Neuropsychological evidence of differential deficit in central executive aspects of working memory in schizophrenia / Junghoon Kim.

Kim, Junghoon.
viii, 78 p. : ill. ; 29 cm.
Local subjects:
Penn dissertations -- Psychology.
Psychology -- Penn dissertations.
Impaired working memory has been proposed to be a primary component of the diverse cognitive deficits found in schizophrenia, but the nature and extent of working memory dysfunction remain unclear. We developed parallel visuospatial and verbal delayed-response tasks to address the question of whether schizophrenic patients have greater deficits in central executive as compared to storage components of working memory. In each task, one condition required subjects to perform a simple delayed-response task, and the other condition required subjects to transform the contents of working memory while maintaining them during the delay period. Patients (N = 16) tended to perform more poorly than controls (N = 16) in both conditions, but simultaneous maintenance and manipulation was associated with a significantly greater performance reduction in the patients. The psychometric properties of sub-tests indicate that these effects are not due to a general increase in task difficulty. In a second experiment using delayed-response tasks that varied the amount of information to be maintained but with comparable central executive demands across load levels, patients' and controls' performance declined at similar rates with increasing storage demands. Our results indicate that while both storage and central executive processes are impaired in schizophrenic patients, central executive processes are more severely affected. This encourages further study into the neural basis of the central executive deficit in schizophrenia.
Supervisor: Tyrone D. Cannon.
Thesis (Ph.D. in Psychology) -- University of Pennsylvania, 2001.
Includes bibliographical references.
Local notes:
University Microfilms order no.: 3003646.
Cannon, Tyrone D., advisor.
University of Pennsylvania.
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