EyeLink Clinical and Oculomotor Eye-Tracking Publications
EyeLink clinical and oculomotor research publications up until 2020 (with some early 2021s) are listed below by year. You can search the publications using keywords such as Saccadic Adaptation, Schizophrenia, Nystagmus, etc. You can also search for individual author names, and limit searches by year (choose the year then click the search button). If we missed any EyeLink clinical or oculomotor article, please email us!
Delia A Gheorghe; Muriel T N Panouillères; Nicholas D Walsh
In: Cerebellum and Ataxias, 8 (1), pp. 1–11, 2021.
Background: Transcranial Direct Current Stimulation (tDCS) over the prefrontal cortex has been shown to modulate subjective, neuronal and neuroendocrine responses, particularly in the context of stress processing. However, it is currently unknown whether tDCS stimulation over other brain regions, such as the cerebellum, can similarly affect the stress response. Despite increasing evidence linking the cerebellum to stress-related processing, no studies have investigated the hormonal and behavioural effects of cerebellar tDCS. Methods: This study tested the hypothesis of a cerebellar tDCS effect on mood, behaviour and cortisol. To do this we employed a single-blind, sham-controlled design to measure performance on a cerebellar-dependent saccadic adaptation task, together with changes in cortisol output and mood, during online anodal and cathodal stimulation. Forty-five participants were included in the analysis. Stimulation groups were matched on demographic variables, potential confounding factors known to affect cortisol levels, mood and a number of personality characteristics. Results: Results showed that tDCS polarity did not affect cortisol levels or subjective mood, but did affect behaviour. Participants receiving anodal stimulation showed an 8.4% increase in saccadic adaptation, which was significantly larger compared to the cathodal group (1.6%). Conclusion: The stimulation effect on saccadic adaptation contributes to the current body of literature examining the mechanisms of cerebellar stimulation on associated function. We conclude that further studies are needed to understand whether and how cerebellar tDCS may module stress reactivity under challenge conditions.
Vassilis Cutsuridis; Shouyong Jiang; Matt J Dunn; Anne Rosser; James Brawn; Jonathan T Erichsen
In: Chaos, 31 , pp. 1–13, 2021.
Huntington's disease (HD), a genetically determined neurodegenerative disease, is positively correlated with eye movement abnormalities in decision making. The antisaccade conflict paradigm has been widely used to study response inhibition in eye movements and reliable performance deficits in HD subjects have been observed including greater number and timing of direction errors. We recorded the error rates and response latencies of early HD patients and healthy age-matched controls performing the mirror antisaccade task. HD participants displayed slower and more variable antisaccade latencies and increased error rates relative to healthy controls. A competitive accumulator-to-threshold neural model was then employed to quantitatively simulate the controls' and patients' reaction latencies and error rates and uncover the mechanisms giving rise to the observed HD antisaccade deficits. Our simulations showed: 1) a more gradual and noisy rate of accumulation of evidence by HD patients is responsible for the observed prolonged and more variable antisaccade latencies in early HD; 2) the confidence level of early HD patients making a decision is unaffected by the disease; and 3) the antisaccade performance of healthy controls and early HD patients is the end product of a neural lateral competition (inhibition) between a correct and an erroneous decision process, and not the end product of a third top-down stop signal suppressing the erroneous decision process as many have speculated.
Gayle DeDe; Denis Kelleher
In: Journal of Neurolinguistics, 57 , pp. 1–19, 2021.
The present study examined how healthy aging and aphasia influence the capacity for readers to generate structural predictions during online reading, and how animacy cues influence this process. Non-brain-damaged younger (n = 24) and older (n = 12) adults (Experiment 1) and individuals with aphasia (IWA; n = 11; Experiment 2) read subject relative and object relative sentences in an eye-tracking experiment. Half of the sentences included animate sentential subjects, and the other half included inanimate sentential subjects. All three groups used animacy information to mitigate effects of syntactic complexity. These effects were greater in older than younger adults. IWA were sensitive to structural frequency, with longer reading times for object relative than subject relative sentences. As in previous work, effects of structural complexity did not emerge on IWA's first pass through the sentence, but were observed when IWA reread critical segments of the sentences. Thus, IWA may adopt atypical reading strategies when they encounter low frequency or complex sentence structures, but they are able to use animacy information to reduce the processing disruptions associated with these structures.
Judith Bek; Emma Gowen; Stefan Vogt; Trevor J Crawford; Ellen Poliakoff; Emma Gowen; Stefan Vogt; Trevor J Crawford; Ellen Poliakoff
In: Neuropsychologia, 150 , pp. 1–11, 2021.
Action observation and imitation have been found to influence movement in people with Parkinson's disease (PD), but simple visual stimuli can also guide their movement. To investigate whether action observation may provide a more effective stimulus than other visual cues, the present study examined the effects of observing human pointing movements and simple visual stimuli on hand kinematics and eye movements in people with mild to moderate PD and age-matched controls. In Experiment 1, participants observed videos of movement sequences between horizontal positions, depicted by a simple cue with or without a moving human hand, then imitated the sequence either without further visual input (consecutive task) or while watching the video again (concurrent task). Modulation of movement duration, in accordance with changes in the observed stimulus, increased when the simple cue was accompanied by the hand and in the concurrent task, whereas modulation of horizontal amplitude was greater with the simple cue alone and in the consecutive task. Experiment 2 compared imitation of kinematically-matched dynamic biological (human hand) and non- biological (shape) stimuli, which moved with a high or low vertical trajectory. Both groups exhibited greater modulation for the hand than the shape, and differences in eye movements suggested closer tracking of the hand. Despite producing slower and smaller movements overall, the PD group showed a similar pattern of imitation to controls across tasks and conditions. The findings demonstrate that observing human action influences aspects of movement such as duration or trajectory more strongly than non-biological stimuli, particularly during concurrent imitation.
William Rosengren; Marcus Nyström; Björn Hammar; Martin Stridh
In: Physiological Measurement, 2021.
Objective: Pathological nystagmus is a symptom of oculomotor disease where the eyes oscillate involuntarily. The underlying cause of the nystagmus and the characteristics of the oscillatory eye movements are patient specific. An important part of clinical assessment in nystagmus patients is therefore to characterise different recorded eye-tracking signals, i.e., waveforms. Approach: A method for characterisation of the nystagmus waveform morphology is proposed. The method extracts local morphologic characteristics based on a sinusoidal model, and clusters these into a description of the complete signal. The clusters are used to characterise and compare recordings within and between patients and tasks. New metrics are proposed that can measure waveform similarity at different scales; from short signal segments up to entire signals, both within and between patients. Main results: The results show that the proposed method robustly can find the most prominent nystagmus waveforms in a recording. The method accurately identifies different eye movement patterns within and between patients and across different tasks. Significance: In conclusion, by allowing characterisation and comparison of nystagmus waveform patterns, the proposed method opens up for investigation and identification of the underlying condition in the individual patient, and for quantifying eye movements during tasks.
Carly Moser; Lyndsay Schmitt; Joseph Schmidt; Amanda Fairchild; Jessica Klusek
In: Brain and Cognition, 148 , pp. 1–10, 2021.
One in 113-178 females worldwide carry a premutation allele on the FMR1 gene. The FMR1 premutation is linked to neurocognitive and neuromotor impairments, although the phenotype is not fully understood, particularly with respect to age effects. This study sought to define oculomotor response inhibition skills in women with the FMR1 premutation and their association with age and fall risk. We employed an antisaccade eye- tracking paradigm to index oculomotor inhibition skills in 35 women with the FMR1 premutation and 28 control women. The FMR1 premutation group exhibited longer antisaccade latency and reduced accuracy relative to controls, indicating deficient response inhibition skills. Longer response latency was associated with older age in the FMR1 premutation and was also predictive of fall risk. Findings highlight the utility of the antisaccade paradigm for detecting early signs of age-related executive decline in the FMR1 premutation, which is related to fall risk. Findings support the need for clinical prevention efforts to decrease and delay the trajectory of age-related executive decline in women with the FMR1 premutation during midlife.
Annabell Coors; Natascha Merten; David D Ward; M Schmid; Monique M B Breteler; Ulrich Ettinger
In: Vision Research, 178 , pp. 124–133, 2021.
Assessing physiological changes that occur with healthy ageing is prerequisite for understanding pathophysiological age-related changes. Eye movements are studied as biomarkers for pathological changes because they are altered in patients with neurodegenerative disorders. However, there is a lack of data from large samples assessing age-related physiological changes and sex differences in oculomotor performance. Thus, we assessed and quantified cross-sectional relations of age and sex with oculomotor performance in the general population. We report results from the first 4,000 participants (aged 30–95 years) of the Rhineland Study, a community- based prospective cohort study in Bonn, Germany. Participants completed fixation, smooth pursuit, pro- saccade and antisaccade tasks. We quantified associations of age and sex with oculomotor outcomes using multivariable linear regression models. Performance in 12 out of 18 oculomotor measures declined with increasing age. No differences between age groups were observed in five antisaccade outcomes (amplitude- adjusted and unadjusted peak velocity, amplitude gain, spatial error and percentage of corrected errors) and for blink rate during fixation. Small sex differences occurred in smooth pursuit velocity gain (men have higher gain) and blink rate during fixation (men blink less). We conclude that performance declines with age in two thirds of oculomotor outcomes but that there was no evidence of sex differences in eye movement performance except for two outcomes. Since the percentage of corrected antisaccade errors was not associated with age but is known to be affected by pathological cognitive decline, it represents a promising candidate preclinical biomarker of neurodegeneration.
Shin ichi Tokushige; Shunichi Matsuda; Satomi Inomata-Terada; Masashi Hamada; Yoshikazu Ugawa; Shoji Tsuji; Yasuo Terao
Premature saccades: A detailed physiological analysis Journal Article
In: Clinical Neurophysiology, 132 (1), pp. 63–76, 2021.
Objective: Premature saccades (PSs) are those made with latencies too short for the direction and amplitude to be specifically programmed. We sought to determine the minimum latency needed to establish accurate direction and amplitude, and observed what occurs when saccades are launched before this minimum latency. Methods: In Experiment 1, 249 normal subjects performed the gap saccade task with horizontal targets. In Experiment 2, 28 normal subjects performed the gap saccade task with the targets placed in eight directions. In Experiment 3, 38 normal subjects, 49 patients with Parkinson's disease (PD), and 10 patients with spinocerebellar degeneration (SCD) performed the gap saccade task with horizontal targets. Results: In Experiment 1, it took 100 ms to accurately establish saccade amplitudes and directions. In Experiment 2, however, the latencies needed for accurate amplitude and direction establishment were both approximately 150 ms. In Experiment 3, the frequencies of PSs in patients with PD and SCD were lower than those of normal subjects. Conclusions: The saccade amplitudes and directions are determined simultaneously, 100–150 ms after target presentation. PSs may result from prediction of the oncoming target direction or latent saccade activities in the superior colliculus. Significance: Saccade direction and amplitude are determined simultaneously.
Jonathan van Leeuwen; Artem V Belopolsky
Rapid spatial oculomotor updating across saccades is malleable Journal Article
In: Vision Research, 178 , pp. 60–69, 2021.
The oculomotor system uses a sophisticated updating mechanism to adjust for large retinal displacements which occur with every saccade. Previous studies have shown that updating operates rapidly and starts before saccade is initiated. Here we used saccade adaptation to alter life-long expectations about how a saccade changes the location of an object on the retina. Participants made a sequence of one horizontal and one vertical saccade and ignored an irrelevant distractor. The time-course of oculomotor updating was estimated using saccade curvature of the vertical saccade, relative to the distractor. During the first saccade both saccade targets were shifted on 80% of trials, which induced saccade adaptation (Experiment 1). Critically, since the distractor was left stationary, successful saccade adaptation (e.g., saccade becoming shorter) meant that after the first saccade the distractor appeared in a different hemifield than without adaptation. After adaptation, second saccades curved away only from the newly learned distractor location starting at 80 ms after the first saccade. When on the minority of trials (20%) the targets were not shifted, saccades again first curved away from the newly learned (now empty) location, but then quickly switched to curving away from the life-long learned, visible location. When on some trials the distractor was removed during the first saccade, saccades curved away only from the newly learned (but empty) location (Experiment 2). The results show that updating of locations across saccades is not only fast, but is highly malleable, relying on recently learned sensorimotor contingencies.
Milena Raffi; Andrea Meoni; Alessandro Piras
In: Neuroscience Letters, 743 , pp. 1–7, 2021.
The spatial location indicated by a visual cue can bias microsaccades directions towards or away from the cue. Aim of this work was to evaluate the microsaccades characteristics during the monkey's training, investigating the relationship between a shift of attention and practice. The monkey was trained to press a lever at a target onset, then an expanding optic flow stimulus appeared to the right of the target. After a variable time delay, a visual cue appeared within the optic flow stimulus and the monkey had to release the lever in a maximum reaction time (RT) of 700 ms. In the control task no visual cue appeared and the monkey had to attend a change in the target color. Data were recorded in 9 months. Results revealed that the RTs at the control task changed significantly across time. The microsaccades directions were significantly clustered toward the visual cue, suggesting that the animal developed an attentional bias toward the visual space where the cue appeared. The microsaccades amplitude differed significantly across time. The microsaccades peak velocity differed significantly both across time and within the time delays, indicating that the monkey made faster microsaccades when it expected the cue to appear. The microsaccades number was significantly higher in the control task with respect to discrimination. The lack of change in microsaccades rate, duration, number and direction across time indicates that the experience acquired during practicing the task did not influence microsaccades generation.
Lijin Huang; Weijie Wei; Zhi Liu; Tianhong Zhang; Jijun Wang; Lihua Xu; Weiyu Chen; Olivier Le Meur
In: Pattern Recognition Letters, 138 , pp. 608–616, 2020.
Eye movement abnormalities have been effective biomarkers that provide the possibility of distinguishing patients with schizophrenia from healthy controls. The existing methods for measuring eye movement abnormalities mostly focus on synchronic parameters, such as fixation duration and saccade amplitude, which can be directly obtained from eye movement data, while lack of considering more thorough features. In this paper, to better characterize eye-tracking dysfunction, we create a dataset containing 100 images with eye movement data of 40 patients and 30 healthy controls via a free-viewing task, and propose two types of features for effective schizophrenia recognition, i.e. the hand-crafted discriminative eye movement features and the model-metric based features via utilizing the computational models of fixation prediction and the metrics of evaluating their prediction performance. Using the proposed features, two commonly used classifiers including support vector machine and random forest have been trained for classification between patients and controls. Experimental results demonstrate the effectiveness of the proposed features for improving classification performance, and the potential that our method can serve as an alternative and promising approach for the computer-aided diagnosis of schizophrenia.
Sabrina E Twilhaar; Artem V Belopolsky; Jorrit F Kieviet; Ruurd M Elburg; Jaap Oosterlaan; Jorrit F de Kieviet; Ruurd M van Elburg; Jaap Oosterlaan
In: Child Development, 91 (4), pp. 1272–1283, 2020.
Very preterm birth is associated with attention deficits that interfere with academic performance. A better understanding of attention processes is necessary to support very preterm born children. This study examined voluntary and involuntary attentional control in very preterm born adolescents by measuring saccadic eye movements. Additionally, these control processes were related to symptoms of inattention, intelligence, and academic performance. Participants included 47 very preterm and 61 full-term born 13-years-old adolescents. Oculomotor control was assessed using the antisaccade and oculomotor capture paradigm. Very preterm born adolescents showed deficits in antisaccade but not in oculomotor capture performance, indicating impairments in voluntary but not involuntary attentional control. These impairments mediated the relation between very preterm birth and inattention, intelligence, and academic performance.
Quan Wang; Carla A Wall; Erin C Barney; Jessica L Bradshaw; Suzanne L Macari; Katarzyna Chawarska; Frederick Shic
In: Autism Research, 13 (1), pp. 61–73, 2020.
Young children with autism spectrum disorder (ASD) look less toward faces compared to their non-ASD peers, limiting access to social learning. Currently, no technologies directly target these core social attention difficulties. This study examines the feasibility of automated gaze modification training for improving attention to faces in 3-year-olds with ASD. Using free-viewing data from typically developing (TD) controls (n = 41), we implemented gaze-contingent adaptive cueing to redirect children with ASD toward normative looking patterns during viewing of videos of an actress. Children with ASD were randomly assigned to either (a) an adaptive Cue condition (Cue
Guillaume Doucet; Roberto A Gulli; Benjamin W Corrigan; Lyndon R Duong; Julio C Martinez-Trujillo
In: Hippocampus, 30 (3), pp. 192–209, 2020.
