Co‐ordinated Changes in Temperature Thresholds for Thermoregulatory Reflexes

Abstract

Summary. 1. In lightly anaesthetized cats and rabbits the threshold temperatures for several temperature regulating reactions, i. e. , onset and cessation of shivering and cutaneous vasoconstriction, were repeatedly determined when stimulating the animals in different ways 2. It was found that various stimuli, such as nociceptive stimulation, pinna reflex, and electrical stimulation of the midbrain tegmentum which all activated the electroencephalogram and the gamma motor system, tended to raise the temperatures at which both heat‐producing and heat‐dissipating reflexes are brought into action with a rise in body temperature as a consequence. 3. Similar shifts of the temperature for thermo‐balance were obtained by systemic infusion of adrenaline and noradrenaline. Changing the composition of the inspired gas was also found to influence thermoregulation. 4. Stimuli which inhibited the activity of the gamma motor system and evoked a synchronized cortical activity, e. g. stroking the back of the animal, lowered the threshold temperatures with as light fall in body temperature as a result. 5. The results support the view that the body temperature is set at different levels in different states of activity.