SWEATING RESPONSES DURING CHANGES OF HYPOTHALAMIC TEMPERATURE IN RHESUS-MONKEY

A technique is presented for preparing a durable thermode implant in the hypothalamus of the rhesus monkey Macaca mulatta. In unanesthetized monkeys implanted with thermodes in the anterior hypothalamic area of the brain, a linear relation was found between local sweat rates on the general body surface and clamped hypothalamic temperature. Changes in skin temperature shifted the hypothalamic set-point temperature at which sweating began but did not alter the gain of the hypothalamic temperature-sweat rate relationship. This study provides direct support for the concept that central brain temperature and skin temperature interact additively in the control of sweating in higher primates. Due to the very close similarity between these responses and those seen with indirect measurements of brain temperature in men, the rhesus monkey is seen as an excellent experimental analogue for studying human thermoregulation.