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Microsaccades

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https://www.readbyqxmd.com/read/28822717/searching-for-monocular-microsaccades-a-red-hering-of-modern-eye-trackers
#1
Marcus Nyström, Richard Andersson, Diederick C Niehorster, Ignace Hooge
Despite early reports and the contemporary consensus on microsaccades as purely binocular phenomena, recent work has proposed not only the existence of monocular microsaccades, but also that they serve functional purposes. We take a critical look at the detection of monocular microsaccades from a signal perspective, using raw data and a state-of-the-art, video-based eye tracker. In agreement with previous work, monocular detections were present in all participants using a standard microsaccade detection algorithm...
August 16, 2017: Vision Research
https://www.readbyqxmd.com/read/28815321/fixational-eye-movements-in-tourette-syndrome
#2
Aasef G Shaikh, Shlomit Ritz Finkelstein, Ronald Schuchard, Glen Ross, Jorge L Juncos
Studies of saccadic eye movements in subjects with Tourette syndrome (TS) have provided additional evidence that there is a link between TS symptoms and deficits in fronto-striato-thalamic networks. These studies revealed impaired timing and inhibition of saccades. We compared fixational eye movements, such as microsaccades and ocular drifts, in subjects with TS and healthy controls.We measured horizontal and vertical eye positions with video-oculography in 14 subjects with Tourette syndrome. We found reduced microsaccade amplitude but increased time between adjacent microsaccades (intersaccadic interval)...
August 16, 2017: Neurological Sciences
https://www.readbyqxmd.com/read/28800343/microsaccade-dysfunction-and-adaptation-in-hemianopia-after-stroke
#3
Ying Gao, Bernhard A Sabel
BACKGROUND: Besides the reduction of visual field size, hemianopic patients may also experience other poorly understood symptoms such as blurred vision, diplopia, or reduced visual acuity, which may be related to microsaccade function. OBJECTIVE: To determine (i) if microsaccades are altered in hemianopia; (ii) how altered microsaccade features correlate with visual performances; and (iii) how their direction relates to visual field defect topography. METHODS: In this case-control study, microsaccades of hemianopic stroke patients (n = 14) were assessed with high-resolution eye-tracking technique, compared with those of healthy controls (n = 14), and correlated with visual performances, visual field defect parameters and lesion age...
2017: Restorative Neurology and Neuroscience
https://www.readbyqxmd.com/read/28794193/sequential-hemifield-gating-of-alpha-and-beta-behavioral-performance-oscillations-after-microsaccades
#4
Joachim Bellet, Chih-Yang Chen, Ziad M Hafed
Microsaccades are tiny saccades that occur during gaze fixation. Even though visual processing has been shown to be strongly modulated close to the time of microsaccades, both at central and peripheral eccentricities, it is not clear how these eye movements might influence longer-term fluctuations in brain activity and behavior. Here we found that visual processing is significantly affected, and in a rhythmic manner, even several hundreds of milliseconds after a microsaccade. Human visual detection efficiency, as measured by reaction time, exhibited coherent rhythmic oscillations in the α and β frequency bands for up to ~650-700 ms after a microsaccade...
August 9, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28789960/multisensory-integration-in-orienting-behavior-pupil-size-microsaccades-and-saccades
#5
Chin-An Wang, Gunnar Blohm, Jeff Huang, Susan E Boehnke, Douglas P Munoz
Signals from different sensory modalities are integrated in the brain to optimize behavior. Although multisensory integration has been demonstrated in saccadic eye movements, its influence on other orienting responses, including pupil size and microsaccades, is still poorly understood. We examined human gaze orienting responses following presentation of visual, auditory, or combined audiovisual stimuli. Transient pupil dilation and microsaccade inhibition were evoked shortly after the appearance of a salient stimulus...
August 5, 2017: Biological Psychology
https://www.readbyqxmd.com/read/28713304/eye-behavior-associated-with-internally-versus-externally-directed-cognition
#6
Mathias Benedek, Robert Stoiser, Sonja Walcher, Christof Körner
What do our eyes do when we are focused on internal representations such as during imagination or planning? Evidence from mind wandering research suggests that spontaneous shifts from externally directed cognition (EDC) to internally directed cognition (IDC) involves oculomotor changes indicative of visual disengagement. In the present study, we investigated potential differences in eye behavior between goal-directed forms of IDC and EDC. To this end, we manipulated the focus of attention (internal versus external) in two demanding cognitive tasks (anagram and sentence generation)...
2017: Frontiers in Psychology
https://www.readbyqxmd.com/read/28689088/looking-for-ideas-eye-behavior-during-goal-directed-internally-focused-cognition
#7
Sonja Walcher, Christof Körner, Mathias Benedek
Humans have a highly developed visual system, yet we spend a high proportion of our time awake ignoring the visual world and attending to our own thoughts. The present study examined eye movement characteristics of goal-directed internally focused cognition. Deliberate internally focused cognition was induced by an idea generation task. A letter-by-letter reading task served as external task. Idea generation (vs. reading) was associated with more and longer blinks and fewer microsaccades indicating an attenuation of visual input...
