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Antimo Buonocore, Chih-Yang Chen, Xiaoguang Tian, Saad Idrees, Thomas Muench, Ziad M Hafed
Microsaccades occur during gaze fixation in order to correct for miniscule foveal motor errors. The mechanisms governing such fine oculomotor control are still not fully understood. In this study, we explored microsaccade control by analyzing the impacts of transient visual stimuli on these movements' kinematics. We found that such kinematics can be altered in systematic ways depending on the timing and spatial geometry of visual transients relative to the movement goals. In two male rhesus macaques, we presented peripheral or foveal visual transients during an otherwise stable period of fixation...
February 15, 2017: Journal of Neurophysiology
Susann Meyberg, Petra Sinn, Ralf Engbert, Werner Sommer
Microsaccades - i.e., small fixational saccades generated in the superior colliculus (SC) - have been linked to spatial attention. While maintaining fixation, voluntary shifts of covert attention toward peripheral targets result in a sequence of attention-aligned and attention-opposing microsaccades. In most previous studies the direction of the voluntary shift is signaled by a spatial cue (e.g., a leftwards pointing arrow) that presents the most informative part of the cue (e.g., the arrowhead) in the to-be attended visual field...
February 17, 2017: Vision Research
Andra Mihali, Bas van Opheusden, Wei Ji Ma
Microsaccades are high-velocity fixational eye movements, with special roles in perception and cognition. The default microsaccade detection method is to determine when the smoothed eye velocity exceeds a threshold. We have developed a new method, Bayesian microsaccade detection (BMD), which performs inference based on a simple statistical model of eye positions. In this model, a hidden state variable changes between drift and microsaccade states at random times. The eye position is a biased random walk with different velocity distributions for each state...
January 1, 2017: Journal of Vision
Richard Veale, Ziad M Hafed, Masatoshi Yoshida
Inherent in visual scene analysis is a bottleneck associated with the need to sequentially sample locations with foveating eye movements. The concept of a 'saliency map' topographically encoding stimulus conspicuity over the visual scene has proven to be an efficient predictor of eye movements. Our work reviews insights into the neurobiological implementation of visual salience computation. We start by summarizing the role that different visual brain areas play in salience computation, whether at the level of feature analysis for bottom-up salience or at the level of goal-directed priority maps for output behaviour...
February 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Louise O'Hare
Op-art-based stimuli have been shown to be uncomfortable, possibly due to a combination of fixational eye movements (microsaccades) and excessive cortical responses. Efforts have been made to measure illusory phenomena arising from these stimuli in the absence of microsaccades, but there has been no attempt thus far to decouple the effects of the cortical response from the effect of fixational eye movements. This study uses flash afterimages to stabilise the image on the retina and thus reduce the systematic effect of eye movements, in order to investigate the role of the brain in discomfort from op-art-based stimuli...
December 11, 2016: Perception
Francisco M Costela, Michael B McCamy, Mary Coffelt, Jorge Otero-Millan, Stephen L Macknik, Susana Martinez-Conde
Fixational eye movements (FEMs), including microsaccades, drift, and tremor, shift our eye position during ocular fixation, producing retinal motion that is thought to help visibility by counteracting neural adaptation to unchanging stimulation. Yet, how each FEM type influences this process is still debated. Recent studies found little to no relationship between microsaccades and visual perception of spatial frequencies (SF). However, these conclusions were based on coarse analyses that make it hard to appreciate the actual effects of microsaccades on target visibility as a function of SF...
November 27, 2016: European Journal of Neuroscience
Matt Craddock, Frank Oppermann, Matthias M Müller, Jasna Martinovic
The organization of visual processing into a coarse-to-fine information processing based on the spatial frequency properties of the input forms an important facet of the object recognition process. During visual object categorization tasks, microsaccades occur frequently. One potential functional role of these eye movements is to resolve high spatial frequency information. To assess this hypothesis, we examined the rate, amplitude and speed of microsaccades in an object categorization task in which participants viewed object and non-object images and classified them as showing either natural objects, man-made objects or non-objects...
January 2017: Vision Research
Bart Gips, Ali Bahramisharif, Eric Lowet, Mark J Roberts, Peter de Weerd, Ole Jensen, Jan van der Eerden
BACKGROUND: Fourier-based techniques are used abundantly in the analysis of electrophysiological data. However, these techniques are of limited value when the signal of interest is non-sinusoidal or non-periodic. NEW METHOD: We present sliding window matching (SWM): a new data-driven method for discovering recurring temporal patterns in electrophysiological data. SWM is effective in detecting recurring but unknown patterns even when they appear non-periodically...
January 1, 2017: Journal of Neuroscience Methods
Jian-Fang Zhou, Wu-Jie Yuan, Zhao Zhou
Microsaccades are involuntary and very small eye movements during fixation. Recently, the microsaccade-related neural dynamics have been extensively investigated both in experiments and by constructing neural network models. Experimentally, microsaccades also exhibit many behavioral properties. It's well known that the behavior properties imply the underlying neural dynamical mechanisms, and so are determined by neural dynamics. The behavioral properties resulted from neural responses to microsaccades, however, are not yet understood and are rarely studied theoretically...
October 14, 2016: Scientific Reports
Tyler R Peel, Ziad M Hafed, Suryadeep Dash, Stephen G Lomber, Brian D Corneil
Microsaccades aid vision by helping to strategically sample visual scenes. Despite the importance of these small eye movements, no cortical area has ever been implicated in their generation. Here, we used unilateral and bilateral reversible inactivation of the frontal eye fields (FEF) to identify a cortical drive for microsaccades. Unexpectedly, FEF inactivation altered microsaccade metrics and kinematics. Such inactivation also impaired microsaccade deployment following peripheral cue onset, regardless of cue side or inactivation configuration...
