Role of the lateral hypothalamus and the amygdala in feeding behavior

Abstract

Unit activities of the lateral hypothalamic area (LHA) and amygdala (AM) were recorded during bar pressing feeding behavior in monkeys. Out of 103 LHA neurons tested, 9 decreased its firing selectively at the sight of food and not to non-food, and most of this initial response continued all through the subsequent bar pressing period. The firing decreased again after the animal put food into mouth. The discrimination ratio of food was calculated to be 54% in the LHA. Even in the AM, some neurons responded uniquely to food, and not to non-food. This differential response became more clear in the repeated subsequent trials. The discrimination ratio of food was calculated to be 25% to 44%. Although almost all of the initial responses were not maintained during the bar pressing period, 22 neurons (18% of tested) increased firing at the reward period in the AM. These data suggest that the LHA is deeply involved in the bar pressing feeding behavior all through the perception of food, the driving mechanism to obtain food, and the final reward response, while the AM seems to be concerned in some perception and reward response.