Mapping study of the parabrachial taste-responsive area for the anterior tongue in the golden hamster.

The locations of taste-responsive areas within the brainstem parabrachial nucleus (PBN), an obligatory taste relay in the golden hamster (Mesocricetus auratus), were mapped in relation to cytoarchitectural boundaries. The PBN was systematically searched for multiunit neural activity in response to a taste mixture composed of 0.1 M sucrose, 0.03 M NaCl, and 0.1 M KCl applied to the anterior tongue. Taste responses were located exclusively in one of three subdivisions of the medial PBN, which is thought to be specialized for gustatory processing, and in one of six subdivisions of the lateral PBN, which is thought to be specialized for general visceral processing. Based on Nissl-stained material, both the medial and lateral PBN subdivisions in the hamster were similar to those reported for the rat PBN. The largest group of taste-responsive cells encompassed two-thirds of the central medial subdivision, while a smaller group of taste cells was exclusively located within the ventral lateral subdivision. The two taste-responsive subdivisions are separated by the superior cerebellar peduncle and contain diverse cell types. The finding that anterior tongue taste may be exclusively represented in circumscribed cytoarchitecturally defined parts of two PBN divisions suggests that taste information from the anterior tongue is required for both specific gustatory and general visceral functions.