Overlapping Brain Circuits for Homeostatic and Hedonic Feeding

Abstract

Central regulation of food intake is a key mechanism contributing to energy homeostasis. Many neural circuits that are thought to orchestrate feeding behavior overlap with the brain's reward circuitry both anatomically and functionally. Manipulation of numerous neural pathways can simultaneously influence food intake and reward. Two key systems underlying these processes-those controlling homeostatic and hedonic feeding-are often treated as independent. Homeostatic feeding is necessary for basic metabolic processes and survival, while hedonic feeding is driven by sensory perception or pleasure. Despite this distinction, their functional and anatomical overlap implies considerable interaction that is often overlooked. Here, we argue that the neurocircuits controlling homeostatic feeding and hedonic feeding are not completely dissociable given the current data and urge researchers to assess behaviors extending beyond food intake in investigations of the neural control of feeding.

Keywords: dopamine; hypothalamus; obesity; reward.

Figure 1

Circuits involved in feeding and reward. Schematic illustration of ventricular, intermediate, and monoaminergic nuclei. There are strong reciprocal connections between ventricular and intermediate as well as intermediate and monoaminergic nuclei (indicated by solid lines). Direct connections between ventricular neurons and monoaminergic nuclei are relatively sparse or absent in adults (indicated by the dashed line). Ventricular neurons express receptors for peripheral signaling molecules implicated in feeding are more densely than do intermediate and monoaminergic nuclei. Arc, arcuate nucleus; BNST, bed nucleus of the stria terminalis; CeA, central nucleus of the amygdala; DA, dopamine; DR, dorsal raphe; Hb, habenula; LHA, lateral hypothalamic area; NAc, nucleus accumbens; PBN, parabrachial nucleus; PFC, prefrontal cortex; PVN, paraventricular nucleus of the hypothalamus; VTA, ventral tegmental area; 5-HT, 5-hydroxytryptamine.

Figure 2

Functional heterogeneity within molecularly-defined hypothalamic neuronal populations. (A) Arc AgRP neurons promote context dependent aversion or reward. Depending on the availability of food, mice will either avoid or lever-press for AgRP stimulation. (B) Anatomically-intermingled, functionally-opposing LHA neurons influence feeding and reward.