Effects of haloperidol, trifluperidol, nitrazepam and chlordiazepoxide upon conditioned midbrain behavioral responses

Abstract

A study was carried out of the actions of haloperidol, trifluperidol, nitrazepam and chlordiazepoxide upon the behavioral and EEG responses during the stages of reinforcement and differentiation of avoidance conditioning in cats with chronically implanted electrodes.

The behavioral conditioned response was characterized by the presence of both attentional and emotional components. During reinforcement the emotional component was selectively depressed by all the administered compounds, while the attentional one and the EEG conditioned response were depressed only after the highest doses of haloperidol and trifluperidol. In the differential conditioning the same changes were present during the responses to the reinforced stimulus, although the conditioned responses were more sensitive to the disrupting effects of the drugs and a selective activity on the emotional component did not appear after the benzodiazepine derivatives administration.

During both paradigms the EEG arousal patterns very frequently showed a delay after the presentation of the conditioned stimulus and were characterized by lower frequencies and higher amplitudes when compared with placebo.

It is suggested that the selectivity of action of the butyrophenone and benzodiazepine derivatives on the emotional component of the conditioned response could be related with a specific action on neural substrates located in the limbic system.