scholarly journals An egocentric straight-ahead bias in primate’s vision

2021 ◽  
Author(s):  
Benoit R. Cottereau ◽  
Yves Trotter ◽  
Jean-Baptiste Durand
Keyword(s):  
Visual Processing ◽  
Peripheral Vision ◽  
Exogenous Attention ◽  
Neuronal Responses ◽  
V1 Neurons ◽  
Behavioral Studies ◽  
New Type ◽  
Underlying Mechanisms ◽  
Attentional Mechanism ◽  
Straight Ahead

AbstractAs we plan to reach or manipulate objects, we generally orient our body so as to face them. Other objects occupying the same portion of space will likely represent potential obstacles for the intended action. Thus, either as targets or as obstacles, the objects located straight in front of us are often endowed with a special behavioral status. Here, we review a set of recent electrophysiological, imaging and behavioral studies bringing converging evidence that the objects which lie straight-ahead are subject to privileged visual processing. More precisely, these works collectively demonstrate that when gaze steers central vision away from the straight-ahead direction, the latter is still prioritized in peripheral vision. Straight-ahead objects evoke (1) stronger neuronal responses in macaque peripheral V1 neurons, (2) stronger EEG and fMRI activations across the human visual cortex and (3) faster reactive hand and eye movements. Here, we discuss the functional implications and underlying mechanisms behind this phenomenon. Notably, we propose that it can be considered as a new type of visuospatial attentional mechanism, distinct from the previously documented classes of endogenous and exogenous attention.

scholarly journals The Neurophysiology of Backward Visual Masking: Information Analysis

1999 ◽  
Vol 11 (3) ◽  
pp. 300-311 ◽  
Author(s):  
Edmund T. Rolls ◽  
Martin J. Tovée ◽  
Stefano Panzeri
Keyword(s):  
Visual Processing ◽  
Visual Information ◽  
Computational Models ◽  
Direct Evidence ◽  
Visual Masking ◽  
Neuronal Response ◽  
Short Soas ◽  
Stimulus Onset ◽  
Backward Masking ◽  
Neuronal Responses

Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects of visual masking on neuronal responses. To investigate the effects of a backward masking paradigm on the responses of neurons in the temporal visual cortex, we have shown that the response of the neurons is interrupted by the mask. Under conditions when humans can just identify the stimulus, with stimulus onset asynchronies (SOA) of 20 msec, neurons in macaques respond to their best stimulus for approximately 30 msec. We now quantify the information that is available from the responses of single neurons under backward masking conditions when two to six faces were shown. We show that the information available is greatly decreased as the mask is brought closer to the stimulus. The decrease is more marked than the decrease in firing rate because it is the selective part of the firing that is especially attenuated by the mask, not the spontaneous firing, and also because the neuronal response is more variable at short SOAs. However, even at the shortest SOA of 20 msec, the information available is on average 0.1 bits. This compares to 0.3 bits with only the 16-msec target stimulus shown and a typical value for such neurons of 0.4 to 0.5 bits with a 500-msec stimulus. The results thus show that considerable information is available from neuronal responses even under backward masking conditions that allow the neurons to have their main response in 30 msec. This provides evidence for how rapid the processing of visual information is in a cortical area and provides a fundamental constraint for understanding how cortical information processing operates.

scholarly journals Privileged visual processing of the straight-ahead direction in humans

2012 ◽  
Vol 12 (6) ◽  
pp. 34-34 ◽  
Author(s):  
J.-B. Durand ◽  
D. Camors ◽  
Y. Trotter ◽  
S. Celebrini
Keyword(s):  
Visual Processing ◽  
Straight Ahead

scholarly journals A P300 brain-computer interface with a reduced visual field

2020 ◽  
Author(s):  
Luiza Kirasirova ◽  
Vladimir Bulanov ◽  
Alexei Ossadtchi ◽  
Alexander Kolsanov ◽  
Vasily Pyatin ◽  
...  
Keyword(s):  
Visual Field ◽  
Visual Processing ◽  
Peripheral Vision ◽  
Brain Computer Interface ◽  
Basic Research ◽  
Computer Interface ◽  
Eye Tracker ◽  
Central Visual Field ◽  
P300 Speller ◽  
User Fatigue

AbstractA P300 brain-computer interface (BCI) is a paradigm, where text characters are decoded from visual evoked potentials (VEPs). In a popular implementation, called P300 speller, a subject looks at a display where characters are flashing and selects one character by attending to it. The selection is recognized by the strongest VEP. The speller performs well when cortical responses to target and non-target stimuli are sufficiently different. Although many strategies have been proposed for improving the spelling, a relatively simple one received insufficient attention in the literature: reduction of the visual field to diminish the contribution from non-target stimuli. Previously, this idea was implemented in a single-stimulus switch that issued an urgent command. To tackle this approach further, we ran a pilot experiment where ten subjects first operated a traditional P300 speller and then wore a binocular aperture that confined their sight to the central visual field. Visual field restriction resulted in a reduction of non-target responses in all subjects. Moreover, in four subjects, target-related VEPs became more distinct. We suggest that this approach could speed up BCI operations and reduce user fatigue. Additionally, instead of wearing an aperture, non-targets could be removed algorithmically or with a hybrid interface that utilizes an eye tracker. We further discuss how a P300 speller could be improved by taking advantage of the different physiological properties of the central and peripheral vision. Finally, we suggest that the proposed experimental approach could be used in basic research on the mechanisms of visual processing.

