title: Visual contrast sensitivity alterations in inferred magnocellular pathways and anomalous perceptual experiences in people at high-risk for psychosis.
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.
authors.affiliation: Semmelweis University, Department of Psychiatry and Psychotherapy, Budapest, Hungary. szkeri@phys.szote.u-szeged.hu
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Kéri
authors.forename: György
authors.initials: G
authors.lastname: Benedek
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000473:pathology* / Q000503:physiopathology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time; D012306:Risk; D014795:Visual Pathways / Q000503:physiopathology*