Perceptual anomalies in schizophrenia co-occur with selective impairments in the gamma frequency component of midlatency auditory ERPs

This study aimed to establish concordance between phenomenological and psychophysiological indices of sensory gating disturbance in schizophrenia. Perceptually normal and deviant subgroups of schizophrenia (SZ) and healthy comparison (HC) participants were empirically determined on the basis of self-rated Sensory Gating Inventory scores. Contrasts by diagnosis and subgroup classification were conducted on event-related brain potential (ERP) response attenuation to paired auditory stimuli, measured in time (P50 ERP) and frequency (low frequency, 1-20 Hz; gamma band, 20-50 Hz) domains. The SZ sample evidenced significantly less low-frequency response attenuation than did HC but comparable P50 and gamma responses. The low-frequency response, however, appeared insensitive to variation in perceptual experience between SZ subgroups. Conversely, smaller P50 amplitude and weaker gamma response attenuation distinguished deviant SZ (n=17) from normal SZ (n=9) and normal HC (n=29) subgroups. Perceptually normal SZ and normal HC subgroups were statistically equivalent across all comparisons. These findings support hypotheses relating perceptual disturbance in schizophrenia to an early sensory input dysfunction, which is thought to involve gamma-mediated thalamocortical integration of sensory stimuli.