July 6, 2017: Consciousness and Cognition
https://www.readbyqxmd.com/read/28638094/microsaccades-are-sensitive-to-word-structure-a-novel-approach-to-study-language-processing
#8
Maya Yablonski, Uri Polat, Yoram S Bonneh, Michal Ben-Shachar
Microsaccades are miniature eye movements that occur involuntarily during fixation. They are typically inhibited following stimulus onset and are released from inhibition about 300 ms post-stimulus. Microsaccade-inhibition is modulated by low level features of visual stimuli, but it is currently unknown whether they are sensitive to higher level, abstract linguistic properties. To address this question, we measured the timing of microsaccades while subjects were presented with written Hebrew words and pronounceable nonwords (pseudowords)...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28637052/subtle-eye-movement-metrics-reveal-task-relevant-representations-prior-to-visual-search
#9
Anouk M van Loon, Katya Olmos-Solis, Christian N L Olivers
Visual search is thought to be guided by an active visual working memory (VWM) representation of the task-relevant features, referred to as the search template. In three experiments using a probe technique, we investigated which eye movement metrics reveal which search template is activated prior to the search, and distinguish it from future relevant or no longer relevant VWM content. Participants memorized a target color for a subsequent search task, while being instructed to keep central fixation. Before the search display appeared, we briefly presented two task-irrelevant colored probe stimuli to the left and right from fixation, one of which could match the current target template...
June 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28298299/time-compression-of-visual-perception-around-microsaccades
#10
Gongchen Yu, Mingpo Yang, Peng Yu, Michael Christopher Dorris
Even during fixation, our eyes are in constant motion. For example, microsaccades are small (typically <1°) eye movements that occur 1~3 times/second. Despite their tiny and transient nature, our percept of visual space is compressed before microsaccades (Hafed ZM, Lovejoy LP, Krauzlis RJ. Eur J Neurosci 37: 1169-1181, 2013). As visual space and time are interconnected at both the physical and physiological levels, we asked whether microsaccades also affect the temporal aspects of visual perception. Here we demonstrate that the perceived interval between transient visual stimuli was compressed if accompanied by microsaccades...
July 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28278311/working-memory-load-modulates-microsaccadic-rate
#11
Mario Dalmaso, Luigi Castelli, Pietro Scatturin, Giovanni Galfano
Microsaccades are tiny eye movements that individuals perform unconsciously during fixation. Despite that the nature and the functions of microsaccades are still lively debated, recent evidence has shown an association between these micro eye movements and higher order cognitive processes. Here, in two experiments, we specifically focused on working memory and addressed whether differential memory load could be reflected in a modulation of microsaccade dynamics. In Experiment 1, participants memorized a numerical sequence composed of either two (low-load condition) or five digits (high-load condition), appearing at fixation...
March 1, 2017: Journal of Vision
https://www.readbyqxmd.com/read/28254651/how-microsaccades-relate-to-lateralized-erp-components-of-spatial-attention-a-co-registration-study
#12
Susann Meyberg, Werner Sommer, Olaf Dimigen
Covert shifts of attention that follow the presentation of a cue are associated with lateralized components in the event-related potential (ERP): the "early directing attention negativity" (EDAN) and the "anterior directing attention negativity" (ADAN). Traditionally, these shifts are thought to take place while gaze is fixated and, thus, in the absence of saccades. However, microsaccades of small amplitude (<1°) occur frequently and involuntarily also during fixation and are closely correlated with spatial attention...
February 28, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28242738/neuronal-control-of-fixation-and-fixational-eye-movements
#13
REVIEW
Richard J Krauzlis, Laurent Goffart, Ziad M Hafed
Ocular fixation is a dynamic process that is actively controlled by many of the same brain structures involved in the control of eye movements, including the superior colliculus, cerebellum and reticular formation. In this article, we review several aspects of this active control. First, the decision to move the eyes not only depends on target-related signals from the peripheral visual field, but also on signals from the currently fixated target at the fovea, and involves mechanisms that are shared between saccades and smooth pursuit...
April 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28242737/unchanging-visions-the-effects-and-limitations-of-ocular-stillness
#14
REVIEW
Susana Martinez-Conde, Stephen L Macknik
Scientists have pondered the perceptual effects of ocular motion, and those of its counterpart, ocular stillness, for over 200 years. The unremitting 'trembling of the eye' that occurs even during gaze fixation was first noted by Jurin in 1738. In 1794, Erasmus Darwin documented that gaze fixation produces perceptual fading, a phenomenon rediscovered in 1804 by Ignaz Paul Vital Troxler. Studies in the twentieth century established that Jurin's 'eye trembling' consisted of three main types of 'fixational' eye movements, now called microsaccades (or fixational saccades), drifts and tremor...
April 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28202573/alteration-of-the-microsaccadic-velocity-amplitude-main-sequence-relationship-after-visual-transients-implications-for-models-of-saccade-control
#15
Antimo Buonocore, Chih-Yang Chen, Xiaoguang Tian, Saad Idrees, Thomas A Münch, Ziad M Hafed
Microsaccades occur during gaze fixation 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...
May 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28163059/revising-the-link-between-microsaccades-and-the-spatial-cueing-of-voluntary-attention
#16
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...
April 2017: Vision Research
https://www.readbyqxmd.com/read/28114483/bayesian-microsaccade-detection
#17
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
https://www.readbyqxmd.com/read/28044023/how-is-visual-salience-computed-in-the-brain-insights-from-behaviour-neurobiology-and-modelling
#18
REVIEW
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
https://www.readbyqxmd.com/read/27956580/visual-discomfort-from-flash-afterimages-of-riloid-patterns
#19
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
https://www.readbyqxmd.com/read/27891684/changes-in-visibility-as-a-function-of-spatial-frequency-and-microsaccade-occurrence
#20
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
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