RESPIRATORY AND PUPILLARY REACTIONS

Abstract

It is generally recognized that the hypothalamus contains centers regulating autonomic activity. Experimental evidence which points to this conclusion has been obtained as a result of gross lesions or extirpation of this region, or by the injection of chemicals into the base of the brain. Karplus and Kreidl¹ (1910) have supplied further data by making transverse ablations through the diencephalon and stimulating the exposed end. Never before has a systematic exploration of the intact hypothalamus with electrical stimulation been undertaken. The foundation for such an investigation has been laid by the accurate anatomic studies of Rioch² (1929, 1931). Using the Horsley-Clarke instrument and a bipolar needle electrode, we have explored the hypothalamic region millimeter by millimeter in each of twenty-two cats. These animals were observed for changes in the pupil, in the respiratory rate, in temperature and in the rate of urinary flow. They were watched also for