抄録
The influence of brain temperature changes upon the electroencephalogram (EEG) in the mammals has been reported by several investigators. Gaenshirt et al. (1) demonstrated that the spontaneous EEG recorded from isolated and artificially perfused cat's head showed marked changes in frequency and voltage at temperature varying from 40°C to 20°C, and that the mean frequency of the cortical EEG fell when the brain temperature was lowered down to 32°C, while mean voltage of the EEG increased when the temperature was lowered from 40°C to 33°C. However, the obvious correlation between the EEG activation and brain temperature was not inferred from their reports, because the perfused head would presumedly suffered from extreme non-physiological surgical procedures. von Euler and Soderberg (2) showed that moderate hypothalamic heating synchronized the EEG and inhibited the gamma motor activity in both rat and rabbit. Little work has hitherto been done to study the influence of drugs on synchronization and desynchronization of EEG caused by changes of brain temperature.
In the previous reports, Tanabe and Takaori (3) observed the changes in temperature of brain, tympanic membrane and rectum, behavior, respiration, blood pressure and heart rate induced by cooling and warming both common carotid arteries in the rabbit. They reported that the carotid cooling produced alerting, shivering, pallor, increase in the respiratory frequency and depth, and increase in frequency and amplitude of the spontaneous undulation of the blood pressure, while the carotid warming caused drowsiness and slight increase in the heart rate. Further, they regarded the tympanic membrane temperature measured through the external auditory canal as a feasible reflexion of the brain temperature.
The present experiments have been designed to elucidate the relationship between the brain temperature and the EEG's in the cortical and subcortical areas, and to trace the influence of central depressants and stimulants on the EEG alterations induced by the carotid cooling and warming.
