Conditioned taste aversions and neophobia in rats with hippocampal lesions.

In the first experiment extensive hippocampal lesions retarded, but did not prohibit, the conditioning of a strong taste aversion to physiological saline (the conditioned stimulus; CS) when illness (the unconditioned stimulus; UCS) was induced by injecting rats with apomorphine 15 min following ingestion of the saline. In the second experiment hippocampal lesions reduced the aversiveness of novelty in a drinking fluid for the thirsty rat. It was suggested that the mild impairment of taste aversion learning in the rats with hippocampal lesions was not the result of destruction of mnemonic mechanisms that serve to span the long CS-UCS interval but rather that the reduced intensity of the aversion resulted from a lesion-altered neophobic disposition that weakened the saliency of the novel flavor CS.