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Tao Yao, Stefan Treue, B Suresh Krishna
While making saccadic eye-movements to scan a visual scene, humans and monkeys are able to keep track of relevant visual stimuli by maintaining spatial attention on them. This ability requires a shift of attentional modulation from the neuronal population representing the relevant stimulus pre-saccadically to the one representing it post-saccadically. For optimal performance, this trans-saccadic attention shift should be rapid and saccade-synchronized. Whether this is so is not known. We trained two rhesus monkeys to make saccades while maintaining covert attention at a fixed spatial location...
March 6, 2018: Nature Communications
Thérèse Collins, Pierre O Jacquet
BACKGROUND: Saccadic eye movements change the retinal location of visual objects, but we do not experience the visual world as constantly moving, we perceive it as seamless and stable. This visual stability may be achieved by an internal or efference copy of each saccade that, combined with the retinal information, allows the visual system to cancel out or ignore the self-caused retinal motion. OBJECTIVE: The current study investigated the underlying brain mechanisms responsible for visual stability in humans with online transcranial magnetic stimulation (TMS)...
November 29, 2017: Brain Stimulation
Emma E M Stewart, Alexander C Schütz
With every saccade, humans must reconcile the low resolution peripheral information available before a saccade, with the high resolution foveal information acquired after the saccade. While research has shown that we are able to integrate peripheral and foveal vision in a near-optimal manner, it is still unclear which mechanisms may underpin this important perceptual process. One potential mechanism that may moderate this integration process is visual attention. Pre-saccadic attention is a well documented phenomenon, whereby visual attention shifts to the location of an upcoming saccade before the saccade is executed...
January 2018: Vision Research
Paul Zerr, Surya Gayet, Kees Mulder, Yaïr Pinto, Ilja Sligte, Stefan Van der Stigchel
Humans typically make several saccades per second. This provides a challenge for the visual system as locations are largely coded in retinotopic (eye-centered) coordinates. Spatial remapping, the updating of retinotopic location coordinates of items in visuospatial memory, is typically assumed to be limited to robust, capacity-limited and attention-demanding working memory (WM). Are pre-attentive, maskable, sensory memory representations (e.g. fragile memory, FM) also remapped? We directly compared trans-saccadic WM (tWM) and trans-saccadic FM (tFM) in a retro-cue change-detection paradigm...
November 21, 2017: Scientific Reports
Dongjun He, Ce Mo, Fang Fang
Saccadic eye movements cause rapid and dramatic displacements of the retinal image of the visual world, yet our conscious perception of the world remains stable and continuous. A popular explanation for this remarkable ability of our visual system to compensate for the displacements is the predictive feature remapping theory. The theory proposes that, before saccades, the representation of a visual stimulus can be predictively transferred from neurons that initially encode the stimulus to neurons whose receptive fields will encompass the stimulus location after the saccade...
May 1, 2017: Journal of Vision
Grace Edwards, Céline Paeye, Philippe Marque, Rufin VanRullen, Patrick Cavanagh
When objects move or the eyes move, the visual system can predict the consequence and generate a percept of the target at its new position. This predictive localization may depend on eye movement control in the frontal eye fields (FEF) and the intraparietal sulcus (IPS) and on motion analysis in the medial temporal area (MT). Across two experiments we examined whether repetitive transcranial magnetic stimulation (rTMS) over right FEF, right IPS, right MT, and a control site, peripheral V1/V2, diminished participants' perception of two cases of predictive position perception: trans-saccadic fusion, and the flash grab illusion, both presented in the contralateral visual field...
