HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Slotnick, S. D. Articles by Hart, J. Search for Related Content PubMed PubMed Citation Articles by Slotnick, S. D. Articles by Hart, J.

Hemispheric Asymmetry in Categorical Versus Coordinate Visuospatial Processing Revealed by Temporary Cortical Deactivation

Johns Hopkins University

Kosslyn (1987) proposed that the left hemisphere is better than the right hemisphere at categorical visuospatial processing while the right hemisphere is better than the left hemisphere at coordinate visuospatial processing. In 134 patients, one hemisphere (and then usually the other) was temporarily deactivated by intracarotid injection of sodium amobarbital. After a hemisphere was deactivated, a cognitive test battery was conducted, which included categorical and coordinate visuospatial tasks. Using this technique, the processing capabilities of the intact hemisphere could be determined, thus directly testing Kosslyn's hypothesis regarding hemispheric specialization. Specifically, if the left hemisphere does preferentially process categorical visuospatial relationships, then its deactivation should result in more errors during categorical tasks than right hemisphere deactivation and vise versa for the right hemisphere regarding coordinate tasks. The pattern of results obtained in both categorical and coordinate tasks was consistent with Kosslyn's hypothesis when task difficulty was sufficiently high. However, when task difficulty was low, a left hemispheric processing advantage was found for both types of tasks indicating that: (1) the left hemisphere may be better at "easy" tasks regardless of the type of task and (2) the proposed hemispheric processing asymmetry may only become apparent during sufficiently demanding task conditions. These results may explain why some investigators have failed to find a significant hemispheric processing asymmetry in visuospatial categorical and coordinate tasks.

Key Words: Categorical processing • Coordinate processing • Hemispheric asymmetry • Task difficulty • Neuropsychological testing • Intracarotid amobarbital procedure

This article has been cited by other articles:

				E. Liebenthal, J. R. Binder, S. M. Spitzer, E. T. Possing, and D. A. Medler Neural Substrates of Phonemic Perception Cereb Cortex, October 1, 2005; 15(10): 1621 - 1631. [Abstract] [Full Text] [PDF]

				T. Indersmitten and R. C. Gur Emotion Processing in Chimeric Faces: Hemispheric Asymmetries in Expression and Recognition of Emotions J. Neurosci., May 1, 2003; 23(9): 3820 - 3825. [Abstract] [Full Text] [PDF]