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38. Impaired contour-object perception in psychosis
Visual contour integration, the process that represents spatially separated elements as a single unified contour, has been consistently found to be impaired in schizophrenia. Recent work suggests that this deficit could be associated with psychosis symptoms, and not specific to a diagnosis of schizophrenia. We examined a transdiagnostic sample of 34 participants with psychosis, 15 unaffected first degree relatives, and 13 healthy controls as a part of the Psychosis Human Connectome Project (P-HCP). We obtained a behavioral index of contour perception by measuring orientation jitter thresholds in a psychophysical task. People with psychosis showed impaired contour perception (i.e., tolerating less contour jitter), in agreement with previous findings. We also used 7 tesla functional MRI (fMRI) to measure responses in primary visual cortex (V1) during an analogous task inside the scanner. Across participant groups, V1 fMRI responses were lower for aligned versus scrambled contours. This effect of contour alignment appears consistent with previous studies of predictive coding in visual cortex. Our results may suggest a relationship between abnormal neural response modulation in early visual cortex, and well-known impairments in visual contour perception among people with psychosis.