Electrophysiological responses to appetitive and consummatory behavior in the rostral nucleus tractus solitarius in awake, unrestrained rats.

The rostral part of the NTS has traditionally, but perhaps narrowly, been thought of as a "taste relay". While it is true that this structure receives and transmits information about tastants in the mouth to higher order structures in the central gustatory pathway, data presented here show that its function is more diverse. Specifically, in addition to the responses to liquid tastants in the mouth, its responses to approach and exploration of solid food define a significant role for the rNTS in the appetitive phase of eating. Moreover, responses to food consumption, albeit weaker than those during appetitive behavior, buttress the idea that the rNTS is part of the larger hindbrain circuit guiding energy regulation.