Synchronous, intersegmental responses in motoneurons to lumbar ventral root injury.

Unilateral transection of lumbar ventral roots in the grass frog, Rana pipiens, causes large, multiphasic transcriptional responses within non-injured motoneurons as far away as the cervical enlargement. The responses, which are not seen after sham surgery, are remarkably similar in their form and timing to those which appear in the injured motoneurons, implying that both axotomized and spared motoneurons are responding to the same external signals. Elucidation of the source, pathway and properties of those signals will help to explain why spared neurons reflect some, but not all, of the features seen within injured motoneurons after motor axon damage.