The stomach releases acid, enzymes, and hormones; the pancreas secretes insulin and enzymes. These anticipatory changes ensure food is digested and metabolized efficiently and prevent dangerous increases in blood glucose levels. Food then passing through the upper GI tract triggers other changes, e.g., slowing of gastric motility to ensure nutrient absorption in the duodenum. Dysfunction in this system can compromise control of meal size and blood glucose levels and underlies conditions such as diabetic gastroparesis. Remarkably, both the feedforward and feedback control of GI function is primarily mediated by a single brain region, the dorsal motor nucleus of the vagus (DMV) - the brain’s major parasympathetic input to the GI tract.

Previous studies in rodents and humans have found remarkable diversity among DMV neurons, leading to a theoretical model in which different subsets of DMV neurons, or “functional units,” mediate its different functions. However, these functional units have yet to be defined in terms of their gene expression, synaptic circuitry, and specific role(s) in GI control. Our research is identifying DMV neuron types, then determine their function by mapping their projections to organs, manipulating their activity, and measuring their response to and anticipation of feeding.