Muscle vibrations improve control over prosthetic hands

An automated brain-computer interface that vibrates the muscles used for control of prosthetic hands helped three amputees gain better movement control over the prosthetic, according to a new study by Paul Marasco and colleagues. The muscle vibration produced an illusory "kinesthetic" sense in the amputees, meaning that they had a greater sense of the spatial positioning and movement of the hand as it performed a series of complex grip motions. This perception of movement is critical to further developing prosthetic devices, the authors say, because the kinesthetic sense can improve how well amputees can control the prosthetic and correct errors in movement. They also note that the kinesthetic sense can help amputees regain the feeling that they are in control of their movements - a feeling that improves quality of life acceptance of a prosthesis. Marasco et al. paired arm muscle vibrations with different aspects of the grip of a virtual hand and found that, within minutes, amputees were able to incorporate this feedback and improve their grip skills - even in the absence of watching the grip and receiving visual feedback. Importantly, combining kinesthetic and visual feedback provided the users with a greater sense of agency over the movements of a robotic hand. The results may someday pave the way to technology that joins together kinesthetic, skin, and motor systems, to provide a more natural perceptual sense of complex artificial hand movement.

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