Motion specific responses from a blind hemifield

In a previous study we showed that fast moving stimuli activate V5, an area specialized for motion, at very short latencies through a pathway that reaches it without passing through VI. Using the same technique of visual evoked responses, we have tested our conclusions by studying patient GY, whose...

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Bibliographic Details
Published in:Brain (London, England : 1878) England : 1878), 1996-12, Vol.119 (6), p.1971-1982
Main Authors: ffytche, D. H., Guy, C. N., Zeki, S.
Format: Article
Language:English
Subjects:
Adult
Biological and medical sciences
dynamic parallelism
Electroencephalography
Functional Laterality
Humans
Injuries of the nervous system and the skull. Diseases due to physical agents
Male
Medical sciences
motion evoked response
residual vision
Traumas. Diseases due to physical agents
Vision Disorders - physiopathology
Visual Cortex - pathology
Visual Cortex - physiopathology
Visual Perception
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Summary:In a previous study we showed that fast moving stimuli activate V5, an area specialized for motion, at very short latencies through a pathway that reaches it without passing through VI. Using the same technique of visual evoked responses, we have tested our conclusions by studying patient GY, whose VI is damaged but whose V5 is intact. In spite of the contralateral hemi-blindness due to his VI lesion, GY has a residual visual capacity that allows him to perceive, consciously, fast but not slow moving stimuli presented in his affected hemifield. By stimulating GY's ‘blind’ hemifield and comparing the responses with those obtained from normal subjects, we were able to study the relative contribution of VI and V5 to the visual evoked response to motion in normal subjects. We found that GY's early response to fast motion is preserved and correlates with activity elicited in control subjects over area V5, while slow motion, pattern offset, and pattern reversal stimuli failed to elicit responses in GY. The results confirm our previous conclusions: namely, that the early part of the motion evoked response is generated in area V5 and that signals reach this area through a dynamically parallel pathway that bypasses area V1. They go on to demonstrate that neurophysiological activity in the prestriate cortex correlates with the conscious visual perception of motion.
ISSN:0006-8950
1460-2156
DOI:10.1093/brain/119.6.1971