IBOTENIC ACID LESIONS OF THE PARABRACHIAL NUCLEUS AND CONDITIONED TASTE-AVERSION - FURTHER EVIDENCE FOR AN ASSOCIATIVE DEFICIT IN RATS

Rats with extensive ibotenic acid lesions centered in the gustatory zo ne of the pontine parabrachial nucleus (PEN) failed to acquire a condi tioned taste aversion (CTA) induced by lithium chloride (LiCl) toxicos is (Experiments 1 and 4). This deficit cannot be explained as an inabi lity to either perceive or process gustatory information because lesio ned rats that failed to acquire a CTA readily acquired a conditioned f lavor preference (Experiment 2). Similarly, the CTA deficit cannot be attributed to an inability to experience or process visceral input bec ause PBN-lesioned rats that failed to acquire a CTA successfully learn ed an aversion to a trigeminal stimulus, capsaicin, when paired with L iCl-induced illness (Experiment 3). This pattern of results supports t he view that cell bodies within the PEN are essential for the associat ive processes that govern CTA learning.