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Steven Silverstein, Sarah Berten, Brian Essex, Ilona Kovács, Teresa Susmaras, Deborah Little; An fMRI examination of contour integration in Schizophrenia. Journal of Vision 2009;9(8):904. doi: https://doi.org/10.1167/9.8.904.
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Background: Behavioral and electrophysiological studies of schizophrenia have consistently demonstrated impairments in the integration of visual features into unified perceptual representations. Specific brain regions involved in this dysfunction, however, remain to be clarified. This study used functional Magnetic Resonance Imaging (fMRI) to examine the relative involvement of visual cortex areas involved in form perception, and parietal and frontal regions involved in attention, in the visual integration impairment in schizophrenia. Methods: Fourteen patients with schizophrenia and 14 healthy controls were compared on behavioral performance and data acquired via fMRI while completing a contour integration task that had previously been used to identify a visual integration deficit in schizophrenia. Results: Schizophrenia patients demonstrated poorer contour integration than controls. Analyses of peak signal change indicated that while the groups were equivalent in area V1, the schizophrenia group demonstrated reduced signal in areas V2–V4, which are the earliest regions sensitive to global configurations of stimuli. Moreover, whereas the control group demonstrated greater recruitment of prefrontal and parietal areas during perception of integrated forms compared to random stimuli, the schizophrenia group demonstrated greater recruitment of frontal regions during perception of random stimuli. The groups differed on brain regions involved in form perception even when they were matched on accuracy levels. Conclusions: The contour integration disturbance in schizophrenia involves both deficient basic visual processes (beginning at least as early as occipital region V2), as well as reduced feedback from visual attention regions that normally serves to amplify relevant visual representations relative to irrelevant information.
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