Hippocampal lesions attenuate latent inhibition of a CS and of a neutral stimulus

Abstract

Rats with hippocampal or sham lesions were exposed extensively to a tone. Subgroups received either nonreinforced presentations of this stimulus or tone-mild footshock pairings. The subjects subsequently received pairings of the tone with a stronger footshock, and it was found that animals with hippocampal lesions learned this relationship more rapidly than did controls, regardless of whether they had received reinforced or nonreinforced prior experience with the tone. Comparisons with other control groups for which the tone was novel indicated that exposure reduced the associability of that stimulus for sham-operated rats. These results suggest that hippocampal lesions may disrupt a common mechanism underlying the loss of associability that occurs after exposure of a CS and of a neutral stimulus. © 1987, Psychonomic Society, Inc.. All rights reserved.