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https://www.readbyqxmd.com/read/28334181/uncovering-the-spatial-profile-of-contour-integration-from-fixational-saccades-evidence-for-widespread-processing-in-v1
#1
Ariel Gilad, Roy Oz, Hamutal Slovin
During contour integration, neuronal populations in the primary visual cortex (V1) enhance their responses to the contour while suppressing their responses to the noisy background. However, the spatial extent and profile of these responses are not fully understood. To investigate this question, 2 monkeys were trained on a contour detection task while we measured population responses in V1 using voltage-sensitive dyes. During stimulus presentation the animals made few fixational saccades, and we used their changing gaze position to image and analyze neuronal responses from large part of the stimulus, encoding multiple contour/background elements...
October 5, 2016: Cerebral Cortex
https://www.readbyqxmd.com/read/28333501/effects-of-word-predictability-and-preview-lexicality-on-eye-movements-during-reading-a-comparison-between-young-and-older-adults
#2
Wonil Choi, Matthew W Lowder, Fernanda Ferreira, Tamara Y Swaab, John M Henderson
Previous eye-tracking research has characterized older adults' reading patterns as "risky," arguing that compared to young adults, older adults skip more words, have longer saccades, and are more likely to regress to previous portions of the text. In the present eye-tracking study, we reexamined the claim that older adults adopt a risky reading strategy, utilizing the boundary paradigm to manipulate parafoveal preview and contextual predictability of a target word. Results showed that older adults had longer fixation durations compared to young adults; however, there were no age differences in skipping rates, saccade length, or proportion of regressions...
March 23, 2017: Psychology and Aging
https://www.readbyqxmd.com/read/28326028/inter-trial-correlations-in-predictive-saccade-endpoints-fractal-scaling-reflects-differential-control-along-task-relevant-and-orthogonal-directions
#3
Pamela Federighi, Aaron L Wong, Mark Shelhamer
Saccades exhibit variation in performance from one trial to the next, even when paced at a constant rate by targets at two fixed locations. We previously showed that amplitude fluctuations in consecutive predictive saccades have fractal structure: the spectrum of the sequence of consecutive amplitudes has a power-law (f(-α)) form, indicative of inter-trial correlations that reflect the storage of prior performance information to guide the planning of subsequent movements. More gradual decay of these inter-trial correlations coincides with a larger magnitude of spectral slope α, and indicates stronger information storage over longer times...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28321288/influence-of-coactors-on-saccadic-and-manual-responses
#4
Manuel Oliva, Diederick C Niehorster, Halszka Jarodzka, Kenneth Holmqvist
Two experiments were conducted to investigate the effects of coaction on saccadic and manual responses. Participants performed the experiments either in a solitary condition or in a group of coactors who performed the same tasks at the same time. In Experiment 1, participants completed a pro- and antisaccade task where they were required to make saccades towards (prosaccades) or away (antisaccades) from a peripheral visual stimulus. In Experiment 2, participants performed a visual discrimination task that required both making a saccade towards a peripheral stimulus and making a manual response in reaction to the stimulus's orientation...
January 2017: I-Perception
https://www.readbyqxmd.com/read/28320694/rectus-muscle-excyclorotation-and-v-pattern-strabismus-a-quantitative-appraisal-of-clinical-relevance-in-syndromic-craniosynostosis
#5
Linda R Dagi, Sarah MacKinnon, David Zurakowski, Sanjay P Prabhu
PURPOSE: V-pattern strabismus observed with syndromic craniosynostosis has been attributed to disparate causes. We compared severity of V pattern with degree of excyclorotation of rectus muscles to appraise significance of this proposed aetiology. METHODS: 43 patients with Apert, Crouzon or Pfeiffer syndrome referred to Boston Children's Hospital Department of Ophthalmology were identified. 28 met inclusion criteria for retrospective cohort study, specifically: (1) sensorimotor measurements in minimum of seven cardinal gazes, (2) quantified fundus torsion and (3) orbital CT imaging sufficient to measure rectus muscle cyclorotation in coronal and quasicoronal planes, posteriorly (near orbital apex) and anteriorly (near pulleys)...
