question motor unit

[Ignacio Novoa Cornejo]

An electrode used in a group of identical fibers in spinal cord dorsal root and encouraged. In response to a pulse, you get a transient increase in flexor muscle activity and a decrease in the activity of the same joint extender.
if actively extends the joint against gravity, is increased activity of the fibers. By stimulating the motor neuron that innervates dynamic range both the flexor and extensor no change in the activity of the fibers. Where do these fibers? thanks!!