scholarly journals Subthalamic and Striatal Neurons Concurrently Process Motor, Limbic, and Associative Information in Rats Performing an Operant Task

2007 ◽  
Vol 97 (3) ◽  
pp. 2042-2058 ◽  
Author(s):  
Mark A. Teagarden ◽  
George V. Rebec
Keyword(s):  
Physiological Data ◽  
Striatal Neurons ◽  
Neuronal Responses ◽  
Firing Patterns ◽  
Associative Processes ◽  
Behavioral Studies ◽  
Sucrose Reinforcement ◽  
Operant Task ◽  
Anatomical Evidence ◽  
Do So

Although the subthalamic nucleus (STN) is commonly assumed to be a relay for striatal (STR) output, anatomical evidence suggests the two structures are connected in parallel, raising the possibility that parallel STN and STR firing patterns mediate behavioral processes. The STR is known to play a role in associative and limbic processes, and although behavioral studies suggest that the STN may do so as well, evaluation of this hypothesis is complicated by a lack of pertinent STN physiological data. We recorded concurrent STN and STR firing patterns in rats learning an operant nose-poke task. Both structures responded in similar proportions to task events including instructive cues, discriminative nose-pokes, and sucrose reinforcement. Neuronal responses to reinforcement comprised phasic excitations preceding reinforcement and inhibitions afterward; the inhibition was attenuated when reinforcement was absent. Reinforcement responses occurred more frequently during later training sessions in which discriminative action was required, suggesting that responses were context-dependent. Nose-pokes were typically preceded by excitations; there also was a nonsignificant trend toward inhibition encoding correct nose-pokes. Sustained changes in firing rate coinciding with specific task events suggested that both nuclei were encoding behavioral sequences; this is the first report of such behavior in the STN. Our findings also reveal complex STN responses to reinforcement. Thus both STN and STR neurons show concurrent involvement in motor, limbic, and associative processes.

Colour Constancy, Categories, and Spectral Sensitivity

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 88-88
Author(s):  
J J Kulikowski ◽  
Z Al-Attar ◽  
H Vaitkevicius
Keyword(s):  
Spectral Sensitivity ◽  
Visual Processing ◽  
Colour Constancy ◽  
Dominant Wavelength ◽  
Multi Stage ◽  
Behavioral Studies ◽  
Colour Changes ◽  
Stage Process ◽  
Series Of Experiments ◽  
Spectral Sensitivity Function

Colour constancy is a multi-stage process whose receptoral and post-receptoral components have been separated by electrophysiological and behavioral studies. A psychophysical study was conducted to determine contributions of the visual processing stage which extracts information about colour categories, and to relate the results to the spectral sensitivity of the chromatic opponent system. Changes in colour appearance with illumination were investigated by using free-viewing and a successive matching method for 40 Munsell hues (saturations: 8 and 4). Subjects were adapted to standard illuminant C and briefly inspected a test chip under a variable illuminant A (tungsten) or g (green). Using criteria similar to those for unique hues, subjects specified ‘typical hues’ under illuminant C: red, yellow, green, blue, and violet (yellow should not contain red or green, green should not contain yellow or blue, etc). For each hue and saturation a dominant wavelength was computed. The degree of colour constancy was then established for all subjects (examined in three series of experiments), all Munsell chips and illuminations, as a one-dimensional Brunswick ratio, BR. The BR was determined by using u‘ v’ coordinates as related to the ratio of perceptual to physical colour changes: BR=1-perceptual/physical. BR was highest for typical (not intermediate) hues and lowest for hues resembling variable illuminants. The BR as a function of dominant wavelength resembles the spectral sensitivity function of chromatic opponency. These findings are interpreted as contributions of high-order opponent interactions to colour constancy.

scholarly journals A P300 Brain-Computer Interface With a Reduced Visual Field

2020 ◽  
Vol 14 ◽  
Author(s):  
Luiza Kirasirova ◽  
Vladimir Bulanov ◽  
Alexei Ossadtchi ◽  
Alexander Kolsanov ◽  
Vasily Pyatin ◽  
...  
Keyword(s):  
Visual Field ◽  
Visual Processing ◽  
Classification Accuracy ◽  
Peripheral Vision ◽  
Brain Computer Interface ◽  
Event Related Potentials ◽  
Computer Interface ◽  
Central Visual Field ◽  
P300 Speller ◽  
Related Potentials

