Viscerosomatic convergence in the dorsal column nuclei of the cat

Abstract

The dorsal column nuclei (DCN) of adult cats were explored with micropipets for single units responding to electrical stimulation of the A-β fiber fraction of the ipsilateral greater splanchnic nerve. Exploration was confined to the gracile and cuneate nuclei, 3 to 5 mm caudal to the obex. Field potential mappings previously showed this region to be highly responsive to input from these fibers. Extracellular records from DCN neurons excited by A-β visceral afferent volleys typically consisted of a burst of two to three spikes with latencies from 5 to 11 ms. Somatic input was also observed in the majority of these cells. Natural stimuli effective in eliciting activity included hair movement, touch, and vibration. Cutaneous receptive fields for neurons exhibiting viscerosomatic convergence were found on the hind limb, tail, and trunk. Many of the DCN units showing convergent input were classified as relay cells on the basis of their responses to electrical stimulation of the contralateral midbrain. The results emphasize the role of the dorsal column nuclei in the integration and transmission of visceral information.