. Changes in adaptive modifications to gaze stability associated with experience level suggest that the mechanisms impacting gaze stabilization can be manipulated through training.
Elle Heusden; Wieske Zoest; Mieke Donk; Christian N. L. Olivers
An attentional limbo: Saccades become momentarily non-selective in between saliency-driven and relevance-driven selection Journal Article
In: Psychonomic Bulletin & Review, vol. 29, pp. 1327–1337, 2022.
Human vision involves selectively directing the eyes to potential objects of interest. According to most prominent theories, selection is the quantal outcome of an ongoing competition between saliency-driven signals on the one hand, and relevance-driven signals on the other, with both types of signals continuously and concurrently projecting onto a common priority map. Here, we challenge this view. We asked participants to make a speeded eye movement towards a target orientation, which was presented together with a non-target of opposing tilt. In addition to the difference in relevance, the target and non-target also differed in saliency, with the target being either more or less salient than the non-target. We demonstrate that saliency- and relevance-driven eye movements have highly idiosyncratic temporal profiles, with saliency-driven eye movements occurring rapidly after display onset while relevance-driven eye movements occur only later. Remarkably, these types of eye movements can be fully separated in time: We find that around 250 ms after display onset, eye movements are no longer driven by saliency differences between potential targets, but also not yet driven by relevance information, resulting in a period of non-selectivity, which we refer to as the attentional limbo. Binomial modeling further confirmed that visual selection is not necessarily the outcome of a direct battle between saliency- and relevance-driven signals. Instead, selection reflects the dynamic changes in the underlying saliency- and relevance-driven processes themselves, and the time at which an action is initiated then determines which of the two will emerge as the driving force of behavior.
Soon Young Park; Kenneth Holmqvist; Diederick C. Niehorster; Ludwig Huber; Zsófia Virányi
How to improve data quality in dog eye tracking Journal Article
In: Behavior Research Methods, pp. 1–24, 2022.
Pupil–corneal reflection (P–CR) eye tracking has gained a prominent role in studying dog visual cognition, despite methodological challenges that often lead to lower-quality data than when recording from humans. In the current study, we investigated if and how the morphology of dogs might interfere with tracking of P–CR systems, and to what extent such interference, possibly in combination with dog-unique eye-movement characteristics, may undermine data quality and affect eye-movement classification when processed through algorithms. For this aim, we have conducted an eye-tracking experiment with dogs and humans, and investigated incidences of tracking interference, compared how they blinked, and examined how differential quality of dog and human data affected the detection and classification of eye-movement events. Our results show that the morphology of dogs' face and eye can interfere with tracking methods of the systems, and dogs blink less often but their blinks are longer. Importantly, the lower quality of dog data lead to larger differences in how two different event detection algorithms classified fixations, indicating that the results of key dependent variables are more susceptible to choice of algorithm in dog than human data. Further, two measures of the Nyström & Holmqvist (Behavior Research Methods, 42(4), 188–204, 2010) algorithm showed that dog fixations are less stable and dog data have more trials with extreme levels of noise. Our findings call for analyses better adjusted to the characteristics of dog eye-tracking data, and our recommendations help future dog eye-tracking studies acquire quality data to enable robust comparisons of visual cognition between dogs and humans.
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.
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.
Christina U. Pfeuffer; Andrea Kiesel; Lynn Huestegge
Similar proactive effect monitoring in free and forced choice action modes Journal Article
In: Psychological Research, pp. 1–16, 2022.
When our actions yield predictable consequences in the environment, our eyes often already saccade towards the locations we expect these consequences to appear at. Such spontaneous anticipatory saccades occur based on bi-directional associations between action and effect formed by prior experience. That is, our eye movements are guided by expectations derived from prior learning history. Anticipatory saccades presumably reflect a proactive effect monitoring process that prepares a later comparison of expected and actual effect. Here, we examined whether anticipatory saccades emerged under forced choice conditions when only actions but not target stimuli were predictive of future effects and whether action mode (forced choice vs. free choice, i.e., stimulus-based vs. stimulus-independent choice) affected proactive effect monitoring. Participants produced predictable visual effects on the left/right side via forced choice and free choice left/right key presses. Action and visual effect were spatially compatible in one half of the experiment and spatially incompatible in the other half. Irrespective of whether effects were predicted by target stimuli in addition to participants' actions, in both action modes, we observed anticipatory saccades towards the location of future effects. Importantly, neither the frequency, nor latency or amplitude of these anticipatory saccades significantly differed between forced choice and free choice action modes. Overall, our findings suggest that proactive effect monitoring of future action consequences, as reflected in anticipatory saccades, is comparable between forced choice and free choice action modes.
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.
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.
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.
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.
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
Emphasizing speed or accuracy in an eye-tracking version of the Trail-Making-Test: Towards experimental diagnostics for decomposing executive functions Journal Article
In: PLoS ONE, vol. 17, pp. 1–19, 2022.
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.
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.
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.
Rebekka Schröder; Kristof Keidel; Peter Trautner; Alexander Radbruch; Ulrich Ettinger
Neural mechanisms of background and velocity effects in smooth pursuit eye movements Journal Article
In: Human Brain Mapping, pp. 1–17, 2022.
Smooth pursuit eye movements (SPEM) are essential to guide behaviour in complex visual environments. SPEM accuracy is known to be degraded by the presence of a structured visual background and at higher target velocities. The aim of this preregistered study was to investigate the neural mechanisms of these robust behavioural effects. N = 33 participants performed a SPEM task with two background conditions (present and absent) at two target velocities (0.4 and 0.6 Hz). Eye movement and BOLD data were collected simultaneously. Both the presence of a structured background and faster target velocity decreased pursuit gain and increased catch-up saccade rate. Faster targets additionally increased position error. Higher BOLD response with background was found in extensive clusters in visual, parietal, and frontal areas (including the medial frontal eye fields; FEF) partially overlapping with the known SPEM network. Faster targets were associated with higher BOLD response in visual cortex and left lateral FEF. Task-based functional connectivity analyses (psychophysiological interactions; PPI) largely replicated previous results in the basic SPEM network but did not yield additional information regarding the neural underpinnings of the background and velocity effects. The results show that the presentation of visual background stimuli during SPEM induces activity in a widespread visuo-parieto-frontal network including areas contributing to cognitive aspects of oculomotor control such as medial FEF, whereas the response to higher target velocity involves visual and motor areas such as lateral FEF. Therefore, we were able to propose for the first time different functions of the medial and lateral FEF during SPEM.
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.
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.
Leah N. Tobin; Christopher R. Sears; Kristin M. Von Ranson
Two eating disorder preventive interventions reduce attentional biases in body-dissatisfied university women: A cluster randomized controlled trial Journal Article
In: Journal of Consulting and Clinical Psychology, pp. 1–15, 2022.
