Descending and ascending influences on neurons of the zona incerta

Abstract

Characteristics of responses of single neurons in zona incerta to electrical stimulation of the amygdala and central gray matter of the midbrain were compared in acute experiments on rats. Analysis of the results showed that stimulation of the central gray matter evokes predominantly excitation (86%), where stimulation of the amygdala invokes inhibition (64%). Convergence of impulses from the amygdala and central gray matter was observed on 58 of 174 responding neurons. Most frequently (57%) the responses were opposite in direction. Stimulation of the amygdala invoked inhibitory effects and stimulation of the central gray matter activation effects. Possible functional relation in the amygdala-zona incerta-central gray matter system are discussed and the role of competitive interactions of flows of impulses descending from the amygdala and ascending from the central gray matter of neurons of zona incerta is examined.