[Ontogenetic characteristics of the participation of the vagus nerves in regulation of the emotional state of dogs].

Bilateral supradiaphragmal section of the vagus nerves in 21 puppies and 12 adult dogs abolished adverse responses to selfstimulation of the lateral hypothalamus. The vagotomy led to facilitation (lowering of threshold, increase in the rate of leverpressing) of the self-stimulation of the posterior-lateral hypothalamic area which was most obvious and stable in the 8-12 week old puppies and adult dogs. When placing the electrodes in the anterior hypothalamic areas and related emotiogenic cerebral structures, the self-stimulation threshold increased. Therefore, the afferent effects on the vagus nerves can both inhibit and facilitate activity of the cerebral areas related to positive reinforcement and connected mainly with the posterior of anterior hypothalamic areas.