Subtelencephalic locale of reinforcement and learning: looking for the minimal necessary structures

This report summarizes 4 experiments which deal with the effects of surgical removal of the rat's telencephalic forebrain structures on performance of an inhibitory avoidance response, which was acquired either before or after the lesion was made. Two experiments provide evidence that inhibitory avoidance learning (using the single-trial up-hill avoidance task) is still possible after removal of all of the forebrain structures except for the hypothalamus. A third study using this preparation dealt with the question of whether this conditioned avoidance response can be eliminated as a consequence of it being punished. In a further experiment the conditioned avoidance response was established prior to ablation of the telencephalon plus thalamus. Recall of the conditioned response survived the lesion, suggesting that the avoidance response is also stored at a subtelencephalic level in the brain-intact animal.