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- Title
Visual contrast sensitivity alterations in inferred magnocellular pathways and anomalous perceptual experiences in people at high-risk for psychosis.
- Authors
SZABOLCS KÉRI; GYÖRGY BENEDEK
- Abstract
Evidence suggests that patients with schizophrenia show impaired performances on tests assessing the magnocellular (M) visual pathway. The aim of this study was to investigate M pathway functioning in persons at high-risk of psychosis. Sixteen high-risk persons at the prodromal phase of psychosis and 20 healthy controls participated. Two types of contrast sensitivity measurements were used, during which participants were asked to detect a briefly presented target Gabor patch. In the pulsed-pedestal paradigm, the luminance of the background field was decreased to saturate M pathways and to bias information processing to parvocellular (P) pathways. In the steady-pedestal paradigm, the luminance of the background field was constant and briefly presented targets were processed by the M pathway. Anomalous perceptual experiences were assessed using the Structured Interview for Assessing Perceptual Anomalies (SIAPA). Results revealed that the high-risk persons showed elevated contrast sensitivity during the M pathway test, and normal sensitivity during the P pathway test. The visual SIAPA scores showed significant positive correlations with the M pathway sensitivity values. These results suggest that the high-risk mental state is associated with hyper-reactive M pathways, which may be responsible for some anomalous perceptual experiences, including abnormal intensity of environmental stimuli, feelings of being flooded and inundated, and inability to focus attention to relevant details.
- Subjects
VISUAL acuity; VISUAL perception; SENSORY perception; PSYCHOSES; SCHIZOPHRENIA
- Publication
Visual Neuroscience, 2007, Vol 24, Issue 2, p183
- ISSN
0952-5238
- Publication type
Article
- DOI
10.1017/S0952523807070253