scholarly journals Cortical Synchrony as a Mechanism of Collinear Facilitation and Suppression in Early Visual Cortex

2021 ◽  
Vol 15 ◽  
Author(s):  
Kris Evers ◽  
Judith Peters ◽  
Mario Senden
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Stimulus Frequency ◽  
Lateral Connectivity ◽  
Neuronal Synchrony ◽  
Neuronal Populations ◽  
Early Visual Cortex ◽  
Neuronal Groups ◽  
Collinear Facilitation ◽  
Suppression Effects

Stimulus-induced oscillations and synchrony among neuronal populations in visual cortex are well-established phenomena. Their functional role in cognition are, however, not well-understood. Recent studies have suggested that neural synchrony may underlie perceptual grouping as stimulus-frequency relationships and stimulus-dependent lateral connectivity profiles can determine the success or failure of synchronization among neuronal groups encoding different stimulus elements. We suggest that the same mechanism accounts for collinear facilitation and suppression effects where the detectability of a target Gabor stimulus is improved or diminished by the presence of collinear flanking Gabor stimuli. We propose a model of oscillators which represent three neuronal populations in visual cortex with distinct receptive fields reflecting the target and two flankers, respectively, and whose connectivity is determined by the collinearity of the presented Gabor stimuli. Our model simulations confirm that neuronal synchrony can indeed explain known collinear facilitation and suppression effects for attended and unattended stimuli.

scholarly journals Visual exposure optimizes stimulus encoding in primary visual cortex

2018 ◽  
Author(s):  
Andreea Lazar ◽  
Chris Lewis ◽  
Pascal Fries ◽  
Wolf Singer ◽  
Danko Nikolić
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Processing ◽  
Neuronal Response ◽  
Extended Period ◽  
Sensory Cells ◽  
Neuronal Populations ◽  
Visual Exposure ◽  
Early Visual Cortex ◽  
Sensory Cortices

SummarySensory exposure alters the response properties of individual neurons in primary sensory cortices. However, it remains unclear how these changes affect stimulus encoding by populations of sensory cells. Here, recording from populations of neurons in cat primary visual cortex, we demonstrate that visual exposure enhances stimulus encoding and discrimination. We find that repeated presentation of brief, high-contrast shapes results in a stereotyped, biphasic population response consisting of a short-latency transient, followed by a late and extended period of reverberatory activity. Visual exposure selectively improves the stimulus specificity of the reverberatory activity, by increasing the magnitude and decreasing the trial-to-trial variability of the neuronal response. Critically, this improved stimulus encoding is distributed across the population and depends on precise temporal coordination. Our findings provide evidence for the existence of an exposure-driven optimization process that enhances the encoding power of neuronal populations in early visual cortex, thus potentially benefiting simple readouts at higher stages of visual processing.

scholarly journals X-Chromosome Insufficiency Alters Receptive Fields across the Human Early Visual Cortex

2019 ◽  
Vol 39 (41) ◽  
pp. 8079-8088 ◽  
Author(s):  
Tamar Green ◽  
Hadi Hosseini ◽  
Aaron Piccirilli ◽  
Alexandra Ishak ◽  
Kalanit Grill-Spector ◽  
...  
Keyword(s):  
Visual Cortex ◽  
X Chromosome ◽  
Receptive Fields ◽  
Early Visual Cortex

scholarly journals Retraction Notice to: Perceptual load affects spatial tuning of neuronal populations in human early visual cortex

2020 ◽  
Vol 30 (23) ◽  
pp. 4814
Author(s):  
Benjamin de Haas ◽  
D. Samuel Schwarzkopf ◽  
Elaine J. Anderson ◽  
Geraint Rees
Keyword(s):  
Visual Cortex ◽  
Perceptual Load ◽  
Neuronal Populations ◽  
Spatial Tuning ◽  
Early Visual Cortex ◽  
Retraction Notice

scholarly journals Sub-Optimality of the Early Visual System Explained Through Biologically Plausible Plasticity

2021 ◽  
Vol 15 ◽  
Author(s):  
Tushar Chauhan ◽  
Timothée Masquelier ◽  
Benoit R. Cottereau
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Receptive Fields ◽  
Spike Timing ◽  
Orientation Tuning ◽  
Biologically Relevant ◽  
Tuning Curves ◽  
Stdp Rule ◽  
Early Visual Cortex ◽  
Minimisation Problem