Objective: This cluster randomized controlled trial evaluated the efficacy of participation in the Body Project—a cognitive-dissonance-based preventive intervention that reduces self-reported body dissatisfaction—for reducing body-dissatisfaction-related attentional biases. We hypothesized that women in a Body Project condition would show a greater reduction in attentional biases to weight-related images and words at postintervention than women in a wait-list control condition. Method: Body-dissatisfied university women (N= 168; Mage = 20.50 ± 3.37 years; 42.0% White; MBMI = 23.08 ± 4.45 kg/m2) were randomly assigned to a Body Project, media psychoeducation (i.e., active control), or wait-list control condition. We assessed attentional biases via eye-gaze tracking and body satisfaction using the Body Shape Questionnaire, at baseline and postintervention. Results: Self-reported outcomes from previous literature were replicated. Compared to wait-list, Body Project participation reduced attention to images of thin models ( ps < .05; ds = .19, .24), but not to weight-related words. Compared to wait-list, the media psychoeducation condition reduced attention to fat-related images and words (ds = .17, .18). Conclusions: This study, which replicates previous self-report findings, is the first to find that two preventive interventions reduced an objective outcome (attentional bias to weight-related images) in body-dissatisfied women.
Chiara Tortelli; Antonella Pomè; Marco Turi; Roberta Igliozzi; David C. Burr; Paola Binda
Contextual information modulates pupil size in autistic children Journal Article
In: Frontiers in Neuroscience, vol. 16, pp. 1–10, 2022.
Recent Bayesian models suggest that perception is more “data-driven” and less dependent on contextual information in autistic individuals than others. However, experimental tests of this hypothesis have given mixed results, possibly due to the lack of objectivity of the self-report methods typically employed. Here we introduce an objective no-report paradigm based on pupillometry to assess the processing of contextual information in autistic children, together with a comparison clinical group. After validating in neurotypical adults a child-friendly pupillometric paradigm, in which we embedded test images within an animation movie that participants watched passively, we compared pupillary response to images of the sun and meaningless control images in children with autism vs. age- and IQ-matched children presenting developmental disorders unrelated to the autistic spectrum. Both clinical groups showed stronger pupillary constriction for the sun images compared with control images, like the neurotypical adults. However, there was no detectable difference between autistic children and the comparison group, despite a significant difference in pupillary light responses, which were enhanced in the autistic group. Our report introduces an objective technique for studying perception in clinical samples and children. The lack of statistically significant group differences in our tests suggests that autistic children and the comparison group do not show large differences in perception of these stimuli. This opens the way to further studies testing contextual processing at other levels of perception.
Tawny Tsang; Adam J. Naples; Erin C. Barney; Minhang Xie; Raphael Bernier; Geraldine Dawson; James Dziura; Susan Faja; Shafali Spurling Jeste; James C. McPartland; Charles A. Nelson; Michael Murias; Helen Seow; Catherine Sugar; Sara J. Webb; Frederick Shic; Scott P. Johnson
Attention allocation during exploration of visual arrays in ASD: Results from the ABC-CT feasibility study Journal Article
In: Journal of Autism and Developmental Disorders, pp. 1–10, 2022.
Visual exploration paradigms involving object arrays have been used to examine salience of social stimuli such as faces in ASD. Recent work suggests performance on these paradigms may associate with clinical features of ASD. We evaluate metrics from a visual exploration paradigm in 4-to-11-year-old children with ASD (n = 23; 18 males) and typical development (TD; n = 23; 13 males). Presented with arrays containing faces and nonsocial stimuli, children with ASD looked less at (p = 0.002) and showed fewer fixations to (p = 0.022) faces than TD children, and spent less time looking at each object on average (p = 0.004). Attention to the screen and faces correlated positively with social and cognitive skills in the ASD group (ps <.05). This work furthers our understanding of objective measures of visual exploration in ASD and its potential for quantifying features of ASD.
Nils S. Berg; Nikki A. Lammers; Anouk R. Smits; Selma Lugtmeijer; Yair Pinto; Edward H. F. De Haan
Mid-range visual functions in relation to higher-order visual functions after stroke Journal Article
In: Journal of Clinical and Experimental Neuropsychology, vol. 44, no. 8, pp. 580–591, 2022.
Introduction: We aimed to investigate whether associations between deficits in “mid-range” visual functions and deficits in higher-order visual cognitive functions in stroke patients are more in line with a hierarchical, two-pathway model of the visual brain, or with a patchwork model, which assumes a parallel organization with many processing routes and cross-talk. Methods: A group of 182 ischemic stroke patients was assessed with a new diagnostic set-up for the investigation of a comprehensive range of visuosensory mid-range functions: color, shape, location, orientation, correlated motion, contrast and texture. With logistic regression analyses we investigated the predictive value of these mid-range functions for deficits in visuoconstruction (Copy of the Rey-Complex Figure Test), visual emotion recognition (Ekman 60 Faces Test of the FEEST) and visual memory (computerized Doors-test). Results: Results showed that performance on most mid-range visual tasks could not predict performance on higher-order visual cognitive tasks. Correlations were low to weak. Impaired visuoconstruction and visual memory were only modestly predicted by a worse location perception. Impaired emotion perception was modestly predicted by a worse orientation perception. In addition, double dissociations were found: there were patients with selective deficits in mid-range visual functions without higher-order visual deficits and vice versa. Conclusions: Our findings are not in line with the hierarchical, two-pathway model. Instead, the findings are more in line with alternative “patchwork” models, arguing for a parallel organization with many processing routes and cross-talk. However, future studies are needed to test these alternative models.
Preeti Verghese; Saeideh Ghahghaei; Zachary Lively
Mapping residual stereopsis in macular degeneration Journal Article
In: Journal of Vision, vol. 22, no. 13, pp. 1–13, 2022.
Individuals with macular degeneration typically lose vision in the central region of one or both eyes. A binocular scotoma occurs when vision loss occurs in overlapping locations in both eyes, but stereopsis is impacted even in the non-overlapping region wherever the visual field in either eye is affected. We used a novel stereoperimetry protocol to measure local stereopsis across the visual field (up to 25° eccentricity) to determine how locations with functional stereopsis relate to the scotomata in the two eyes. Participants included those with monocular or binocular scotomata and age-matched controls with healthy vision. Targets (with or without depth information) were presented on a random dot background. Depth targets had true binocular disparity of 20' (crossed), whereas non-depth targets were defined by monocular cues such as contrast and dot density. Participants reported target location and whether it was in depth or flat. Local depth sensitivity (d') estimates were then combined to generate a stereopsis map. This stereopsis map was compared to the union of the monocular microperimetry estimates that mapped out the functional extent of the scotoma in each eye. The "union" prediction aligned with residual stereopsis, showing impaired stereopsis within this region and residual stereopsis outside this region. Importantly, the stereoblind region was typically more extensive than the binocular scotoma defined by the intersection (overlap) of the scotomata. This explains why individuals may have intact binocular visual fields but be severely compromised in tasks of daily living that benefit from stereopsis, such as eye-hand coordination and navigation.
Simone Vespa; Lars Stumpp; Giulia Liberati; Jean Delbeke; Antoine Nonclercq; André Mouraux; Riëm El Tahry
Characterization of vagus nerve stimulation-induced pupillary responses in epileptic patients Journal Article
In: Brain Stimulation, vol. 15, pp. 1498–1507, 2022.
