Mesh : Afferent Pathways / physiopathology Artifacts Cerebral Cortex / physiopathology Documentation / methods standards Electroencephalography / instrumentation standards Equipment Safety Evoked Potentials, Auditory / physiology Evoked Potentials, Somatosensory / physiology Humans Monitoring, Intraoperative / instrumentation standards Reaction Time Reference Values Spinal Cord / physiopathology