GENDER DIFFERENCES IN GATING OF THE AUDITORY-EVOKED POTENTIAL IN NORMAL SUBJECTS

Central nervous system (CNS) inhibitory mechanisms hypothesized to ''g ate'' repetitive sensory inputs have been implicated in the pathology of schizophrenia. The present study investigated gender differences in inhibitory gating of evoked brain responses to repeated stimuli in no rmal subjects (30 women and 30 men) using an auditory conditioning-tes ting paradigm. Pairs of click stimuli (SI and S2) were presented with a 0.5 s intrapair and a 10 s interpair interval. The amplitudes and la tencies of the P50, N100, P180 components of the auditory evoked respo nse to the conditioning (S1) and test response (S2) were measured and the gating ratios were computed (T/C ratio = S2/S1 100). The amplitu des to S1 were not significantly different between men and women at P5 0, N100, or P180. However, women had significantly higher amplitudes t o S2 at P50 (p = 0.03) and N100 (p = 0.04). The T/C ratios for women w ere higher (i.e., less suppression of response to S2) for P50 (p = 0.0 8) and N100 (p = 0.04) compared to men. The results suggested that dif ferences in auditory gating between men and women were not due to biol ogical differences in the P50 and N100 generators but possibly to diff erential influence of inhibitory mechanisms acting on the generator su bstrates of these evoked responses.