The Relation between Pretraining Plasma Corticosterone Levels and the Acquistion of an Avoidance Response in the Rat

Abstract

This chapter focuses on the relation between pretraining plasma corticosterone levels and the acquisition of an avoidance response in the rat. The influence of the pituitary-adrenal system on the acquisition of conditioned avoidance behavior is less well established, although interesting interrelationships have been noted between individual differences in learning capacity and pituitary-adrenal activity. Pre-training levels of pituitary-adrenocortical activity, as well as the rise in corticosterone secretion following ether stress, are associated with learning ability of rats in a conditioned avoidance situation. The higher the pre-conditioning level of corticosterone, the lower the ability of the rat to acquire the avoidance response. The rise in plasma corticosterone is very constant in the various individual animals, and the final concentration of corticosterone depends on the initial level. Although the pituitary-adrenal system is activated during the acquisition of conditioned responses, neither adrenocorticotropic hormone (ACTH) nor corticosteroids seem to be essential for the acquisition of an avoidance response.