Primates use saccades to gather information about objects and their relative spatial arrangement, a process essential for visual perception and memory. It has been proposed that signals linked to saccades reset the phase of local field potential (LFP) oscillations in the hippocampus, providing a temporal window for visual signals to activate neurons in this region and influence memory formation. We investigated this issue by measuring hippocampal LFPs and spikes in two macaques performing different tasks with unconstrained eye movements. We found that LFP phase clustering (PC) in the alpha/beta (8–16 Hz) frequencies followed foveation onsets, while PC in frequencies lower than 8 Hz followed spontaneous saccades, even on a homogeneous background. Saccades to a solid grey background were not followed by increases in local neuronal firing, whereas saccades toward appearing visual stimuli were. Finally, saccade parameters correlated with LFPs phase and amplitude: saccade direction correlated with delta (≤4 Hz) phase, and saccade amplitude with theta (4–8 Hz) power. Our results suggest that signals linked to saccades reach the hippocampus, producing synchronization of delta/theta LFPs without a general activation of local neurons. Moreover, some visual inputs co-occurring with saccades produce LFP synchronization in the alpha/beta bands and elevated neuronal firing. Our findings support the hypothesis that saccade-related signals enact sensory input-dependent plasticity and therefore memory formation in the primate hippocampus.
Francesca Beilharz; Andrea Phillipou; David J Castle; Susan L Rossell
Saccadic eye movements in body dysmorphic disorder Journal Article
In: Journal of Obsessive-Compulsive and Related Disorders, 25 , pp. 1–6, 2020.
Body dysmorphic disorder (BDD) is characterised by a preoccupation with perceived flaws in appearance, which significantly disrupts functioning and causes distress. The difference in self-perception characteristic of BDD has been related to a bias in visual processing across a variety of stimuli and tasks. However, it is unknown how BDD participants perform on basic saccade tasks using eye tracking. Eighteen BDD and 21 healthy control participants completed a battery of saccadic eye movement tasks (fixation, prosaccade, anti-saccade, and memory guided). No significant differences were noted between the groups regarding behavioural performance or patterns of eye movements; however, there was a trend for BDD participants to make increased anticipatory errors on the prosaccade task. Overall, BDD participants demonstrated largely intact saccadic eye movement characteristics which may differentiate BDD from other obsessive-compulsive related disorders, although future research using larger samples is required. It is consequently argued that abnormalities in visual processing apparent among people with BDD may reflect abnormalities in higher-order visual systems.
Ming Ray Liao; Brian A Anderson
Reward learning biases the direction of saccades Journal Article
In: Cognition, 196 , pp. 1–9, 2020.
The role of associative reward learning in guiding feature-based attention and spatial attention is well established. However, no studies have looked at the extent to which reward learning can modulate the direction of saccades during visual search. Here, we introduced a novel reward learning paradigm to examine whether reward-associated directions of eye movements can modulate performance in different visual search tasks. Participants had to fixate a peripheral target before fixating one of four disks that subsequently appeared in each cardinal position. This was followed by reward feedback contingent upon the direction chosen, where one direction consistently yielded a high reward. Thus, reward was tied to the direction of saccades rather than the absolute location of the stimulus fixated. Participants selected the target in the high-value direction on the majority of trials, demonstrating robust learning of the task contingencies. In an untimed visual foraging task that followed, which was performed in extinction, initial saccades were reliably biased in the previously rewarded-associated direction. In a second experiment, following the same training procedure, eye movements in the previously high-value direction were facilitated in a saccade-to-target task. Our findings suggest that rewarding directional eye movements biases oculomotor search patterns in a manner that is robust to extinction and generalizes across stimuli and task.
Elizabeth Carolina Jiménez; August Romeo; Laura Pérez Zapata; Maria Solé Puig; Patricia Bustos-Valenzuela; José Cañete; Paloma Varela Casal; Hans Supèr
In: Vision Research, 169 , pp. 6–11, 2020.
Vergence eye movements are movements of both eyes in opposite directions. Vergence is known to have a role in binocular vision. However recent studies link vergence eye movements also to attention and attention disorders. As attention may be involved in dyslexia, it is sensible to guess that the presence of reading difficulties can be associated with specific patterns in vergence responses. Data from school children performing a word-reading task have been analysed. In the task, children had to distinguish words from non-words (scrambled words or row of X's), while their eye positions were recorded. Our findings show that after stimulus presentation eyes briefly converge. These vergence responses depend on the stimulus type and age of the child, and are different for children with reading difficulties. Our findings support the idea of a role of attention in word reading and offer an explanation of altered attention in dyslexia.
Raymond M Klein; Maryam Kavyani; Alireza Farsi; Michael A Lawrence
In: Cortex, 122 , pp. 123–130, 2020.
Slower reaction times to targets presented at a previously cued or attended location are often attributed to inhibition of return (IOR). It has been suggested that IOR affects a process at the output end of processing continuum when it is generated while the oculomotor system is activated. Following the path set by Kavyani, Farsi, Abdoli, and Klein (2017) we used the locus of slack logic embedded in the psychological refractory period (PRP) paradigm to test this idea. We generated what we expected would be the output form of IOR by beginning each with participants making a target directed saccade which was followed by two tasks. Task 1, was a 2-choice auditory discrimination task and Task 2 was a 2-choice visual localization task. We varied the interval between the onsets of the two targets associated with these two tasks (using TTOAs of 200, 400, or 800 msec). As expected the visual task suffered from a robust PRP effect (substantially delayed RTs at the shorter TTOAs). There was also a robust IOR effect with RTs to localize visual targets being slower when the targets were presented at a previously fixated location. Importantly, and in striking to our previous results wherein we generated the input form of IOR, in the present study there was an additive effect between IOR and TTOA on RT2. As implied by the locus of slack logic, we therefore conclude that the form of IOR generated when the oculomotor system is activated affects a late stage of processing. Converging evidence for this conclusion, from a variety of neuroscientific methods, is presented and the dearth of such evidence about the input form of IOR is noted.
Satoshi Kodama; Shin ichi Tokushige; Yusuke Sugiyama; Kazuya Sato; Juuri Otsuka; Yuichiro Shirota; Masashi Hamada; Atsushi Iwata; Tatsushi Toda; Shoji Tsuji; Yasuo Terao
In: Journal of the Neurological Sciences, 408 , pp. 1–7, 2020.
Objective: Stiff person syndrome (SPS) is usually characterized by truncal muscle rigidity and episodic painful spasms, but it sometimes appears with ocular symptoms called “stiff eyes”. We recorded saccade movements in an SPS patient manifesting with “stiff eyes” conditions with slow saccade velocity and evaluated the effect of immunotherapy including rituximab on saccade parameters. Methods: We repeatedly conducted saccade eye recordings using video-based eye tracking system on a 42-year-old male SPS patient with slow saccade. The velocity and onset latency of visual guided saccades (VGS) were measured at each recording. Because VGS velocity is affected by saccade amplitude, estimated peak velocity (Vmax) was also calculated by taking the relationship between the velocity and the amplitude of saccade into account. Results: The mean VGS velocity improved significantly after two courses of rituximab administration compared with its lowest value. The estimated Vmax decreased as the clinical manifestations worsened, but it increased after rituximab administration. Other neurological symptoms in this patient such as muscle rigidity and gait instability also improved after the treatment. Conclusion: Slow saccade in a “stiff eyes” patient improved after rituximab administration. Our study also indicated that the saccade eye recording is useful for evaluating the clinical condition of SPS when it is complicated with ocular symptoms.
Cassandra Philine Köller; Christian H Poth; Arvid Herwig
In: Psychological Research, 84 (1), pp. 231–244, 2020.
Object perception across saccadic eye movements is assumed to result from integrating two information sources: incoming peripheral object information and information from a foveal prediction (Herwig and Schneider, J Exp Psychol Gen 143(5):1903–1922, 2014, Herwig, J Vis 15(16), 7, 2015). Predictions are supposed to be based on transsaccadic associations of peripheral and foveal object information. The main function of these predictions may be to conceal discrepancies in resolution and locations across saccades. Here we ask how predictions are affected by discrepancies between peripheral and foveal objects. Participants learned unfamiliar transsaccadic associations by making saccades to objects whose shape systematically changed during the saccade. Importantly, we manipulated the size of this change between participants to induce different magnitudes of object discrepancy. In a subsequent test, we found that judgment shifts of peripheral shape perception toward the predicted foveal input depended on change size during acquisition. Specifically, the contribution of prediction decreased for large changes but did not reach zero, showing that even for large changes (i.e., square to circle or vice versa) the prediction was not ignored completely. These findings indicate that object discrepancy during learning determines how much the resulting foveal prediction contributes to perception in the periphery.
Anna Kosovicheva; Peter J Bex
In: Journal of Vision, 20 (5), pp. 1–21, 2020.
The binocular coordination of eye movements in a three-dimensional environment involves a combination of saccade and vergence movements. To maintain binocular accuracy and control in the face of sensory and motor changes (that occur with e.g., normal aging, surgery, corrective lenses), the oculomotor system must adapt in response to manifest visual errors. This may be achieved through a combination of binocular and monocular mechanisms, including the recalibration of saccade and vergence amplitudes in response to different visual errors induced in each eye (Maiello, Harrison, & Bex, 2016). This work has used a double-step paradigm to recalibrate eye movements in response to visual errors produced by dichoptic target steps (e.g., leftward in the left eye and rightward in the right eye). Here, we evaluated the immediate perceptual effects of this adaptation. Experiment 1 measured localization errors following adaptation by comparing the apparent locations of pre-and postsaccadic probes. Consistent with previous work showing localization errors following saccadic adaptation, our results demonstrated that adaptation to a dichoptic step produces different localization errors in the two eyes. Furthermore, in Experiment 2, this effect was reduced for a vergence shift in the absence of a saccade, indicating that saccade programming is responsible for a large component of this illusory shift. Experiment 3 measured postsaccadic stereopsis thresholds and indicated that, unlike localization judgments, adaptation did not influence stereoacuity. Together, these results demonstrate novel dichoptic visual errors following oculomotor adaptation and point to monocular and binocular mechanisms involved in the maintenance of binocular coordination.
Krzysztof Krejtz; Justyna Zurawska; Andrew T Duchowski; Szymon Wichary
In: Journal of Eye Movement Research, 13 (5), pp. 1–15, 2020.
A large body of literature documents the sensitivity of pupil response to cognitive load (e.g., Krejtz et al. 2018) and emotional arousal (Bradley et al., 2008). Recent empirical evidence also showed that microsaccade characteristics and dynamics can be modulated by mental fatigue and cognitive load (e.g., Dalmaso et al. 2017). Very little is known about the sensitivity of microsaccadic characteristics to emotional arousal. The present paper demonstrates in a controlled experiment pupillary and microsaccadic responses to information processing during multi-attribute decision making under affective priming. Twenty-one psychology students were randomly assigned into three affective priming conditions (neutral, aversive, and erotic). Participants were tasked to make several discriminative decisions based on acquired cues. In line with the expectations, results showed microsaccadic rate inhibition and pupillary dilation depending on cognitive effort (number of acquired cues) prior to decision. These effects were moderated by affective priming. Aversive priming strengthened pupillary and microsaccadic response to information processing effort. In general, results suggest that pupillary response is more biased by affective priming than microsaccadic rate. The results are discussed in the light of neuropsychological mechanisms of pupillary and microsaccadic behavior generation.
André Krügel; Lars Rothkegel; Ralf Engbert
In: Journal of Vision, 20 (7), pp. 1–14, 2020.
In an influential theoretical model, human sensorimotor control is achieved by a Bayesian decision process, which combines noisy sensory information and learned prior knowledge. A ubiquitous signature of prior knowledge and Bayesian integration in human perception and motor behavior is the frequently observed bias toward an average stimulus magnitude (i.e., a central-tendency bias, range effect, regression-to-the-mean effect). However, in the domain of eye movements, there is a recent controversy about the fundamental existence of a range effect in the saccadic system. Here we argue that the problem of the existence of a range effect is linked to the availability of prior knowledge for saccade control. We present results from two prosaccade experiments that both employ an informative prior structure (i.e., a nonuniform Gaussian distribution of saccade target distances). Our results demonstrate the validity of Bayesian integration in saccade control, which generates a range effect in saccades. According to Bayesian integration principles, the saccadic range effect depends on the availability of prior knowledge and varies in size as a function of the reliability of the prior and the sensory likelihood.
Kaleb A Lowe; Wolf Zinke; Anthony M Phipps; Josh Cosman; Micala Maddox; Jeffrey D Schall; Charles F Caskey
In: Ultrasound in Medicine & Biology, pp. 1–14, 2020.
Neuromodulation with focused ultrasound (FUS) is being widely explored as a non-invasive tool to stimulate focal brain regions because of its superior spatial resolution and coverage compared with other neuro- modulation methods. The precise effects of FUS stimulation on specific regions of the brain are not yet fully understood. Here, we characterized the behavioral effects of FUS stimulation directly applied through a craniot- omy over the macaque frontal eye field (FEF). In macaque monkeys making directed eye movements to perform visual search tasks with direct or arbitrary responses, focused ultrasound was applied through a craniotomy over the FEF. Saccade response times (RTs) and error rates were determined for trials without or with FUS stim- ulation with pulses at a peak negative pressure of either 250 or 425 kPa. Both RTs and error rates were affected by FUS. Responses toward a target located contralateral to the FUS stimulation were approximately 3 ms slower in the presence of FUS in both monkeys studied, while only one exhibited a slowing of responses for ipsilateral targets. Error rates were lower in one monkey in this study. In another search task requiring making eye move- ments toward a target (pro-saccades) or in the opposite direction (anti-saccades), the RT for pro-saccades increased in the presence of FUS stimulation. Our results indicate the effectiveness of FUS to modulate saccadic responses when stimulating FEF in awake, behaving non-human primates. (E-mail:
Inbar Avni; Gal Meiri; Asif Bar-Sinai; Doron Reboh; Liora Manelis; Hagit Flusser; Analya Michaelovski; Idan Menashe; Ilan Dinstein
In: Autism Research, 13 (6), pp. 935–946, 2020.
Previous eye-tracking studies have reported that children with autism spectrum disorders (ASD) fixate less on faces in comparison to controls. To properly understand social interactions, however, children must gaze not only at faces but also at actions, gestures, body movements, contextual details, and objects, thereby creating specific gaze patterns when observing specific social interactions. We presented three different movies with social interactions to 111 children (71 with ASD) who watched each of the movies twice. Typically developing children viewed the movies in a remarkably predictable and reproducible manner, exhibiting gaze patterns that were similar to the mean gaze pattern of other controls, with strong correlations across individuals (intersubject correlations) and across movie presentations (intra-subject correlations). In contrast, children with ASD exhibited significantly more variable/idiosyncratic gaze patterns that differed from the mean gaze pattern of controls and were weakly correlated across individuals and presentations. Most importantly, quantification of gaze idiosyncrasy in individual children enabled separation of ASD and control children with higher sensitivity and specificity than traditional measures such as time gazing at faces. Individual magnitudes of gaze idiosyncrasy were also significantly correlated with ASD severity and cognitive scores and were significantly correlated across movies and movie presentations, demonstrating clinical sensitivity and reliability. These results suggest that gaze idiosyncrasy is a potent behavioral abnormality that characterizes a considerable number of children with ASD and may contribute to their impaired development. Quantification of gaze idiosyncrasy in individual children may aid in assessing symptom severity and their change in response to treatments. Autism Res 2020, 13: 935-946. textcopyright 2019 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary: Typically, developing children watch movies of social interactions in a reliable and predictable manner, attending faces, gestures, actions, body movements, and objects that are relevant to the social interaction and its narrative. Here, we demonstrate that children with ASD watch such movies with significantly more variable/idiosyncratic gaze patterns that differ across individuals and across movie presentations. We demonstrate that quantifying this gaze variability may aid in identifying children with ASD and in determining the severity of their symptoms.
Naila Ayala; Matthew Heath
In: Journal of Neurotrauma, 37 , pp. 2558–2568, 2020.
A sport-related concussion (SRC) results in short- and long-term deficits in oculomotor control; however, it is unclear whether this change reflects executive dysfunction and/or a performance decrement due to an increase in task-based symptom burden. Here, individuals with a SRC - and age- and sex-matched controls - completed an antisaccade task (i.e., saccade mirror-symmetrical to a target) during the early (initial assessment: textless=12 days) and later (follow-up assessment: textless 30 days) stages of recovery. Antisaccades were used because they require top-down executive control and exhibit performance decrements following a SRC. Reaction time (RT) and directional errors were included with pupillometry because pupil size in the antisaccade task has been shown to provide a neural proxy for executive control. In addition, the Sport-Concussion Assessment Tool (SCAT-5) symptom checklist was completed prior to and after each oculomotor assessment to identify a possible task-based increase in symptomology. The SRC group yielded longer initial assessment RTs, more directional errors and larger task-evoked pupil dilations (TEPD) than the control group. At the follow-up assessment, RTs for the SRC and control group did not reliably differ; however, the former demonstrated more directional errors and larger TEPDs. SCAT-5 symptom severity scores did not vary from the pre- to post-oculomotor evaluation for either initial or follow-up assessments. Accordingly, a SRC imparts a persistent executive dysfunction to oculomotor planning independent of a task-based increase in symptom burden. These findings evince that antisaccades serve as an effective tool to identify subtle executive deficits during the early and later stages of SRC recovery.
