The purpose of this project is to use cognitive neuroscience techniques to explore schizophrenia as a connective disorder. A verbal memory task will be used to investigate semantic and phonological representations of information in working memory, and the extent to which maintenance of this information may differ in schizophrenia. The task will then be used to probe functional connectivity in patients and controls. The first phase will be a behavioral study in which a set of target words will be encoded, followed by a recognition period when the subject will see phonetic foils, semantic foils, unrelated foils, and target matches, and decide whether the items were part of the initial list. The goal of the behavioral component is to ensure the behavioral profile is well characterized in patients before moving the task to a functional imaging environment. The second phase will be a functional magnetic resonance imaging (fMRI) study of the same task. In this study, functional activation associated with responses to phonological probes is expected to include frontal and parietal regions while that associated with responses to semantic probes is expected to include frontal and temporal regions. Since this task has been shown to activate multiple regions, fMRI data will be analyzed to assess functional connectivity (correlation of activity) between these regions. Since schizophrenic patients are impaired on verbal working memory tasks, and previous studies have demonstrated disruptions in the coordination of neural activity in other domains, it is hypothesized that cerebral connectivity during this task will be disturbed in patients.
