Could enhanced reflex function contribute to improving locomotion after spinal cord repair

Although numerous treatments have been found to improve locomotion in spina l cord injured mammals, the underlying mechanisms are very poorly understoo d. Some of the main possibilities are: (1) regeneration of axons across the injury site and the re-establishment of descending pathways needed to volu ntarily initiate and maintain stepping in the hind legs, (2) enhanced effec tiveness of undamaged neurons in preparations with incomplete transections of the cord, (3) non-specific facilitation of reflexes and intrinsic spinal networks by transmitters released from regenerated axons and/or by substan ces introduced by the treatment;, and (4) enhanced trunk movements close to the injury site strengthening the mechanical coupling of the trunk to the hind legs via spinal reflexes. In addition, any procedure that even slightl y improves stepping may be further enhanced by use-dependent modification o f reflex pathways and interneuronal networks in the lumbar cord. The emphas is of this review is on the contribution of spinal reflexes to the patterni ng of motor activity for walking, and how enhancing reflex function may con tribute to the improvement of locomotion by treatments aimed at restoring l ocomotion after complete transection of the spinal cord.