Recovery of locomotor function in cats after localized cerebellar lesions.

Cats were trained to walk on a motorized treadmill, at speeds up to a brisk walk, for food reward. A cerebellar lesion was placed in each animal, either unilateral removal of paravermal cortex, or unilateral coagulation of n. interpositus, or bilateral coagulation of the fastigial nuclei. The effects of these lesions upon locomotor activity were measured by conventional kinematic methods, and were found to be generally in agreement with prior observations. Also in agreement with prior work was the fact that these initial deficits disappeared in a relatively short time. The kinematic data suggest that this recovery of function was genuine in the sense that compensatory alterations in limb motion could not be demonstrated. In disagreement with prior studies, we failed to elicit decompensation (e.g. reinstatement of the original deficits) by subsequent pyramidal tract sections, or ablation of the 'motor' cortex. We conclude that the corticospinal system is probably not essential to the recovery observed, and also that perhaps there are substantial differences in the mechanisms of recovery of 'spontaneous' overground locomotion, compared to walking on a treadmill as a conditioned instrumental response.