Document Detail

Differential pupillary constriction and awareness in the absence of striate cortex.
MedLine Citation:
PMID:  10430836     Owner:  NLM     Status:  MEDLINE    
The fact that the pupil constricts differentially to visual stimuli in the absence of changes in light energy makes it a valuable tool for studying normal function as well as residual capacity in hemianopic subjects. When pupillometrically effective stimuli such as equiluminant gratings or coloured patches with an abrupt onset and offset are presented to the 'blind' hemifield, a hemianopic subject with damage largely restricted to striate cortex (V1) sometimes reports being 'aware' of the transient onset/offset, although without 'seeing' as such. The question addressed here is whether the pupil still responds in the condition of blindsight in its strict sense--i.e. discriminative capacity in the absence of acknowledged awareness--when stimuli are deliberately designed to eliminate awareness. This was accomplished by making stimulus onset and offset slow and gradual. The results with a well-studied hemianope, G.Y., demonstrate that there is still a pupillary constriction to isoluminant achromatic gratings and red-coloured stimuli, although reduced in size, in the absence of acknowledged awareness.
L Weiskrantz; A Cowey; J L Barbur
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Publication Detail:
Type:  Case Reports; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Brain : a journal of neurology     Volume:  122 ( Pt 8)     ISSN:  0006-8950     ISO Abbreviation:  Brain     Publication Date:  1999 Aug 
Date Detail:
Created Date:  1999-09-07     Completed Date:  1999-09-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372537     Medline TA:  Brain     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1533-8     Citation Subset:  AIM; IM    
Department of Experimental Psychology, University of Oxford and Applied Vision Research Centre, City University, London, UK.
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MeSH Terms
Accidents, Traffic
Awareness / physiology*
Brain Injuries / pathology,  physiopathology*
Color Perception*
Functional Laterality
Occipital Lobe / pathology*
Photic Stimulation
Reaction Time
Reflex, Pupillary / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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