How Artificial Arms Could Connect to the Nervous System [Preview]

A new way to link artificial arms and hands to the nervous system could allow the brain to control prostheses as smoothly as if they were natural limbs

By D. Kacy Cullen and Douglas H. Smith

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REACH: Advances in neuroengineering are starting to catch up to the tremendous progress that has recently been made in prosthetic design.
Image: Jean-François Podevin

In Brief

• Bioengineers would like to connect prosthetic arms and hands directly to the nervous system.
• Two-way communication would allow the brain to control a limb's movements and to feel its presence.
• The first step is to develop a kind of adapter cord that translates nerve impulses into electrical signals.
• The authors are developing such an interface with laboratory-grown nerve fibers and electricity-conducting polymers.

In one of the most iconic scenes in science-fiction films, Luke Skywalker casually examines his new synthetic forearm and hand. The Star Wars hero is able to move the fingers by extending and contracting pistons shown through an open flap along the wrist. Then he senses the robotic surgeon's pinprick of one of the fingers. Not only can the prosthesis be moved with Skywalker's thoughts, it feels to him like his own hand.
What the audience does not see, however, is the actual connection between man and machine. And yet to neuroscientists like the two of us, it is precisely this hidden interface that should have been at the center the scene. In order for such a linkup to work, it would have to have converted nerve impulses from the brain into electrical signals in the artificial arm, and vice versa. In the world beyond movies, however, no one has yet figured out how to splice together nerves and electrical wires in a way that allows them to control an artificial limb as if it were a natural extension of the body.

This article was originally published with the title Bionic Connections.