Paleostriatal lesions in the pigeon (Columba livia) potentiate classical conditioning: evidence from fixed-interval responding, free operant go-no-go discrimination, and alternation.

The paleostriatum augmentatum was the major site of interest for four experiments in which pigeons were given bilateral electrolytic lesions. Experiment 1 investigated the effects of lesions on key pecking for reinforcement on a 1-min fixed-interval schedule. The lesions were found to increase total response rates, but response timing was not disrupted in paleostriatal pigeons. In Experiment 2, naive subjects were given variable-interval baseline training and, in contrast to the results of Experiment 1, paleostriatal lesions did not increase responding. Go-no-go discrimination, which followed baseline training, revealed enhanced positive behavioral contrast in paleostriatal subjects, which was explained in terms of additivity theory, and together, the results of Experiments 1 and 2 suggested potentiated classical conditioning and paleostriatal pigeons. In Experiment 3, naive subjects were given spatial alternation training, and performance was temporarily impaired following paleostriatal lesions. The same paleostriatal subjects showed superior differentiation performance in Experiment 4 with a classical go-no-go alternation procedure (which also suggested potentiated classical conditioning), and it is argued that disruption of (irrelevant) response-produced information may account for paleostriatal superiority.