Skin, preoptic, and core temperatures influence behavioral thermoregulation.

Squirrel monkeys (Saimiri sciureus) will learn to regulate their chamber air temperature (Ta) behaviorally by selecting between two air temperatures, 10 and 50 degrees C. When transient (10-min) displacements of local preoptic temperature (Tpo) are made around neutral, via water-perfused thermodes, changes in Ta selected are linear and inversely proportional to the Tpo displacement. The same result occurred in the present study when 10-min Tpo displacements were made around a clamped (36--41 degrees C) Tpo. The higher the clamped Tpo level, the steeper the linear functions relating behavioral response to Tpo transients. This change of gain was manifested in behavioral adjustments of Ta or skin temperature. The data showed that the temperature of the extrahypothalamic body core (measured rectally) was driven by the clamped Tpo to a nonneutral level. When this level was maintained stable during the Tpo transients, core temperature was shown to be a multiplicative factor governing the gain of the behavioral effector responses.