The early visual cortex is the site of crucial pre-processing for more complex, biologically relevant computations that drive perception and, ultimately, behaviour. This pre-processing is often studied under the assumption that neural populations are optimised for the most efficient (in terms of energy, information, spikes, etc.) representation of natural statistics. Normative models such as Independent Component Analysis (ICA) and Sparse Coding (SC) consider the phenomenon as a generative, minimisation problem which they assume the early cortical populations have evolved to solve. However, measurements in monkey and cat suggest that receptive fields (RFs) in the primary visual cortex are often noisy, blobby, and symmetrical, making them sub-optimal for operations such as edge-detection. We propose that this suboptimality occurs because the RFs do not emerge through a global minimisation of generative error, but through locally operating biological mechanisms such as spike-timing dependent plasticity (STDP). Using a network endowed with an abstract, rank-based STDP rule, we show that the shape and orientation tuning of the converged units are remarkably close to single-cell measurements in the macaque primary visual cortex. We quantify this similarity using physiological parameters (frequency-normalised spread vectors), information theoretic measures [Kullback–Leibler (KL) divergence and Gini index], as well as simulations of a typical electrophysiology experiment designed to estimate orientation tuning curves. Taken together, our results suggest that compared to purely generative schemes, process-based biophysical models may offer a better description of the suboptimality observed in the early visual cortex.

Internal Spatial Organization of Receptive Fields of Complex Cells in the Early Visual Cortex

2007 ◽  
Vol 98 (3) ◽  
pp. 1194-1212 ◽  
Author(s):  
Kota S. Sasaki ◽  
Izumi Ohzawa
Keyword(s):  
Visual Cortex ◽  
Minimal Model ◽  
Spatial Organization ◽  
Receptive Fields ◽  
Simple Cell ◽  
Complex Cell ◽  
Linear Filters ◽  
Simple Cells ◽  
Complex Cells ◽  
Early Visual Cortex

The receptive fields of complex cells in the early visual cortex are economically modeled by combining outputs of a quadrature pair of linear filters. For actual complex cells, such a minimal model may be insufficient because many more simple cells are thought to make up a complex cell receptive field. To examine the minimalist model physiologically, we analyzed spatial relationships between the internal structure (subunits) and the overall receptive fields of individual complex cells by a two-stimulus interaction technique. The receptive fields of complex cells are more circular and only slightly larger than their subunits in size. In addition, complex cell subunits occupy spatial extents similar to those of simple cell receptive fields. Therefore in these respects, the minimalist schema is a fair approximation to actual complex cells. However, there are violations against the minimal model. Simple cell receptive fields have significantly fewer subregions than complex cell subunits and, in general, simple cell receptive fields are elongated more horizontally than vertically. This bias is absent in complex cell subunits and receptive fields. Thus simple cells cannot be equated to individual complex cell subunits and spatial pooling of simple cells may occur anisotropically to constitute a complex cell subunit. Moreover, when linear filters for complex cell subunits are examined separately for bright and dark responses, there are significant imbalances and position displacements between them. This suggests that actual complex cell receptive fields are constructed by a richer combination of linear filters than proposed by the minimalist model.

Attention Field Size Alters Patterns of Population Receptive Fields in the Early Visual Cortex

2021 ◽  
Author(s):  
Bo Liu ◽  
Xiaochun Wang ◽  
Le Wang ◽  
Qiaojun Qu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Field Size ◽  
Early Visual Cortex

An evaluation of 3-D binocular receptive fields in the early visual cortex

2007 ◽  
Vol 58 ◽  
pp. S154
Author(s):  
Yuka Tabuchi ◽  
Kota Sasaki ◽  
Izumi Ohzawa
Keyword(s):  
Visual Cortex ◽  
Receptive Fields ◽  
Early Visual Cortex

Functional Organization of the Cat Visual Cortex in Relation to the Representation of a Uniform Surface

2003 ◽  
Vol 89 (2) ◽  
pp. 1112-1125 ◽  
Author(s):  
Toshiki Tani ◽  
Isao Yokoi ◽  
Minami Ito ◽  
Shigeru Tanaka ◽  
Hidehiko Komatsu
Keyword(s):  
Visual Cortex ◽  
Functional Organization ◽  
Receptive Fields ◽  
Singular Points ◽  
Intrinsic Signals ◽  
Contour Representation ◽  
Early Visual Cortex ◽  
Preference Map ◽  
Surface Covering ◽  
Uniform Plane

Neuronal activity in the early visual cortex has been extensively studied from the standpoint of contour representation. On the other hand, representation of the interior of a surface surrounded by a contour is much less well understood. Several studies have identified neurons activated by a uniform surface covering their receptive fields, but their distribution within the cortex is not yet known. The aim of the present study was to obtain a better understanding of the distribution of such neurons in the visual cortex. Using optical imaging of intrinsic signals, we found that there are a group of surface-responsive regions located in area 18, along the area 17/18 border, that tend to overlap the singular points of the orientation-preference map. Extracellular recordings confirmed that neurons responsive to uniform plane stimuli are accumulated in these regions. Such neurons also existed outside the surface-responsive regions around the singular points. These results suggest that there exists a functional organization related to the representation of a uniform surface in the early visual cortex.

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