Shahab Bakhtiari; Ayca Altinkaya; Christopher C Pack; Abbas F Sadikot
In: Scientific Reports, 10 , pp. 1–11, 2020.
Inhibiting inappropriate actions in a context is an important part of the human cognitive repertoire, and deficiencies in this ability are common in neurological and psychiatric disorders. An anti-saccade is a simple oculomotor task that tests this ability by requiring inhibition of saccades to peripheral targets (pro-saccade) and producing voluntary eye movements toward the mirror position (anti-saccades). Previous studies provide evidence for a possible contribution from the basal ganglia in anti-saccade behavior, but the precise role of different components is still unclear. Parkinson's disease patients with implanted deep brain stimulators (DBS) in subthalamic nucleus (STN) provide a unique opportunity to investigate the role of the STN in anti-saccade behavior. Previous attempts to show the effect of STN DBS on anti-saccades have produced conflicting observations. For example, the effect of STN DBS on anti-saccade error rate is not yet clear. Part of this inconsistency may be related to differences in dopaminergic states in different studies. Here, we tested Parkinson's disease patients on anti- and pro-saccade tasks ON and OFF STN DBS, in ON and OFF dopaminergic medication states. First, STN DBS increases anti-saccade error rate while patients are OFF dopamine replacement therapy. Second, dopamine replacement therapy and STN DBS interact: L-dopa reduces the effect of STN DBS on anti-saccade error rate. Third, STN DBS induces different effects on pro- and anti-saccades in different patients. These observations provide evidence for an important role for the STN in the circuitry underlying context-dependent modulation of visuomotor action selection.
Sonia Bansal; Gi Yeul Bae; Kyle Frankovich; Benjamin M Robinson; Carly J Leonard; James M Gold; Steven J Luck
In: Journal of Abnormal Psychology, 129 (8), pp. 845–857, 2020.
Computational neuroscience models propose that working memory (WM) involves recurrent excitatory feedback loops that maintain firing over time along with lateral inhibition that prevents the spreading of activity to other feature values. In behavioral paradigms, this lateral inhibition appears to cause a repulsion of WM representations away from each other and from other strong sources of input. Recent computational models of schizophrenia have proposed that reduction in the strength of inhibition relative to strength of excitation may underlie impaired cognition, and this leads to the prediction that repulsion effects should be reduced in people with schizophrenia spectrum disorders (PSZ) relative to healthy control subjects (HCS). We tested this hypothesis in 2 experiments measuring WM repulsion effects. In Experiment 1, 45 PSZ and 32 HCS remembered the location of a single object relative to a centrally presented visual landmark and reported this location after a short delay. The reported location was repelled away from the landmark in both groups, but this repulsion effect was increased rather than decreased in PSZ relative to HCS. In Experiment 2, 41 PSZ and 34 HCS remembered 2 sequentially presented orientations and reported each orientation after a short delay. The reported orientations were biased away from each other in both groups, and this repulsion effect was again more pronounced in PSZ than in HCS. Contrary to the widespread hypothesis of reduced inhibition in schizophrenia, we provide robust evidence from 2 experiments showing that the behavioral performance of PSZ exhibited an exaggeration rather than a reduction of competitive inhibition.
Joseph R Bardeen; Thomas A Daniel; Robert D Gordon; Benjamin J Hinnant; Frank W Weathers
Individual differences in attentional control explain the differential expression of threat-related attentional bias among those with posttraumatic stress symptomatology and predict symptom maintenance up to one year later Journal Article
In: Behaviour Research and Therapy, 133 , pp. 1–10, 2020.
Individual differences in attentional control may explain null findings and inconsistent patterns of threat-related attentional bias (ABT) that are common in the posttraumatic stress disorder (PTSD) literature. At Time 1 (T1), trauma-exposed community participants (N = 89) completed a clinical interview, self-report measures, and an eye-tracking task developed to assess ABT. Participants completed follow-up assessments online 6 (T2) and 12 (T3) months later. Those with higher PTSD symptoms and deficits in attentional control exhibited a pattern of undercontrol, characterized by attention maintenance on threat and increased arousal. In contrast, those with higher PTSD symptoms and relatively better attentional control exhibited a pattern of overcontrol, characterized by threat avoidance and reduced arousal. These effects were specific to threat stimuli. Among PTSD symptom clusters, symptoms of hyperarousal were of central importance to the observed effects. Results from the longitudinal analysis indicate that both of these patterns of ABT are maladaptive, resulting in symptom maintenance at T2 and T3. These results have implications for (a) reconciling tensions between disparate models of ABT (i.e., vigilance-avoidance vs. attention maintenance), (b) precision medicine based approaches to targeting PTSD-related ABT, and (c) understanding the transdiagnostic role that attentional control may play in influencing ABT expression.
Mahsa Barzy; Ruth Filik; David Williams; Heather J Ferguson
In: Autism Research, 13 (4), pp. 563–578, 2020.
Typically developing adults are able to keep track of story characters' emotional states online while reading. Filik et al. showed that initially, participants expected the victim to be more hurt by ironic comments than literal, but later considered them less hurtful; ironic comments were regarded as more amusing. We examined these processes in autistic adults, since previous research has demonstrated socio-emotional difficulties among autistic people, which may lead to problems processing irony and its related emotional processes despite an intact ability to integrate language in context. We recorded eye movements from autistic and nonautistic adults while they read narratives in which a character (the victim) was either criticized in an ironic or a literal manner by another character (the protagonist). A target sentence then either described the victim as feeling hurt/amused by the comment, or the protagonist as having intended to hurt/amused the victim by making the comment. Results from the nonautistic adults broadly replicated the key findings from Filik et al., supporting the two-stage account. Importantly, the autistic adults did not show comparable two-stage processing of ironic language; they did not differentiate between the emotional responses for victims or protagonists following ironic versus literal criticism. These findings suggest that autistic people experience a specific difficulty taking into account other peoples' communicative intentions (i.e., infer their mental state) to appropriately anticipate emotional responses to an ironic comment. We discuss how these difficulties might link to atypical socio-emotional processing in autism, and the ability to maintain successful real-life social interactions.
Julian Basanovic; Lies Notebaert; Patrick J F Clarke; Colin MacLeod
In: Cognitive Therapy and Research, pp. 1–9, 2020.
Background: Individuals with heightened anxiety vulnerability demonstrate a bias favouring attention to negative information, and it has been argued that this reflects a difficulty to disengage from negative information. Methods to manipulate attentional bias have demonstrated inconsistent effectiveness, however such methods have not targeted biases in attentional disengagement specifically. A recently developed approach to attentional bias modification, labelled Emotion-in-Motion, has been proposed to result in facilitated attentional disengagement from information. Thus, the present study empirically investigated whether the Emotion-in-Motion task modifies biased attentional disengagement from negative information using eye-movement recordings. Methods: Forty-four participants completed the Emotion-in-Motion attention manipulation task under conditions designed to enhance attention (Attend Negative) or attenuate attention (Avoid Negative) to negative information. Biased attentional engagement with, and attentional disengagement from, negative information was examined subsequently. Results: Participants in the Avoid Negative condition demonstrated lower levels of biased attentional disengagement from negative information as compared to participants in the Attend Negative condition. No difference in biased attentional engagement with negative information was observed. Conclusions: It is concluded that the Emotion-in-Motion task serves to independently manipulate selective attentional disengagement from negative information and may be useful in investigating the specific role of biased attentional disengagement in emotional vulnerability.
Denise Baumeler; Sabine Born; Nicolas Burra; Radek Ptak
In: Vision, 4 , pp. 1–13, 2020.
Illusory visual phenomena, such as palinopsia, polyopsia or allesthesia, are rare manifestations of posterior cortical damage. Symptoms are characterized by illusory perceptions, ranging from isolated stationary objects to scenes and moving persons. Such illusions may appear while the original object is still in view, or become manifest with a delay and last for minutes, hours or even days. Some authors have suggested a disinhibited cortical response underlying visual illusions, but experimental studies supporting this hypothesis are lacking. Here, we examined a rare patient who after focal right parietal injury consistently reported a second stimulus on the left when briefly shown a target in his right hemifield. The patient perceived the illusory stimulus as less intense, and therefore concluded that it must have a different shape than the original stimulus. A masking experiment revealed that the frequency of the illusion was inversely related to the visibility of the original stimulus, suggesting that it depended on early, feedforward visual processing. We propose that illusory perceptions reflect the interplay of two physiological processes: a fast and automatic activation of contralateral, homotopic visual cortex after unilateral stimulation, and the lack of top-down inhibition following damage to the posterior parietal cortex.
Judith Bek; Ellen Poliakoff; Karen Lander
In: Journal of Neuroscience Methods, 331 , pp. 1–7, 2020.
Background: Motion is an important cue to emotion recognition, and it has been suggested that we recognize emotions via internal simulation of others' expressions. There is a reduction of facial expression in Parkinson's disease (PD), which may influence the ability to use motion to recognise emotions in others. However, the majority of previous work in PD has used only static expressions. Moreover, few studies have used eye-tracking to explore emotion processing in PD. New method: We measured accuracy and eye movements in people with PD and healthy controls when identifying emotions from both static and dynamic facial expressions. Results: The groups did not differ overall in emotion recognition accuracy, but motion significantly increased recognition only in the control group. Participants made fewer and longer fixations when viewing dynamic expressions, and interest area analysis revealed increased gaze to the mouth region and decreased gaze to the eyes for dynamic stimuli, although the latter was specific to the control group. Comparison with existing methods: Ours is the first study to directly compare recognition of static and dynamic emotional expressions in PD using eye-tracking, revealing subtle differences between groups that may otherwise be undetected. Conclusions: It is feasible and informative to use eye-tracking with dynamic expressions to investigate emotion recognition in PD. Our findings suggest that people with PD may differ from healthy older adults in how they utilise motion during facial emotion recognition. Nonetheless, gaze patterns indicate some effects of motion on emotional processing, highlighting the need for further investigation in this area.
Eileen E Birch; Yolanda S Castañeda; Christina S Cheng-Patel; Sarah E Morale; Krista R Kelly; Reed M Jost; Lindsey A Hudgins; David A Leske; Jonathan M Holmes
In: Investigative ophthalmology & visual science, 61 (11), pp. 1–6, 2020.
Purpose: To evaluate associations between eye-related quality of life (ER-QOL) assessed by the Child Pediatric Eye Questionnaire (Child PedEyeQ) and functional measures (vision, visuomotor function, self-perception) in children with strabismus, anisometropia, or both. Our hypothesis was that children with functional deficits would have lower ER-QOL, and if so, these associations would support the convergent construct validity of the Child PedEyeQ. Methods: We evaluated 114 children (ages 5-11 years) with strabismus, anisometropia, or both. Each child completed the Child PedEyeQ to assess four Rasch-scored domains of ER-QOL: Functional Vision, Bothered by Eyes/Vision, Social, and Frustration/Worry. In addition, children completed one or more functional tests: visual acuity (n = 114), Randot Preschool Stereoacuity (n = 92), contrast balance index (suppression; n = 91), Readalyzer reading (n = 44), vergence instability (n = 50), Movement Assessment Battery for Children-2 manual dexterity (n = 57), and Pictorial Scale of Perceived Competence and Social Acceptance for Young Children (n = 44). Results: Child PedEyeQ Functional Vision domain scores were correlated with self-perception of physical competence (rs = 0.65; 95% confidence interval [CI], 0.35-0.96) and reading speed (rs = 0.47; 95% CI, 0.16-0.77). Bothered by Eyes/Vision domain scores were correlated with self-perception of physical competence (rs = 0.52; 95% CI, 0.21-0.83). Moderate correlations were observed between Social domain scores and vergence instability (rs = -0.46; 95% CI, -0.76 to -0.15) and self-perception of physical competence (rs = 0.43; 95% CI, 0.12-0.73) and peer acceptance (rs = 0.49; 95% CI, 0.18-0.80). Frustration/Worry domain scores were moderately correlated with self-perception of physical competence (rs = 0.41; 95% CI, 0.10-0.71) and peer acceptance (rs = 0.47; 95% CI, 0.16-0.77). Conclusions: Strong and moderate correlations were observed between functional measures and Child PedEyeQ domain scores. These associations provide supporting evidence that the Child PedEyeQ has convergent construct validity.
Hazel I Blythe; Jonathan H Dickins; Colin R Kennedy; Simon P Liversedge
In: PLoS ONE, 15 (3), pp. e0229934, 2020.
We examined phonological recoding during silent sentence reading in teenagers with a history of dyslexia and their typically developing peers. Two experiments are reported in which participants' eye movements were recorded as they read sentences containing correctly spelled words (e.g., church), pseudohomophones (e.g., cherch), and spelling controls (e.g., charch). In Experiment 1 we examined foveal processing of the target word/nonword stimuli, and in Experiment 2 we examined parafoveal pre-processing. There were four participant groups-older teenagers with a history of dyslexia, older typically developing teenagers who were matched for age, younger typically developing teenagers who were matched for reading level, and younger teenagers with a history of dyslexia. All four participant groups showed a pseudohomophone advantage, both from foveal processing and parafoveal preprocessing, indicating that teenagers with a history of dyslexia engage in phonological recoding for lexical identification during silent sentence reading in a comparable manner to their typically developing peers.
Jessica Bourgin; Laetitia Silvert; Céline Borg; Alexandrine Morand; Mathilde Sauvée; Olivier Moreaud; Pascal Hot
In: Brain and Cognition, 145 , pp. 1–12, 2020.
Impairments of emotional processing have been reported in Alzheimer's disease (AD), consistently with the existence of early amygdala atrophy in the pathology. In this study, we hypothesized that patients with AD might show a deficit of orientation toward emotional information under conditions of visual search. Eighteen patients with AD, 24 age-matched controls, and 35 young controls were eye-tracked while they performed a visual search task on a computer screen. The target was a vehicle with implicit (negative or neutral) emotional content, presented concurrently with one, three, or five non-vehicle neutral distractors. The task was to find the target and to report whether a break in the target frame was on the left or on the right side. Both control groups detected negative targets more efficiently than they detected neutral targets, showing facilitated engagement toward negative information. In contrast, patients with AD showed no influence of emotional information on engagement delays. However, all groups reported the frame break location more slowly for negative than for neutral targets (after accounting for the last fixation delay), showing a more difficult disengagement from negative information. These findings are the first to highlight a selective lack of emotional influence on engagement processes in patients with AD. The involvement of amygdala alterations in this behavioral impairment remains to be investigated.
Anissa Boutabla; Samuel Cavuscens; Maurizio Ranieri; Céline Crétallaz; Herman Kingma; Raymond van de Berg; Nils Guinand; Angélica Pérez Fornos
In: Journal of Neurology, 267 (1), pp. S273–S284, 2020.
Background and purpose: Vestibular implants seem to be a promising treatment for patients suffering from severe bilateral vestibulopathy. To optimize outcomes, we need to investigate how, and to which extent, the different vestibular pathways are activated. Here we characterized the simultaneous responses to electrical stimuli of three different vestibular pathways. Methods: Three vestibular implant recipients were included. First, activation thresholds and amplitude growth functions of electrically evoked vestibulo-ocular reflexes (eVOR), cervical myogenic potentials (ecVEMPs) and vestibular percepts (vestibulo-thalamo-cortical, VTC) were recorded upon stimulation with single, biphasic current pulses (200 µs/phase) delivered through five different vestibular electrodes. Latencies of eVOR and ecVEMPs were also characterized. Then we compared the amplitude growth functions of the three pathways using different stimulation profiles (1-pulse, 200 µs/phase; 1-pulse, 50 µs/phase; 4-pulses, 50 µs/phase, 1600 pulses-per-second) in one patient (two electrodes). Results: The median latencies of the eVOR and ecVEMPs were 8 ms (8–9 ms) and 10.2 ms (9.6–11.8 ms), respectively. While the amplitude of eVOR and ecVEMP responses increased with increasing stimulation current, the VTC pathway showed a different, step-like behavior. In this study, the 200 µs/phase paradigm appeared to give the best balance to enhance responses at lower stimulation currents. Conclusions: This study is a first attempt to evaluate the simultaneous activation of different vestibular pathways. However, this issue deserves further and more detailed investigation to determine the actual possibility of selective stimulation of a given pathway, as well as the functional impact of the contribution of each pathway to the overall rehabilitation process.
Marie Luise Brandi; Dorothea Gebert; Anna Kopczak; Matthias K Auer; Leonhard Schilbach
In: Journal of Neuroendocrinology, 32 (5), pp. 1–13, 2020.
