 Stage 1B: Surgical Procedure Stage 1C: Stimulation with standing and stepping interventions Stage 2A: Stimulation with standing and stepping assessments Stage 2B: Adaptive Multielectrode Epidural Stimulation and LT Stage 1A: Standing and stepping interventions Prior to the initial surgery the participant will undergo 80 sessions of stepstand training screening. We will evaluate the research participants for 1 functional neurophysiological assessment FNPA, 2 nerve conduction study NCS; 3 somatosensory evoked potentials SEP; 4 sympathetic skin responses SSR, 5 efferent motor activity during standing, 6 efferent motor activity during stepping and 7 reflexes during supine, prone, sitting standing before the initiation of training, 9 bladder function, 10 CV function, 11 MRI of the spinal cord. Each of these measurements will take between 1 and 4 hours. We will repeat these measurements at the end of the initial 80 training sessions. 