The identification of these two populations of neurons is the paper’s key contribution, says Allison Shapiro, a specialist in neurodevelopment at the University of Colorado Anschutz Medical Campus in Aurora who was not involved in the research. It fits in with the anecdotal idea that there are two types of fullness: one that is anticipatory and another that arises in response to eating. “Based on what they’ve found, it appears that this specific region of the hypothalamus is responsible for both, which is pretty cool.”