Oxytocin is a neuropeptide known to affect social behaviour and cognition. Craniopharyngioma patients are considered to have an oxytocin-release-deficit caused by a rare tumour affecting the pituitary and/or the hypothalamus relevant for oxytocin production and release. To assess social behaviour and socio-cognitive abilities in this patient group, we tested 13 patients and 23 healthy controls on self-report questionnaires and an eye-tracking paradigm including fast facial emotion recognition. Additionally, saliva oxytocin levels acquired before and after a physical stress induction were available from a previous study, representing the reactivity of the oxytocin system. The data revealed three major results. First, patients with an oxytocin-release-deficit scored higher on self-reported autistic traits and reduced levels of hedonia for social encounters, although they showed no impairments in attributing mental states. Second, patients showed more difficulties in the fast emotion recognition task. Third, although automatic gaze behaviour during emotion recognition did not differ between groups, gaze behaviour was related to the reactivity of the oxytocin system across all participants. Taken together, these findings demonstrate the importance of investigating the reactivity of the oxytocin system and its relationship with social cognition. Our findings suggest that reduced emotional processing abilities may represent a pathological feature in a group of craniopharyngioma patients, indicating that this patient group might benefit from specific treatments within the social domain.
Tanja M Brückl; Victor I Spoormaker; Philipp G Sämann; Anna Katharine Brem; Lara Henco; Darina Czamara; Immanuel Elbau; Norma C Grandi; Lee Jollans; Anne Kühnel; Laura Leuchs; Dorothee Pöhlchen; Maximilian Schneider; Alina Tontsch; Martin E Keck; Leonhard Schilbach; Michael Czisch; Susanne Lucae; Angelika Erhardt; Elisabeth B Binder
In: BMC Psychiatry, 20 (1), pp. 1–25, 2020.
Background: A major research finding in the field of Biological Psychiatry is that symptom-based categories of mental disorders map poorly onto dysfunctions in brain circuits or neurobiological pathways. Many of the identified (neuro) biological dysfunctions are "transdiagnostic", meaning that they do not reflect diagnostic boundaries but are shared by different ICD/DSM diagnoses. The compromised biological validity of the current classification system for mental disorders impedes rather than supports the development of treatments that not only target symptoms but also the underlying pathophysiological mechanisms. The Biological Classification of Mental Disorders (BeCOME) study aims to identify biology-based classes of mental disorders that improve the translation of novel biomedical findings into tailored clinical applications. Methods: BeCOME intends to include at least 1000 individuals with a broad spectrum of affective, anxiety and stress-related mental disorders as well as 500 individuals unaffected by mental disorders. After a screening visit, all participants undergo in-depth phenotyping procedures and omics assessments on two consecutive days. Several validated paradigms (e.g., fear conditioning, reward anticipation, imaging stress test, social reward learning task) are applied to stimulate a response in a basic system of human functioning (e.g., acute threat response, reward processing, stress response or social reward learning) that plays a key role in the development of affective, anxiety and stress-related mental disorders. The response to this stimulation is then read out across multiple levels. Assessments comprise genetic, molecular, cellular, physiological, neuroimaging, neurocognitive, psychophysiological and psychometric measurements. The multilevel information collected in BeCOME will be used to identify data-driven biologically-informed categories of mental disorders using cluster analytical techniques. Discussion: The novelty of BeCOME lies in the dynamic in-depth phenotyping and omics characterization of individuals with mental disorders from the depression and anxiety spectrum of varying severity. We believe that such biology-based subclasses of mental disorders will serve as better treatment targets than purely symptom-based disease entities, and help in tailoring the right treatment to the individual patient suffering from a mental disorder. BeCOME has the potential to contribute to a novel taxonomy of mental disorders that integrates the underlying pathomechanisms into diagnoses. Trial registration: Retrospectively registered on June 12, 2019 on ClinicalTrials.gov (TRN: NCT03984084).
Andrea Caoli; Silvio P Sabatini; Agostino Gibaldi; Guido Maiello; Anna Kosovicheva; Peter Bex
In: Scientific Reports, 10 , pp. 1–13, 2020.
Strabismus is a prevalent impairment of binocular alignment that is associated with a spectrum of perceptual deficits and social disadvantages. Current treatments for strabismus involve ocular alignment through surgical or optical methods and may include vision therapy exercises. In the present study, we explore the potential of real-time dichoptic visual feedback that may be used to quantify and manipulate interocular alignment. A gaze-contingent ring was presented independently to each eye of 11 normally-sighted observers as they fixated a target dot presented only to their dominant eye. Their task was to center the rings within 2° of the target for at least 1 s, with feedback provided by the sizes of the rings. By offsetting the ring in the non-dominant eye temporally or nasally, this task required convergence or divergence, respectively, of the non-dominant eye. Eight of 11 observers attained 5° asymmetric convergence and 3 of 11 attained 3° asymmetric divergence. The results suggest that real-time gaze-contingent feedback may be used to quantify and transiently simulate strabismus and holds promise as a method to augment existing therapies for oculomotor alignment disorders.
Louise F Carey; Giles M Anderson; Sanjay Kumar
In: Global Psychiatry, 3 (1), pp. 17–27, 2020.
Background: Attention bias modification (ABM) can reduce anxiety and attentional bias towards threatening stimuli, but evidence of its usefulness as a potential intervention for socially anxious individuals has been mixed. Eye contact avoidance, a maladaptive attentional strategy in social anxiety disorder (SAD), has yet to be targeted by ABM research. Aims: This study sought to establish whether a new ABM training paradigm could increase attentional deployment towards eyes and what effect this would have on social and gaze-related anxiety. Method: Participants (n = 23) recruited through adverts calling for people who felt anxious in social situations completed either a novel ABM training task designed to induce attentional bias towards images of eyes over images of noses, or control training. Data on response times (RTs), accuracy of responses, gaze behaviour (using an eye tracker) and scores on clinical measures of social and gaze- related anxiety were collected before and after both training tasks. Results: ABM training produced a greater number of initial saccades towards eye images than did the control task, indicating an induced shift in early attentional deployment. ABM training was also associated with a marginal increase in fixation durations on eye images. No effect was observed on RTs or social and gaze-related anxiety. Conclusions: Our results indicate that ABM can alter the gaze behaviour of socially anxious individuals. They also highlight the importance of eye tracking to ABM research, because it was more sensitive than analyses of RTs to changes in early attentional deployment.
Éric Castet; Marine Descamps; Ambre Denis-Noël; Pascale Colé
In: Scientific Studies of Reading, 24 (2), pp. 159–169, 2020.
The potential role of iconic memory in dyslexia-specific partial report deficits has never been investigated although it may help distinguish between different visuo-attentional theories of dyslexia. The present study is a first step towards such an investigation within an iconic memory framework. 20 French-speaking university students with dyslexia and 20 controls were administered the partial report task. Five-item strings were displayed for a short duration and participants had to report one item in a cued position (post-cueing condition). A pre-cueing condition was used to control for potential visual and attentional differences in letter identification performance between the dyslexic and control groups. The group difference in accuracy was larger in the post-cueing condition than in the pre-cueing condition. This suggests that crowding and symbol-sound mapping are not causing the dyslexia-specific deficit in partial report tasks, and that iconic memory is a plausible interpretative framework for visuo-attentional deficits in dyslexia.
Matthew R Cavanaugh; Lisa M Blanchard; Michael McDermott; Byron L Lam; Madhura Tamhankar; Steven E Feldon
In: Ophthalmology, pp. 1–11, 2020.
Purpose: To evaluate the efficacy of motion discrimination training as a potential therapy for stroke-induced hemianopic visual field defects. Design: Clinical trial. Participants: Forty-eight patients with stroke-induced homonymous hemianopia (HH) were randomized into 2 training arms: intervention and control. Patients were between 21 and 75 years of age and showed no ocular issues at presentation. Methods: Patients were trained on a motion discrimination task previously evidenced to reduce visual field deficits, but not in a randomized clinical trial. Patients were randomized with equal allocation to receive training in either their sighted or deficit visual fields. Training was performed at home for 6 months, consisting of repeated visual discriminations at a single location for 20 to 30 minutes daily. Study staff and patients were masked to training type. Testing before and after training was identical, consisting of Humphrey visual fields (Carl Zeiss Meditech), macular integrity assessment perimetry, OCT, motion discrimination performance, and visual quality- of-life questionnaires. Main Outcome Measures: Primary outcome measures were changes in perimetric mean deviation (PMD) on Humphrey Visual Field Analyzer in both eyes. Results: Mean PMDs improved over 6 months in deficit-trained patients (mean change in the right eye, 0.58 dB; 95% confidence interval, 0.07e1.08 dB; mean change in the left eye 0.84 dB; 95% confidence interval, 0.22e1.47 dB). No improvement was observed in sighted-trained patients (mean change in the right eye, 0.12 dB; 95% confidence interval, e0.38 to 0.62 dB; mean change in the left eye, 0.10 dB; 95% confidence interval, e0.52 to 0.72 dB). However, no significant differences were found between the alternative training methods (right eye
Frederick H F Chan; Tom J Barry; Antoni B Chan; Janet H Hsiao
In: Cognition and Emotion, 34 (8), pp. 1704–1710, 2020.
Theoretical models propose that attentional biases might account for the maintenance of social anxiety symptoms. However, previous eye-tracking studies have yielded mixed results. One explanation is that existing studies quantify eye-movements using arbitrary, experimenter-defined criteria such as time segments and regions of interests that do not capture the dynamic nature of overt visual attention. The current study adopted the Eye Movement analysis with Hidden Markov Models (EMHMM) approach for eye-movement analysis, a machine-learning, data-driven approach that can cluster people's eye-movements into different strategy groups. Sixty participants high and low in self-reported social anxiety symptoms viewed angry and neutral faces in a free-viewing task while their eye-movements were recorded. EMHMM analyses revealed novel associations between eye-movement patterns and social anxiety symptoms that were not evident with standard analytical approaches. Participants who adopted the same face-viewing strategy when viewing both angry and neutral faces showed higher social anxiety symptoms than those who transitioned between strategies when viewing angry versus neutral faces. EMHMM can offer novel insights into psychopathology-related attention processes.
Frederick H F Chan; Hin Suen; Janet H Hsiao; Antoni B Chan; Tom J Barry
In: European Journal of Pain, 24 (7), pp. 1242–1256, 2020.
Background: Theories propose that interpretation biases and attentional biases might account for the maintenance of chronic pain symptoms, but the interactions between these two forms of biases in the context of chronic pain are understudied. Methods: To fill this gap, 63 participants (40 females) with and without chronic pain completed an interpretation bias task that measures participants' interpretation styles in ambiguous scenarios and a novel eye-tracking task where participants freely viewed neutral faces that were given ambiguous pain/health-related labels (i.e. ‘doctor', ‘patient' and ‘healthy people'). Eye movements were analysed with the Hidden Markov Models (EMHMM) approach, a machine-learning data-driven method that clusters people's eye movements into different strategy subgroups. Results: Adults with chronic pain endorsed more negative interpretations for scenarios related to immediate bodily injury and long-term illness than healthy controls, but they did not differ significantly in terms of their eye movements on ambiguous faces. Across groups, people who interpreted illness-related scenarios in a more negative way also focused more on the nose region and less on the eye region when looking at patients' and healthy people's faces and, to a lesser extent, doctors' faces. This association between interpretive and attentional processing was particularly apparent in participants with chronic pain. Conclusions: In summary, the present study provided evidence for the interplay between multiple forms of cognitive biases. Future studies should investigate whether this interaction might influence subsequent functioning in people with chronic pain.
Lyndsey J Chong; Alexandria Meyer
In: Developmental Psychobiology, pp. 1–12, 2020.
Anxiety is one of the most common forms of child psychopathology associated with persistent impairment across the lifespan. Therefore, investigating mechanisms that underlie anxiety in early childhood may improve prevention and intervention efforts. Researchers have linked selective attention toward threat (i.e., attentional bias to threat) with the development of anxiety. However, previous work on attentional bias has used less reliable, reaction time (RT)-based measures of attention. Additionally, few studies have used eye-tracking to measure attentional bias in young children. In the present study, we investigated the psychometric properties of an eye-tracking measure of attentional bias in a sample of young children between 6- and 9-years-old and explored if trait and clinical anxiety were related to attentional biases to threat. Results showed good psychometric properties for threat and neutral attentional biases, comparable to those found in adult eye-tracking studies. Temperamental and clinical anxiety did not significantly relate to threat/neutral dwell time and attentional biases. The significance of these null findings was discussed in relation to existing developmental theories of attentional biases. Future studies should explore if temperamental or clinical anxiety prospectively predict threat attentional bias and the onset of anxiety in older children using a longitudinal design.
M Clough; J Dobbing; J Stankovich; A Ternes; S Kolbe; O B White; J Fielding
In: Multiple Sclerosis and Related Disorders, 38 , pp. 1–7, 2020.
Background: The assessment of cognitive information processing speed (IPS) is complicated in MS, with altered performance on tests such as the Symbol Digit Modalities Test (SDMT) potentially representing changes not only within cognitive networks but in the initial sensorial transmission of information to cognitive networks, and/or efferent transmission of the motor response. Objective: We aimed to isolate and characterise cognitive IPS deficits in MS using ocular motor tasks; a prosaccade task (used to assess and control for sensorial and motor IPS) which was then used to adjust performance on the Simon task (cognitive IPS). Methods: All participants (22 MS patients with early disease, 22 healthy controls) completed the ocular motor tasks and the SDMT. The Simon task assessed cognitive IPS by manipulating the relationship between a stimulus location and its associated response direction. Two trial types were interleaved: (1) congruent, where stimulus location = response direction; or (2) incongruent, where stimulus location ≠ response direction. RESULTS MS patients did not perform differently to controls on the SDMT. For OM tasks, when sensorial and motor IPS was controlled, MS patients had significantly slower cognitive IPS (incongruent trials only) and poorer conflict resolution. SDMT performance did not correlate with slower cognitive IPS in MS patients, highlighting the limitation of using SDMT performance to interpret cognitive IPS changes in patients with MS. Conclusion: Cognitive IPS deficits in MS patients are dissociable from changes in other processing stages, manifesting as impaired conflict resolution between automatic and non-automatic processes. Importantly, these results raise concerns about the SDMT as an accurate measure of cognitive IPS in MS.
Natalie V Covington; Jake Kurczek; Melissa C Duff; Sarah Brown-Schmidt
In: Journal of Clinical and Experimental Neuropsychology, 42 (2), pp. 171–184, 2020.
Referring to things in the world–that woman, her idea, she–is a central component of language. Understanding reference requires the listener to keep track of the unfolding discourse history while integrating multiple sources of information to interpret the speech stream as it unfolds in time. Pronouns are a common way to establish reference. But due to their impoverished form, to understand them listeners must relate features of the pronoun (e.g., gender, animacy) with existing representations of potential discourse referents. Successful referential processing seems to place demands on memory. In a previous study, patients with hippocampal amnesia and healthy participants listened to short stories as their eye movements were monitored. When interpreting ambiguous pronouns, healthy participants demonstrated order-of-mention effects, whereby ambiguous pronouns are interpreted as referring to the first-mentioned referent in the story. By contrast, memory-impaired patients exhibited significant disruptions in their ability to use information about which character had been mentioned first to interpret pronouns. Repetition of the most salient information is a common clinical recommendation for improving pronoun resolution and communication in individuals with memory disorders (e.g., Alzheimer's disease) but this recommendation lacks an evidentiary basis. The present study seeks to determine whether the pronoun resolution performance of hippocampal patients can be improved, by repetition of the target referent, increasing its salience. Results indicate that patients with hippocampal damage demonstrate improved processing of pronouns following repetition of the target referent, but benefit from this repetition to a significantly smaller degree compared to healthy participants. These results provide further evidence for the role of the hippocampal-dependent memory system in language processing and point to the need for empirically tested communication interventions.
Jessica L O'Rielly; Anna Ma-Wyatt
In: Journal of Vision, 20 (13), pp. 1–17, 2020.
Goal-directed movements rely on the integration of both visual and motor information, especially during the online control of movement, to fluidly and flexibly control coordinated action. Eye-hand coordination typically plays an important role in goal-directed movements. As people age, various aspects of motor control and visual performance decline (Haegerstrom-Portnoy, Schneck, & Brabyn, 1999; Seidler et al., 2010), including an increase in saccade latencies (Munoz, Broughton, Goldring, & Armstrong, 1998). However, there is limited insight into how age-related changes in saccadic performance impact eye-hand coordination during online control. We investigated this question through the use of a target perturbation paradigm. Older and younger participants completed a perturbation task where target perturbations could occur either early (0 ms) or later (200 ms) after reach onset. We analyzed reach correction latencies and the frequency of the reach correction, coupled with analyses of saccades across all stages of movement. Older participants had slower correction latencies and initiated corrections less frequently compared to younger participants, with this trend being exacerbated in the later (200 ms) target perturbation condition. Older participants also produced slower saccade latencies toward both the initial target and the perturbed target. For trials in which a correction occurred to a late perturbation, touch responses were more accurate when there was more time between the saccade landing and the touch. Altogether, our results suggest that these age-related effects may be due to the delayed acquisition of visual and oculomotor information used to inform the reaching movement, stemming from the increase in saccade latencies before and after target perturbation.