August 2016: PLoS Biology
Pengxiao Zang, Gangjun Liu, Miao Zhang, Changlei Dongye, Jie Wang, Alex D Pechauer, Thomas S Hwang, David J Wilson, David Huang, Dengwang Li, Yali Jia
We propose an innovative registration method to correct motion artifacts for wide-field optical coherence tomography angiography (OCTA) acquired by ultrahigh-speed swept-source OCT (>200 kHz A-scan rate). Considering that the number of A-scans along the fast axis is much higher than the number of positions along slow axis in the wide-field OCTA scan, a non-orthogonal scheme is introduced. Two en face angiograms in the vertical priority (2 y-fast) are divided into microsaccade-free parallel strips. A gross registration based on large vessels and a fine registration based on small vessels are sequentially applied to register parallel strips into a composite image...
July 1, 2016: Biomedical Optics Express
Moritz Köster
No abstract text is available yet for this article.
July 27, 2016: Proceedings. Biological Sciences
Alex L White, Martin Rolfs
Saccadic eye movements occur frequently even during attempted fixation, but they halt momentarily when a new stimulus appears. Here, we demonstrate that this rapid, involuntary "oculomotor freezing" reflex is yoked to fluctuations in explicit visual perception. Human observers reported the presence or absence of a brief visual stimulus while we recorded microsaccades, small spontaneous eye movements. We found that microsaccades were reflexively inhibited if and only if the observer reported seeing the stimulus, even when none was present...
September 1, 2016: Journal of Neurophysiology
Sven Ohl, Reinhold Kliegl
Saccadic eye movements are frequently followed by smaller secondary saccades which are generally assumed to correct for the error in primary saccade landing position. However, secondary saccades can also occur after accurate primary saccades and they are often as small as microsaccades, therefore raising the need to further scrutinize the processes involved in secondary saccade generation. Following up a previous study, we analyzed secondary saccades using rate analysis which allows us to quantify experimental effects as shifts in distributions, therefore going beyond comparisons of mean differences...
July 2016: Vision Research
Alessandro Piras, Milena Raffi, Michela Persiani, Monica Perazzolo, Salvatore Squatrito
The present study shows the relationship between microsaccades and heading perception. Recent research demonstrates that microsaccades during fixation are necessary to overcome loss of vision due to continuous stimulation of the retinal receptors, even at the potential cost of a decrease in visual acuity. The goal of oculomotor fixational mechanisms might be not retinal stabilization, but controlled image motion adjusted to be optimal for visual processing. Thus, patterns of microsaccades may be exploited to help to understand the oculomotor system, aspects of visual perception, and the dynamics of visual attention...
October 1, 2016: Behavioural Brain Research
Zongpeng Sun, Marc Junker, Peter W Dicke, Peter Thier
Recent studies have suggested that microsaccades, the small amplitude saccades made during fixation, are precisely controlled. Two lines of evidence suggest that the cerebellum plays a key role not only in improving the accuracy of macrosaccades but also of microsaccades. First, lesions of the fastigial oculomotor regions (FOR) cause horizontal dysmetria of both micro- and macrosaccades. Secondly, our previous work on Purkinje cell simple spikes in the oculomotor vermis (OV) has established qualitatively similar response preferences for these two groups of saccades...
June 3, 2016: European Journal of Neuroscience
Uday K Jagadisan, Neeraj J Gandhi
UNLABELLED: Executive control of voluntary movements is a hallmark of the mammalian brain. In the gaze-control network, this function is thought to be mediated by a critical balance between neurons responsible for generating movements and those responsible for fixating or suppressing movements, but the nature of this balance between the relevant elements-saccade-generating and fixation-related neurons-remains unclear. Specifically, it has been debated whether the two functions are necessarily coupled (i...
June 1, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Wu-Jie Yuan, Jian-Fang Zhou, Changsong Zhou
Microsaccades are very small eye movements during fixation. Experimentally, they have been found to play an important role in visual information processing. However, neural responses induced by microsaccades are not yet well understood and are rarely studied theoretically. Here we propose a network model with a cascading adaptation including both retinal adaptation and short-term depression (STD) at thalamocortical synapses. In the neural network model, we compare the microsaccade-induced neural responses in the presence of STD and those without STD...
April 2016: Physical Review. E
Yoram S Bonneh, Yael Adini, Uri Polat
Spontaneous eyeblinks are known to serve important physiological functions, and recent evidence shows that they are also linked to cognitive processes. It is yet unclear whether this link reflects a crude rate modulation or, alternatively, an automatic and precise process, tightly linked to the low-level properties of sensory stimuli. We have recently reported (Y. S. Bonneh, Adini, & Polat, 2015) that, for microsaccades, the onset and release from inhibition in response to transient stimuli depend systematically on the low-level stimulus parameters...
May 1, 2016: Journal of Vision
Timothée Masquelier, Geoffrey Portelli, Pierre Kornprobst
It is now reasonably well established that microsaccades (MS) enhance visual perception, although the underlying neuronal mechanisms are unclear. Here, using numerical simulations, we show that MSs enable efficient synchrony-based coding among the primate retinal ganglion cells (RGC). First, using a jerking contrast edge as stimulus, we demonstrate a qualitative change in the RGC responses: synchronous firing, with a precision in the 10 ms range, only occurs at high speed and high contrast. MSs appear to be sufficiently fast to be able reach the synchronous regime...
2016: Scientific Reports
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