Functional analysis of hypothalamic control of the cardiovascular responses accompanying emotional behavior.

The cardiovascular (CV) responses to an acute emotional situation in unanesthetized, chair-restrained baboons include elevations in heart rate, blood pressure, and terminal aortic flow and a complex biphasic reduction in renal flow. The same CV responses can be produced by stimulating an area in the hypothalamus. Furthermore, bilateral ablation of the hypothalamic area eliminates CV responses to the emotional behavior while responses to exercise, free feed, and lever press remain unaltered. This effect is not due to memory loss, loss of emotionality, or a general loss of CV regulatory capacity. Efferent projections of the hypothalamic site were traced by means of autoradiography and afferent sources were traced by horseradish peroxidase injections. Efferents include projections to amygdala, central gray, zona incerta, midline thalamic nuclei, dorsal midbrain tegmentum, the parabrachial region. Afferents were widely distributed and included inputs from the subiculum, amygdala, septal area, central gray, locus ceruleus, interpeduncular nucleus, and bilateral labeling in and around the dorsal motor nucleus of X and the nucleus ambiguus.