Lateral hypothalamus: Learning of food-seeking response motivated by electrical stimulation

Electrical stimulation of the lateral hypothalamus (ESLH), which causes satiated animals to eat, resembles in effect the hunger normally produced by deprivation of food in that it also motivates them to perform a response that they previously had learned as a way of getting food (1). Grasty{m, Lissak, and Kekesi (2), however, have suggested that the elicitation by ESLH of an already learned response is due not to the specific arousal of the hunger mechanism but to the nonspecific facilitation of a dominant habit. If ESLH can motivate the trial-and-error learning of a new response that is rewarded by food, this alternative interpretation is ruled out because the response to be learned is not dominant at the beginning of training. Furthermore, if the effects of ESLH resemble normal hunger, shifting the reward of food to another response, after one response has been learned and has become dominant, should cause the first response to be extinguished and a new response to be learned. It is clearly impossible for the hypothesis of nonspecific facilitation to account for such reversal learning.