National Geographic : 2010 Jan
• lets him move his ngers to grip a fork. Jo Ann Lewis, a blind woman, can see the shapes of trees with the help of a tiny camera that commu- nicates with her optic nerve. And Tammy Kenny can speak to her 18-month-old son, Aiden, and he can reply, because the boy, born deaf, has 22 electrodes inside his ear that change sounds picked up by a microphone into signals his auditory nerve can understand. e work is extremely delicate, a series of tri- als lled with many errors. As scientists have learned that it's possible to link machine and mind, they have also learned how di cult it is to maintain that connection. If the cup atop Kitts's arm shi s just slightly, for instance, she might not be able to close her ngers. Still, bionics rep- resents a big leap forward, enabling researchers to give people back much more of what they've lost than was ever possible before. " at's really what this work is about: restora- tion," says Joseph Pancrazio, program director for neural engineering at the National Institute of Neurological Disorders and Stroke. "When a person with a spinal-cord injury can be in a res- taurant, feeding himself, and no one else notices, that is my de nition of success." - attempts, in the form of man-made hands and legs and feet, lines the shelves in Robert Lipschutz's o ce at the Rehabilitation Institute of Chicago (RIC). " e basic technology of prosthetic arms hasn't changed much in the last hundred years," he says. "Materials are di erent, so we use plastic instead of leather, but the basic idea has been the same: hooks and hinges moved by cables or motors, controlled by levers. A lot of amputees coming back from Iraq get devices like these. Here, try this on." Lipschutz drags a plastic shell o one of his shelves. It turns out to be a le shoulder and arm. e shoulder part is a kind of breastplate, secured across the chest by a harness. e arm, hinged at the shoulder and elbow, ends in a metal pin- cer. To extend the arm, you twist your head to the le and press a lever with your chin, and use a little body English to swing the limb out. It is as awkward as it sounds. And heavy. A er 20 minutes your neck hurts from the odd posture and the e ort of pressing the levers. Many ampu- tees end up putting such arms aside. "It's hard for me to give people these devices sometimes," Lipschutz says, "because we just don't know if they will really help." What could help more, he and others at RIC think, is the kind of prosthesis Amanda Kitts has volunteered to test---one controlled by the brain, not by body parts that normally have nothing to do with moving the hand. A tech- nique called targeted muscle reinnervation uses nerves remaining a er an amputation to control an arti cial limb. It was rst tried in a patient in 2002. Four years later Tommy Kitts, Amanda's husband, read about it on the Internet as his wife lay in a hospital bed a er her accident. e truck that had crushed her car had also crushed her arm, from just above the elbow down. "I was angry, sad, depressed. I just couldn't accept it," she says. But what Tommy told her about the Chicago arm sounded hopeful. "It seemed like the best option out there, a lot bet- ter than motors and switches," Tommy says. "Amanda actually got excited about it." Soon they were on a plane to Illinois. Todd Kuiken, a physician and biomedical engineer at RIC, was the person responsible for what the institute had begun calling the When Kitts thinks about flexing her elbow, the phantom moves, and the arti cial elbow bends. "I don't really think about it. I just move it," she says. Josh Fischman is a senior editor for research and technology at the Chronicle of Higher Education. Mark iessen is a Geographic sta photographer.