Identity of Hypothalamic Feeding Mechanisms

Summary

Taken together, these data suggest the following conclusions. It seems clear that all authors who have decided that the ventromedial nucleus constitutes the medial or satiety system have studied animals with lesions that also destroyed other areas of the hypothalamus. Those few authors, however, whose operations were limited to the ventromedial nucleus have not observed hyperphagia or obesity in their animals. Moreover, incisions that do not directly invade these nuclei may lead to hyperphagia and obesity. Finally, hyperphagia and obesity follow lesions of the mesencephalic tegmentum. My conclusion from this survey is that the medial system runs in the neighbourhood of the ventromedial nuclei, but probably does not begin or end there, and that it is most easily destroyed by lesions lateral and ventral to these nuclei. The lesions of our original study (Brobeck, Tepperman and Long, 1943) were in the region identified by Albert and Storlien (1969), near the base of the brain and one millimeter from the midline, a plane that in the rat is at the lateral border of the ventromedial nuclei. One should therefore consider the possibility that the medial system begins in the mesencephalon, runs rostrally into the hypothalamus in a position mainly ventral and lateral to the ventromedial nuclei, and then turns laterad into the lateral hypothalamus.