Summation and Reciprocal Innervation in Autonomic Control

Abstract

The mechanism of autonomic control of homeostasis are not yet fully understood. Thus, although it is well accepted that the central nervous regulation of vasomotricity and cardiac activity is subserved by a series of superposed nervous centres, the manner in which these centres influence one another is not sufficiently known. On the other hand, the role played by the mesencephalic reticular formation (MRF) in the autonomic homeostasis has not been systematically studied yet. In view of these facts, we have undertaken in dogs and cats a series of investigations concerning the interrelations of higher nervous centres and their reciprocal influence in the control of autonomic homeostasis. The results obtained are indicative of complex relations between these centres. Attention must be focussed at least on the following evidences:1. the occurence of a pressor tensional effect after subliminar simultaneous stimulation of some vasopressor points in the central nervous system represents a very clear case of spatial summation;2. the study of the autonomic control exerted by the MRF demonstrates, apart from overall activatory effects, influences of the reciprocal innervation type, the latter seeming to be dispersed over a wide projection area.