Neural Dynamics Underlying Feeding

Project Summary This proposal investigates the mechanisms that control satiation. This is a fundamental problem in physiology and also has relevance to obesity, because meal size is an important determinant of overall food intake. The caudal nucleus of the solitary tract (cNTS) contains key neural circuits for meal termination. These circuits integrate input from vagal afferents innervating the abdominal viscera as well as circulating hormonal and nutrient signals in order to trigger the termination of feeding. While cNTS cell types have long been studied using a variety of approaches, their natural activity patterns during behavior are almost completely unknown. Addressing this knowledge gap would reveal the nature of the key signals that regulate cNTS neurons during normal feeding, how these signals are integrated in specific cell types, and how they evolve during the course of a meal. In preliminary studies, we developed methods to record the activity of cNTS neurons in freely behaving mice and characterized their dynamics during feeding and in response to a variety of visceral stimuli. Here we propose to build on these findings to systematically dissect the signals that regulate cNTS satiety circuits in vivo. In Aims 1 and 2, we manipulate inputs at various stages of the GI tract and measure how this alters cNTS dynamics during feeding. In Aim 3, we use targeted optogenetic manipulations to boost or block elements of the natural activity patterns of these neurons and measure how this alters food intake and meal microstructure. Together, these experiments will reveal how the caudal brainstem dynamically integrates diverse inputs to enable the moment-by-moment control of feeding behavior.