EFFECT OF CHLORDIAZEPOXIDE UPON EXPERIMENTAL EXTINCTION IN THE STRAIGHT RUNWAY AS A FUNCTION OF PARTIAL REINFORCEMENT IN THE RAT

Abstract

4 groups of rats were trained to run for food in the straight runway. The groups were differentiated in terms of reinforcement schedule (50% vs. 100% reward) and drug condition (saline vs. 20 mg/kg of CDP). After 64 acquisition trials, the rats in Section I were given 32 extinction trials, half of each group being injected with CDP and half with saline. The rats in Section II were run similarly but with additional 32 extinction trials during which the drug state was changed twice. A clear-cut drug-learning dissociation effect was found during extinction as well as from acquisition to extinction. CDP retarded extinction ratio after 100% reward when the drug condition was unchanged from acquisition to extinction. However, the partial-reinforcement effect (PRE) in extinction was not affected by CDP although the PRE in acquisition was inhibited by the same drug.