Samantha Parker; Andrew Heathcote; Matthew Finkbeiner
In: Journal of Experimental Psychology. Human perception and performance, 46 (4), pp. 416–433, 2020.
A typical way to investigate the relationship between spatial attention and the programming of an eye movement is with a dual-task. Here, participants simultaneously make an eye movement in 1 direction and discriminate a target at the same or a different location. Results of these tasks consistently find that performance is best at the goal of an upcoming eye movement. It is less clear, however, the extent to which spatial attention can shift independently of the programmed saccade. In this article, for the first time, we use an evidence accumulation model to examine this longstanding question. Specifically, across 2 studies, we quantify the relative contributions of spatial attention and saccade preparation in a perceptual dual-task. Our results establish that there is a unique and measurable effect of spatial attention away from the saccade goal, and, interestingly, that the relative magnitude of this effect varies by cue type. There is a larger influence of spatial attention when a peripheral rather than a central cue is employed. We suggest that these results support the claim that each form of orienting is mediated by a distinct underlying mechanism. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Samantha Parker; Andrew Heathcote; Matthew Finkbeinera
In: Advances in Cognitive Psychology, 16 (4), pp. 329–343, 2020.
The extent to which the preparation of an eye movement and spatial attention both independently influence performance within the same task has long been debated. In a recent study that combined computational modelling with a dual-task, both saccade preparation and spatial cueing were revealed to separately contribute to the discrimination of targets oriented along the cardinal axis (horizontal and vertical). However, it remains to be seen whether and to what degree the same holds true when different perceptual stimuli are used. In the present study, we combined evidence accumulation modelling with a dual-task paradigm to assess the extent to which both saccade preparation and spatial attention contribute to the discrimination of full contrast targets oriented along the oblique axis (diagonal). The results revealed a separate and quantifiable contribution of both types of orienting to discrimination performance. Comparison of the magnitude of these effects to those obtained for cardinal orientation discrimination revealed the influence of saccade preparation and spatial attention to be six times smaller for oblique orientations. Importantly, the results revealed a separate and quantifiable contribution of both saccade preparation and spatial attention regardless of perceptual stimuli or stimulus contrast
Chloé Pasturel; Anna Montagnini; Laurent Udo Perrinet
In: PLoS Computational Biology, 16 (4), pp. 1–28, 2020.
Animal behavior constantly adapts to changes, for example when the statistical properties of the environment change unexpectedly. For an agent that interacts with this volatile setting, it is important to react accurately and as quickly as possible. It has already been shown that when a random sequence of motion ramps of a visual target is biased to one direction (e.g. right or left), human observers adapt their eye movements to accurately anticipate the target's expected direction. Here, we prove that this ability extends to a volatile environment where the probability bias could change at random switching times. In addition, we also recorded the explicit prediction of the next outcome as reported by observers using a rating scale. Both results were compared to the estimates of a probabilistic agent that is optimal in relation to the assumed generative model. Compared to the classical leaky integrator model, we found a better match between our probabilistic agent and the behavioral responses, both for the anticipatory eye movements and the explicit task. Furthermore, by controlling the level of preference between exploitation and exploration in the model, we were able to fit for each individual's experimental dataset the most likely level of volatility and analyze inter-individual variability across participants. These results prove that in such an unstable environment, human observers can still represent an internal belief about the environmental contingencies, and use this representation both for sensory-motor control and for explicit judgments. This work offers an innovative approach to more generically test the diversity of human cognitive abilities in uncertain and dynamic environments.
Jacob M Paul; Robert A Reeve; Jason D Forte
In: Cognition, 198 , pp. 1–13, 2020.
Brain regions involved in saccadic eye movements partially overlap with a frontoparietal network implicated in encoding numerosities. Eye movement patterns may plausibly reflect strategic scanning behaviours to resolve the open-ended task of efficiently enumerating visual arrays. If so, these patterns may help explain individual differences in enumeration acuity in terms of well-understood visual attention mechanisms. Most enumeration eye-tracking paradigms, however, do not allow for direct manipulation of eye movement behaviours to test these claims. In the current study we terminated trials after a specified number of saccades to systematically probe the time course of enumeration strategies. Fifteen adults (11 naïve, 4 informed) enumerated random dot arrays under three conditions: (1) a novel saccade-terminated design where arrays were visible until one, two or four saccades had occurred; (2) a duration-terminated design where arrays were shown for 250, 500 or 1000 ms; and (3) a response-terminated design where arrays were visible until a response. Participants gave more accurate responses when enumerating saccade-terminated trials despite taking a similar time as in the duration-terminated trials. When participants were informed how trials would terminate, their saccade onset latencies shifted to match task demands. Rotating saccade vectors to align with salient image locations accounted for variability in the orientation of saccade trajectories. These findings (1) show a combination of stimulus-derived visual processing and task-based strategic demands account for enumeration eye movements patterns, (2) validate a novel saccade-contingent trial termination procedure for studying sequences of enumeration eye movements, and (3) highlight the need to include analyses of spatial and temporal eye movement patterns into models of visual enumeration strategies.
Tyler R Peel; Suryadeep Dash; Stephen G Lomber; Brian D Corneil
In: Journal of Computational Neuroscience, pp. 1–21, 2020.
Saccades require a spatiotemporal transformation of activity between the intermediate layers of the superior colliculus (iSC) and downstream brainstem burst generator. The dynamic linear ensemble-coding model (Goossens and Van Opstal, 2006) proposes that each iSC spike contributes a fixed mini-vector to saccade displacement. Although biologically-plausible, this model assumes cortical areas like the frontal eye fields (FEF) simply provide the saccadic goal to be executed by the iSC and brainstem burst generator. However, the FEF and iSC operate in unison during saccades, and a pathway from the FEF to the brainstem burst generator that bypasses the iSC exists. Here, we investigate the impact of large yet reversible inactivation of the FEF on iSC activity in the context of the model across four saccade tasks. We exploit the overlap of saccade vectors generated when the FEF is inactivated or not, comparing the number of iSC spikes for metrically-matched saccades. We found that the iSC emits fewer spikes for metrically-matched saccades during FEF inactivation. The decrease in spike count is task-dependent, with a greater decrease accompanying more cognitively-demanding saccades. Our results show that FEF integrity influences the readout of iSC activity in a task-dependent manner. We propose that the dynamic linear ensemble-coding model be modified so that FEF inactivation increases the gain of a readout parameter, effectively increasing the influence of a single iSC spike. We speculate that this modification could be instantiated by a direct pathway from the FEF to the omnipause region that modulates the excitability of the brainstem burst generator. Significance statement One of the enduring puzzles in the oculomotor system is how it achieves the spatiotemporal transformation, converting spatial activity within the intermediate layers of the superior colliculus (iSC) into a rate code within the brainstem burst generator. The spatiotemporal transformation has traditionally been viewed as the purview of the oculomotor brainstem. Here, within the context of testing a biologically-plausible model of the spatiotemporal transformation, we show that reversible inactivation of the frontal eye fields (FEF) decreases the number of spikes issued by the iSC for metrically-matched saccades, with greater decreases accompanying more cognitively-demanding tasks. These results show that signals from the FEF influence the spatiotemporal transformation.
Christina U Pfeuffer; Stefanie Aufschnaiter; Roland Thomaschke; Andrea Kiesel
In: Journal of Experimental Psychology: Human Perception and Performance, 46 (10), pp. 1183–1200, 2020.
Humans form associations between time intervals and subsequent events and thus develop time-based expectancies that enable time-based action preparation. For instance, when each of two foreperiods (short vs. long) is frequently paired with one specific task (e.g., number magnitude judgment vs. number parity judgment) and infrequently with the alternative task, participants are faster to respond to frequent rather than infrequent foreperiod-task combinations. Here, we investigated the time course of time-based task expectancy by measuring eye movements toward a left and right target location. Foreperiods predicted target locations with 100% validity and tasks with 90% validity. In 2 experiments, without having any explicit knowledge about the foreperiod-location or foreperiod-task contingencies, participants first moved their eyes to the location associated with the short foreperiod and then looked toward the location of the long foreperiod (if no stimulus had been presented after the short foreperiod had passed). That is, they proactively moved their eyes to optimize perception in line with the specific time and location they expected an event to occur at. Importantly, these eye movements reflected not only time-based location expectations, but also time-based task expectations. We discuss new insights in time-based expectancy and its temporal dynamics obtained from anticipatory eye movements and highlight spontaneous eye movements as a window into cognitive processes that cannot be assessed via behavioral response measures.
Andrea Phillipou; Larry A Abel; Caroline Gurvich; David J Castle; Susan L Rossell
Eye movements in anorexia nervosa: State or trait markers? Journal Article
In: International Journal of Eating Disorders, 53 (10), pp. 1678–1684, 2020.
Objective: Differences in saccadic eye movements are widely reported in mental illnesses, and can indirectly inform our understanding of neurobiological and cognitive underpinnings of psychiatric conditions, including anorexia nervosa (AN). Preliminary research has suggested that individuals with AN may show specific eye movement abnormalities; whether these deficits are representative of state or trait effects is, however, unclear. The aim of this study was to identify whether there are demonstrable differences in performance on saccadic eye movement tasks in individuals with current AN (c-AN), those who are weight-restored from AN (wr-AN), biological sisters of individuals with AN (AN-sis), and healthy controls (HC). Methods: Eighty participants took part in the study (n = 20/group). A set of saccadic eye movement tasks was administered, including prosaccade, antisaccade, memory-guided saccade, and visual scanpath tasks. Results: The c-AN group showed an increased rate of inhibitory errors to 10° targets on the memory-guided saccade task. Discussion: The results are discussed in terms of the potential role of the superior colliculus in AN, and that the findings may reflect a state measure of AN.
Alessandro Piras; Matthew Timmis; Aurelio Trofè; Milena Raffi
In: European Journal of Sport Science, pp. 1–10, 2020.
Experts keep a steady final fixation at a specific location just before final movement initiation, the so-called “quiet eye” (QE). However, the eyes are rarely “quiet”, and small eye movements occur during visual fixation. The current research investigated the subtle eye movements and underlying mechanisms immediately prior to and during QE. The gaze behaviour of 8 intermediate-level goalkeepers was recorded as they moved (either left or right) in an attempt to predict the future direction of the ball during a soccer penalty kick. Goalkeepers were more likely to predict the direction of the penalty, which was coupled with delaying movement initiation. The temporal sequence of microsaccade rates dropped ∼1000 ms before goalkeepers' final movement initiation. Saccade rates increased, reaching a peak ∼500 ms before final movement initiation, concomitant with microsaccades reduction. Microsaccades predicted the goalkeepers' direction, oriented to the right when goalkeepers moved to the right, and conversely to the left when they moved to the left. Microsaccades may be modulated by attention and appear functionally related to saccadic intrusions. Pupil-size increased proportionally with the lead up to the instance of the penalty being kicked, reaching a plateau at final movement initiation. In conclusion, microsaccades and small saccades could improve the perception of the soccer penalty kick, helping athletes during the period that precedes the critical movement initiation, shifting from covert to overt attention for identifying the useful cues necessary to guide the action.
Lilla A Porffy; Victoria Bell; Antoine Coutrot; Rebekah Wigton; Teresa D'Oliveira; Isabelle Mareschal; Sukhwinder S Shergill
In: Schizophrenia Research, 216 , pp. 279–287, 2020.
Background: Individuals with schizophrenia have difficulty in extracting salient information from faces. Eye-tracking studies have reported that these individuals demonstrate reduced exploratory viewing behaviour (i.e. reduced number of fixations and shorter scan paths) compared to healthy controls. Oxytocin has previously been demonstrated to exert pro-social effects and modulate eye gaze during face exploration. In this study, we tested whether oxytocin has an effect on visual attention in patients with schizophrenia. Methods: Nineteen male participants with schizophrenia received intranasal oxytocin 40UI or placebo in a double-blind, placebo-controlled, crossover fashion during two visits separated by seven days. They engaged in a free-viewing eye-tracking task, exploring images of Caucasian men displaying angry, happy, and neutral emotional expressions; and control images of animate and inanimate stimuli. Eye-tracking parameters included: total number of fixations, mean duration of fixations, dispersion, and saccade amplitudes. Results: We found a main effect of treatment, whereby oxytocin increased the total number of fixations, dispersion, and saccade amplitudes, while decreasing the duration of fixations compared to placebo. This effect, however, was non-specific to facial stimuli. When restricting the analysis to facial images only, we found the same effect. In addition, oxytocin modulated fixation rates in the eye and nasion regions. Discussion: This is the first study to explore the effects of oxytocin on eye gaze in schizophrenia. Oxytocin had enhanced exploratory viewing behaviour in response to both facial and inanimate control stimuli. We suggest that the acute administration of intranasal oxytocin may have the potential to enhance visual attention in schizophrenia.
Seema Prasad; Ramesh Mishra
In: Journal of Eye Movement Research, 13 (4), pp. 1–29, 2020.
Subliminal cues have been shown to capture attention and modulate manual response behaviour but their impact on eye movement behaviour is not well-studied. In two experiments, we examined if subliminal cues influence constrained free-choice saccades and if this influence is under strategic control as a function of task-relevancy of the cues. On each trial, a display containing four filled circles at the centre of each quadrant was shown. A central coloured circle indicated the relevant visual field on each trial (Up or Down in Experiment 1; Left or Right in Experiment 2). Next, abrupt-onset cues were presented for 16 ms at one of the four locations. Participants were then asked to freely choose and make a saccade to one of the two target circles in the relevant visual field. The analysis of the frequency of saccades, saccade endpoint deviation and saccade latency revealed a significant influence of the relevant subliminal cues on saccadic decisions. Latency data showed reduced capture by spatiallyirrelevant cues under some conditions. These results indicate that spatial attentional control settings as defined in our study could modulate the influence of subliminal abrupt-onset cues on eye movement behaviour. We situate the findings of this study in the attention-capture debate and discuss the implications for the subliminal cueing literature.
Alexandra Pressigout; Karine Dore-Mazars
In: Experimental Brain Research, 238 , pp. 101–109, 2020.
The influence of numerical processing on individuals' behavior is now well documented. The spatial representation of numbers on a left-to-right mental line (i.e., SNARC effect) has been shown to have sensorimotor consequences, the majority of studies being mainly concerned with its impact on the response times. Its impact on the motor programming stage remains less documented, although swiping movement amplitudes have recently been shown to be modulated by number magnitude. Regarding saccadic eye movements, the few available studies have not provided clear-cut conclusions. They showed that spatial–numerical associations modulated ocular drifts, but not the amplitude of memory-guided saccades. Because these studies held saccadic coordinates constant, which might have masked potential numerical effects, we examined whether spontaneous saccadic eye movements (with no saccadic target) could reflect numerical effects. Participants were asked to look either to the left or to the right side of an empty screen to estimate the magnitude (textless or textgreater 5) of a centrally presented digit. Latency data confirmed the presence of the classical SNARC and distance effects. More critically, saccade amplitude reflected a numerical effect: participants' saccades were longer for digits far from the standard (1 and 9) and were shorter for digits close to it (4 and 6). Our results suggest that beyond response times, kinematic parameters also offer valuable information for the understanding of the link between numerical cognition and motor programming.
Alexandra Pressigout; Céline Paeye; Karine Doré-Mazars
In: Attention, Perception, and Psychophysics, 82 (7), pp. 3676–3685, 2020.
Recent findings suggest that perceptual and motor systems share common codes; for instance, perceived object location is known to correlate with motor changes in the oculomotor system. Here, we investigate whether modifying saccade amplitude affects object size perception. Participants saw in peripheral vision a test disk that could vary in size across trials. This disk was then replaced by a small target cross, which was the signal to make a saccade. After the saccade, the target cross was extinguished and replaced by a reference disk (thus seen in foveal vision). Participants had to compare the post- to the pre-saccade disk sizes. Psychometric functions were obtained before and after one session of 142 saccades made toward the cross that either stepped toward the fixation point during the saccade (backward adaptation group) or remained stationary (control group). In the experimental group, stepping the target cross toward fixation during saccades decreased movement amplitude, a phenomenon called saccadic adaptation. We observed a concurrent shift in the psychometric functions reflecting a decrease in perceived object size. Such a perceptual modification did not occur in the control group. Our results reveal that motor changes co-occur with changes in perceived object size. Unlike previous studies evaluating the impact of saccadic adaptation on perceived location, we measured here the perception of another spatial feature (the object size) that is not relevant for the sensorimotor transformation. Theoretical implications of the strong links between oculomotor parameters and object perception are discussed.
Gal Rosenzweig; Yoram S Bonneh
In: Scientific Reports, 10 , pp. 1–15, 2020.
