Role of Corticosterone in Extinction of an Appetitive Instrumental Response

Abstract

Corticosteroids appear to be involved in a variety of cognitive processes. The present research examined their role during extinction of an appetitive instrumental response in rats. In the first experiment, a high negative correlation was documented between the magnitude of the corticosterone level evoked by removal of reinforcement and the number of behavioral responses given during the session. In the second experiment, administration of exogenous corticosterone decreased the number of behavioral responses occurring during the extinction session; dexa-methasone had no significant effect. It would appear possible that the behavioral effects reflect corticosterone mediated changes in neuronal activity within brain structures contributing to learning and memory processes. Thus, in appetitive instrumental conditioning, corticosterone levels are elevated by a removal of reinforcement (extinction) and may contribute to the suppression or decay of the previously reinforced behavioral response.

Keywords:

• Corticosterone
• learning
• extinction