Electrophysiological studies of feeding and satiety centers in the rat

Abstract

Bipolar stimulating electrodes were implanted in the hypothalamus of rats to study the neural organization of the feeding and satiety "centers." Far-lateral hypothalamic stimulation provoked feeding in satiated animals and "motivated" crossing of electrical barriers to lever-press for food reward on several reinforcement schedules. Midlateral hypothalamic stimulation resulted in feeding in sated animals but never motivated grid crossing to lever-press. Medial forebrain bundle (MFB) lesions or stimulations anterior and posterior to the level of the feeding centers did not alter basic feeding behavior. Following MFB lesions, however, far-lateral hypothalamic stimulation never resulted in animals crossing an electrified grid to lever-press for food reward. Concomitant far-lateral hypothalamic and posterior periventricular stimulation inhibited grid crossing to lever-press, and, instantly suppressed this activity if already in progress. Simultaneous far-lateral hypothalamic and ventromedial (VM) hypothalamic stimulation only provoked basic feeding in sated animals. In animals feeding or lever-pressing in response to far-lateral stimulation, addition of VM stimulation slowed but did not completely suppress either activity. VM stimulation alone never provoked feeding or grid crossing, but "rebound" feeding in the sated state and nonelectrified grid crossing to lever-press resulted when this stimulation was turned off.