Interlimb coordination during stepping in the cat: the role of the dorsal spinocerebellar tract.

The role of the dorsal spinocerebellar tract (DSCT) in the neural control of normal interlimb coordination during overground stepping in adult cats was investigated using select spinal cord lesions. Previously, it had been shown that lesions of the caudal thoracic dorsal columns (DCs) which might involve the DSCT or its afferent fibers resulted in a marked change in the patterns of forelimb-hind limb coupling during locomotion. In the present study, more rostral DC lesions, which probably included the DSCT or its afferent fibers considerably less, resulted in nearly identical changes in the patterns of interlimb coordination during stepping. Lesions of the dorsolateral funniculus (DLF) at similar spinal levels resulted in no significant changes in interlimb coordination. These lesions did destroy the DSCT, since retrograde transport of horseradish peroxidase (HRP) from the anterior cerebellar vermis to the nucleus dorsalis was blocked caudal to the lesion. These results are consistent with the notion that the DSCT plays little if any role in the precise timing of step cycles of the different limbs.