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To see better to the left when looking more to the right: Effects of gaze direction and frames of spatial coordinates in unilateral neglect

Published online by Cambridge University Press:  01 January 1999

PATRIK VUILLEUMIER
Affiliation:
Department of Neurology and Neuropsychology, University Hospital of Geneva, Switzerland
NATHALIE VALENZA
Affiliation:
Department of Neurology and Neuropsychology, University Hospital of Geneva, Switzerland
EUGÈNE MAYER
Affiliation:
Department of Neurology and Neuropsychology, University Hospital of Geneva, Switzerland
STEPHEN PERRIG
Affiliation:
Department of Neurology and Neuropsychology, University Hospital of Geneva, Switzerland
THEODOR LANDIS
Affiliation:
Department of Neurology and Neuropsychology, University Hospital of Geneva, Switzerland

Abstract

Unilateral spatial neglect entails a failure to detect or respond to stimuli in the space opposite to a brain lesion. However, the contralesional hemispace can be determined by different frames of spatial coordinates, such as eyes-, head-, body-, or environment-centered coordinates. We observed 2 patients with a right hemisphere stroke whose left spatial neglect was modulated by distinct coordinates systems depending on the task. Four tasks were given in different conditions of central gaze and either the eyes or the head rotated 30° to the right or 30° to the left. While the 2 patients had a retinotopic defect in 1 visual field quadrant that remained the same irrespective of gaze direction (upper or lower quadrant in 1 case each), the other quadranopic field defect improved with eyes rotation to the right but not with head rotation, suggesting a head-centered spatiotopic deficit. Performance on line bisection was influenced both by eyes and head rotation, as well as by the position of the lines with respect to the trunk midline, suggesting the involvement of both head-centered and body-centered coordinates. Visual imagery and auditory extinction were not modified by changing the eyes or head position. These findings suggest that distinct spatial coordinates are brought into play depending on the tasks demands. (JINS, 1999, 5, 75–82.)

Type
CASE STUDIES
Copyright
© 1999 The International Neuropsychological Society

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