Hyperthermia and inhibition of feeding produced by self-stimulation in the septum and preoptic area in dogs.

Dogs bearing electrodes implanted in the anterior part of the basal forebrain were tested for their response to food upon electric stimulation of rewarding sites, and for self-stimulation-produced hyperthermia. Self-stimulation and forced (experimenter-induced) stimulation of 12 out of 16 loci evoked a negative reaction to food the strength of which was determined according to occurrence and persistence of three effects: ignoring food (the dog performing self-stimulation in the presence of readily available meat), food rejection (the dog's failure to take meat offered together with passive stimulation of the rewarding site), and food ejection (throwing meat out of the mouth upon passive stimulation). The rise in body temperature during self-stimulation was positively correlated with the rate of responding. Hyperthermia was significantly higher during self-stimulation in sites where stimulation produced a strong negative reaction to food, as compared with those where stimulation failed to stop the animal from eating. The stimulus-contingent negative reaction to food may reflect a short-term satiety which is supposed to play an essential role in the mechanism of reinforcement. Hyperthermia, and particularly stabilization of hypothalamic temperature on an elevated but fairly constant level, argues for a shift of the set-point for temperature regulation. Occurrence of the two effects supports the claim that self-stimulation produces some complex activation of neural processes controlling energy homeostasis.