Visual restoration in cortical blindness: insights from natural and TMS-induced blindsight.

Full Abstract

Unilateral damage to visual cortex of the parietal or occipital lobe can cause the patient to be unaware of contralesional visual information due to either hemispatial neglect or hemianopia. It is now known that both neglect and hemianopia result from the disruption of a dynamic interaction between cortical visual pathways and more phylogenetically primitive visual pathways to the midbrain. We consider the therapeutic implications of these cortical-subcortical interactions in the rehabilitation of hemianopia. We start with the pheonmenon of "blindsight", in which patients with hemianopia can be shown, by implicit measures of visual detection or discrimination, to process visual information without conscious awareness. Some variants of blindsight have been postulated to recruit subcortical processes, while others may reflect compensatory optimisation of processing of spared visual cortex. Both mechanisms may offer opportunities for innovative strategies for rehabilitation of visual field defects. We relate the neural mechanisms that have been proposed to underlie blindsight to those that have been suggested to underlie the recovery of visual function after rehabilitation. It is suggested that the similarity and overlap of the neural processes supporting blindsight and recovery of visual function might provide insights for effective rehabilitation strategies for restoring visual functions.

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Author information

Author/s: Ro, Tony (T); Rafal, Robert (R);

Affiliation: Department of Psychology, Rice University, Houston, TX, USA. tro(-atsign-)rice.edu

Journal and publication information

Publication Type: Journal Article; Review

Journal: Neuropsychological rehabilitation (Neuropsychol Rehabil), published in England. (Language: eng)

Reference: 2006-Aug; vol 16 (issue 4) : pp 377-96

Dates: Created 2006/07/25; Completed 2006/10/18; Revised 2008/11/21;

PMID: 16864478, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals
Awareness - physiology
Blindness, Cortical - rehabilitation
Functional Laterality - physiology
Hemianopsia - physiopathology; rehabilitation
Humans

Humans
Recovery of Function - physiology
Transcranial Magnetic Stimulation
Vision, Ocular - physiology; radiation effects
Visual Cortex - physiopathology
Visual Pathways - physiopathology

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