Intracerebral temperatures in free-moving cats

Abstract

In free-moving cats, electrical activity and temperature of the brain were recorded by means of permanently implanted thermocouples. Results were as follows: The brain is thermaUy heterogeneous and has greater lability than the blood with the amygdala-pyriform region showing greater reactivity than the hypothalamus. Spontaneous motor activity or alerting of the cat by tape-recorded sounds produced a moderate thermal increase in the brain. Stimuli with emotional content had a greater effect. During sleep characterized by slow-ave activity, brain temperature decreased. Paradoxical sleep was accompanied by a slow thermal rise. Petting was one of the most effective stimuli for increasing intracerebral temperature affecting mainly the pyrtform region whereas blood temperature remained constant. Ingestion of cold drinks produced a greater decrease in carotid than in cerebral temperature. Heating the cat''s head augmented temperature in the motor cortex far more than in the orbital cortex or rectum. Intraperitoneal acetylchollne and chlorpromazine produced a drop whereas adrenaline Induced a rise in intracerebral temperature. Electrical stimulation of the brain at motor threshold did not modify cerebral temperature. Seizures evoked by amygdala stimulation were accompanied by greater thermal rise in amygdala and motor cortex than in thalamus and hypothalamus and by a fall in the intracarotid temperature. Thalamlc seizures produced a greater increase in temperature in thalamuand reticular formation than in motor cortex and hypothalamus. Curarization of the animal diminished the increase of intracerebral temperature during electrically evoked seizures.