Prominent working memory (WM) deficits have been observed in people with schizophrenia (PSZ) across multiple sensory modalities, including the visuospatial realm. Observed deficits in electrophysiological correlates of early visual processing as well as later cognitive processes in PSZ are thought to underlie deficiencies in WM ability, though the mechanisms linking the two are not well understood. WM deficits and associated electrophysiological abnormalities have also been observed in unaffected relatives of PSZ (REL), suggesting WM dysfunction may be indicative of genetic liability for the disorder. We administered a delayed response visuospatial WM task to 23 PSZ, 30 of their REL, and 37 healthy controls (CTRL) in an effort to better understand the contributions of neural abnormalities to WM performance deficits associated with schizophrenia. PSZ performed more poorly on the WM task and gained less benefit from the presence of irrelevant stimuli than did CTRL and REL. In terms of electrophysiological responses, N1 responses to probes during retrieval differentiated the type and locations of stimuli presented during encoding in CTRL. Retrieval N1 responses in PSZ, however, failed to do so, while retrieval responses in REL showed more pronounced differentiation of stimulus features during encoding. Furthermore, neural responses during retrieval predicted behavioral performance in PSZ and REL, but not CTRL. These results suggest retrieval processes are particularly important to efficient visuospatial WM function in PSZ and REL, and support further investigation of WM retrieval as a potential target for improving overall WM function through clinical intervention.
University of Minnesota M.A. thesis. July 2016. Major: Psychology. Advisors: William Iacono, Scott Sponheim. 1 computer file (PDF); vi, 42 pages.
Neural Abnormalities Related to Visual Working Memory in People with Schizophrenia and their First-Degree Relatives.
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