Psychology ETDs

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Previous research has demonstrated various neuroanatomical and neuropsychological abnormalities in schizophrenia. Although results vary depending on population characteristics, medication status, imaging methodology, and choice of cognitive assessment measures, overall results suggest decreased cerebral volume within frontal and temporal lobes and in individual structures, particularly hippocampus, within these regions; abnormal connectivity within fronto-temporal networks; and deficits in executive function, working memory, processing speed, and memory, with verbal memory deficits more reliably demonstrated than non-verbal impairment. In particular, left-hemisphere hippocampal-dependent verbal memory impairments have been proposed to be a core feature of schizophrenia, as these deficits are reliably demonstrated in first-episode, medication-na\xefve patients, chronic in- and outpatients, and at-risk populations such as individuals with prodromal schizophrenia symptoms and first-degree relatives of patients with schizophrenia. Verbal memory deficits have also been reliably demonstrated in patients with left-hemisphere temporal lobe epilepsy (TLE), and those who have undergone temporal lobe resection (TLR). Given the known localization of structural abnormalities in TLR groups and their relation to deficits in memory, it seemed reasonable to compare memory and other neuropsychological functions in schizophrenia and TLR groups to determine whether similar profiles emerged which might provide additional evidence of significant left-hemisphere involvement in the development and maintenance of schizophrenia. A comprehensive neuropsychological battery was administered to a total of 43 schizophrenia, left and right TLR, and control participants. Consistent with hypotheses, the schizophrenia and left TLR groups performed worse than controls on verbal memory, and the right TLR group performed worse than controls on non-verbal memory tasks, with a trend in the predicted direction for the schizophrenia group. Patients with schizophrenia also performed worse than controls on working memory, motor skills, and processing speed, as predicted. Hypotheses were not supported regarding overall memory profiles: the left and right TLR groups showed the expected interactive performance on verbal versus non-verbal memory, but the schizophrenia group was not found to have a memory profile similar to that of the left TLR group. Overall, results suggested that the cognitive profile of schizophrenia may best be represented as a complex interaction pattern rather than a hemisphere-specific model as seen in TLE.

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First Committee Member (Chair)

Thoma, Robert J.

Second Committee Member

Hamilton, Derek

Third Committee Member

Verney, Steven




schizophrenia, neuropsychology, temporal lobe epilepsy, memory

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