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Abstract:
Abstract: Executive attention is the goal-driven activation
of task-appropriate processing to produce unified, voluntary
behavior. Split-brain patients and other individuals with impaired
callosal function often exhibit deficits of executive attention.
This study tested the hypothesis that in normal adults, executive
attention benefits from interhemispheric communication mediated by
the corpus callosum. The role of callosal function in executive
attention was assessed by within-subjects comparisons of MRI-based
measurements of the corpus callosum, performance on two behavioral
measures of callosal function, and performance on a behavioral
measure of executive attention. Midsagittal callosal area was
measured on a T1-weighted MRI image. Callosal function was measured
with a visual task which required unilateral and bilateral
comparison of stimuli, and with a bimanual coordination task.
Executive attention was measured with a visual task which tested
the subject's ability to shift attention between two processing
goals. Superior performance on the executive attention task was
associated with superior performance on the visual and manual
measures of callosal function, and with larger anterior and
posterior midsagittal callosal areas. These results support the
hypothesis that interhemispheric communication is involved in
executive attention. The implications of this hypothesis for
neuroanatomic models of attention are discussed.
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