March 20, 2017: British Journal of Ophthalmology
https://www.readbyqxmd.com/read/28316563/a-saccade-based-framework-for-real-time-motion-segmentation-using-event-based-vision-sensors
#6
Abhishek Mishra, Rohan Ghosh, Jose C Principe, Nitish V Thakor, Sunil L Kukreja
Motion segmentation is a critical pre-processing step for autonomous robotic systems to facilitate tracking of moving objects in cluttered environments. Event based sensors are low power analog devices that represent a scene by means of asynchronous information updates of only the dynamic details at high temporal resolution and, hence, require significantly less calculations. However, motion segmentation using spatiotemporal data is a challenging task due to data asynchrony. Prior approaches for object tracking using neuromorphic sensors perform well while the sensor is static or a known model of the object to be followed is available...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28303385/after-effects-of-cerebellar-continuous-theta-burst-stimulation-on-reflexive-saccades-and-smooth-pursuit-in-humans
#7
Silvia Colnaghi, P Colagiorgio, S Ramat, E D'Angelo, G Koch, M Versino
The use of cerebellar repetitive transcranial magnetic stimulation has been attempted for perturbing reflexive and voluntary eye movements, but discrepancies are seen between the results of distinct studies possibly due to the different stimulation sites, intensities, and paradigms. We describe the after effects of 20 and 40 s continuous Theta Burst Stimulation (cTBS) as compared to sham stimulation, applied over the lateral cerebellar vermis and paravermis on Reflexive Saccades (RS) and Smooth Pursuit (SP) eye movements, recorded in the 30 min following stimulation...
March 16, 2017: Cerebellum
https://www.readbyqxmd.com/read/28302586/mantisbot-is-a-robotic-model-of-visually-guided-motion-in-the-praying-mantis
#8
Nicholas S Szczecinski, Andrew P Getsy, Joshua P Martin, Roy E Ritzmann, Roger D Quinn
Insects use highly distributed nervous systems to process exteroception from head sensors, compare that information with state-based goals, and direct posture or locomotion toward those goals. To study how descending commands from brain centers produce coordinated, goal-directed motion in distributed nervous systems, we have constructed a conductance-based neural system for our robot MantisBot, a 29 degree-of-freedom, 13.3:1 scale praying mantis robot. Using the literature on mantis prey tracking and insect locomotion, we designed a hierarchical, distributed neural controller that establishes the goal, coordinates different joints, and executes prey-tracking motion...
March 13, 2017: Arthropod Structure & Development
https://www.readbyqxmd.com/read/28298302/visual-and-presaccadic-activity-in-area-8ar-of-the-macaque-monkey-lateral-prefrontal-cortex
#9
Kelly R Bullock, Florian Pieper, Adam J Sachs, Julio C Martinez-Trujillo
Common trends observed in many visual and oculomotor-related cortical areas include retinotopically organized receptive and movement fields exhibiting a Gaussian shape and increasing size with eccentricity. These trends are demonstrated in the frontal eye fields (FEF), many visual areas, and the superior colliculus (SC), but have not been thoroughly characterized in prearcuate area 8Ar of the prefrontal cortex. This is important since area 8Ar, located anterior to the FEF, is more cytoarchitectonically similar to prefrontal areas than premotor areas...
March 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28298299/time-compression-of-visual-perception-around-microsaccades
#10
Gongchen Yu, Mingpo Yang, Peng Yu, Michael C 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 prior to microsaccades (Hafed 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...
