Fig. 2.
The figure illustrates P50 gating measure. Evoked potential responses to S1 (solid line) and S2 (dashed line) stimuli are overlaid in the figure for illustrative purposes. Subject was presented with 150 trials of paired clicks (S1 and S2) 500 ms apart; the intertrial interval was 10 s. The figure gives averaged data across all trials that were not rejected because of artifacts. P50 amplitudes were measured by the absolute differences between the positive peak and the preceding negative trough occurring near 50 (operationally, S1 amplitude is within 35–70 ms of stimulus, and S2 within a window of the S1 latency ± 10 ms for the subject). As one can see, the S2 amplitude was not reduced in this schizophrenia subject with S2/S1 ratio being about 1 suggesting failure to gate.