Hardwired locomotor network in cat revealed by a retained motor pattern to gastrocnemius after muscle transposition.

Locomotor output to the gastrocnemius muscle was studied after a transposition giving the muscle a dorsi-flexing action around the ankle. Except for a slight prolongation of the activity, the old extensor pattern was retained in all cats throughout the study. A peak of activity before termination was seen in one cat at higher walking speed. It is concluded that neither the spinal locomotor network controlling the gastrocnemius muscle nor the supraspinal circuits influencing the network exhibit a high degree of plasticity in response to locating the muscle in a position antagonistic to the original.