March 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28296958/interaction-between-the-oculomotor-and-postural-systems-during-a-dual-task-compensatory-reductions-in-head-sway-following-visually-induced-postural-perturbations-promote-the-production-of-accurate-double-step-saccades-in-standing-human-adults
#11
Mathieu Boulanger, Guillaume Giraudet, Jocelyn Faubert
Humans routinely scan their environment for useful information using saccadic eye movements and/or coordinated movements of the eyes and other body segments such the head and the torso. Most previous eye movement studies were conducted with seated subject and showed that single saccades and sequences of saccades (e.g. double-step saccades) made to briefly flashed stimuli were equally accurate and precise. As one can easily appreciate, most gaze shifts performed daily by a given person are not produced from a seated position, but rather from a standing position either as subjects perform an action from an upright stance or as they walk from one place to another...
2017: PloS One
https://www.readbyqxmd.com/read/28295571/further-tests-of-a-dynamic-adjustment-account-of-saccade-targeting-during-the-reading-of-chinese
#12
Yanping Liu, Ren Huang, Dingguo Gao, Erik D Reichle
There are two accounts of how readers of unspaced writing systems (e.g., Chinese) know where to move their eyes: (a) saccades are directed toward default targets (e.g., centers of words that have been segmented in the parafovea); or (b) saccade lengths are adjusted dynamically, as a function of ongoing parafoveal processing. This article reports an eye-movement experiment supporting the latter hypothesis by demonstrating that the slope of the relationship between the saccade launch site on word N and the subsequent fixation landing site on word N + 1 is > 1, suggesting that saccades are lengthened from launch sites that afford more parafoveal processing...
March 13, 2017: Cognitive Science
https://www.readbyqxmd.com/read/28288201/optokinetic-nystagmus-reflects-perceptual-directions-in-the-onset-binocular-rivalry-in-parkinson-s-disease
#13
Mana Fujiwara, Catherine Ding, Lisandro Kaunitz, Julie C Stout, Dominic Thyagarajan, Naotsugu Tsuchiya
Optokinetic nystagmus (OKN), the reflexive eye movements evoked by a moving field, has recently gained interest among researchers as a useful tool to assess conscious perception. When conscious perception and stimulus are dissociated, such as in binocular rivalry-when dissimilar images are simultaneously presented to each eye and perception alternates between the two images over time-OKN correlates with perception rather than with the physical direction of the moving field. While this relationship is well established in healthy subjects, it is yet unclear whether it also generalizes to clinical populations, for example, patients with Parkinson's disease...
2017: PloS One
https://www.readbyqxmd.com/read/28287758/cerebral-hemodynamics-during-scene-viewing-hemispheric-lateralization-predicts-temporal-gaze-behavior-associated-with-distinct-modes-of-visual-processing
#14
Mark Mills, Mohammed Alwatban, Benjamin Hage, Erin Barney, Edward J Truemper, Gregory R Bashford, Michael D Dodd
Systematic patterns of eye movements during scene perception suggest a functional distinction between 2 viewing modes: an ambient mode (characterized by short fixations and large saccades) thought to reflect dorsal activity involved with spatial analysis, and a focal mode (characterized by long fixations and small saccades) thought to reflect ventral activity involved with object analysis. Little neuroscientific evidence exists supporting this claim. Here, functional transcranial Doppler ultrasound (fTCD) was used to investigate whether these modes show hemispheric specialization...
March 13, 2017: Journal of Experimental Psychology. Human Perception and Performance
https://www.readbyqxmd.com/read/28280554/eye-and-head-movements-are-complementary-in-visual-selection
#15
Grayden J F Solman, Tom Foulsham, Alan Kingstone
In the natural environment, visual selection is accomplished by a system of nested effectors, moving the head and body within space and the eyes within the visual field. However, it is not yet known if the principles of selection for these different effectors are the same or different. We used a novel gaze-contingent display in which an asymmetric window of visibility (a horizontal or vertical slot) was yoked to either head or eye position. Participants showed highly systematic changes in behaviour, revealing clear differences in the principles underlying selection by eye and head...
