This project utilizes the technique of hypothalamic disconnection in Macaca mulatta to study the neural organization of feeding. The ventromedial hypothalamus is isolated from the rest of the brain by surgical knife cuts; the monkeys survive this procedure and their feeding is subsequently studied. We have demonstrated: (1) that cuts which biliterally separate ventromedial from lateral hypothalamus results in overeating and weight gain, and (2) that some "non-specific" inhibitions on feeding (those related to emotional arousal and bad taste) are unaffected by ventromedial disconnections, but (3) that the anorexia caused by amphetamine administration is reduced in these monkeys. We are now studying the influence of another inhibition on feeding-food in the gastrointestinal tract--to test the hypothesis that the ventromedial region specifically transmits satiety signals. Total nutrient and specific food substrate preloads are administered through chronic gastric catheters maintained in caged animals, and the effects of these preloads on food intake are examined during a subsequent test meal. This procedure is carried out before and after neural disconnection of the ventromedial region.