Rhythmic activity in a motor axon induced by axotomy.

Rhythmic bursting in the axon of a flexor motoneuron in the stick insect Cuniculina impigra was evoked by cutting the main leg nerve at the autotomy plane of a leg. Bursts of up to 12 spikes were recorded extracellularly from the distal stump of the cut nerve for up to 30 min. With time the number of spikes per burst and mean burst duration decreased and interspike intervals increased. Maximum burst duration gained was very constant, approximately 0.19 s, and independent of spike number per burst. Mean cycle period was also relatively constant, approximately 0.7 s, apparently due to a waning excitation that was countered by a waning spike dependent inhibition.