Contextual control of conditioned responding in rats with dorsal hippocampal lesions

The control exerted by contextual cues over classically conditioned responding was assessed for rats with electrolytic lesions of the dorsal hippocampus and sham-operated controls. In 3 experiments the rats received initial training with 2 reinforced cues, each presented in its own distinctive context, followed by a nonreinforced test in which the cues were presented in the other context. Both control and operated subjects showed context specificity, as evidenced by less vigorous responding to these cues than to cues presented on test in their original contexts. The groups did not differ in their ability to learn an explicit discrimination in which a given cue was reinforced in one context and nonreinforced in a different context (although the groups did differ on a simple autoshaping task). It is concluded that a special role for the hippocampus in the contextual control of conditioned responding still remains to be demonstrated.