Background: Modulation of the locus coeruleus (LC)-noradrenergic system is a key mechanism of vagus nerve stimulation (VNS). Activation of the LC produces pupil dilation, and the VNS-induced change in pupil diameter was demonstrated in animals as a possible dose-dependent biomarker for treatment titration. Objective: This study aimed to characterize VNS-induced pupillary responses in epileptic patients. Methods: Pupil diameter was recorded in ten epileptic patients upon four stimulation conditions: three graded levels of VNS intensity and a somatosensory control stimulation (cutaneous electrical stimulation over the left clavicle). For each block, the patients rated the intensity of stimulation on a numerical scale. We extracted the latency of the peak pupil dilation and the magnitude of the early (0e2.5 s) and late components (2.5e5 s) of the pupil dilation response (PDR). Results: VNS elicited a peak dilation with longer latency compared to the control condition (p ¼ 0.043). The magnitude of the early PDR was significantly correlated with the intensity of perception (p ¼ 0.046), whereas the late PDR was not (p ¼ 0.19). There was a significant main effect of the VNS level of intensity on the magnitude of the late PDR (p ¼ 0.01) but not on the early PDR (p ¼ 0.2). The relationship between late PDR magnitude and VNS intensity was best fit by a Gaussian model (inverted-U). Conclusions: The late component of the PDR might reflect specific dose-dependent effects of VNS, as compared to control somatosensory stimulation. The inverted-U relationship of late PDR with VNS in- tensity might indicate the engagement of antagonist central mechanisms at high stimulation intensities.
Chiara Visentin; Chiara Valzolgher; Matteo Pellegatti; Paola Potente; Francesco Pavani; Nicola Prodi
A comparison of simultaneously-obtained measures of listening effort: Pupil dilation, verbal response time and self-rating Journal Article
In: International Journal of Audiology, vol. 61, no. 7, pp. 561–573, 2022.
Objective: The aim of this study was to assess to what extent simultaneously-obtained measures of listening effort (task-evoked pupil dilation, verbal response time [RT], and self-rating) could be sensitive to auditory and cognitive manipulations in a speech perception task. The study also aimed to explore the possible relationship between RT and pupil dilation. Design: A within-group design was adopted. All participants were administered the Matrix Sentence Test in 12 conditions (signal-to-noise ratios [SNR] of −3, −6, −9 dB; attentional resources focussed vs divided; spatial priors present vs absent). Study sample: Twenty-four normal-hearing adults, 20–41 years old (M = 23.5), were recruited in the study. Results: A significant effect of the SNR was found for all measures. However, pupil dilation discriminated only partially between the SNRs. Neither of the cognitive manipulations were effective in modulating the measures. No relationship emerged between pupil dilation, RT and self-ratings. Conclusions: RT, pupil dilation, and self-ratings can be obtained simultaneously when administering speech perception tasks, even though some limitations remain related to the absence of a retention period after the listening phase. The sensitivity of the three measures to changes in the auditory environment differs. RTs and self-ratings proved most sensitive to changes in SNR.
Cécile Vullings; Zachary Lively; Preeti Verghese
Saccades during visual search in macular degeneration Journal Article
In: Vision Research, vol. 201, pp. 1–14, 2022.
Macular degeneration (MD) compromises both high-acuity vision and eye movements when the foveal regions of both eyes are affected. Individuals with MD adapt to central field loss by adopting a preferred retinal locus (PRL) for fixation. Here, we investigate how individuals with bilateral MD use eye movements to search for targets in a visual scene under realistic binocular viewing conditions. Five individuals with binocular scotomata, 3 individuals with monocular scotomata and 6 age-matched controls participated in our study. We first extensively mapped the binocular scotoma with an eyetracker, while fixation was carefully monitored (Vullings & Verghese, 2020). Participants then completed a visual search task where 0, 1, or 2 Gaussian blobs were distributed randomly across a natural scene. Participants were given 10 s to actively search the display and report the number of blobs. An analysis of saccade characteristics showed that individuals with binocular scotomata made more saccades in the direction of their scotoma than controls for the same directions. Saccades in the direction of the scotoma were typically of small amplitude, and did not fully uncover the region previously hidden by the scotoma. Rather than make more saccades to explore this hidden region, participants frequently made saccades back toward newly uncovered regions. Backward saccades likely serve a similar purpose to regressive saccades exhibited during reading in MD, by inspecting previously covered regions near the direction of gaze. Our analysis suggests that the higher prevalence of backward saccades in individuals with binocular scotomata might be related to the PRL being adjacent to the scotoma.
Josefine Waldthaler; Lena Stock; Charlotte Krüger-Zechlin; Zain Deeb; Lars Timmermann
Cluster analysis reveals distinct patterns of saccade impairment and their relation to cognitive profiles in Parkinson's disease Journal Article
In: Journal of Neuropsychology, pp. 1–13, 2022.
Saccade performance has been reported to be altered in Parkinson's disease (PD), however, with a large variability between studies as both motor and cognitive impairment interfere with oculomotor control. The aim of this study was to identify different patterns in saccade alterations in PD using a data-driven approach and to explore their relationship with cognitive phenotypes. Sixty-one participants with PD and 25 controls performed eye-tracking (horizontal and vertical prosaccades, antisaccades) and neuropsychological testing. Hierarchical cluster analysis was applied to the eye-tracking data to subsequently compare the clusters based on demographical, clinical and cognitive characteristics. The three identified clusters of saccade alterations differed in cognitive profiles from healthy controls, but not in PD-related motor symptoms or demographics. The rate of directive errors in the antisaccade task was increased in clusters 1 and 2. Further, cluster 1 was defined by a general disinhibition of reflexive saccades and executive dysfunction in the neuropsychological evaluation. In cluster 2, prolonged saccade latencies and hypometria were accompanied by multidomain cognitive impairment. The cluster 3 showed increased antisaccade latency and vertical hypometria despite lack of evidence for cognitive impairment. Our results suggest that there may be at least two opposing patterns of saccade alterations associated with cognitive impairment in PD, which may explain some of the contradictory results of previous studies.
Josefine Waldthaler; Mikkel C. Vinding; Allison Eriksson; Per Svenningsson; Daniel Lundqvist
Neural correlates of impaired response inhibition in the antisaccade task in Parkinson's disease Journal Article
In: Behavioural Brain Research, vol. 422, pp. 1–12, 2022.
