BEHAVIORAL THERMOREGULATION IN RESPONSE TO LOCAL COOLING OF THE RAT BRAIN.

Local cooling of the anterior hypothalamic-preoptic area in rats, at environmental temperatures of 5 and 24 C, caused their rectal temperatures to increase as much as 3.1 C, as well as vigorous shivering. When the animals were allowed to press a bar to turn on a heat lamp directly overhead, they pressed more at both ambient temperatures when their brains were cooled than when they were not, although they worked harder in the cold. They shivered continuously during brain cooling at either temperature. The behavioral and physiological temperature regulations appeared to be complementary, since the same temperature levels were reached whether or not heat could be obtained voluntarily. Central cooling produced, in addition to the usual reflex mechanisms of increased body temperature and shivering, the behavioral motivation for heat.