- Somatosensory evoked responses: This test examines how sensory information travels form the nerves to the spinal cord and brain in the nervous system. An electrode placed on the arm, leg, or face delivers a small electrical stimulus that may tingle and cause a twitch of a hand, foot, or face muscle. Additional electrodes may sometimes be placed on the scalp, neck, and over the collarbone to record how the impulse from the stimulus travels over nerve pathways.