Caudate-putamen lesions in the rat may impair or potentiate maze learning depending upon availability of stimulus cues and relevance of response cues

In Experiment 1 rats were required to learn a Y-maze in which reward was made available after a given response (e.g. a left turn) regardless of which arm was used as the start-box. Subjects with lesions of the caudate-putamen showed a deficit on this response-learning task compared with control subjects (unoperated animals and rats having lesions of the posterior cortex). In Experiment 2 rats with caudate-putamen lesions were unimpaired when the direction of the turn required to reach the correct goal-box (identified by means of a salient visual intra-maze cue) varied from trial to trial. In the absence of salient intramaze cues, but with enriched room (extra-maze) cues, the rats with caudate-putamen lesions were superior to controls on this task. It is argued that caudate-putamen lesions disrupt a mechanism responsible for processing information about responses, but that the other (spatial) mechanisms responsible for maze-learning remain intact and that caudate-putamen lesions may enhance performance on spatial tasks for which information about responses is irrelevant.