Lateral parabrachial nucleus lesions in the rat: aversive and appetitive gustatory conditioning.

Previous research involving tests of innate preferences and aversions shows that bilateral ibotenic acid lesions of the visceral neurons located in the lateral parabrachial nucleus of the pons selectively disrupt consumption of those gustatory stimuli whose intake is augmented or restricted by their postoral consequences. The present study examined the performance of the same experimental subjects in learned preference and aversion tasks. The lesioned rats failed to develop a conditioned taste aversion (Experiment 1), a conditioned flavor preference (Experiment 2), and a conditioned aversion to the oral trigeminal stimulus, capsaicin (Experiment 3). The pattern of results from both types of taste-guided behaviors (innate and learned) suggests that excitotoxic lesions of the lateral parabrachial nucleus diminish sensitivity to gastrointestinal feedback which, in the present experiments, precludes aversive and appetitive associative learning.