Deficits in response inhibition are a central feature of the highly prevalent dysexecutive syndrome found in Parkinson's disease (PD). Such deficits are related to a range of common clinically relevant symptoms including cognitive impairment as well as impulsive and compulsive behaviors. In this study, we explored the cortical dynamics underlying response inhibition during the mental preparation for the antisaccade task by recording magnetoencephalography (MEG) and eye-movements in 21 non-demented patients with early to mid-stage Parkinson's disease and 21 age-matched healthy control participants (HC). During the pre-stimulus preparatory period for antisaccades we observed: • a preparation-related increase in beta band activity in the right dorsolateral prefrontal cortex (DLPFC) of HC (n = 15) for antisaccades compared with prosaccades that was not detectable in the PD group (n = 17); • a significant attenuation of the preparation-related increase in alpha band power in bilateral FEF and reduced alpha band connectivity between the right DLPFC and right FEF in the PD group compared with HC, suggesting reduced top-down control to inhibit pre-potent activation of FEF in PD; and • a positive correlation between the magnitude of pre-stimulus beta desynchronization in FEF and subsequent antisaccade latency in PD and HC, indicating a relationship between preparatory beta band modulation and effectiveness of subsequent antisaccade execution. Taken together, the results indicate that alterations in pre-stimulus prefrontal alpha and beta activity hinder proactive response inhibition and in turn result in higher error rates and prolonged response latencies in PD.
Carla A. Wall; Frederick Shic; Sreeja Varanasi; Jane E. Roberts
Distinct social attention profiles in preschoolers with autism contrasted to fragile X syndrome Journal Article
In: Autism Research, pp. 1–15, 2022.
Social attention is a critical skill for learning and development. Social attention difficulties are present in both non-syndromic autism spectrum disorder (nsASD) and fragile X syndrome (FXS), and our understanding of these difficulties is complicated by heterogeneity in both disorders, including co-occurring diagnoses like intellectual disability and social anxiety. Existing research largely utilizes a single index of social attention and rarely includes children with intellectual impairment or uses a cross-syndrome approach. This study investigated whether multi-trait social attention profiles including naturalistic initial eye contact, facial attention, and social scene attention differ in preschool children with nsASD and FXS matched on developmental ability (DQ) and contrasted to neurotypical (NT) controls. The relationship between DQ, ASD severity, and social anxiety and social attention profiles was also examined. Initial eye contact related to social scene attention, implicating that naturalistic social attention is consistent with responses during experimental conditions. Reduced eye contact and lower social scene attention characterized nsASD and FXS. Children with nsASD displayed less facial attention than FXS and NT children, who did not differ. Lower DQ and elevated ASD severity associated with decreased eye contact in nsASD and FXS, and lower DQ was associated with lower social scene attention in FXS. Sex, social anxiety, and age were not associated with social attention. These findings suggest social attention profiles of children with nsASD are highly similar to, yet distinct from, children with FXS. Children with nsASD may present with a global social attention deficit whereas FXS profiles may reflect context-dependent social avoidance.
Shuai Wang; Jialing Li; Siyu Wang; Can Mi; Wei Wang; Zhengjia Xu; Wenjing Xiong; Longxing Tang; Yanzhang Li
Escapism-based motivation affected the psychological performances of high-risk internet gaming disorder individuals Journal Article
In: Frontiers in Psychiatry, vol. 13, pp. 1–10, 2022.
Background: Escapism-based motivation (EBM) is considered as one of the diagnostic criteria for internet gaming disorder (IGD). However, how EBM affects the high risk of IGD (HIGD) population remains unclear. Methods: An initial number of 789 college students participated in the general, internet gaming behavior, and motivation surveys. After multiple evaluations, 57 individuals were identified as HIGD (25 with EBM, H-EBM; 32 with non-EBM, H-nEBM). In addition, 51 no-gaming individuals were included as the control group (CONTR). The cohorts completed the psychological assessments and eye-tracking tests, and analyses of group differences, correlations, and influencing factors of the indicators were performed. Results: The Barratt impulsiveness score of H-nEBM and H-EBM was significantly higher than that of CONTR (MD = 3.605
Shuai Wang; Jialing Li; Siyu Wang; Wei Wang; Can Mi; Wenjing Xiong; Zhengjia Xu; Longxing Tang; Yanzhang Li
Abnormal psychological performance as potential marker for high risk of internet gaming disorder: An eye-tracking study and support vector machine analysis Journal Article
In: Frontiers in Psychology, vol. 13, pp. 1–9, 2022.
Individuals with high risk of internet gaming disorder (HIGD) showed abnormal psychological performances in response inhibition, impulse control, and emotion regulation, and are considered the high-risk stage of internet gaming disorder (IGD). The identification of this population mainly relies on clinical scales, which are less accurate. This study aimed to explore whether these performances have highly accurate for discriminating HIGD from low-risk ones. Eye tracking based anti-saccade task, Barratt impulsiveness scale (BIS), and Wong and Law emotional intelligence scale (WLEIS) were used to evaluate psychological performances in 57 individuals with HIGD and 52 matched low risk of internet gaming disorder (LIGD). HIGD group showed significantly increased BIS total (t = −2.875
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.
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.
Charlotte Elisabeth Piechaczek; Pia Theresa Schröder; Lisa Feldmann; Gerd Schulte-Körne; Ellen Greimel
The effects of attentional deployment on reinterpretation in depressed adolescents: Evidence from an eye-tracking study Journal Article
In: Cognitive Therapy and Research, vol. 46, pp. 967–982, 2022.
Background: Individuals with major depression have difficulties employing cognitive reappraisal. Most prior studies have not accounted for attentional deployment, which seems to be involved in this process. Methods: We investigated the cognitive reappraisal tactic reinterpretation in 20 depressed and 28 healthy youths and assessed regulation success in response to negative pictures via self-report. To investigate attentional deployment during reinterpretation, we applied eye-tracking and manipulated gaze focus by instructing participants to direct their attention towards/away from emotional picture aspects. Results: Depressed adolescents, compared with healthy youths, had a diminished regulation success when their gaze was focused on emotional aspects. Both depressed and healthy adolescents spent less time fixating on emotional facets of negative pictures when using reinterpretation as compared with simply attending to the pictures. Conclusions: Results from this study suggest that adolescents with major depression have emotion regulation deficits when being confronted with negative emotional facets, while showing intact overt attentional processes. The findings provide important starting points for future research investigating the role of other factors which might impact on emotion regulation processes in this patient group, such as cognitive control deficits.
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.
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.
Barbara L. Pitts; Michelle L. Eisenberg; Heather R. Bailey; Jeffrey M. Zacks
PTSD is associated with impaired event processing and memory for everyday events Journal Article
In: Cognitive Research: Principles and Implications, vol. 7, pp. 1–13, 2022.
Current theories of posttraumatic stress disorder (PTSD) propose that memory abnormalities are central to the development and persistence of symptoms. While the most notable memory disturbances in PTSD involve memory for the trauma itself, individuals often have trouble remembering aspects of everyday life. Further, people with PTSD may have difficulty segmenting ongoing activity into discrete units, which is important for our perception and later memory of the activity. The current study investigated whether PTSD diagnosis and symptom severity predicted event segmentation and memory for everyday activities. To do so, 63 people with PTSD and 64 controls with a trauma history watched, segmented, and recalled videos of everyday activities. Viewers with higher PTSD symptom severity showed lower agreement on locations of event boundaries and recalled fewer fine-grained actions than did those with lower symptom severity. These results suggest that PTSD symptoms alter event segmentation, which may contribute to subsequent memory disturbances.
