This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Cognitive impairment is a central feature of schizophrenia, and it is widely thought that impairments of attention are among the most striking and severe deficits documented in an extensive literature. These impairments are largely stable over the course of the disorder, do not benefit from available treatments, and are predictive of functional outcome. The proposed experiments are part of a larger program of research that focuses on the nature of attention and working memory deficits in schizophrenia. The experiments are based on a large body of cognitive neuroscience research that suggests that attention operates in different ways in different cognitive systems. Therefore, it is possible that the impairments in schizophrenia may be limited to the operation of attention in specific domains. The proposed experiment focuses on the boundaries between visual attention and visual working memory. Current behavioral research from our lab shows that patients with schizophrenia have slowed visual search compared to healthy control subjects but these slower search rates could be a consequence of slowed or poor control of attention, or slower responses, rather than impaired perceptual processes. Is this slowing confined to one system (ie motor) or is it seen across various modes of attentional and working memory systems?We will measure the P3 component, which is generated as an endogenous response to low probability task relevant stimuli. We will alo measure the Lateralized Readiness Potential (LRP), which is an electrophysiological indicator of partial response activation - that is preparation to move. Thus a subject should present a P3 component to a low probability stimulus and should present an LRP prior to any response.We predict that patients with schizophrenia wil show normal P3 to visual stimuli but will show a delayed LRP latency and slower RTs reflecting an impairment in movement preparation.
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