Partial and complete deafferentation of cat hindlimb: the contribution of behavioral substitution to recovery of motor function.

After partial (spared-root) or complete hindlimb deafferentation, locomotion and accurate limb placement during locomotion recover considerably. In the present study movement was studied during and after recovery to determine whether altered motor patterns could substitute for normal ones in the recovery of motor behavior. In acute L6 spared-root preparations somatosensory postural reflexes are impaired, accurate limb placement deficient and joint angle measurements show altered kinematic motor patterns during locomotion. As somatosensory postural reflexes and accurate limb placement recover, so do the motor patterns. After complete deafferentation motor patterns are more disturbed. Somatosensory postural reflexes remain absent but as descending reflexes recover, so does accurate limb placement during locomotion. In deafferented hindlimbs, in contrast to spared-root preparations motor patterns observed chronically (after recovery of accurate placement) are persistently abnormal indicating that novel motor patterns can replace normal ones in the recovery of goal-directed behavior. The results suggest that behavioral substitution can contribute to recovery of useful movement.