The effect of early movement restriction: an EMG study in the rat.

The effect of early immobilization upon the adult locomotor pattern was studied. One hindlimb of neonatal rats was immobilized during 20 days and the EMG pattern was studied 3-8 weeks after termination of movement restriction. All rats showed a fluent locomotion pattern at these ages, but the EMG pattern revealed differences in the timing of flexor and extensor activity between the previously immobilized and the contralateral side. We suggest that interference with movement related afferent feedback at young ages has subtle but long-lasting effects upon the locomotion generating neural circuits.