Neurophysiological aspects of the pleasure of eating

Eating is a complex motivated behaviour that includes factors directly involved in the regulation of energy homeostasis (homeostatic factors) and other factors related to individual experience - habits, opportunities, circumstances - (non homeostatic factors). Regulation of food intake behaviour begins at the pre-prandial phase and involves hormones that prepare the body to the nutritional challenge. Then, ingested nutriments, satiety and adiposity hormones regulate the quantity of food to ingest. These signals exert both an action at peripheral and central levels, more specially on the hypothalamus and targeted brainstem regions. The pleasure to eat food is a reinforcing stimulus of the episodic feeding. The dopaminergic meso-cortico-limbic system intervenes in such reinforcement process to direct efficiently the organism to sources of food essential to maintain a well-balanced energy metabolism. In the case of obesity and anorexia nervosa, noteworthy deficits are described in the regulation of endocrine factors (leptin, insulin, ghrelin) as well as in the dopaminergic/serotoninergic circuitries. These changes are suspected to generate alterations in pleasure and the means to reach it.