Involuntary eye movements during fixation are typically inhibited following stimulus onset (Oculomotor Inhibition, OMI), depending on the stimulus saliency and attention, with an earlier and longer OMI for barely visible familiar faces. However, it is still unclear whether OMI regarding familiarities and perceptual saliencies differ enough to allow a reliable OMI-based concealed information test (CIT). In a “mock terror” experiment with 25 volunteers, 13 made a concealed choice of a “terror-target” (one of eight), associated with 3 probes (face, name, and residence), which they learned watching text and videos, whereas 12 “innocents” pre-learned nothing. All participants then watched ~ 25 min of repeated brief presentations of barely visible (masked) stimuli that included the 8 potential probes, as well as a universally familiar face as a reference, while their eye movements were monitored. We found prolonged and deviant OMI regarding the probes. Incorporated with the individual pattern of responses to the reference, our analysis correctly identified 100% of the terror targets, and was 95% correct in discriminating “terrorists” from “innocents”. Our results provide a “proof of concept” for a novel approach to CIT, based on involuntary oculomotor responses to barely visible stimuli, individually tailored, and with high accuracy and theoretical resistance to countermeasures.
Yuki Sakazume; Sho Furubayashi; Eizo Miyashita
Functional roles of saccades for a hand movement Journal Article
In: Applied Sciences, 10 , pp. 1–12066, 2020.
An eye saccade provides appropriate visual information for motor control. The present study was aimed to reveal the role of saccades in hand movements. Two types of movements, i.e., hitting and circle-drawing movements, were adopted, and saccades during the movements were classified as either a leading saccade (LS) or catching saccade (CS) depending on the relative gaze position of the saccade to the hand position. The ratio of types of the saccades during the movements was heavily dependent on the skillfulness of the subjects. In the late phase of the movements in a less skillful subject, CS tended to occur in less precise movements, and precision of the movement tended to be improved in the subsequent movement in the hitting. While LS directing gaze to a target point was observed in both types of the movements regardless of skillfulness of the subjects, LS in between a start point and a target point, which led gaze to a local minimum variance point on a hand movement trajectory, was exclusively found in the drawing in a less skillful subject. These results suggest that LS and some types of CS may provide positional information of via-points in addition to a target point and visual information to improve precision of a feedforward controller in the brain, respectively.
Carola Salvi; Claudio Simoncini; Jordan Grafman; Mark Beeman
In: NeuroImage, 217 , pp. 1–9, 2020.
According to the Gestalt theorists, restructuring is an essential component of insight problem-solving, contributes to the “Aha!” experience, and is similar to the perceptual switch experienced when reinterpreting ambiguous figures. Previous research has demonstrated that pupil diameter increases during the perceptual switch of ambiguous figures, and indexes norepeinephrine functioning mediated by the locus coeruleus. In this study, we investigated if pupil diameter similarly predicts the switch into awareness people experience when solving a problem via insight. Additionally, we explored eye movement dynamics during the same task to investigate if the problem-solving strategies used are linked to specific oculomotor behaviors. In 38 participants, pupil diameter increased about 500 msec prior to solution only in trials for which subjects report having an insight. In contrast, participants increased their microsaccade rate only prior to non-insight solutions. Pupil dilation and microsaccades were not reliably related, but both appear to be robust markers of how people solve problems (with or without insight). The pupil size change seen when people have an “Aha!” moment represents an indicator of the switch into awareness of unconscious processes humans depend upon for insight, and suggests important involvement of norepinephrine, via the locus coeruleus, in sudden insight.
Matteo Scaramuzzi; Jordan Murray; Jorge Otero-Millan; Paolo Nucci; Aasef G Shaik; Fatema F Ghasi
In: PLoS ONE, 15 (8), pp. 1–19, 2020.
Purpose: We investigated how the abnormalities of fixation eye movements (FEMs) of the amblyopic eye were linked with treatment outcomes following part-time patching therapy in children with amblyopia. Methods: We recruited 53 patients, with at least 12 months of patching, and measured FEMs at the end of treatment. Subjects were classified based on FEM waveforms (those without nystagmus = 21, those with nystagmus without fusion maldevelopment nystagmus (FMN) = 21, and those with FMN = 11) and based on clinical type of amblyopia (anisometropic = 18
Rebekka Schröder; Anna-Maria Kasparbauer; Inga Meyhöfer; Maria Steffens; Peter Trautner; Ulrich Ettinger
Functional connectivity during smooth pursuit eye movements Journal Article
In: Journal of Neurophysiology, 124 , pp. 1839–1856, 2020.
Smooth pursuit eye movements (SPEM) hold the image of a slowly moving stimulus on the fovea. The neural system underlying SPEM primarily includes visual, parietal and frontal areas. In the present study, we investigated how these areas are functionally coupled and how these couplings are influenced by target motion frequency. To this end, healthy participants (N=57) were instructed to follow a sinusoidal target stimulus moving horizontally at two different frequencies (0.2 Hz, 0.4 Hz). Eye movements and BOLD activity were recorded simultaneously. Functional connectivity of the key areas of the SPEM network was investigated using a Psychophysiological Interaction (PPI) approach. It was analyzed how activity in five eye movement related seed regions (lateral geniculate nucleus, V1, V5, posterior parietal cortex, frontal eye fields) relates to activity in other parts of the brain during SPEM. The behavioral results showed clear deterioration of SPEM performance at higher target frequency. BOLD activity during SPEM vs. fixation occurred in a geniculo-occipito-parieto-frontal network, replicating previous findings. PPI analysis yielded wide-spread, partially overlapping networks. Especially frontal eye fields and posterior parietal cortex showed task-dependent connectivity to large parts of the entire cortex, while other seed regions demonstrated more regionally focused connectivity. Higher target frequency was associated with stronger activations in visual areas but had no effect on functional connectivity. In summary, the results confirm and extend previous knowledge regarding the neural mechanisms underlying SPEM and provide a valuable basis for further investigations such as in patients with SPEM impairments and known alterations in brain connectivity.
Dekel Abeles; Roy Amit; Noam Tal-Perry; Marisa Carrasco; Shlomit Yuval-Greenberg
In: Nature Communications, 11 , pp. 1–12, 2020.
Eye movements are inhibited prior to the onset of temporally-predictable visual targets. This oculomotor inhibition effect could be considered a marker for the formation of temporal expectations and the allocation of temporal attention in the visual domain. Here we show that eye movements are also inhibited before predictable auditory targets. In two experiments, we manipulate the period between a cue and an auditory target to be either predictable or unpredictable. The findings show that although there is no perceptual gain from avoiding gaze-shifts in this procedure, saccades and blinks are inhibited prior to predictable relative to unpredictable auditory targets. These findings show that oculomotor inhibition occurs prior to auditory targets. This link between auditory expectation and oculomotor behavior reveals a multimodal perception action coupling, which has a central role in temporal expectations.
Ioannis Agtzidis; Inga Meyhöfer; Michael Dorr; Rebekka Lencer
In: NeuroImage, 216 , pp. 1–11, 2020.
Most fMRI studies investigating smooth pursuit (SP) related brain activity have used simple synthetic stimuli such as a sinusoidally moving dot. However, real-life situations are much more complex and SP does not occur in isolation but within sequences of saccades and fixations. This raises the question whether the same brain networks for SP that have been identified under laboratory conditions are activated when following moving objects in a movie. Here, we used the publicly available studyforrest data set that provides eye movement recordings along with 3 T fMRI recordings from 15 subjects while watching the Hollywood movie “Forrest Gump”. All three major eye movement events, namely fixations, saccades, and smooth pursuit, were detected with a state-of-the-art algorithm. In our analysis, smooth pursuit (SP) was the eye movement of interest, while saccades were acting as the steady state of viewing behaviour due to their lower variability. For the fMRI analysis we used an event-related design modelling saccades and SP as regressors initially. Because of the interdependency of SP and content motion, we then added a new low-level content motion regressor to separate brain activations from these two sources. We identified higher BOLD-responses during SP than saccades bilaterally in MT+/V5, in middle cingulate extending to precuneus, and in the right temporoparietal junction. When the motion regressor was added, SP showed higher BOLD-response relative to saccades bilaterally in the cortex lining the superior temporal sulcus, precuneus, and supplementary eye field, presumably due to a confounding effect of background motion. Only parts of V2 showed higher activation during saccades in comparison to SP. Taken together, our approach should be regarded as proof of principle for deciphering brain activity related to SP, which is one of the most prominent eye movements besides saccades, in complex dynamic naturalistic situations.
Kiki Arkesteijn; Mieke Donk; Jeroen B J Smeets; Artem V Belopolsky
Visual information is required to reduce the global effect Journal Article
In: Attention, Perception, and Psychophysics, 82 (5), pp. 2340–2347, 2020.
When a distractor appears in close proximity to a saccade target, the saccadic end point is biased towards the distractor. This so-called global effect reduces with the latency of the saccade if the saccade is visually guided. We recently reported that the global effect does not reduce with the latency of a double-step memory-guided saccade. The aim of this study was to investigate why the global effect in memory-guided saccades does not show the typically observed reduction with saccadic latency. One possibility is that reduction of the global effect requires continuous access to visual information about target and distractor locations, which is lacking in the case of a memory-guided saccade. Alternatively, participants may be inclined to routinely preprogram a memory-guided saccade at the moment the visual information disappears, with the result that a memory-guided saccade is typically programmed on the basis of an earlier representation than necessary. To distinguish between these alternatives, two potential targets were presented, and participants were asked to make a saccade to one of them after a delay. In one condition, the target identity was precued, allowing preprogramming of the saccade, while in another condition, it was revealed by a retro cue after the delay. The global effect remained present in both conditions. Increasing visual exposure of target and distractor led to a reduction of the global effect, irrespective of whether participants could preprogram a saccade or not. The results suggest that continuous access to visual information is required in order to eliminate the global effect.
Naila Ayala; Ewa Niechwiej-Szwedo
In: Experimental Brain Research, pp. 1–11, 2020.
Eye movements have been used extensively to assess information processing and cognitive function. However, significant variability in saccade performance has been observed, which could arise from methodological variations across different studies. For example, prosaccades and antisaccades have been studied using either a blocked or interleaved design, which has a significant influence on error rates and latency. This is problematic as it makes it difficult to compare saccade performance across studies and may limit the ability to use saccades as a behavioural assay to assess neurocognitive function. Thus, the current study examined how administration mode influences saccade related preparatory activity by employing pupil size as a non-invasive proxy for neural activity related to saccade planning and execution. Saccade performance and pupil dynamics were examined in eleven participants as they completed pro- and antisaccades in blocked and interleaved paradigms. Results showed that administration mode significantly modulated saccade performance and preparatory activity. Reaction times were longer for both pro- and antisaccades in the interleaved condition, compared to the blocked condition (p textless 0.05). Prosaccade pupil dilations were larger in the interleaved condition (p textless 0.05), while antisaccade pupil dilations did not significantly differ between administration modes. Additionally, ROC analysis provided preliminary evidence that pupil size can effectively predict saccade directional errors prior to saccade onset. We propose that task-evoked pupil dilations reflect an increase in preparatory activity for prosaccades and the corresponding cognitive demands associated with interleaved administration mode. Overall, the results highlight the importance that administration mode plays in the design of neurocognitive tasks.
Brendan T Barrett; Alice G Cruickshank; Jonathan C Flavell; Simon J Bennett; John G Buckley; Julie M Harris; Andrew J Scally
In: Scientific Reports, 10 , pp. 1–9, 2020.
The issue of whether visually-mediated, simple reaction time (VRT) is faster in elite athletes is contentious. Here, we examined if and how VRT is affected by gaze stability in groups of international cricketers (16 females, 28 males), professional rugby-league players (21 males), and non-sporting controls (20 females, 30 males). VRT was recorded via a button-press response to the sudden appearance of a stimulus (circular target—diameter 0.8°), that was presented centrally, or 7.5° to the left or right of fixation. The incidence and timing of saccades and blinks occurring from 450 ms before stimulus onset to 225 ms after onset were measured to quantify gaze stability. Our results show that (1) cricketers have faster VRT than controls; (2) blinks and, in particular, saccades are associated with slower VRT regardless of the level of sporting ability; (3) elite female cricketers had steadier gaze (fewer saccades and blinks) compared to female controls; (4) when we accounted for the presence of blinks and saccades, our group comparisons of VRT were virtually unchanged. The stability of gaze is not a factor that explains the difference between elite and control groups in VRT. Thus we conclude that better gaze stability cannot explain faster VRT in elite sports players.
Denise Baumeler; Josef G Schönhammer; Sabine Born
Microsaccade dynamics in the attentional repulsion effect Journal Article
In: Vision Research, 170 , pp. 46–52, 2020.
A briefly flashed peripheral cue has been shown to repulse the perceived position of a subsequently presented foveal probe - a bias called the Attentional Repulsion Effect (ARE). While this bias has originally been assumed to reflect attentional capturing by the cue, its attentional nature has recently been questioned. To investigate the ARE's attentional properties, we recorded microsaccades as an attentional marker in the ARE paradigm. Microsaccades, small fixational eye movements performed during fixation, have previously been described to reflect the dynamics of spatial attention deployment. Our results favor an attentional explanation for the ARE: In trials in which an ARE was found, microsaccades were directed more often toward the cue, presumably reflecting the covert shift of attention. In contrast, more cue-incongruent microsaccades were observed in trials in which no ARE was found. Therefore, both repulsion as well as measured microsaccade modulations, are most likely an outcome of the preceding shifts of covert attention.
Valerie M Beck; Timothy J Vickery
In: Cortex, 122 , pp. 159–169, 2020.
Evidence from attentional and oculomotor capture, contingent capture, and other paradigms suggests that mechanisms supporting human visual working memory (VWM) and visual attention are intertwined. Features held in VWM bias guidance toward matching items even when those features are task irrelevant. However, the neural basis of this interaction is underspecified. Prior examinations using fMRI have primarily relied on coarse comparisons across experimental conditions that produce varying amounts of capture. To examine the neural dynamics of attentional capture on a trial-by-trial basis, we applied an oculomotor paradigm that produced discrete measures of capture. On each trial, subjects were shown a memory item, followed by a blank retention interval, then a saccade target that appeared to the left or right. On some trials, an irrelevant distractor appeared above or below fixation. Once the saccade target was fixated, subjects completed a forced-choice memory test. Critically, either the target or distractor could match the feature held in VWM. Although task irrelevant, this manipulation produced differences in behavior: participants were more likely to saccade first to an irrelevant VWM-matching distractor compared with a non-matching distractor – providing a discrete measure of capture. We replicated this finding while recording eye movements and scanning participants' brains using fMRI. To examine the neural basis of oculomotor capture, we separately modeled the retention interval for capture and non-capture trials within the distractor-match condition. We found that frontal activity, including anterior cingulate cortex and superior frontal gyrus regions, differentially predicted subsequent oculomotor capture by a memory-matching distractor. Other regions previously implicated as involved in attentional capture by VWM-matching items showed no differential activity across capture and non-capture trials, even at a liberal threshold. Our findings demonstrate the power of trial-by-trial analyses of oculomotor capture as a means to examine the underlying relationship between VWM and attentional guidance systems.
Sonya Bells; Silvia L Isabella; Donald C Brien; Brian C Coe; Douglas P Munoz; Donald J Mabbott; Douglas O Cheyne
In: Human Brain Mapping, 41 (7), pp. 1934–1949, 2020.
Our ability to control and inhibit automatic behaviors is crucial for negotiating complex environments, all of which require rapid communication between sensory, motor, and cognitive networks. Here, we measured neuromagnetic brain activity to investigate the neural timing of cortical areas needed for inhibitory control, while 14 healthy young adults performed an interleaved prosaccade (look at a peripheral visual stimulus) and antisaccade (look away from stimulus) task. Analysis of how neural activity relates to saccade reaction time (SRT) and occurrence of direction errors (look at stimulus on antisaccade trials) provides insight into inhibitory control. Neuromagnetic source activity was used to extract stimulus-aligned and saccade-aligned activity to examine temporal differences between prosaccade and antisaccade trials in brain regions associated with saccade control. For stimulus-aligned antisaccade trials, a longer SRT was associated with delayed onset of neural activity within the ipsilateral parietal eye field (PEF) and bilateral frontal eye field (FEF). Saccade-aligned activity demonstrated peak activation 10ms before saccade-onset within the contralateral PEF for prosaccade trials and within the bilateral FEF for antisaccade trials. In addition, failure to inhibit prosaccades on anti-saccade trials was associated with increased activity prior to saccade onset within the FEF contralateral to the peripheral stimulus. This work on dynamic activity adds to our knowledge that direction errors were due, at least in part, to a failure to inhibit automatic prosaccades. These findings provide novel evidence in humans regarding the temporal dynamics within oculomotor areas needed for saccade programming and the role frontal brain regions have on top-down inhibitory control.
