The use of transcutaneous electrical nerve stimulation (TENS) to aid perceptual embodiment of prosthetic limbs.

Integration of prosthetic limb awareness into body schema is likely to aid manual control of the prosthesis. Physiotherapists and prosthetists use techniques to generate mechanical, visual and/or auditory feedback related to stimulation of the stump and proximal residual limb to improve prosthetic limb awareness. Electrical stimulation of afferent nerves using implanted electrodes can generate sensations of touch, joint movement, and position, in the missing, phantom limbs of amputees. We report here a novel hypothesis that non-invasive transcutaneous electrical nerve stimulation (TENS) could be used to facilitate the process of perceptual embodiment of a prosthesis into the body schema of amputees. Using a modified version of the rubber hand illusion (RHI), we have found that TENS paraesthesiae can be made to feel like it is emanating from a prosthetic hand in healthy participants with intact limbs. In addition, participants reported perceptual embodiment of the prosthetic hand into their body schema, i.e. it felt as if it is part of their body. We predict that projecting TENS paraesthesiae into the prosthetic limb(s) of amputees will provide sufficient sensory input to facilitate perceptual embodiment. This could prove to be a simple and inexpensive training aid to improve ambulation and prosthesis success.