Cortical Control of Visuomotor Reflexes

Robert Rafal

in Principles of Frontal Lobe Function

Published in print August 2002 | ISBN: 9780195134971
Published online May 2009 | e-ISBN: 9780199864157 | DOI:
Cortical Control of Visuomotor Reflexes

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This chapter uses eye movements as a model system to investigate how midbrain reflex circuits and frontal and parietal systems for eye movement control combine to produce goal-directed behavior. Converging evidence from patients with midbrain lesions and from hemianopic patients reveals that midbrain pathways are responsible for reflexive orienting in humans. The visual grasp reflex (VGR) mediated by the colliculus is modulated by a dynamic interaction between cortical and subcortical systems. Chronic lesions of the frontal eye field (FEF) cause a slowing of visually guided saccades toward the ipsilesional field; whereas parietal lesions cause a bias against making voluntary saccades toward the contralesional field. The FEF and parietal lobes appear to normally have opposing influences on collicular function: the parietal lobe facilitates the VGR and the FEF inhibits it.

Keywords: visual grasp reflex; eye movements; visuomotor control; frontal eye field; midbrain reflex circuits

Chapter.  5681 words.  Illustrated.

Subjects: Neuroscience

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