WASHINGTON, D.C.—Former army sergeant Glen Lehman lost his arm in Iraq. But he can still pick up small objects with fine motor control, thanks to a bionic appendage wired to his remaining nerves. “Just by believing I’m moving my phantom limb," he said, "the arm is in tune with my thoughts."
Lehman showed off his new arm here yesterday at the annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW). His demonstration was part of a session on breaking down the barriers between mind and machine. In addition to creating better prosthetics for amputees, scientists talked about developing communication devices for locked-in patients and even creating virtual reality avatars that might someday allow people to transfer their entire consciousness into a machine.
But first back to Lehman's arm. Previous arm prosthetics have relied on the remaining muscles of the arm to guess at what the amputee wants to do, which panelist Todd Kuiken of Northwestern University in Evanston, Illinois, described as a “Morse code game.” The technique his group is developing, by contrast, uses the arm’s nerves, which appear to remain intact even 10 years after an amputation. Using this method, his advanced prosthetics can restore fine motor control down to the fingers.
Andrew Schwartz of the University of Pittsburgh had a different approach to mind-controlled prosthetics: an electrode array placed directly on the surface of the brain. His group has previously had success allowing monkeys to control a robotic arm in this way; with training, the monkeys began to treat the arm as their own, even trying to groom it. This summer, Schwartz’s group will begin testing the technique in 20 human patients with spinal cord injuries. Schwartz also showed video of a high-performance, extraordinarily dexterous prosthetic arm developed at Johns Hopkins University, which he called “the best prosthetic in existence.” His group is about to begin trials in monkeys using this arm.
Although prosthetics and other brain-powered devices have been around for some time, José del R. Millán of the Ecole Polytechnique Fédérale de Lausanne in Switzerland said that one difficulty is the amount of continuous concentration required to use them. His goal, he said, is to perfect brain-computer interfaces so that their control is as natural as writing or driving a car. A volunteer demonstrated an electrode cap with which he could drive a wheeled robot around the room. Millan listed a number of uses for this technology for bedridden and locked-in patients; joining their families virtually without leaving their beds, participating in research studies, and controlling their own wheelchairs.
No matter how good a prosthetic or robot is, however, “the perception of self is at the core of neuroprosthetics,” Millan said. Olaf Blanke, also of Ecole Polytechnique Fédérale de Lausanne, has made progress trying to understand what defines “self,” and how self-awareness can be transferred into a robot or avatar. His research recreates out-of-body experiences. By touching a volunteer on his real body while he viewed a virtual representation of himself on a computer, Blanke and colleagues were able to change the volunteer’s perception of where he was in space: the volunteer believed his consciousness had been transferred to the avatar. Intriguingly, the researchers flipped genders, giving a male volunteer a female avatar, but this didn’t seem to affect the outcome. The only aspect important for the transfer of consciousness, Blanke said, was that the avatar had a vaguely human shape.
Integrating the consciousness transfer with real-time, thought-controlled prosthetics, the presenters said, could eventually restore autonomy to bed-bound or locked-in patients, providing them with a higher quality of life.
Science will be hosting a live chat with Olaf Blanke and Jose del R. Millan at noon EST on Sunday, 20 February.
See our complete coverage of the 2011 AAAS annual meeting in Washington, D.C.