Within-session changes in sensory gating assessed by P50 evoked potentials in normal subjects.

1. The authors studied within-session changes in P50 suppression occurring in a group of 28 normal subjects. 2. A conditioning-testing paradigm was used with 120 pairs of 110 Db peak intensity clicks. Clicks were of 0.04 msec duration, 500 msec separation and delivered through headphones at 10 second intervals. 3. Mean P50 suppression ranged from 60.5% during the first 30 click pairs to -19.1% during the last 30 pairs, with an overall mean suppression of 25.4%. 4. The authors concluded that P50 suppression is a dynamic process in normal subjects, and that further work is necessary to elucidate the factors affecting P50 suppression.