January 2017: Royal Society Open Science
https://www.readbyqxmd.com/read/28279711/altered-saccadic-targets-when-processing-facial-expressions-under-different-attentional-and-stimulus-conditions
#16
Frank A Boutsen, Justin D Dvorak, Vinay K Pulusu, Elliott D Ross
Depending on a subject's attentional bias, robust changes in emotional perception occur when facial blends (different emotions expressed on upper/lower face) are presented tachistoscopically. If no instructions are given, subjects overwhelmingly identify the lower facial expression when blends are presented to either visual field. If asked to attend to the upper face, subjects overwhelmingly identify the upper facial expression in the left visual field but remain slightly biased to the lower facial expression in the right visual field...
March 13, 2017: Vision Research
https://www.readbyqxmd.com/read/28270573/saccadic-suppression-is-embedded-within-extended-oscillatory-modulation-of-sensitivity
#17
Alessandro Benedetto, Maria Concetta Morrone
Action and perception are intimately coupled systems; one clear case is saccadic suppression, the reduced visibility around the time of saccades, important in mediating visual stability; another is the oscillatory modulation of visibility synchronized with hand action. To suppress effectively the spurious retinal motion generated by the eye movements, it is crucial that saccadic suppression and saccadic onset be temporally synchronous. However, the mechanisms that determine this temporal synchrony are unknown...
March 7, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28268209/patterns-of-eye-movement-impairment-correlate-with-regional-brain-atrophy-in-neurodegenerative-parkinsonism
#18
Olga Vintonyak, Martin Gorges, Hans-Peter Müller, Elmar H Pinkhardt, Albert C Ludolph, Hans-Jürgen Huppertz, Jan Kassubek
BACKGROUND: One common feature of neurodegenerative parkinsonism including Parkinson's disease (PD), multisystem atrophy (MSA), and progressive supranuclear palsy (PSP) is altered eye movement control. Characteristic regional structural atrophy patterns in MRI can be observed in PD, MSA, and PSP. OBJECTIVE: To investigate the association between eye movement disturbances and regional brain atrophy in patients with PD, MSA, and PSP. METHODS: High-resolution 3-dimensional T1-weighted MRI images and video-oculographic recordings (EyeLink®) were obtained from 39 PD, 32 PSP, and 18 MSA patients and 24 matched healthy control subjects...
March 8, 2017: Neuro-degenerative Diseases
https://www.readbyqxmd.com/read/28266311/averted-body-postures-facilitate-orienting-of-the-eyes
#19
Bobby Azarian, George A Buzzell, Elizabeth G Esser, Alexander Dornstauder, Matthew S Peterson
It is well established that certain social cues, such as averted eye gaze, can automatically initiate the orienting of another's spatial attention. However, whether human posture can also reflexively cue spatial attention remains unclear. The present study directly investigated whether averted neutral postures reflexively cue the attention of observers in a normal population of college students. Similar to classic gaze-cuing paradigms, non-predictive averted posture stimuli were presented prior to the onset of a peripheral target stimulus at one of five SOAs (100ms-500ms)...
March 7, 2017: Acta Psychologica
https://www.readbyqxmd.com/read/28265650/the-effect-of-object-centered-instructions-in-cartesian-and-polar-coordinates-on-saccade-vector
#20
Jay A Edelman, Alexa M Mieses, Kira Konnova, David Shiu
Express saccades (ES) are the most reflexive saccadic eye movements, with very short reaction times of 70-110 ms. It is likely that ES have the shortest saccade reaction times (SRTs) possible given the known physiological and anatomical delays present in sensory and motor systems. Nevertheless, it has been demonstrated that a vector displacement of ES to spatially extended stimuli can be influenced by spatial cognition. Edelman, Kristjansson, and Nakayama (2007) found that when two horizontally separated visual stimuli appear at a random location, the spatial vector, but not the reaction time, of human ES is strongly influenced by an instruction to make a saccade to one side (either left or right) of a visual stimulus array...
March 1, 2017: Journal of Vision
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