scholarly journals Visual cortex invaded by higher cognitive functions as a result of early blindness

2013 ◽  
Vol 13 (15) ◽  
pp. T10-T10
Author(s):  
M. Bedny
Keyword(s):  
Visual Cortex ◽  
Cognitive Functions ◽  
Higher Cognitive Functions ◽  
Early Blindness

scholarly journals Cortical Connectivity In A Macaque Model Of Congenital Blindness

2017 ◽  
Author(s):  
Loïc Magrou ◽  
Pascal Barone ◽  
Nikola T. Markov ◽  
Herbert Killackey ◽  
Pascale Giroud ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cognitive Functions ◽  
Large Scale ◽  
Extrastriate Cortex ◽  
Local Network ◽  
Cortical Function ◽  
Long Distance ◽  
Extrinsic Factors ◽  
Higher Cognitive Functions ◽  
Local Circuits

Abstract:Brain-mapping of the congenitally blind human reveals extensive plasticity(1). The visual cortex of the blind has been observed to support higher cognitive functions including language and numerical processing(2, 3). This functional shift is hypothesized to reflect a metamodal cortical function, where computations are defined by the local network. In the case of developmental deafferentation, local circuits are considered to implement higher cognitive functions by accommodating diverse long-distance inputs(4–7). However, the extent to which visual deprivation triggers a reorganization of the large-scale network in the cortex is still controversial(8). Here we show that early prenatal ablation of the retina, an experimental model of anophthalmia in macaque, leads to a major reduction of area V1 and the creation of a default extrastriate cortex (DEC)(9, 10). Anophthalmic and normal macaques received retrograde tracer injections in DEC, as well as areas V2 and V4 post-natally. This revealed a six-fold expansion of the spatial extent of local connectivity in the DEC and a surprisingly high location of the DEC derived from a computational model of the cortical hierarchy(11). In the anophthalmic the set of areas projecting to the DEC, area V2 and V4 does not differ from that of normal adult controls, but there is a highly significant increase in the relative cumulative weight of the ventral stream areas input to the early visual areas. These findings show that although occupying the territory that would have become primary visual cortex the DEC exhibits features of a higher order area, thus reflecting a combination of intrinsic and extrinsic factors on cortical specification. Understanding the interaction of these contributing factors will shed light on cortical plasticity during primate development and the neurobiology of blindness.

scholarly journals Voluntary control of illusory contour formation

2017 ◽  
Author(s):  
William J Harrison ◽  
Reuben Rideaux
Keyword(s):  
Spatial Attention ◽  
Cognitive Functions ◽  
Image Features ◽  
Perceptual Decision Making ◽  
Voluntary Attention ◽  
Visual Appearance ◽  
Visual Form ◽  
Neural Computations ◽  
Novel Variant ◽  
Higher Cognitive Functions

ABSTRACTThe extent to which visual inference is shaped by attentional goals is unclear. Voluntary attention may simply modulate the priority with which information is accessed by higher cognitive functions involved in perceptual decision making. Alternatively, voluntary attention may influence fundamental visual processes, such as those involved in segmenting an incoming retinal signal into a structured scene of coherent objects, thereby determining perceptual organisation. Here we tested whether the segmentation and integration of visual form can be determined by an observer’s goals by exploiting a novel variant of the classical Kanizsa figure. We generated predictions about the influence of attention with a machine classifier, and tested these predictions with a psychophysical response classification technique. Despite seeing the same image on each trial, observers’ perception of illusory spatial structure depended on their attentional goals. These attention-contingent illusory contours directly conflicted with equally plausible visual form implied by the geometry of the stimulus, revealing that attentional selection can determine the perceived layout of a fragmented scene. Attentional goals, therefore, not only select pre-computed features or regions of space for prioritised processing, but, under certain conditions, also greatly influence perceptual organisation and thus visual appearance.SIGNIFICANCE STATEMENTThe extent to which higher cognitive functions can influence perceptual organisation is debated. The role of voluntary spatial attention, the ability to focus on only some parts of a scene, has been particularly controversial among neuroscientists and psychologists who aim to uncover the basic neural computations involved in grouping image features into coherent objects. To address this issue, we repeatedly presented the same novel ambiguous image to observers and changed their attentional goals by having them make fine spatial judgements about only some elements of the image. We found that observers’ attentional goals determine the perceived organisation of multiple illusory shapes. We thus reveal that voluntary spatial attention can control the fundamental processes that determine perceptual organisation.

scholarly journals Using perceptual tasks to selectively measure magnocellular and parvocellular performance: Rationale and a user’s guide

2021 ◽  
Author(s):  
Mark Edwards ◽  
Stephanie C. Goodhew ◽  
David R. Badcock
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Lateral Geniculate Nucleus ◽  
Cognitive Functions ◽  
Visual Information ◽  
Visual Stimuli ◽  
Visual Scene ◽  
Ongoing Debate ◽  
Parvocellular Pathway ◽  
Lesion Studies

AbstractThe visual system uses parallel pathways to process information. However, an ongoing debate centers on the extent to which the pathways from the retina, via the Lateral Geniculate nucleus to the visual cortex, process distinct aspects of the visual scene and, if they do, can stimuli in the laboratory be used to selectively drive them. These questions are important for a number of reasons, including that some pathologies are thought to be associated with impaired functioning of one of these pathways and certain cognitive functions have been preferentially linked to specific pathways. Here we examine the two main pathways that have been the focus of this debate: the magnocellular and parvocellular pathways. Specifically, we review the results of electrophysiological and lesion studies that have investigated their properties and conclude that while there is substantial overlap in the type of information that they process, it is possible to identify aspects of visual information that are predominantly processed by either the magnocellular or parvocellular pathway. We then discuss the types of visual stimuli that can be used to preferentially drive these pathways.

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