Convergence and interaction of somatic and visceral impulsation on neurons of the ventral posterolateral thalamic nucleus.

Acute experiments on anesthetized and immobilized cats using extracellular derivation of neuronal responses and field potentials demonstrated the predominant localization of somatic (radial nerve) responses in the mediocentral and of visceral (splanchnic nerve) responses in the centrolateral regions of the ventral posterolateral thalamic nucleus. Both similarities and differences were found in patterns of neuronal responses to peripheral stimuli of different types. A quite high degree of convergence of somato-visceral impulsation was found in the central part of the nucleus compared with its medial and lateral regions. Predominance of comparatively long-latency convergent neurons over short-latency was observed. The inhibitory character of somatovisceral interaction and the more effective inhibitory influence of conditioning stimulation of the radial nerve on test-response of splanchnic origin were demonstrated.