[Mechanism of change in vasomotor sympathetic activity after stimulation of various amygdaloid structures]

The influence of low- and high-frequency stimulation of cortico-medial, baso-lateral and central nuclei of the amygdala was studied in anesthetized cats by means of recording arterial blood pressure and electrical activity of the amygdala. The induced vasomotor effects were compared with the effect of hypothalamic stimulation. The low-frequency stimulation of all amygdaloid nuclei induced depressor reactions, while the high-frequency stimulation of the same areas induced an obvious pressure response. The pressure effect, however, was less obvious and of shorter duration as compared with the hypothalamic pressure responses. No correlation was found between electrical seizure discharges and blood pressure reactions to the low- and high-frequency stimulation. Mechanisms of reversal of vasomotor responses to stimulation of amygdala, diffuse organization of amygdaloid sympathoactivating mechanisms, and amygdaloid mechanisms of vasomotor regulation, are discussed.