Relation of abnormal burst activity of spinal neurons to the recurrence of autotomy in rats.

Two groups of rats received different amounts of peripheral deafferentations; one group received sections of sciatic nerve (S-rats) and the other received sections of sciatic and saphenous nerves (SS-rats). In Experiment 1 the occurrence of autotomy was compared between S- and SS-rats for up to 70 days after the surgery. Autotomy in SS-rats frequently recurred until 40 days after denervation whereas in S-rats it scarcely recurred. In Experiment 2 spontaneous activity was recorded from the spinal cords in S- and SS-rats, and the proportion of burst firing cells (B-cells), characterized by periodic and high frequency bursts, was compared. In both S- and SS-rats with fresh wounds the occurrence of B-cells was high until 40 days after denervation. However, B-cells were still frequently observed in SS-rats with old wounds until 40 days after denervation, whereas B-cells were scarcely found in S-rats with similar old wounds. This finding corresponded well with the behavioral observation in Experiment 1. The data strongly suggests that the continuance of a high proportion of B-cells in the spinal cord plays an essential role for the induction of recurrent autotomy.