The influence of drugs on bioelectrical responses evoked by interacting light flash and tooth pulp stimuli

Abstract

Electrical responses to tooth pulp stimulation (TPS) and to a flashing light have been recorded from acute cats having electrodes in the dorsal tegmentum of the mesencephalon, centrum medianum, the lateral geniculate and the lateral gyrus. The effects of morphine, chlorpromazine, pentobarbital and meprobamate upon these responses were determined in three types of experimental situations: (a) those in which only TPS was given (b) those in which light plus TPS were given, and (c) those in which only the light flashes were given. In general, the presentation of the TPS did not alter the evoked responses to the light nor the drug effect upon these responses. In contrast, the responses in centrum medianum to TPS were differentially affected depending upon whether or not the light flashes had been delivered. Morphine significantly depressed these responses only in situation (b). Pentobarbital and meprobamate depressed the responses in both situations but were less effective in situation (b). No consistent effect was observed with chlorpromazine. It was concluded that these experiments present a method which may be useful in disclosing neurophysiological changes which otherwise may not be apparent and/or detecting subtle differences between neuropharmacological agents.