Monkey lateral hypothalamic neuron response to sight of food, and during bar press and ingestion.

Unit activity of 144 lateral hypothalamus (LHA) neurons was analyzed in monkey during bar pressing feeding behavior. Eighteen neurons responded only when the animal saw food, and 23 responded only during ingestion of food. Ten responded at both the sight of food and throughout the bar pressing and ingestion periods, even in high fixed ratio schedules. Three neurons responded, not at the sight of food, but at the sight of non-food. Nineteen out of a total of 54 of the above responding neurons were studied for response to differences between food and non-food. Eight responded similarly at the sight of both food and non-food, while 11 responded differently. Responses during the ingestion period were strong and lasted longer than 5--10 sec. The data indicate that some LHA neurons are involved in the discrimination of food, the drive to obtain it and the perception of reward.