June 2017: NeuroImage
David P M Northmore
Only ray-finned fishes possess a torus longitudinalis (TL), a paired, elongated body attached to the medial margins of the optic tectum. Its granule cells project large numbers of fine fibers running laterally over adjacent tectum, synapsing excitatorily on the spiny dendrites of pyramidal cells. Sustained TL activity is evoked visuotopically by dark stimuli; TL bursting is a corollary discharge of saccadic eye movements. To suggest a function for this ancient structure, neural network models were constructed to show that: (1) pyramidal cells could form an attentional locus, selecting one out of several moving objects to track, but rapid image shifts caused by saccades disrupt tracking; (2) TL could supply both the pre-saccade position of a locus, and the shift predicted from a saccade so as to prime pyramidal dendrites at the target location, ensuring the locus stays with the attended object; (3) that the specific pattern of synaptic connections required for such predictive priming could be learned by an unsupervised rule; (4) temporal and spatial filtering of visual pattern input to TL allows learning from a complex scene...
January 3, 2017: Vision Research
Scott L Fairhall, Jens Schwarzbach, Angelika Lingnau, Martijn Gerbrand Van Koningsbruggen, David Melcher
Brain representations of visual space are predominantly eye-centred (retinotopic) yet our experience of the world is largely world-centred (spatiotopic). A long-standing question is how the brain creates continuity between these reference frames across successive eye movements (saccades). Here we use functional magnetic resonance imaging (fMRI) to address whether spatially specific repetition suppression (RS) is evident during trans-saccadic perception. We presented two successive Gabor patches (S1 and S2) in either the upper or lower visual field, left or right of fixation...
February 15, 2017: NeuroImage
Benjamin T Dunkley, Bianca Baltaretu, J Douglas Crawford
The cortical sites for the trans-saccadic storage and integration of visual object features are unknown. Here, we used a variant of fMRI-Adaptation where subjects fixated to the left or right of a briefly presented visual grating, maintained fixation or saccaded to the opposite side, then judged whether a re-presented grating had the same or different orientation. fMRI analysis revealed trans-saccadic interactions (different > same orientation) in a visual field-insensitive cluster within right supramarginal gyrus...
September 2016: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
David Souto, Karl R Gegenfurtner, Alexander C Schütz
Visual uncertainty may affect saccade adaptation in two complementary ways. First, an ideal adaptor should take into account the reliability of visual information for determining the amount of correction, predicting that increasing visual uncertainty should decrease adaptation rates. We tested this by comparing observers' direction discrimination and adaptation rates in an intra-saccadic-step paradigm. Second, clearly visible target steps may generate a slower adaptation rate since the error can be attributed to an external cause, instead of an internal change in the visuo-motor mapping that needs to be compensated...
2016: Frontiers in Human Neuroscience
Naoko Inaba, Kenji Kawano
After a saccade, most MST neurons respond to moving visual stimuli that had existed in their post-saccadic receptive fields and turned off before the saccade ("trans-saccadic memory remapping"). Neuronal responses in higher visual processing areas are known to be modulated in relation to gaze angle to represent image location in spatiotopic coordinates. In the present study, we investigated the eye position effects after saccades and found that the gaze angle modulated the visual sensitivity of MST neurons after saccades both to the actually existing visual stimuli and to the visual memory traces remapped by the saccades...
February 23, 2016: Scientific Reports
Matteo Valsecchi, Karl R Gegenfurtner
The same object produces quite distinct images in the cortical representation, depending on whether it is looked at foveally or with the periphery, yet some form of size constancy prevents us from experiencing objects inflating or deflating as we move our eyes. According to the prominent sensorimotor account of vision by O'Regan and Noë [1], we constantly learn to discount the predictable sensory effects of motor actions, such as the projection of a stimulus on a larger cortical area as it gets foveated. Although previous studies have shown that foveal and parafoveal inputs can be associated in visual memory [2, 3], trans-saccadic prediction error could in principle re-calibrate even the appearance of peripheral and foveal stimuli...
January 11, 2016: Current Biology: CB
Laurence C Jayet Bray, Sonia Bansal, Wilsaan M Joiner
Extraretinal information, such as corollary discharge (CD), is hypothesized to help compensate for saccade-induced visual input disruptions. However, support for this hypothesis is largely for one-dimensional transsaccadic visual changes, with little comprehensive information on the spatial characteristics. Here we systematically mapped the two-dimensional extent of this compensation by quantifying the insensitivity to different displacement metrics. Human subjects made saccades to targets positioned at different amplitudes (4° or 8°) and directions (rightward, oblique, or upward)...
