Anatomical correlates of return of locomotor function after partial spinal cord lesions in cats.

We trained cats to walk on a moving treadmill belt, then subjected them to partial transverse sections of the thoracic spinal cord. Afterwards, we observed their ability to walk on the treadmill, over a period of several weeks, using gait analysis techniques to describe the resultant deficits. The extent of the lesions was verified histologically, and the identity of the spared descending axons from the brain stem was demonstrated by retrograde labeling with horseradish peroxidase. We found that significant sparing or recovery of hindlimb locomotor function is closely linked to sparing of axons in at least one ventrolateral quadrant of the cord. The essential elements probably belong to vestibulospinal and reticulospinal systems.