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RESEARCH

Schizophrenia: Cognitive Deficits

 

A major component of Deanna Barch's work has been to better characterize the nature of cognitive disturbances in schizophrenia and to determine whether at least a subset of the seemingly diverse cognitive deficits present in schizophrenia can be accounted for by a deficit in a single underlying cognitive process. In previous work with Jonathan Cohen, we used computational models to demonstrate that schizophrenic deficits in a range of tasks (i.e., WM, inhibition) can be explained by a single disturbance in one particular function of PFC: the ability to represent and maintain context information necessary to guide appropriate task behavior (e.g., a specific component of WM). We have completed a number of studies that have provided support for these hypotheses. Specifically, we have demonstrated that schizophrenia patients demonstrate predicted deficits on multiple tasks designed to measure the representation and maintenance of context: the Continuous Performance Test (AX-CPT), the Stroop Task, and a lexical disambiguation task (Barch, Carter et al., 1999a; Barch, Braver et al., 1998; Barch & Carter, 1998; Barch, Carter et al., 1999b; Cohen, Barch et al., 1999) . In addition, we demonstrated that performance in conditions sensitive to context processing were highly correlated across tasks, while performance in psychometrically matched conditions thought not to be sensitive to context processing were not correlated (Cohen et al., 1999) . Further, Barch and collegues have found that patients with schizophrenia demonstrated the predicted relationships among Stroop task and WM performance (Barch et al., 1998). To follow up on this work, Dr. Barch has begun to examine how a disturbance in the ability to represent and maintain context information might also influence deficits in long term memory among patients with schizophrenia. More specifically, we are currently conducting a large study with schizophrenia patients, designed to examine the association between more traditional measures of context processing/WM and measures of encoding and retrieval from long term memory. If a common underlying cognitive deficits contributes to disturbances in both of these domains, we should again find strong associations among performance on these tasks from putatively different domains.