Sophia Antonia Press; Stefanie C. Biehl; C. Carolyn Vatheuer; Gregor Domes; Jennifer Svaldi
Neural correlates of body image processing in binge eating disorder Journal Article
In: Journal of Psychopathology and Clinical Science, vol. 131, no. 4, pp. 350–364, 2022.
Although body image disturbances play a central role in the development, maintenance and relapse of binge eating disorder (BED), studies investigating the neural basis underlying body processing in BED are still missing. To address this gap, we conducted a preregistered (German Clinical Trials Register [Deutsches Register Klinischer Studien; DRKS], Registration DRKS00008107) combined functional magnetic resonance (fMRI)/eye tracking study in which 38 women with BED and 22 healthy controls weight-matched for overall equivalence processed images of their own bodies, an unfamiliar weight- matched body, and visually matched nonbody control stimuli while performing a one-back task. Women with BED responded with higher left fusiform body area (FBA) activity than controls during body image processing. Despite higher levels of self-reported body dissatisfaction, women with BED did not show overactivation in emotion-processing areas in response to their own body. The eye-track- ing results indicated that visual attention toward the presented stimuli was associated with increased ac- tivity in the extrastriate body area (EBA) and FBA across groups. Our results thus provide evidence for an aberrant neural processing of body images in BED and highlight the importance of controlling for visual attention in future studies assessing neuronal body processing.
Jonathan E. Prunty; Jolie R. Keemink; David J. Kelly
Infants show pupil dilatory responses to happy and angry facial expressions Journal Article
In: Developmental Science, vol. 25, no. 2, pp. 1–11, 2022.
Facial expressions are one way in which infants and adults communicate emotion. Infants scan expressions similarly to adults, yet it remains unclear whether they are receptive to the affective information they convey. The current study investigates 6-, 9- and 12-month infants' (N = 146) pupillary responses to the six “basic” emotional expressions (happy, sad, surprise, fear, anger, and disgust). To do this we use dynamic stimuli and gaze-contingent eye-tracking to simulate brief interactive exchanges, alongside a static control condition. Infants' arousal responses were stronger for dynamic compared to static stimuli. And for dynamic stimuli we found that, compared to neutral, infants showed dilatory responses for happy and angry expressions only. Although previous work has shown infants can discriminate perceptually between facial expressions, our data suggest that sensitivity to the affective content of all six basic emotional expressions may not fully emerge until later in ontogeny.
Xiao-jing Qin; Jia-li Liu; Ji-fang Cui; Hai-song Shi; Jun-yan Ye; Tian-xiao Yang; Ya Wang
Prospective memory performance and its improvement in individuals with high schizotypal traits: Evidence from eye-tracking studies Journal Article
In: Clinical Neurophysiology, vol. 143, pp. 133–142, 2022.
Objective: This study aimed to examine prospective memory (PM) performance and the potential effect of implementation intention on PM performance and the underlying mechanisms in individuals with high schizotypyal traits (HSTs) using eye-tracking paradigms. Methods: In Experiment 1, 30 individuals with HSTs and 30 individuals with low schizotypal traits (LSTs) underwent a visual search task that involved PM cues, and participants' eye movements were recorded. In Experiment 2, 50 individuals with HSTs were randomly assigned to the implementation intention group and typical instruction group. Results: In Experiment 1, individuals with HSTs had a lower PM accuracy and performed less PM cue monitoring (indicated by fewer total fixation counts on distractor words) than individuals with LSTs. In Experiment 2, implementation intention significantly improved PM accuracy and increased total fixation counts on distractor words in individuals with HSTs compared to the HST group with typical instruction. Conclusions: Individuals with HSTs were impaired in PM and showed reduced cue monitoring compared to individuals with LSTs. Implementation intention improved PM performance and facilitated cue monitoring in individuals with HSTs. Significance: Our findings indicate that cue monitoring may be an important process of intervention target for PM for individuals in the schizophrenia spectrum.
Hanane Ramzaoui; Sylvane Faure; Renaud David; Sara Spotorno
Top-down and bottom-up sources of eye-movement guidance during realistic scene search in Alzheimer's disease Journal Article
In: Neuropsychology, vol. 36, no. 7, pp. 597–613, 2022.
Objective: Visual search is a crucial task in daily life, but in Alzheimer's disease (AD) it has usually been investigated using simple arrays. Here, we used scenes depicting real environments and studied the time course of attentional guidance. Method: We analyzed eye-movement differences between mild AD patients and age-matched healthy controls during search. We examined top-down guidance, manipulating the target template (precise picture vs. word cue) and the target-scene semantic consistency (consistent vs. inconsistent), and bottom-up guidance, manipulating the perceptual salience (high vs. low) of targets and distractors. Results: During scene scanning, AD patients had longer search times, made more fixations before the first target fixation, and showed a greater probability of distractor selection, with longer distractor fixation. AD also led to longer target fixation. In patients and controls, picture cues and highly salient targets improved all search phases, whereas consistent targets only improved search initiation (first saccade). Moreover, topdown and bottom-up guidance interacted in initiation and scanning, and this did not differ between the two groups of participants. However, AD led to a smaller picture cue benefit in shortening distractor fixation and greater bottom-up search facilitation during scanning, where a high-salience target reduced the performance gap between patients and controls. Conclusions: Our study shows the importance of top-down and bottomup guidance, and their integration, in improving search in AD patients. It suggests that precise target cues and, even more, highly salient targets may act as environmental supports that enhance attentional processing and search performance.
Ileana Ratiu; Schea Fissel-Brannick; Miyka Whiting; Lindsay Murnion; Tamiko Azuma
The impact of mild traumatic brain injury on reading comprehension and eye movements: preliminary results Journal Article
In: Journal of Communication Disorders, vol. 96, pp. 1–18, 2022.
Introduction: Individuals who sustain a mild traumatic brain injury (mTBI) can suffer from executive function, working memory, and attention deficits, which can impact functional task performance, including reading comprehension. Individuals with mTBI commonly report reading difficulties, but such difficulties have been historically difficult to capture using behavioral measures. The current study examined reading performance in those with and without mTBI using eye-tracking measures, which may be more sensitive to reading impairment in mTBI. Method/Results: In Experiment 1, 26 participants with a history of mTBI and 26 healthy control participants completed working memory (WM) and reading comprehension tasks. We found no differences in behavioral measures but found that spontaneous eye-blinking frequency was lower during the reading task in the mTBI group. In Experiment 2, we explored the impact of auditory distraction (e.g., multi-talker babble) on reading and memory performance. Twenty-three new participants with a history of mTBI and 26 healthy control participants completed a short-term memory (STM) task, a WM task, and a reading comprehension task under two distraction conditions. As in Experiment 1, we found no differences on behavioral measures, but observed significant differences on spontaneous eye-blinking frequency between those with and without mTBI. Group differences in distraction effects were also observed and performance on the WM task predicted reading comprehension performance. Conclusions: The lack of differences on behavioral measures between groups, but lower frequencies of spontaneous eye blinking in the mTBI group suggests that while these individuals successfully completed the reading comprehension task, they may require more cognitive resources to do so.
