抄録
Although it is generally accepted that the level of the systemic blood pressure is regulated centrally, the mode of the regulation or the mechanism of the regulation still remains to be settled. In many of the experiments concerned with the above-mentioned central regulation, electrical stimulation and destruction of the various nuclei or the nerve tracts in the brain, as well as the administration of drugs which stimulate or depress the central nervous system, have been studied. The responses of the blood pressure to the above-mentioned procedures in the cerebral cortex, hypothalamus, pons and medulla oblongata are reported in the literature, but very little attention has been paid in the past to the response of the thalamus or to the interrelation of this area to the hypothalamic autonomic centre. Moreover, the physiological significance of the blood pressure responses are merely interpreted as the localization of the sympathetic or parasympathetic regulation.
All sensory tracts, except the olfactory, are interrupted by a synapse in the thalamus or the diencephalon before coming to the cerebral cortex. However, the physiological significance of the thalamic nuclei in the rabbit is not fully known. Head (1) believed that the thalamus subserves the affective site of sensation and therefore of pain, which is a strongly affective experience. Affectivity is considered as a primitive function, which, in the course of evolution, remained at a thalamic level despite development of the cerebral cortex. The so-called sham-rage or angry behavior as used by Bard (2), which is caused by prolonged stimulation of the hypothalamic nuclei in the cat, always reveals an autonomic manifestation, such as a rise of blood pressure or a dilatation of the pupils (3). The authors also observed a marked hypertensive response to stimulation of the thalamic nuclei in the rabbit, which was as strong as in the case of the hypothalamic or pontic nuclei and which could not be distinguished from these. Accordingly an attempt has been made to study the mechanism of why the thalamic affection does reveal such a marked hypothalamic manifestation.
