Peripheral modification of sensory nerve responses after cross-regeneration.

1. Chemical responses of skin and tongue, recorded in vivo from intact and self-regenerated cutaneous or lingual nerves, were compared to responses from cutaneous nerves cross-united with distal stumps of lingual nerves. Cross-innervated tongue grafts were also studied.2. In contrast to normal tongue-nerve preparations, skin preparations usually showed responses to chemical stimulation with longer latency, higher threshold, and less variation of temporal pattern with diverse stimuli. These characteristics were similar when the nerve, having been cut, had regenerated.3. On chemical stimulation of the tongue, cutaneous nerves cross-innervating the tongue often yielded records which were ;gustatory' by all criteria. Some responses with low threshold and short latency were also obtained from dorsal cutaneous nerves innervating tongue grafts.4. Thus, cutaneous nerves can serve the same role as gustatory nerves. The functional characteristics of these sensory neurones are not predetermined and must depend on the environment of the nerve endings.