[Effect of phenactil (chlorpromazine) on cortical visual evoked potentials in clinically healthy subjects with normal...

The results of a study of averaged cortical visual evoked potentials in healthy subjects with abnormal EEG records and in subjects with normal EEG are presented. The investigations were performed at rest and after activation with chlorpromazine. The potentials were recorded from typical sites in the visual cortex (O2--CZ and O1--CZ). Stimulation with flashes at 1 c/sec., 40 msec. duration, 2000 lux light intensity at a distance of 60 cm from the eyes was applied. The pupils were dilated with homatropine. The mean amplitudes of potential components measured by the method peak-to-peak, the mean latency time, and the mean duration of components were measured. It was found that at rest the inter-group differences included an amplitude rise at the time of change of the specific part into non-specific and the change of the evoked potential to the after-discharge, and the duration of positive components in the non-specific part prevailed over the negative ones. Chlorpromazine changed somewhat the amplitude of components (fall in the specific part and rise in the non-spefific one) but the differences were statistically not significant. Similar changes were observed in the latency time of various components (prolongation of latency time of late components was statistically not significant). The results suggest differences in the reactivity of cerebral structures of these groups at rest as well as after chlorpromazine activation.