Mariel Roberts; Marisa Carrasco
Exogenous attention generalizes location transfer of perceptual learning in adults with amblyopia Journal Article
In: iScience, vol. 25, no. 3, pp. 1–29, 2022.
Visual perceptual learning (VPL) is a behavioral manifestation of brain neuroplasticity. However, its practical effectiveness is limited because improvements are often specific to the trained conditions and require significant time and effort. It is critical to understand the conditions that promote learning and transfer. Covert endogenous (voluntary) and exogenous (involuntary) spatial attention help overcome VPL location specificity in neurotypical adults, but whether they also do so for people with atypical visual development is unknown. This study investigates the role of exogenous attention during VPL in adults with amblyopia, an ideal population given their asymmetrically developed, but highly plastic, visual cortex. Here we show that training on a discrimination task leads to improvements in foveal contrast sensitivity, acuity, and stereoacuity. Notably, exogenous attention helps generalize learning beyond trained spatial locations. Future large-scale studies can verify the extent to which attention enhances the effectiveness of perceptual learning during rehabilitation of visual disorders.
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.
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.
Anat Rudich-Strassler; Nimrod Hertz-Palmor; Amit Lazarov
Looks interesting: Attention allocation in depression when using a news website – An eye tracking study Journal Article
In: Journal of Affective Disorders, vol. 304, pp. 113–121, 2022.
Background: Eye-tracking-based attention research has shown attentional biases toward dysphoric and away from positive stimuli in depression. However, most research used prototypical stimuli (co-presented contrasting emotional faces/pictures), less reflective of real-life situations. The current study addressed this limitation by examining participants' attentional allocation patterns while freely viewing a news website containing dysphoric and positive news articles. Methods: Participants with high levels of depression (HD; n = 30) and with minimal levels of depression (MD; n = 30) freely viewed a fictitious news website for 3.5 min, containing six articles (picture + text) with dysphoric content and six with positive content. Gaze patterns on corresponding areas of interest (AOIs) were compared. Following the task, participants rated each article's valence, authenticity, and interest. Results: Compared to MD participants, HD participants spent more time dwelling on dysphoric articles and less time dwelling on positive articles. Within group analyses showed that while HD participants spent more time dwelling on dysphoric compared to positive articles, MD participants showed no preference, allocating their attention equally to both article types. Echoing within-group gaze patterns, HD participants rated the dysphoric articles as being more interesting than the positive articles, while MD participants rated both types of articles as being equally interesting. Conclusion: Attentional biases in depression were also evident when using a more ecologically valid task such as viewing a news website, manifesting as increase attention allocation to dysphoric over positive content. This attention pattern may be related to corresponding differences in the level of interest participants found in each article type.
Ying Wang; Hai-Long Lyu; Xiao-Han Tian; Bing Lang; Xiao-Yi Wang; David St Clair; Renrong Wu; Jingping Zhao
The similar eye movement dysfunction between major depressive disorder, bipolar depression and bipolar mania Journal Article
In: The World Journal of Biological Psychiatry, vol. 23, no. 9, pp. 689–702, 2022.
Objective: To find eye movement characteristics in patients with affective disorders. Method: The demographic and clinical evaluation data of patients with major depressive disorder (MDD), bipolar disorder (BPD), and healthy control (HC) were collected. EyeLink 1000 eye tracker was used to collect eye movement data. Chi-squared test and independent sample t-test were used for demographics and clinical characteristics. The Mann–Whitney U-test was used to compare the eye movement variables among four groups, and the FDR method was used for multiple comparison correction. Pearson correlation analysis was used to analyse the relationship between clinical symptoms and eye movement variables. Results: Patients with affective disorders showed smaller saccade amplitude under free-viewing task, more fixations and saccades, shorter fixation duration, longer saccade duration under fixation stability and smooth pursuit tasks (all, p < 0.05) when compared to HC, but there was no significant difference in all eye movement variables among patients in the three groups. Also, all eye movement variables under the three paradigms had no significant correlation with clinical scale scores. Conclusion: Patients with major depression, bipolar depression and bipolar mania share similar eye movement dysfunction under free-viewing, fixation stability and smooth pursuit tasks.
Jaimie C. Wilkie; Nathan A. Ryckman; Lynette J. Tippett; Anthony J. Lambert
A test of the unified model of vision and attention: Effects of parietal-occipital damage on visual orienting Journal Article
In: Neuropsychologia, vol. 168, pp. 1–12, 2022.
Visual orienting was studied in a patient (FM) with parietal-occipital damage due to oligodendroglioma and associated surgery, and in eighteen control participants. The ability of FM and control participants to shift attention in response to spatial landmark cues, and in response to cues that recruit endogenous orienting via encoding of cue identity, were assessed. According to the unified model of vision and attention (Lambert, A. et al., Journal of Experimental Psychology: Human Perception & Performance, 44, 412–432) FM should find it difficult to orient attention in response to spatial landmarks due to impaired functioning of the dorsal visual stream; but shifting attention in response to cue identity, encoded via the ventral visual stream, should be spared. Consistent with these predictions, FM was unable to shift attention in the landmark cueing task, but shifted attention effectively in response to identity cues; and her visual orienting performance differed reliably from controls. These findings complement our earlier observation of preserved orienting towards landmark cues in a patient with bilateral damage to the ventral visual stream, and add to a growing body of evidence in support of the unified model of vision and attention.
Chen Xing; Yajuan Zhang; Hongliang Lu; Xia Zhu; Danmin Miao
Trait anxiety affects attentional bias to emotional stimuli across time: A growth curve analysis Journal Article
In: Frontiers in Neuroscience, vol. 16, pp. 1–22, 2022.
Many studies have illustrated the close relationship between anxiety disorders and attentional functioning, but the relationship between trait anxiety and attentional bias remains controversial. This study examines the effect of trait anxiety on the time course of attention to emotional stimuli using materials from the International Affective Picture System. Participants with high vs. low trait anxiety (HTA vs. LTA) viewed four categories of pictures simultaneously: dysphoric, threatening, positive, and neutral. Their eye-movements for each emotional stimulus were recorded for static and dynamic analysis. Data were analyzed using a mixed linear model and growth curve analysis. Specifically, the HTA group showed a greater tendency to avoid threatening stimuli and more pupil diameter variation in the early period of stimulus presentation (0–7.9 s). The HTA group also showed a stronger attentional bias toward positive and dysphoric stimuli in the middle and late period of stimulus presentation (7.9–30 s). These results suggest that trait anxiety has a significant temporal effect on attention to emotional stimuli, and that this effect mainly manifests after 7 s. In finding stronger attentional avoidance of threatening stimuli and more changes in neural activity, as well as a stronger attentional bias toward positive stimuli, this study provides novel insights on the relationship between trait anxiety and selective attention.
Farnaz Zamani Esfahlani; Lisa Byrge; Jacob Tanner; Olaf Sporns; Daniel P. Kennedy; Richard F. Betzel
Edge-centric analysis of time-varying functional brain networks with applications in autism spectrum disorder Journal Article
In: NeuroImage, vol. 263, pp. 1–12, 2022.
