DIFFERENTIAL RECOVERY OF BIPEDAL AND OVERGROUND LOCOMOTION FOLLOWING COMPLETE SPINAL-CORD HEMISECTION IN CATS

We used behavioral assessment techniques to investigate the recovery o f locomotion after spinal cord injury. Complete hemisections were made at T13 and L1 in the cat spinal cord. Observational and high-speed ki nematic analyses of bipedal treadmill and overground locomotion were m ade from 1 to 5 weeks postoperatively. Both bipedal and overground loc omotion showed partial recovery. The early stage of recovery was chara cterized by an increased range of joint movement in a proximal to dist al progression. During later stages, hindlimb movements became more co mplex and interjoint coordination markedly improved. Overground locomo tion recovered faster and to a greater extent than bipedal locomotion, as indicated by the time course of recovery, joint angular excursions and intralimb coordination. We propose that the recovery of bipedal l ocomotion may be more limited by reorganization of segmental sensory s ystems than overground locomotion, perhaps because alternate strategie s for overground locomotion are available.