Useful or Not? How Schizophrenic Patients Process the Relevance of a Visual Stimulus

Abstract

Introduction: The impairment of relevant information selection results in clinical symptoms of schizophrenia. Previous studies assessing visual modality, have reported an impairment of automatic sensory information processing related to abnormal irrelevant stimuli processing. In healthy subjects, neurophysiologic studies have distinguished two early posterior components which the second could be considered as a deviant processing marker. We propose to explore early selective properties of attention in acute patients using event related potential (ERP) methods. We hypothesize an impairment of the detection of deviant stimuli processing, supported by sensory integration neural region. Materiel and method: Ten patients suffering from an acute episode of schizophrenia and ten controls were assessed with a simple three stimuli oddball paradigm analysed by principal components analysis (PCA) method which allows to separate overlapping components and to evaluate their modifications. Result: PCA distinguished two posterior negative components between 100 and 230 msec. The early one was not different between controls and patients. The later one was significantly decreased in the patients group. Discussion: two different physiological components involved in stimuli detection were clearly isolated. The earliest, reflecting elementary perceptive process seems to be preserved in patients with acute schizophrenia whereas the later component, reflecting integrative processing involved in detection of deviance was impaired. These results could be a clue to understand clinical distractibility.