The interaction between brain regions changes over time, which can be characterized using time-varying functional connectivity (tvFC). The common approach to estimate tvFC uses sliding windows and offers limited temporal resolution. An alternative method is to use the recently proposed edge-centric approach, which enables the tracking of moment-to-moment changes in co-fluctuation patterns between pairs of brain regions. Here, we first examined the dynamic features of edge time series and compared them to those in the sliding window tvFC (sw-tvFC). Then, we used edge time series to compare subjects with autism spectrum disorder (ASD) and healthy controls (CN). Our results indicate that relative to sw-tvFC, edge time series captured rapid and bursty network-level fluctuations that synchronize across subjects during movie-watching. The results from the second part of the study suggested that the magnitude of peak amplitude in the collective co-fluctuations of brain regions (estimated as root sum square (RSS) of edge time series) is similar in CN and ASD. However, the trough-to-trough duration in RSS signal is greater in ASD, compared to CN. Furthermore, an edge-wise comparison of high-amplitude co-fluctuations showed that the within-network edges exhibited greater magnitude fluctuations in CN. Our findings suggest that high-amplitude co-fluctuations captured by edge time series provide details about the disruption of functional brain dynamics that could potentially be used in developing new biomarkers of mental disorders.
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.
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.
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.
Dan Zhang; Lihua Xu; Yuou Xie; Xiaochen Tang; Yegang Hu; Xu Liu; Guisen Wu; Zhenying Qian; Yingying Tang; Zhi Liu; Tao Chen; HaiChun Liu; Tianhong Zhang; Jijun Wang
Eye movement indices as predictors of conversion to psychosis in individuals at clinical high risk Journal Article
In: European Archives of Psychiatry and Clinical Neuroscience, pp. 1–11, 2022.
Eye movement abnormalities have been established as an “endophenotype” of schizophrenia. However, less is known about the possibility of these abnormalities as biomarkers for psychosis conversion among clinical high risk (CHR) populations. In the present study, 108 CHR individuals and 70 healthy controls (HC) underwent clinical assessments and eye-tracking tests, comprising fixation stability and free-viewing tasks. According to three-year follow-up outcomes, CHR participants were further stratified into CHR-converter (CHR-C; n = 21) and CHR-nonconverter (CHR-NC; n = 87) subgroups. Prediction models were constructed using Cox regression and logistic regression. The CHR-C group showed more saccades of the fixation stability test (no distractor) and a reduced saccade amplitude of the free-viewing test than HC. Moreover, the CHR-NC group exhibited excessive saccades and an increased saccade amplitude of the fixation stability test (no distractor; with distractor) compared with HC. Furthermore, two indices could effectively discriminate CHR-C from CHR-NC with an area under the receiver-operating characteristic (ROC) curve of 0.80, including the saccade number of the fixation stability test (no distractor) and the saccade amplitude of the free-viewing test. Combined with negative symptom scores of the Scale of Prodromal Symptoms, the area was 0.81. These findings support that eye movement alterations might emerge before the onset of clinically overt psychosis and could assist in predicting psychosis transition among CHR populations.
TianHong Zhang; YingYu Yang; LiHua Hua Xu; XiaoChen Tang; YeGang Hu; Xin Xiong; YanYan Wei; HuiRu Ru Cui; YingYing Tang; HaiChun Liu; Tao Chen; Zhi Liu; Li Hui; ChunBo Li; XiaoLi Guo; JiJun Wang
Inefficient integration during multiple facial processing in pre-morbid and early phases of psychosis Journal Article
In: The World Journal of Biological Psychiatry, vol. 23, no. 5, pp. 1–13, 2022.
Objectives: We used eye-tracking to evaluate multiple facial context processing and event-related potential (ERP) to evaluate multiple facial recognition in individuals at clinical high risk (CHR) for psychosis. Methods: In total, 173 subjects (83 CHRs and 90 healthy controls [HCs]) were included and their emotion perception performances were accessed. A total of 40 CHRs and 40 well-matched HCs completed an eye-tracking task where they viewed pictures depicting a person in the foreground, presented as context-free, context-compatible, and context-incompatible. During the two-year follow-up, 26 CHRs developed psychosis, including 17 individuals who developed first-episode schizophrenia (FES). Eighteen well-matched HCs were made to complete the face number detection ERP task with image stimuli of one, two, or three faces. Results: Compared to the HC group, the CHR group showed reduced visual attention to contextual processing when viewing multiple faces. With the increasing complexity of contextual faces, the differences in eye-tracking characteristics also increased. In the ERP task, the N170 amplitude decreased with a higher face number in FES patients, while it increased with a higher face number in HCs. Conclusions: Individuals in the very early phase of psychosis showed facial processing deficits with supporting evidence of different scan paths during context processing and disruption of N170 during multiple facial recognition.
Hong Zhou; Yunchuang Sun; Luhua Wei; Xia Wang; Yanyan Jiang; Fan Li; Jing Chen; Wei Sun; Lin Zhang; Guiping Zhao; Zhaoxia Wang
Quantitative assessment of oculomotor function by videonystagmography in multiple system atrophy Journal Article
In: Clinical Neurophysiology, vol. 141, pp. 15–23, 2022.
Objective: To quantitatively assess oculomotor impairments in multiple system atrophy (MSA) and to explore their correlation with clinical characteristics. Methods: We recruited 45 patients with MSA, including 21 with dominant ataxia (MSA-C), 24 with dominant parkinsonism (MSA-P), and 40 age-matched healthy controls. Detailed oculomotor performance in the horizontal direction was measured using videonystagmography (VNG). Results: We found that the proportion of abnormal eye movements in patients with MSA was 93.3% (37.7%, 51.1%, 73.3%, 71.1%, and 37.8% on fixation and gaze-holding, without fixation, saccade, smooth pursuit, and optokinetic nystagmus tests, respectively). Patients with MSA-C showed significantly lower gains in smooth pursuit test and optokinetic nystagmus test, and a higher incidence of hypermetria in the saccade test than patients with MSA-P (all P < 0.05). No oculomotor deficits were correlated with age, age of onset, sex, disease duration, or Unified Multiple System Atrophy Rating Scale (USMARS) (all r < 0.25, P > 0.1). Conclusions: An extremely high incidence of oculomotor impairments could be observed using VNG in both the MSA-C and MSA-P subtypes, although there were some differences between them. Significance: A comprehensive oculomotor examination could serve as a valuable tool in the diagnostic workup of patients with MSA.
Junyi Zhou; Lulu Wang
Differences in the effects of reading and aerobic exercise interventions on inhibitory control of college students with mobile phone addiction Journal Article
In: Frontiers in Psychiatry, vol. 13, pp. 1–9, 2022.
