Individuals with schizophrenia consistently demonstrate early visual processing deficits. Because these deficits have been demonstrated in remitted schizophrenic patients, as well as in their unaffected siblings, they are thought to reflect vulnerability to schizophrenia and a potential trait marker of the disorder. However, despite their association with profound impairments in social and occupational functioning, the physiological mechanisms that may underlie early visual processing deficits in schizophrenia remain unclear. In order to understand visual processing deficits in schizophrenia, it is first necessary to isolate the processes involved in visual perception. An important obstacle to understanding these deficits has been the inability to disentangle feedforward and reentrant visual processes. Feedforward process is the early unidirectional flow of information from the retina to the visual cortex, whereas reentrant visual processes represent the iterative feedforward-feedback exchanges of neural signals among levels in the brain. The primary aim of the present proposal is to disentangle these visual processes, with the over-arching, long-term objective of understanding the mechanisms that may underlie early visual processing deficits in schizophrenia. To probe the visual system, two procedures will be used: visual masking and transcranial magnetic stimulation (TMS) masking. Stabilized schizophrenia outpatients and healthy control subjects will complete these procedures in a within-subject design. As these two procedures have distinct ways of disrupting visual information processing, it will be possible to separately assess feedforward and reentrant visual processes. This initial study will provide the groundwork for conducting more comprehensive examinations of the neural substrate of early visual processing deficits in schizophrenia using fMRI-guided TMS. This line of investigation, in turn, may shed light on the precise nature of early visual processing deficits in schizophrenia, and would thereby facilitate the development of pharmacological and cognitive intervention strategies for this debilitating disorder.
Intact early visual processing is a prerequisite for effective higher-order visual perceptual processes. Early visual processing deficits have been consistently reported in schizophrenia and are associated with profound impairments in independent living, vocational functioning, and social relationships that characterize schizophrenia. The proposed research will lead to a better understanding of these deficits, potentially leading to innovative treatments, as well as alternative ways of developing and testing new treatments. Interventions that improve the functional disabilities associated with schizophrenia are of particular public health significance.
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| Rassovsky, Yuri; Lee, Junghee; Nori, Poorang et al. (2013) Assessing temporal processing of facial emotion perception with transcranial magnetic stimulation. Brain Behav 3:263-72 |
| Rassovsky, Y; Horan, W P; Lee, J et al. (2011) Pathways between early visual processing and functional outcome in schizophrenia. Psychol Med 41:487-97 |