A P300 brain-computer interface (BCI) is a paradigm, where text characters are decoded from event-related potentials (ERPs). In a popular implementation, called P300 speller, a subject looks at a display where characters are flashing and selects one character by attending to it. The selection is recognized as the item with the strongest ERP. The speller performs well when cortical responses to target and non-target stimuli are sufficiently different. Although many strategies have been proposed for improving the BCI spelling, a relatively simple one received insufficient attention in the literature: reduction of the visual field to diminish the contribution from non-target stimuli. Previously, this idea was implemented in a single-stimulus switch that issued an urgent command like stopping a robot. To tackle this approach further, we ran a pilot experiment where ten subjects operated a traditional P300 speller or wore a binocular aperture that confined their sight to the central visual field. As intended, visual field restriction resulted in a replacement of non-target ERPs with EEG rhythms asynchronous to stimulus periodicity. Changes in target ERPs were found in half of the subjects and were individually variable. While classification accuracy was slightly better for the aperture condition (84.3 ± 2.9%, mean ± standard error) than the no-aperture condition (81.0 ± 2.6%), this difference was not statistically significant for the entire sample of subjects (N = 10). For both the aperture and no-aperture conditions, classification accuracy improved over 4 days of training, more so for the aperture condition (from 72.0 ± 6.3% to 87.0 ± 3.9% and from 72.0 ± 5.6% to 97.0 ± 2.2% for the no-aperture and aperture conditions, respectively). Although in this study BCI performance was not substantially altered, we suggest that with further refinement this approach could speed up BCI operations and reduce user fatigue. Additionally, instead of wearing an aperture, non-targets could be removed algorithmically or with a hybrid interface that utilizes an eye tracker. We further discuss how a P300 speller could be improved by taking advantage of the different physiological properties of the central and peripheral vision. Finally, we suggest that the proposed experimental approach could be used in basic research on the mechanisms of visual processing.

scholarly journals Modulation of Neuronal Responses by Exogenous Attention in Macaque Primary Visual Cortex

2015 ◽  
Vol 35 (39) ◽  
pp. 13419-13429 ◽  
Author(s):  
F. Wang ◽  
M. Chen ◽  
Y. Yan ◽  
L. Zhaoping ◽  
W. Li
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Exogenous Attention ◽  
Neuronal Responses

scholarly journals Are Visual Peripheries Forever Young?

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Kalina Burnat
Keyword(s):  
Visual Processing ◽  
Visual Experience ◽  
Peripheral Vision ◽  
Postnatal Life ◽  
Central Vision ◽  
Central Processing ◽  
Afferent Projections ◽  
Vision Processing ◽  
Experimental Findings ◽  
Normal Perception

The paper presents a concept of lifelong plasticity of peripheral vision. Central vision processing is accepted as critical and irreplaceable for normal perception in humans. While peripheral processing chiefly carries information about motion stimuli features and redirects foveal attention to new objects, it can also take over functions typical for central vision. Here I review the data showing the plasticity of peripheral vision found in functional, developmental, and comparative studies. Even though it is well established that afferent projections from central and peripheral retinal regions are not established simultaneously during early postnatal life, central vision is commonly used as a general model of development of the visual system. Based on clinical studies and visually deprived animal models, I describe how central and peripheral visual field representations separately rely on early visual experience. Peripheral visual processing (motion) is more affected by binocular visual deprivation than central visual processing (spatial resolution). In addition, our own experimental findings show the possible recruitment of coarse peripheral vision for fine spatial analysis. Accordingly, I hypothesize that the balance between central and peripheral visual processing, established in the course of development, is susceptible to plastic adaptations during the entire life span, with peripheral vision capable of taking over central processing.

scholarly journals Online Transcranial Random Noise stimulation improves perception at high levels of visual white noise

2020 ◽  
Author(s):  
Michael D. Melnick ◽  
Woon Ju Park ◽  
Sholei Croom ◽  
Shuyi Chen ◽  
Lorella Batelli ◽  
...  
Keyword(s):  
White Noise ◽  
Task Performance ◽  
Visual Processing ◽  
Random Noise ◽  
External Noise ◽  
Orientation Discrimination ◽  
Perceptual Training ◽  
Transcranial Random Noise Stimulation ◽  
Perceptual Performance ◽  
Underlying Mechanisms

AbstractTranscranial random noise stimulation (tRNS), a relatively recent addition to the field of non-invasive, electrical brain stimulation, has been shown to improve perceptual and cognitive functions across a wide variety of tasks. However, the underlying mechanisms of visual improvements caused by tRNS remain unclear. To study this question, we employed a well-established, equivalent-noise approach, which measures perceptual performance at various levels of external noise and is formalized by the Perceptual Template Model (PTM). This approach has been used extensively to infer the underlying mechanisms behind changes in visual processing, including those from perceptual training, adaptation and attention. Here, we used tRNS during an orientation discrimination task in the presence of increasing quantities of external visual white noise and fit the PTM to gain insights into the effects of tRNS on visual processing. Our results show that tRNS improves visual processing when stimulation is applied during task performance, but only at high levels of external visual white noise—a signature of improved external noise filtering. There were no significant effects of tRNS on task performance after the stimulation period. Of interest, the reported effects of tRNS on visual processing mimic those previously reported for endogenous spatial attention, offering a potential area of investigation for future work.

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