Evidence for a Spinal Central Pattern Generator in Humansa

A bstract : Non‐patterned electrical stimulation of the posterior structures of the lumbar spinal cord in subjects with complete, long‐standing spinal cord injury, can induce patterned, locomotor‐like activity. We show that epidural spinal cord stimulation can elicit step‐like EMG activity and locomotor synergies in paraplegic subjects. An electrical train of stimuli applied over the second lumbar segment with a frequency of 25 to 60 Hz and an amplitude of 5‐9 V was effective in inducing rhythmic, alternating stance and swing phases of the lower limbs. This finding suggests that spinal circuitry in humans has the capability of generating locomotor‐like activity even when isolated from brain control, and that externally controlled sustained electrical stimulation of the spinal cord can replace the tonic drive generated by the brain.