Parabrachial nucleus lesions block taste and attenuate flavor preference and aversion conditioning in rats

Rats with ibotenic acid lesions of the parabrachial nucleus (PBN) failed to learn a taste aversion induced by lithium chloride (LiCl) toxicosis. The s ame rats also did not learn to prefer a taste that was paired with intragas tric (IG) carbohydrate infusions during 22 hr/day trials. The PBN-lesioned rats did learn to prefer a flavor (odor + taste) paired with the IG carbohy drate infusions over a different flavor paired with IG water. The PBN-lesio ned rats also learned to avoid a flavor paired with IG LiCl infusions durin g 22 hr/day trials. The flavor preference and aversion, however, were less pronounced than those displayed by control rats. These data indicate that t he PBN is essential for forming orosensory-viscerosensory associations when taste is the primary cue but is less critical when more complex flavor cue s are available.