Katharina Bey; Julia V Lippold; Behrem Aslan; René HWIBBLEemann; Ulrich Ettinger
Effects of lorazepam on prosaccades and saccadic adaptation Journal Article
In: Journal of Psychopharmacology, 35 (1), pp. 91–99, 2020.
Background: Benzodiazepines have reliable adverse effects on saccadic eye movements, but the impact of sex as a potential modulator of these effects is less clear. A recent study reported stronger adverse effects on the spatial consistency of saccades in females, which may reflect sex differences in cerebellar mechanisms. Aims: We aimed to further examine the role of sex as a potential modulator of benzodiazepine effects by employing the saccadic adaptation paradigm, which is known to be sensitive to cerebellar functioning. Methods: A total of n=50 healthy adults performed a horizontal step prosaccade task and a saccadic adaptation task under 0.5 mg lorazepam, 1 mg lorazepam and placebo in a double-blind, within-subjects design. Results: In the prosaccade task, lorazepam had adverse effects on measures of peak velocity, latency and spatial consistency. The administration of 0.5 mg lorazepam led to significant reductions in gain-decrease adaptation, while a dose of 1 mg did not impair adaptation learning. Gain-increase adaptation was generally less pronounced, and unaffected by the drug. There were no significant drug×sex interactions in either task. Conclusions: We conclude that a low dose of lorazepam impairs gain-decrease adaptation independent of sex. At higher doses, however, increasing fatigue may facilitate adaptation and thus counteract the adverse effects observed at lower doses. With regards to prosaccades, our findings confirm peak velocity as well as latency and spatial measures as sensitive biomarkers of GABAergic effects.
Klinton Bicknell; Roger Levy; Keith Rayner
In: Psychological Science, 31 (4), pp. 351–362, 2020.
Reading is a highly complex learned skill in which humans move their eyes three to four times every second in response to visual and cognitive processing. The consensus view is that the details of these rapid eye-movement decisions—which part of a word to target with a saccade—are determined solely by low-level oculomotor heuristics. But maximally efficient saccade targeting would be sensitive to ongoing word identification, sending the eyes farther into a word the farther its identification has already progressed. Here, using a covert text-shifting paradigm, we showed just such a statistical relationship between saccade targeting in reading and trial-to-trial variability in cognitive processing. This result suggests that, rather than relying purely on heuristics, the human brain has learned to optimize eye movements in reading even at the fine-grained level of character-position targeting, reflecting efficiency-based sensitivity to ongoing cognitive processing.
Francesca Bonetti; Matteo Valsecchi; Massimo Turatto
In: Cortex, 131 , pp. 251–264, 2020.
The oculomotor capture triggered by a peripheral onset is subject to habituation, a basic form of learning consisting in a response decrement toward a repeatedly presented stimulus. However, it is unclear whether habituation of reflexive saccades takes place at the saccadic programming or execution stage (or both). To address this issue, we exploited the fact that during fixation the programming of a reflexive saccade exerts a robust but short-lasting phasic inhibition in the absolute microsaccadic frequency. Hence, if habituation of reflexive saccades occurs at the programming stage, then this should also affect the microsaccadic frequency, with a progressive reduction of the inhibitory phase. Conversely, if habituation occurs only at the later stage of saccade execution, the no change in the microsaccadic pattern is expected. Participants were repeatedly exposed to a peripheral onset distractor, and when eye movements were allowed, we replicated the oculomotor capture habituation. Crucially, however, when fixation was maintained the microsaccadic response did not change as exposure to the onset progressed, suggesting that habituation of reflexive saccades does not take place at the programming stage in the superior colliculus (SC), but at the later stage of saccade execution in the brainstem, where the competition between different saccades might be resolved. This scenario challenges one of the main assumptions of the competitive integration model for oculomotor control, which assumes that competition between exogenous and endogenous saccade programs occurs in the (SC). Our results and interpretation are instead in agreement with neurophysiological studies in non-human primates showing that saccadic adaption, another form of oculomotor plasticity, takes place downstream from the SC.
Annalisa Bosco; Katharina Rifai; Siegfried Wahl; Patrizia Fattori; Markus Lappe
In: Journal of Vision, 20 (7), pp. 1–11, 2020.
Systematic shortening or lengthening of target objects during saccades modifies saccade amplitudes and perceived size of the objects. These two events are concomitant when size change during the saccade occurs asymmetrically, thereby shifting the center of mass of the object. In the present study, we asked whether or not the two are necessarily linked. We tested human participants in symmetrical systematic shortening and lengthening of a vertical bar during a horizontal saccade, aiming to not modify the saccade amplitude. Before and after a phase of trans-saccadic changes of the target bar, participants manually indicated the sizes of various vertically oriented bars by open-loop grip aperture. We evaluated the effect of trans-saccadic changes of bar length on manual perceptual reports and whether this change depended on saccade amplitude. As expected, we did not induce any change in horizontal or vertical components of saccade amplitude, but we found a significant difference in perceived size after the lengthening experiment compared to after the shortening experiment. Moreover, after the lengthening experiment, perceived size differed significantly from pre-lengthening baseline. These findings suggest that a change of size perception can be induced trans-saccadically, and its mechanism does not depend on saccadic amplitude change.
Antimo Buonocore; Olaf Dimigen; David Melcher
In: Journal of Neuroscience, 40 (11), pp. 2305–2313, 2020.
Humans actively sample their environment with saccadic eye movements to bring relevant information into high-acuity foveal vision. Despite being lower in resolution, peripheral information is also available before each saccade. How the pre-saccadic extrafoveal preview of a visual object influences its post-saccadic processing is still an unanswered question. The current study investigated this question by simultaneously recording behavior and fixation-related brain potentials while human subjects made saccades to face stimuli. We manipulated the relationship between pre-saccadic "previews" and post-saccadic images to explicitly isolate the influences of the former. Subjects performed a gender discrimination task on a newly foveated face under three preview conditions: scrambled face, incongruent face (different identity from the foveated face), and congruent face (same identity). As expected, reaction times were faster after a congruent-face preview compared with a scrambled-face preview. Importantly, intact face previews (either incongruent or congruent) resulted in a massive reduction of post-saccadic neural responses. Specifically, we analyzed the classic face-selective N170 component at occipitotemporal electroencephalogram electrodes, which was still present in our experiments with active looking. However, the post-saccadic N170 was strongly attenuated following intact-face previews compared with the scrambled condition. This large and long-lasting decrease in evoked activity is consistent with a trans-saccadic mechanism of prediction that influences category-specific neural processing at the start of a new fixation. These findings constrain theories of visual stability and show that the extrafoveal preview methodology can be a useful tool to investigate its underlying mechanisms.
Elisa Castaldi; David Burr; Marco Turi; Paola Binda
In: Proceedings of the Royal Society B: Biological Sciences, 287 , pp. 1–9, 2020.
Fast saccades are rapid automatic oculomotor responses to salient and ecologically important visual stimuli such as animals and faces. Discriminating the number of friends, foe, or prey may also have an evolutionary advantage. In this study, participants were asked to saccade rapidly towards the more numerous of two arrays. Participants could discriminate numerosities with high accuracy and great speed, as fast as 190 ms. Intermediate numerosities were more likely to elicit fast saccades than very low or very high numerosities. Reaction-times for vocal responses (collected in a separate experiment) were slower, did not depend on numerical range, and correlated only with the slow not the fast saccades, pointing to different systems. The short saccadic reaction-times we observe are surprising given that discrimination using numerosity estimation is thought to require a relatively complex neural circuit, with several relays of information through the parietal and prefrontal cortex. Our results suggest that fast numerosity-driven saccades may be generated on a single feed-forward pass of information recruiting a primitive system that cuts through the cortical hierarchy and rapidly transforms the numerosity information into a saccade command.
Soazig Casteau; Daniel T Smith
In: Attention, Perception, and Psychophysics, 82 (2), pp. 518–532, 2020.
It has been proposed that covert visual search can be fast, efficient, and stimulus driven, particularly when the target is defined by a salient single feature, or slow, inefficient, and effortful when the target is defined by a nonsalient conjunction of features. This distinction between fast, stimulus-driven orienting and slow, effortful orienting can be related to the distinction between exogenous spatial attention and endogenous spatial attention. Several studies have shown that exogenous, covert orienting is limited to the range of saccadic eye movements, whereas covert endogenous orienting is independent of the range of saccadic eye movements. The current study examined whether covert visual search is affected in a similar way. Experiment 1 showed that covert visual search for feature singletons was impaired when stimuli were presented beyond the range of saccadic eye movements, whereas conjunction search was unaffected by array position. Experiment 2 replicated and extended this effect by measuring search times at 6 eccentricities. The impairment in covert feature search emerged only when stimuli crossed the effective oculomotor range and remained stable for locations further into the periphery, ruling out the possibility that the results of Experiment 1 were due to a failure to fully compensate for the effects of cortical magnification. The findings are interpreted in terms of biased competition and oculomotor theories of spatial attention. It is concluded that, as with covert exogenous orienting, biological constraints on overt orienting in the oculomotor system constrain covert, preattentive search.
Johan Chandra; André Krügel; Ralf Engbert
In: Attention, Perception, and Psychophysics, 82 (3), pp. 1230–1240, 2020.
During reading, rapid eye movements (saccades) shift the reader's line of sight from one word to another for high-acuity visual information processing. While experimental data and theoretical models show that readers aim at word centers, the eye-movement (oculomotor) accuracy is low compared to other tasks. As a consequence, distributions of saccadic landing positions indicate large (i) random errors and (ii) systematic over- and undershoot of word centers, which additionally depend on saccade lengths (McConkie et al. Visual Research, 28(10), 1107–1118, 1988). Here we show that both error components can be simultaneously reduced by reading texts from right to left in German language (N = 32). We used our experimental data to test a Bayesian model of saccade planning. First, experimental data are consistent with the model. Second, the model makes specific predictions of the effects of the precision of prior and (sensory) likelihood. Our results suggest that it is a more precise sensory likelihood that can explain the reduction of both random and systematic error components.
Chih-Yang Chen; Denis Matrov; Richard Veale; Hirotaka Onoe; Masatoshi Yoshida; Kenichiro Miura; Tadashi Isa
In: Journal of Neurophysiology, 2020.
The saccade is a stereotypic behavior whose investigation improves our understanding of how primate brains implement precise motor control. Furthermore, saccades offer an important window into the cognitive and attentional state of the brain. Historically, saccade studies have largely relied on macaque. However, the cortical network giving rise to the saccadic command is difficult to study in macaque because relevant cortical areas lie in sulci and are difficult to access. Recently, a New World monkey – the marmoset – has garnered attention as an attractive alternative to macaque because of its smooth cortical surface, its smaller body, and its amenability to transgenic technology. However, adoption of marmoset for oculomotor research has been limited due to a lack of in-depth descriptions of marmoset saccade kinematics and their ability to perform psychophysical and cognitive tasks. Here, we directly compare free-viewing and visually-guided behavior of marmoset, macaque, and human engaged in identical tasks under similar conditions. In video free-viewing task, all species exhibited qualitatively similar saccade kinematics including saccade main sequence up to 25° in amplitude. Furthermore, the conventional bottom-up saliency model predicted gaze targets at similar rates for all species. We further verified their visually-guided behavior by training them with step and gap saccade tasks. All species showed similar gap effect and express saccades in the gap paradigm. Our results suggest that the three species have similar natural and task-guided visuomotor behavior. The marmoset can be trained on saccadic tasks and thus can serve as a model for oculomotor, attention, and cognitive research.
Valentina Vencato; Laurent Madelain
Perception of saccadic reaction time Journal Article
In: Scientific Reports, 10 , pp. 1–11, 2020.
That saccadic reaction times (SRTs) may depend on reinforcement contingencies has been repeatedly demonstrated. It follows that one must be able to discriminate one's latencies to adequately assign credit to one's actions, which is to connect behaviour to its consequence. To quantify the ability to perceive one's SRT, we used an adaptive procedure to train sixteen participants in a stepping visual target saccade paradigm. Subsequently, we measured their RTs perceptual threshold at 75% in a conventional constant stimuli procedure. For each trial, observers had to saccade to a stepping target. Then, in a 2-AFC task, they had to choose one value representing the actual SRT, while the other value proportionally differed from the actual SRT. The relative difference between the two alternatives was computed by either adding or subtracting from the actual SRT a percent-difference value randomly chosen among a fixed set. Feedback signalling the correct choice was provided after each response. Overall, our results showed that the 75% SRT perceptual threshold averaged 23% (about 40 ms). The ability to discriminate small SRT differences provides support for the possibility that the credit assignment problem may be solved even for short reaction times.
Manuel Vidal; Andrea Desantis; Laurent Madelain
In: PLoS ONE, 15 (2), pp. 1–27, 2020.
Saccadic eye movements bring events of interest to the center of the retina, enabling detailed visual analysis. This study explored whether irrelevant auditory (experiments A, B & F), visual (C & D) or tactile signals (E & F) delivered around the onset of a visual target modulates saccade latency. Participants were instructed to execute a quick saccade toward a target stepping left or right from a fixation position. We observed an interaction between auditory beeps or tactile vibrations and the oculomotor reaction that included two components: a warning effect resulting in faster saccades when the signal and the target were presented simultaneously; and a modulation effect with shorter - or longer - latencies when auditory and tactile signals were delivered before - or after - the target onset. Combining both modalities only increased the modulation effect to a limited extent, pointing to a saturation of the multisensory interaction with the motor control. Interestingly, irrelevant visual stimuli (black background or isoluminant noise stripes in peripheral vision, flashed for 10 ms) increased saccade latency whether they were presented just before or after target onset. The lack of latency reduction with visual signals suggests that the modulation observed in the auditory and tactile experiments was not related to priming effects but rather to low-level audio- and tactile-visual integration. The increase in saccade latency observed with irrelevant visual stimuli is discussed in relation to saccadic inhibition. Our results demonstrate that signals conveying no information regarding where and when a visual target would appear modulate saccadic reactivity, much like in multisensory temporal binding, but only when these signals come from a different modality.
Chin An Wang; Jeff Huang; Donald C Brien; Douglas P Munoz
In: Biological Psychology, 153 , pp. 1–9, 2020.
A salient stimulus can trigger a coordinated orienting response consisting of a saccade, pupil, and microsaccadic responses. Saliency models predict that the degree of visual conspicuity of all visual stimuli guides visual orienting. By presenting a multiple-item array that included an oddball colored item (pop-out), randomly mixed colored items (mixed-color), or single-color items (single-color), we examined the effects of saliency and priority (saliency + relevancy) on pupil size and microsaccade responses. Larger pupil responses were produced in the pop-out compared to the mixed-color or single-color conditions after stimulus presentation. However, the saliency modulation on microsaccades was not significant. Furthermore, although goal-relevancy information did not modulate pupil responses and microsaccade rate, microsaccade direction was biased toward the pop-out item when it was the subsequent saccadic target. Together, our results demonstrate saliency modulation on pupil size and priority effects on microsaccade direction during visual pop-out.
Christian Wolf; Markus Lappe
In: Attention, Perception, and Psychophysics, 82 (8), pp. 3863–3877, 2020.
Humans scan their visual environment using saccade eye movements. Where we look is influenced by bottom-up salience and top-down factors, like value. For reactive saccades in response to suddenly appearing stimuli, it has been shown that short-latency saccades are biased towards salience, and that top-down control increases with increasing latency. Here, we show, in a series of six experiments, that this transition towards top-down control is not determined by the time it takes to integrate value information into the saccade plan, but by the time it takes to inhibit suddenly appearing salient stimuli. Participants made consecutive saccades to three fixation crosses and a vertical bar consisting of a high-salient and a rewarded low-salient region. Endpoints on the bar were biased towards salience whenever it appeared or reappeared shortly before the last saccade was initiated. This was also true when the eye movement was already planned. When the location of the suddenly appearing salient region was predictable, saccades were aimed in the opposite direction to nullify this sudden onset effect. Successfully inhibiting salience, however, could only be achieved by previewing the target. These findings highlight the importance of inhibition for top-down eye-movement control.
Luca Wollenberg; Nina M Hanning; Heiner Deubel
In: Journal of Vision, 20 (9), pp. 1–17, 2020.
Saccadic eye movements are typically preceded by selective shifts of visual attention. Recent evidence, however, suggests that oculomotor selection can occur in the absence of attentional selection when saccades erroneously land in between nearby competing objects (saccade averaging). This study combined a saccade task with a visual discrimination task to investigate saccade target selection during episodes of competition between a saccade target and a nearby distractor. We manipulated the spatial predictability of target and distractor locations and asked participants to execute saccades upon variably delayed go-signals. This allowed us to systematically investigate the capacity to exert top-down eye movement control (as reflected in saccade endpoints) based on the spatiotemporal dynamics of visual attention during movement preparation (measured as visual sensitivity). Our data demonstrate that the predictability of target and distractor locations, despite not affecting the deployment of visual attention prior to movement preparation, largely improved the accuracy of short-latency saccades. Under spatial uncertainty, a short go-signal delay likewise enhanced saccade accuracy substantially, which was associated with a more selective deployment of attentional resources to the saccade target. Moreover, we observed a systematic relationship between the deployment of visual attention and saccade accuracy, with visual discrimination performance being significantly enhanced at the saccade target relative to the distractor only before the execution of saccades accurately landing at the saccade target. Our results provide novel insights linking top-down eye movement control to the operation of selective visual attention during movement preparation.
