Locomotor recovery in spinal-transected lamprey: regenerated spinal coordinating neurons and mechanosensory inputs couple locomotor activity across a spinal lesion.
Larval lampreys recover locomotor function several weeks after receiving complete spinal transections. In behaviorally recovered whole-animals, the phase-coupling of locomotor activity across a lesion was similar to that observed along the body in normal, unlesioned lampreys. Two factors were found to contribute to recovery of locomotor coupling above and below a spinal transection. Firstly, under in vitro conditions regenerated spinal coordinating neurons could couple brainstem-evoked locomotor activity above and below a lesion in the absence of mechanosensory inputs. Secondly, in whole-animals mechanosensory inputs were capable of coupling locomotor activity across an acute, mid-body spinal transection in the absence of direct neural coupling through spinal coordinating neurons. Since neither regenerated coordinating neurons nor mechanosensory inputs resulted in phase-lags that were as stable as those observed in recovered whole-animals, presumably both mechanisms contribute significantly to the restoration of locomotor coupling across a healed spinal lesion.
Department of Physiology and Biophysics, University of Iowa, Iowa City 52242.
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McClellan
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001921:Brain / Q000502:physiology*; D001933:Brain Stem / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D005399:Fishes / Q000502:physiology*; D007798:Lampreys / Q000502:physiology*; D008465:Mechanoreceptors / Q000502:physiology; D009043:Motor Activity / Q000187:drug effects; D009068:Movement; D009132:Muscles / Q000294:innervation; D016202:N-Methylaspartate; D009416:Nerve Regeneration; D012016:Reference Values; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*
D001224:Aspartic Acid; D016202:N-Methylaspartate