Comparison of four components of sensory gating in schizophrenia and normal subjects: a preliminary report.

Dysfunction of sensory gating has been implicated in the pathophysiology of schizophrenia. The goal of this study was to provide evidence that sensory gating dysfunction in schizophrenia patients is a compounded problem with difficulty in filtering out irrelevant input and filtering in relevant input at both an early-preattentive stage and a later, early-attentive stage of information processing. Four components of sensory gating were examined in 12 medicated, stable schizophrenia patients and 12 age- and sex-matched normal control subjects. Evoked potential paradigms designed to examine the effects of stimulus repetition and stimulus change were utilized. Attenuation of the amplitude of the P50 and the N100 evoked potentials with stimulus repetition was significantly decreased in schizophrenia patients as compared to normal control subjects. The presentation of deviant stimuli caused the degree of attenuation to decrease in normal subjects. This effect was much decreased (and at times reversed) in schizophrenia subjects. These data suggest that schizophrenia patients have difficulty inhibiting incoming, irrelevant stimuli and responding to incoming, significant input as measured by preattentive EPs (P50). The data also suggest that similar abnormalities can be demonstrated at a slightly later phase of information processing (i.e. early-attentive phase) using the N100 EP.