Although many previous studies have shown that short-time moderate-intensity aerobic exercise can improve one's inhibitory control, some researchers suggested that its effect on inhibitory control is small. Meanwhile, some studies have shown that reading has a positive effect on inhibitory control. Since many studies examining the effect of exercise on inhibitory control used reading as a filler task, it is important to compare their effects. The present study used the antisaccade task as a tool to examine the differences in the effects of aerobic exercise and reading on inhibitory control of college students with mobile phone addiction. Thirty healthy college students with mobile phone addiction (range: 17–20 years, mean: 19.2 years) took part in the experiment. Participants were randomly assigned to an aerobic exercise group and a reading group. For the aerobic exercise group, participants were asked to perform moderate-intensity aerobic exercise for 15 min. For the reading group, participants were asked to sit quietly and read articles from newspapers for 15 min. Each participant's inhibitory control was examined pre- and post-intervention using the antisaccade task. In the antisaccade task, they have to direct their gaze toward the mirror image location of the target appearing parafoveally as quickly and as accurately as possible. The results showed significant main effects of Time (pre-test vs. post-test) on antisaccade latency and error rate. More importantly, a significant interaction of Time (pre-test vs. post-test) and Group (aerobic exercise vs. reading) was found on antisaccade latency. Specifically, the antisaccade latencies in the post-test were significantly shorter than those in the pre-test for the reading group, but the antisaccade latencies in the post-test and pre-test were comparable for the aerobic exercise group. The results of the present study imply that although both exercise and reading have effects on inhibitory control of college students with mobile phone addiction, the effect of reading may be somehow superior to exercise. Moreover, the current results also imply that researchers should be cautious when using reading as a filler task in future studies regarding the effect of aerobic exercise. The limitations of the present study were discussed.
Li Zhou; Li Zhang; Yuening Xu; Fuyi Yang; Valerie Benson
Attentional engagement and disengagement differences for circumscribed interest objects in young Chinese children with autism Journal Article
In: Brain Sciences, vol. 12, pp. 1–22, 2022.
The current study aimed to investigate attentional processing differences for circumscribed interest (CI) and non-CI objects in young Chinese children with autism spectrum condition (ASC) and typically developing (TD) controls. In Experiment 1, a visual preference task explored attentional allocation to cartoon CI and non-CI materials between the two groups. We found that ASC children (n = 22, 4.95 ± 0.59 years) exhibited a preference for CI-related objects compared to non-CI objects, and this effect was absent in the TD children (n = 22, 5.14 ± 0.44 years). Experiment 2 utilized the traditional gap-overlap paradigm (GOP) to investigate attentional disengagement from CI or non-CI items in both groups (ASC: n = 20, 5.92 ± 1.13 years; TD: n = 25, 5.77 ± 0.77 years). There were no group or stimulus interactions in this study. Experiment 3 adopted a modified GOP (MGOP) to further explore disengagement in the two groups (ASC: n = 20, 5.54 ± 0.95 years; TD: n = 24, 5.75 ± 0.52 years), and the results suggested that exogenous disengagement performance was preserved in the ASC group, but the children with ASC exhibited increased endogenous attentional disengagement compared to TD peers. Moreover, endogenous disengagement was influenced further in the presence of CI-related objects in the ASC children. The current results have implications for understanding how the nature of engagement and disengagement processes can contribute to differences in the development of core cognitive skills in young children with ASC.
Wei Zhou; Yi Fan; Yulin Chang; Wenjuan Liu; Jiuju Wang; Yufeng Wang
Pathogenesis of comorbid ADHD and Chinese developmental dyslexia: Evidence from eye-movement tracking and rapid automatized naming Journal Article
In: Journal of Attention Disorders, pp. 1–13, 2022.
Background: ADHD and Chinese developmental dyslexia (DD) have a very high comorbidity rate; however, which cognitive deficits characterize the comorbidity and when they occur during cognitive processing are still under debate. Methods: Rapid automatic naming (RAN) tasks with eye-movement tracking were conducted with 75 children who were typically developing, had comorbid ADHD and DD, had only ADHD, and had only DD. Results: The clinical groups had longer first fixation durations than the control for RAN digits. Temporal eye-movement measures, such as gaze duration and total reading time, were found to vary between the comorbidity and ADHD groups. Spatial eye-movement measures, such as regression probability and incoming saccade amplitude, differed between the comorbidity and DD groups. Conclusions: These results indicate that investigation with eye-movement measures combined with RAN tasks can strengthen the understanding of the pathogenesis of comorbid ADHD and DD.
Jing Zhu; Shiqing Wei; Xiannian Xie; Changlin Yang; Yizhou Li; Xiaowei Li; Bin Hu
Content-based multiple evidence fusion on EEG and eye movements for mild depression recognition Journal Article
In: Computer Methods and Programs in Biomedicine, vol. 226, pp. 1–11, 2022.
Background and objective: Depression is a serious neurological disorder that has become a major health problem worldwide. The detection of mild depression is important for the diagnosis of depression in early stages. This research seeks to find a more accurate fusion model which can be used for mild depression detection using Electroencephalography and eye movement data. Methods: This study proposes a content-based multiple evidence fusion (CBMEF) method, which fuses EEG and eye movement data at decision level. The method mainly includes two modules, the classification performance matrix module and the dual-weight fusion module. The classification performance matrices of different modalities are estimated by Bayesian rule based on confusion matrix and Mahalanobis distance, and the matrices were used to correct the classification results. Then the relative conflict degree of each modality is calculated, and different weights are assigned to the above modalities at the decision fusion layer according to this conflict degree. Results: The experimental results show that the proposed method outperforms other fusion methods as well as the single modality results. The highest accuracies achieved 91.12%, and sensitivity, specificity and precision were 89.20%, 93.03%, 92.76%. Conclusions: The promising results showed the potential of the proposed approach for the detection of mild depression. The idea of introducing the classification performance matrix and the dual-weight model to multimodal biosignals fusion casts a new light on the researches of depression recognition.
Jing Zhu; Changlin Yang; Xiannian Xie; Shiqing Wei; Yizhou Li; Xiaowei Li; Bin Hu
Mutual Information Based Fusion Model (MIBFM): Mild depression recognition using EEG and pupil area signals Journal Article
In: Journal of LATEX Class Files, vol. 3045, pp. 1–14, 2022.
The detection of mild depression is conducive to the early intervention and treatment of depression. This study explored the fusion of electroencephalography (EEG) and pupil area signals to build an effective and convenient mild depression recognition model. We proposed Mutual Information Based Fusion Model (MIBFM), which innovatively used pupil area signals to select EEG electrodes based on mutual information. Then we extracted features from EEG and pupil area signals in different bands, and fused bimodal features using the denoising autoencoder. Experimental results showed that MIBFM could obtain the highest accuracy of 87.03%. And MIBFM exhibited better performance than other existing methods. Our findings validate the effectiveness of the use of pupil area as signals, which makes eye movement signals can be easily obtained using high resolution camera, and the EEG electrode selection scheme based on mutual information is also proved to be an applicable solution for data dimension reduction and multimodal complementary information screening. This study casts a new light for mild depression recognition using multimodal data of EEG and pupil area signals, and provides a theoretical basis for the development of portable and universal application systems.