Effect of Nasopharyngeal Temperature Change on Preoptic and Anterior Hypothalamic Thermosensitive Units

Multiunit action potentials were recorded from neurons in the preoptic and anterior hypothalamic area (preoptic region) of the cat. A new method to change brain temperature in the cat was used. It consisted of perfusing the nasal cavity with warm and cold water through tubes inserted into the nostrils. The principle of this method was based on the knowledge that the brain temperature of the cat is dependent upon that of the venous blood in the pterygoid plexus through which the external carotid rete supplying the brain in this species has to pass.Evidence for temperature-sensitive units in the preoptic region was found under these conditions. The response characteristics of the units observed were similar to those obtained in thermode experiments used by other investigators. A regular increase in firing rate with increasing temperature was found in 16.6% of the temperature-sensitive nerve cell population in the preoptic region, A regular increase of firing rate with decrease in brain temperature was obser...