The effects of preliminary training conditions upon DRL performance in the hippocampectomized rat

Abstract

Rats suffering radical bilateral hippocampal destruction, destruction of the posterolateral neocortex, and normal animals were trained on a DRL 20 reinforcement schedule in an operant conditioning situation. Half of the animals received prior training on a continuous reinforcement schedule while the other half did not. Hippocampectomized rats placed on the DRL 20 schedule without prior experience on CRF were found to bar press significantly more than control animals, but received as many reinforcements and achieved as high a percentage of reinforced responses as did these animals. Hippocampectomized rats given long experience on CRF before the DRL 20 schedule bar pressed significantly more, received fewer reinforcements, and achieved a lower percentage of reinforced responses than control animals. Control animals with partial neodecortication did not differ in performance from unoperated rats in either situation. Data are reported concerning the relationship of the brain lesions to acquisition of the bar press response.