DORSAL HIPPOCAMPAL-LESIONS IMPAIR BLOCKING BUT NOT LATENT INHIBITION OF TASTE-AVERSION LEARNING IN RATS

The aim of the present experiments was to study the effect of nonselec tive electrolytic lesions of the rat dorsal hippocampus on 2 learning phenomena: the L. J. Kamin (1969) blocking effect and latent inhibitio n of taste aversion learning. Bilateral dorsal hippocampal lesions sel ectively impaired blocking induced by 1 saccharin-lithium chloride pai ring previous to 1 serial compound (saccharin-cider vinegar)-lithium p airing, but lesions had no effect on latent inhibition of a saline ave rsion, induced by 6 saline preexposures, in the same group of animals. Moreover, dorsal hippocampal lesions did not affect latent inhibition of saccharin-conditioned aversion induced by 1 or 6 preexposures. It is argued that blocking and latent inhibition of taste aversion learni ng do not share a common neural mechanism.