Effect of a local rise of temperature of the anterior hypothalamus on the electroencephalogram.

In chronic experiments on rabbits the anterior hypothalamic region was heated by means of water thermodes. Heating the anterior hypothalamus to +3.0 degrees C caused no change in the character of the initial EEG. Heating the anterior hypothalamus to +6.0 degrees C caused activation of the initially synchronized EEG. The EEG weakly activated by heating the anterior hypothalamus to between +1.0 and +2.0 degrees C could be synchronized; this effect depended on the strength of the activating influences of the experimental external situation on the animal. The threshold of EEG activation by heating the anterior thalamus was 1.5-2 times higher than the threshold of activation of the EEG by cooling the anterior hypothalamus. In every case a change in the temperature of the anterior hypothalamus evoked appropriate thermoregulatory responses.