[Reactions of the neurons of the anterior and posterior regions of the hypothalamus to light stimulation and stimulation of the splanchnic and sciatic nerves].

Responses of single hypothalamic neurons to splanchnic, sciatic nerves and photic stimulation were studied in anesthetized, curarized cats. It is found that units of the posterior and anterior hypothalamus are "convergence neurons" with multisensory inputs. Convergence of somatosensory and visceral (splanchnic) impulses to such neurons was complete. No neurons responding only to the splanchnic nerve stimulation were found. In the posterior hypothalamus some units responded only to stimulation of splanchnic and sciatic nerves and were unresponsive to a flash. On the contrary, in the anterior hypothalamus a part of units responded only to photic stimulation. The polysensory neurons of the posterior and anterior hypothalamus were of a nonspecific modality: they responded with a similar pattern of phasic or tonic discharge with a predominance of phasic responses. Units were more often excited than inhibited. A high responsibility (68%) of spontaneously active neurons to somato-visceral and photic stimulation was observed in the posterior, as well as in the anterior hypothalamus. The principles of functional organization of hypothalamic afferent system are discussed.