Untangling Appetite Circuits with Optogenetics and Chemogenetics

Excerpt

The word “hunger” encapsulates many concepts. At its core, the interoceptive detection of hunger, foraging to locate a potential food source, and ensuing consumption of calories and nutrients are the most primitive and conserved behavior across Kingdom Animalia. In mammals, the homeostatic maintenance of energetic state is highlighted by a sensorimotor feedback system that strives to maintain stability through the concerted regulation of both energy intake (via caloric consumption) and energy expenditure (via basal metabolism, adaptive thermogenesis, and physical exertion). This simple formula, whose unbalanced equilibrium results in alterations in body weight and subsequent maladaptive physiology, has influenced our genes, lifestyles, and landscapes throughout human history.