Reduced P300 amplitude in a visual recognition task in patients with schizophrenia

We studied top-down visual processes in schizophrenia by analyzing visual event-related potentials (ERPs) during a gestalt recognition task, after subjects (patients with schizophrenia, n = 10; controls, n = 14) were trained to perceive three different geometrical shapes. Recognition performance of patients was poorer under both the figure and the nonfigure conditions then that of normal controls. ERPs analysis indicated that P300 amplitudes of the patients were significantly smaller than those of controls during correct figure detection trials. Moreover, topographical analysis of the differences in ERPs during the figure vs the nonfigure condition showed an earlier, more positive and more widely distributed P300 in controls than in patients with schizophrenia. Our study supports the misconnection hypothesis of schizophrenia and highlights the difficulty of the patients to refer to previous experience in order to filter incoming information. In a visual recognition task, this misconnection syndrome might induce a failure to integrate information stored in the frontal and prefrontal sites with incoming stimuli.