CONVERGENCE OF VISCERAL AND CUTANEOUS AFFERENT PATHWAYS IN LUMBAR SPINAL CORD

1. 1. A method has been devised for stimulating visceral afferents in the caudal portion of the sympathetic chain, while recording from the lumbar spinal cord. This makes it possible to study interactions in the spinal cord between visceral afferents and simultaneously activated cutaneous afferents. 2. 2. Mapping the spinal cord with microelectrodes shows that both visceral afferents and the small myelinated (A delta) cutaneous afferents evoke maximum focal negativity in the same layer of dorsal horn, Rexed's lamina V. 3. 3. Many neurons in lamina V can be activated by both visceral nerve and skin nerve stimulation. 4. 4. The large myelinated (A beta) afferents of visceral nerves seem to differ from those of cutaneous nerves in that only the latter have recordable actions on cells of Rexed's lamina IV of the dorsal horn. 5. 5. The demonstrated convergence of visceral and cutaneous afferent pathways onto common interneurons in the dorsal horn, many of which send axons into ascending tracts in the white matter, provides a mechanism by which the referral of visceral pain to the skin might be explained. © 1969.