Translational neuroscience approaches to hyperphagia.

Introduction 1Food intake in humans and other mammals is a complex process, resulting from the integration of homeostatic systems that monitor energy stores with hedonic drive resulting from the behaviorally reinforcing properties of food (Fig. 1) (Lutter and Nestler, 2009). Under conditions of food scarcity, the hedonic and homeostatic drives cooperate to enhance the intake of highly palatable food. During times of nutrient excess, the homeostatic drive reduces food intake and increases energy expenditure in an attempt to maintain body weight. However, the hedonic drive to feed, conditioned through exposure to highly palatable food, continues to promote food consumption and excessive intake of calories. Several neuropsychiatric disorders, including Prader-Willi syndrome (PWS), bulimia nervosa, and binge eating disorder exhibit derangements in food intake resulting from perturbations in the hedonic drive to feed. In addition, genetic studies in patients with obesity are identifying mutations in genes that increase food consumption. Techniques developed in recent years now allow for a more sophisticated assessment of feeding behaviors in both laboratory animals and humans (Fig. 2). In this review, we will discuss recent advances in our understanding of food reward using a combination of laboratory animal and human research techniques.