Latent inhibition of conditioned taste aversion in rats with amygdaloid or hippocampal lesions

The amygdala and hippocampus play crucial roles in the latent inhibition of different conditioned responses, such as fear conditioned. Nevertheless, the involvement of these structures in the latent inhibition of conditioned taste aversion (CTA) is uncertain. In the present study, we explore the relevance of the amygdala and hippocampus in latent inhibition using a CTA paradigm. The effects of taste pre-exposures vs. non-pre-exposures on taste aversion conditioning were compared in Wistar rats with amygdaloid or hippocampal excitotoxic lesions. All pre-exposed animals consumed significantly more on the test day than did non-pre-exposed animals. Therefore, neither amygdaloid nor hippocampal lesions prevented the latent inhibition phenomenon. However, the expected taste neophobia was potentially affected by lesions to either the amygdala or hippocampus. These findings suggest that the amygdala and hippocampus seem to be necessary for taste neophobia but not for the acquisition of latent inhibition of CTA. The differential involvement of both structures in latent inhibition under different associative learning paradigms is briefly discussed.