Cheng Xue; Antonino Calapai; Julius Krumbiegel; Stefan Treue
In: Scientific Reports, 10 , pp. 1–10, 2020.
Small ballistic eye movements, so called microsaccades, occur even while foveating an object. Previous studies using covert attention tasks have shown that shortly after a symbolic spatial cue, specifying a behaviorally relevant location, microsaccades tend to be directed toward the cued location. This suggests that microsaccades can serve as an index for the covert orientation of spatial attention. However, this hypothesis faces two major challenges: First, effects associated with visual spatial attention are hard to distinguish from those that associated with the contemplation of foveating a peripheral stimulus. Second, it is less clear whether endogenously sustained attention alone can bias microsaccade directions without a spatial cue on each trial. To address the first issue, we investigated the direction of microsaccades in human subjects while they attended to a behaviorally relevant location and prepared a response eye movement either toward or away from this location. We find that directions of microsaccades are biased toward the attended location rather than towards the saccade target. To tackle the second issue, we verbally indicated the location to attend before the start of each block of trials, to exclude potential visual cue-specific effects on microsaccades. Our results indicate that sustained spatial attention alone reliably produces the microsaccade direction effect. Overall, our findings demonstrate that sustained spatial attention alone, even in the absence of saccade planning or a spatial cue, is sufficient to explain the direction bias observed in microsaccades.
Shimpei Yamagishi; Shigeto Furukawa
In: Frontiers in Human Neuroscience, 14 , pp. 1–11, 2020.
It is often assumed that the reaction time of a saccade toward visual and/or auditory stimuli reflects the sensitivities of our oculomotor-orienting system to stimulus saliency. Endogenous factors, as well as stimulus-related factors, would also affect the saccadic reaction time (SRT). However, it was not clear how these factors interact and to what extent visual and auditory-targeting saccades are accounted for by common mechanisms. The present study examined the effect of, and the interaction between, stimulus saliency and audiovisual spatial congruency on the SRT for visual- and for auditory-target conditions. We also analyzed pre-target pupil size to examine the relationship between saccade preparation and pupil size. Pupil size is considered to reflect arousal states coupling with locus-coeruleus (LC) activity during a cognitive task. The main findings were that (1) the pattern of the examined effects on the SRT varied between visual- and auditory-auditory target conditions, (2) the effect of stimulus saliency was significant for the visual-target condition, but not significant for the auditory-target condition, (3) Pupil velocity, not absolute pupil size, was sensitive to task set (i.e., visual-targeting saccade vs. auditory-targeting saccade), and (4) there was a significant correlation between the pre-saccade absolute pupil size and the SRTs for the visual-target condition but not for the auditory-target condition. The discrepancy between target modalities for the effect of pupil velocity and between the absolute pupil size and pupil velocity for the correlation with SRT may imply that the pupil effect for the visual-target condition was caused by a modality-specific link between pupil size modulation and the SC rather than by the LC-NE (locus coeruleus-norepinephrine) system. These results support the idea that different threshold mechanisms in the SC may be involved in the initiation of saccades toward visual and auditory targets.
Tehrim Yoon; Afareen Jaleel; Alaa A Ahmed; Reza Shadmehr
In: Journal of Neurophysiology, 123 (6), pp. 2161–2172, 2020.
Decisions are made based on the subjective value that the brain assigns to options. However, subjective value is a mathematical construct that cannot be measured directly, but rather is inferred from choices. Recent results have demonstrated that reaction time, amplitude, and velocity of movements are modulated by reward, raising the possibility that there is a link between how the brain evaluates an option and how it controls movements toward that option. Here, we asked people to choose among risky options represented by abstract stimuli, some associated with gain (points in a game), and others with loss. From their choices we estimated the subjective value that they assigned to each stimulus. In probe trials, a single stimulus appeared at center, instructing subjects to make a saccade to a peripheral target. We found that the reaction time, peak velocity, and amplitude of the peripherally directed saccade varied roughly linearly with the subjective value that the participant had assigned to the central stimulus: reaction time was shorter, velocity was higher, and amplitude was larger for stimuli that the participant valued more. Naturally, participants differed in how much they valued a given stimulus. Remarkably, those who valued a stimulus more, as evidenced by their choices in decision trials, tended to move with shorter reaction time and greater velocity in response to that stimulus in probe trials. Overall, the reaction time of the saccade in response to a stimulus partly predicted the subjective value that the brain assigned to that stimulus.
Li Zhang; Guoli Yan; Li Zhou; Zebo Lan; Valerie Benson
In: Journal of Autism and Developmental Disorders, 50 , pp. 500–512, 2020.
The current study examined eye movement control in autistic (ASD) children. Simple targets were presented in isolation, or with central, parafoveal, or peripheral distractors synchronously. Sixteen children with ASD (47–81 months) and nineteen age and IQ matched typically developing children were instructed to look to the target as accurately and quickly as possible. Both groups showed high proportions (40%) of saccadic errors towards parafoveal and peripheral distractors. For correctly executed eye movements to the targets, centrally presented distractors produced the longest latencies (time taken to initiate eye movements), followed by parafoveal and peripheral distractor conditions. Central distractors had a greater effect in the ASD group, indicating evidence for potential atypical voluntary attentional control in ASD children.
Saccade suppression depends on context Journal Article
In: eLife, 9 , pp. 1–16, 2020.
Although our eyes are in constant movement, we remain unaware of the high-speed stimulation produced by the retinal displacement. Vision is drastically reduced at the time of saccades. Here, I investigated whether the reduction of the unwanted disturbance could be established through a saccade-contingent habituation to intra-saccadic displacements. In more than 100 context trials, participants were exposed either to an intra-saccadic or to a post-saccadic disturbance or to no disturbance at all. After induction of a specific context, I measured peri-saccadic suppression. Displacement discrimination thresholds of observers were high after participants were exposed to an intra-saccadic disturbance. However, after exposure to a post-saccadic disturbance or a context without any intra-saccadic stimulation, displacement discrimination improved such that observers were able to see shifts as during fixation. Saccade-contingent habituation might explain why we do not perceive trans-saccadic retinal stimulation during saccades.
Eckart Zimmermann; Marta Ghio; Giulio Pergola; Benno Koch; Michael Schwarz; Christian Bellebaum
In: Neuropsychologia, 147 , pp. 1–9, 2020.
How the perception of space is generated from the multiple maps in the brain is still an unsolved mystery in neuroscience. A neural pathway ascending from the superior colliculus through the medio-dorsal (MD) nucleus of thalamus to the frontal eye field has been identified in monkeys that conveys efference copy information about the metrics of upcoming eye movements. Information sent through this pathway stabilizes vision across saccades. We investigated whether this motor plan information might also shape spatial perception even when no saccades are performed. We studied patients with medial or lateral thalamic lesions (likely involving either the MD or the ventrolateral (VL) nuclei). Patients performed a double-step task testing motor updating, a trans-saccadic localization task testing visual updating, and a localization task during fixation testing a general role of motor signals for visual space in the absence of eye movements. Single patients with medial or lateral thalamic lesions showed deficits in the double-step task, reflecting insufficient transfer of efference copy. However, only a patient with a medial lesion showed impaired performance in the trans-saccadic localization task, suggesting that different types of efference copies contribute to motor and visual updating. During fixation, the MD patient localized stationary stimuli more accurately than healthy controls, suggesting that patients compensate the deficit in visual prediction of saccades - induced by the thalamic lesion - by relying on stationary visual references. We conclude that partially separable efference copy signals contribute to motor and visual stability in company of purely visual signals that are equally effective in supporting trans-saccadic perception.
Marcus Nyström; Diederick C Niehorster; Richard Andersson; Ignace Hooge
In: Behavior Research Methods, pp. 1–19, 2020.
Due to its reported high sampling frequency and precision, the Tobii Pro Spectrum is of potential interest to researchers who want to study small eye movements during fixation. We test how suitable the Tobii Pro Spectrum is for research on microsaccades by computing data-quality measures and common properties of microsaccades and comparing these to the currently most used system in this field: the EyeLink 1000 Plus. Results show that the EyeLink data provide higher RMS precision and microsaccade rates compared with data acquired with the Tobii Pro Spectrum. However, both systems provide microsaccades with similar directions and shapes, as well as rates consistent with previous literature. Data acquired at 1200 Hz with the Tobii Pro Spectrum provide results that are more similar to the EyeLink, compared to data acquired at 600 Hz. We conclude that the Tobii Pro Spectrum is a useful tool for researchers investigating microsaccades.
Rick A Adams; Daniel Bush; Fanfan Zheng; Sofie S Meyer; Raphael Kaplan; Stelios Orfanos; Tiago Reis Marques; Oliver D Howes; Neil Burgess
In: Brain, 143 (3), pp. 1261–1277, 2020.
Frontotemporal dysconnectivity is a key pathology in schizophrenia. The specific nature of this dysconnectivity is unknown, but animal models imply dysfunctional theta phase coupling between hippocampus and medial prefrontal cortex (mPFC). We tested this hypothesis by examining neural dynamics in 18 participants with a schizophrenia diagnosis, both medicated and unmedicated; and 26 age, sex and IQ matched control subjects. All participants completed two tasks known to elicit hippocampal-prefrontal theta coupling: a spatial memory task (during magnetoencephalography) and a memory integration task. In addition, an overlapping group of 33 schizophrenia and 29 control subjects underwent PET to measure the availability of GABAARs expressing the a5 subunit (concentrated on hippocampal somatostatin interneurons). We demonstrate-in the spatial memory task, during memory recall-that theta power increases in left medial temporal lobe (mTL) are impaired in schizophrenia, as is theta phase coupling between mPFC and mTL. Importantly, the latter cannot be explained by theta power changes, head movement, antipsychotics, cannabis use, or IQ, and is not found in other frequency bands. Moreover, mPFC-mTL theta coupling correlated strongly with performance in controls, but not in subjects with schizophrenia, who were mildly impaired at the spatial memory task and no better than chance on the memory integration task. Finally, mTL regions showing reduced phase coupling in schizophrenia magnetoencephalography participants overlapped substantially with areas of diminished a5-GABAAR availability in the wider schizophrenia PET sample. These results indicate that mPFC-mTL dysconnectivity in schizophrenia is due to a loss of theta phase coupling, and imply a5-GABAARs (and the cells that express them) have a role in this process.
Sara Ajina; Miriam Pollard; Holly Bridge
In: Frontiers in Neurology, 11 , pp. 1–18, 2020.
Humans can respond rapidly to viewed expressions of fear, even in the absence of conscious awareness. This is demonstrated using visual masking paradigms in healthy individuals and in patients with cortical blindness due to damage to the primary visual cortex (V1) - so called affective blindsight. Humans have also been shown to implicitly process facial expressions representing important social dimensions. Two major axes, dominance and trustworthiness, are proposed to characterize the social dimensions of face evaluation. The processing of both types of implicit stimuli is believed to occur via similar subcortical pathways involving the amygdala. However, we do not know whether unconscious processing of more subtle expressions of facial traits can occur in blindsight, and if so, how. To test this, we studied 13 patients with unilateral V1 damage and visual field loss. We assessed their ability to detect and discriminate faces that had been manipulated along two orthogonal axes of trustworthiness and dominance to generate five trait levels inside the blind visual field: dominant, submissive, trustworthy, untrustworthy, and neutral. We compared neural activity and functional connectivity in patients classified as blindsight positive or negative for these stimuli. We found that dominant faces were most likely to be detected above chance, with individuals demonstrating unique interactions between performance and face trait. Only patients with blindsight (n = 8) showed significant preference in the superior colliculus and amygdala for face traits in the blind visual field, and a critical functional connection between the amygdala and superior colliculus in the damaged hemisphere. We also found a significant correlation between behavioral performance and fMRI activity in the amygdala and lateral geniculate nucleus across all participants. Our findings confirm that affective blindsight involving the superior colliculus and amygdala extends to the processing of socially salient but emotionally neutral facial expressions when V1 is damaged. This pathway is distinct from that which supports motion blindsight, as both types of blindsight can exist in the absence of the other with corresponding patterns of residual connectivity.
Noor Z Al Dahhan; John R Kirby; Donald C Brien; Rina Gupta; Allyson Harrison; Douglas P Munoz; Noor Z Al
In: Brain Communications, pp. 1–16, 2020.
We examined the naming speed performance of 18 typically achieving and 16 dyslexic adults while simultaneously recording eye movements, articulations and fMRI data. Naming speed tasks, which require participants to name a list of letters or objects, have been proposed as a proxy for reading and are thought to recruit similar reading networks in the left hemisphere of the brain as more complex reading tasks. We employed letter and object naming speed tasks, with task manipulations to make the stimuli more or less phonologically and/or visually similar. Compared to typically achieving readers, readers with dyslexia had a poorer behav-ioural naming speed task performance, longer fixation durations, more regressions and increased activation in areas of the reading network in the left-hemisphere. Whereas increased network activation was positively associated with performance in dyslexics, it was negatively related to performance in typically achieving readers. Readers with dyslexia had greater bilateral activation and recruited additional regions involved with memory, namely the amygdala and hippocampus; in contrast, the typically achieving readers additionally activated the dorsolateral prefrontal cortex. Areas within the reading network were differentially activated by stimulus manipulations to the naming speed tasks. There was less efficient naming speed behavioural performance, longer fixation durations, more regressions and increased neural activity when letter stimuli were both phonologically and visually similar. Discussion focuses on the differences in activation within the reading network, how they are related to behavioural task differences, and how progress in furthering the understanding of the relationship between behavioural performance and brain activity can change the overall trajectories of children with reading difficulties by contributing to both early identification and remediation processes. Abbreviations: AC-PC ¼ anterior commissure-posterior commissure plane; AG ¼ angular gyrus; DLPFC ¼ dorsolateral pre-frontal cortex; FEF ¼ frontal eye fields; FG ¼ fusiform gyrus; fMRI ¼ functional magnetic resonance imaging; IFG ¼ inferior frontal gyrus; LC ¼ letters control NS task; MFG ¼ middle frontal gyrus; MOG ¼ middle occipital gyrus; MP-RAGE ¼ magnet-ization-prepared rapid gradient-echo; MTG ¼ middle temporal gyrus; NS ¼ naming speed; OC ¼ object control NS task; OPS ¼ phonologically similar object NS task; PEF ¼ parietal eye field; PS ¼ phonologically similar NS task; RFX GLM ¼ random-effects multi-subject general linear model; ROI ¼ regions of interest; SEF ¼ supplementary eye field; SMG ¼ supramarginal gyrus; STG ¼ superior temporal gyrus; VS ¼ visually similar NS task; VPS ¼ visually and phonologically similar NS task.
Fredrik Allenmark; Zhuanghua Shi; Rasmus L Pistorius; Laura A Theisinger; Nikolaos Koutsouleris; Peter Falkai; Hermann J Müller; Christine M Falter-Wagner
In: Journal of Autism and Developmental Disorders, pp. 1–15, 2020.
Individuals with Autism Spectrum Disorder (ASD) are thought to under-rely on prior knowledge in perceptual decision-making. This study examined whether this applies to decisions of attention allocation, of relevance for ‘predictive-coding' accounts of ASD. In a visual search task, a salient but task-irrelevant distractor appeared with higher probability in one display half. Individuals with ASD learned to avoid ‘attentional capture' by distractors in the probable region as effectively as control participants—indicating typical priors for deploying attention. However, capture by a ‘surprising' distractor at an unlikely location led to greatly slowed identification of a subsequent target at that location—indicating that individuals with ASD attempt to control surprise (unexpected attentional capture) by over-regulating parameters in post-selective decision-making.
Susana Araújo; Falk Huettig; Antje Meyer
In: Scientific Studies of Reading, pp. 1–16, 2020.
This eye-tracking study explored how phonological encoding and speech production planning for successive words are coordinated in adult readers with dyslexia (N = 22) and control readers (N = 25) during rapid automatized naming (RAN). Using an object-RAN task, we orthogonally manipulated the word-form frequency and phonological neighborhood density of the object names and assessed the effects on speech and eye movements and their temporal coordination. In both groups, there was a significant interaction between word frequency and neighborhood density: shorter fixations for dense than for sparse neighborhoods were observed for low- but not for high-frequency words. This finding does not suggest a specific difficulty in lexical phonological access in dyslexia. However, in readers with dyslexia only, these lexical effects percolated to the late processing stages, indicated by longer offset eye-speech lags. We close by discussing potential reasons for this finding, including suboptimal specification of phonological representations and deficits in attention control or in multi-item coordination.