 The investigators 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 and standing; 9 bladder function; 10 CV function. The FNPA, NCS, SEP and SSR will be performed while the research participant is lying supine on a mat. The efferent motor assessments will be performed in the body weight support treadmill with the assistance of trainers at the hip and at each leg. 