March 2016: Journal of Neurophysiology
Jonathan Grainger, Katherine J Midgley, Phillip J Holcomb
We used a trans-saccadic priming paradigm combined with ERP recordings to track the time-course of integration of information across a prime word briefly presented at fixation and a subsequent target word presented 4 degrees to the right of fixation. Trans-saccadic repetition priming effects (Experiments 1 and 2) were compared with priming effects obtained with centrally located targets (Experiment 3). In Experiment 2, target stimuli were preceded by a 100ms forward mask at the target location, hence allowing an attention shift to the target location prior to target onset...
January 8, 2016: Neuropsychologia
Christian Wolf, Alexander C Schütz
Due to the inhomogenous visual representation across the visual field, humans use peripheral vision to select objects of interest and foveate them by saccadic eye movements for further scrutiny. Thus, there is usually peripheral information available before and foveal information after a saccade. In this study we investigated the integration of information across saccades. We measured reliabilities--i.e., the inverse of variance-separately in a presaccadic peripheral and a postsaccadic foveal orientation--discrimination task...
2015: Journal of Vision
Annalisa Bosco, Markus Lappe, Patrizia Fattori
When saccadic eye movements consistently fail to land on the intended target, saccade accuracy is maintained by gradually adapting the amplitude of successive saccades to the same target. Such saccadic adaptation is usually induced by systematically displacing a small visual target during the execution of the saccade. However, saccades are normally performed to extended objects. Here we report changes in saccade amplitude when the size of a target object is systematically changed during a saccade. Moreover, we find that this manipulation also affected the visual perception of the size of that object...
October 28, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Benjamin Bolte, Markus Lappe
Virtual reality strives to provide a user with an experience of a simulated world that feels as natural as the real world. Yet, to induce this feeling, sometimes it becomes necessary for technical reasons to deviate from a one-to-one correspondence between the real and the virtual world, and to reorient or reposition the user's viewpoint. Ideally, users should not notice the change of the viewpoint to avoid breaks in perceptual continuity. Saccades, the fast eye movements that we make in order to switch gaze from one object to another, produce a visual discontinuity on the retina, but this is not perceived because the visual system suppresses perception during saccades...
April 2015: IEEE Transactions on Visualization and Computer Graphics
Martin Szinte, David Aagten-Murphy, Donatas Jonikaitis, Heiner Deubel
Our perception of the auditory and visual stimuli in the world remains stable despite frequent head and eye movements. For visual stimuli, this stability is achieved through the correction (remapping) of the object's visual representation in retinotopically organized visual and oculomotor maps. In the present study, we use saccade curvature to investigate the competition between visual saccade targets and different multi-sensory distractors. We report clear physiological evidence for the existence of a supra-modal map of locations across saccades...
2015: Journal of Vision
Jean-Baptiste Bernard, Carlos Aguilar, Françoise Vitu, Eric Castet
Reading involves multiple eye movements and necessitates the integration of visual information from successive fixations. Here, we quantify the efficiency of trans-saccadic integration during foveal and peripheral word recognition by comparing performance for a human and an ideal observer. In Experiment 1, subjects were asked to identify random trigram letters presented at 13 possible positions on an invisible horizontal line at 0° or 10° eccentricity in lower visual field (horizontal distance from fixation dot: -6 to +6 letter slots)...
2015: Journal of Vision
Christian Poth, Arvid Herwig, Werner Schneider
By making saccadic eye movements, we can bring interesting peripheral objects into the fovea for high-acuity examination. Every saccade abruptly displaces and alters the retinal image of objects. Nevertheless, we perceive objects as stable in their locations. The visual system seems to deal with the retinal image displacement by actively assuming object stability across saccades. This assumption seems to be responsible for concealing actual object displacements across the saccade, rendering them hard to detect (cf...
2015: Journal of Vision
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