[The role of several limbic structures in neocortical activation following brain stem section at the level of the corpora quadrigemina]

Abstract

In chronic experiments on 25 adult cats, after transection of the brain-stem at the level of oral margins of the anterior colliculus, the effect of high-frequency electrical stimulation of the posterior hypothalamus and basal-lateral portion of the amygdala was studied. While stimulation of the posterior hypothalamus resulted in diffuse activation, that of basal-lateral portion of the amygdala rather rarely evoked a relatively weak long-latency activation of the neocortex. Frequently, stimulation of the basal-lateral amygdala induced epileptiform activity in the neocortex. Bilateral lesion of the amygdaloid complex did not affect the activating influence of the posterior hypothalamus on neocortex. It is suggested that the posterior hypothalamus, independently of the mesencephalic reticular formation and amygdaloid complex, exerts an activating influence on the neocortex.