National Geographic : 2010 Jan
• the signal and radios it back to a receiver im- planted in his chest, where the signal is sent by wires down Schremp's arm to his hand. ere the signal tells his nger muscles to close in a grip--- all within a microsecond. "I can grab a fork and feed myself," Schremp says. " at means a lot." About 250 people have been treated with this technique, which is still experimental. But another bionic device has shown that the mar- riage of mind and machine can be both powerful and enduring, having been implanted in nearly 200,000 people around the world during the past 30 years. at device is the cochlear implant, and Aiden Kenny is among the latest recipients. Tammy Kenny, his mother, remembers when, a year ago, she learned that her baby was beyond the help of hearing aids. "I would just hold him in my arms and cry," she says, "knowing he couldn't hear me. How would he ever get to know me? One time, my husband banged pots together, hoping for a response." Aiden never heard the noise. He hears banging pots now. In February 2009 surgeons at Johns Hopkins Hospital snaked thin lines with 22 electrodes into each cochlea, the part of the inner ear that normally detects sound vibrations. In Aiden, a microphone picks up sounds and sends signals to the electrodes, which pass them directly to the nerves. " e day they turned on the implant, a month a er surgery, we noticed he responded to sound," Tammy Kenny says. "He turned at the sound of my voice. at was amazing." Today, she says, with intensive therapy, he's picking up language, quickly catching up to his hearing peers. bionic ears. Jo Ann Lewis lost her sight years ago to ret- initis pigmentosa, a degenerative disease that destroys light-detecting cells in the eyes called rods and cones. Lately, however, she has partially regained her vision as a result of Laboratory, RIC has been developing a new prototype for Kitts and other patients that not only has more flexibility---more motors and joints---but also has pressure-sensing pads on the ngertips. e pads are connected to small, pistonlike rods that poke into Kitts's stump. e harder the pressure, the stronger the sensation in her phantom ngers. "I can feel how hard I'm grabbing," she says. She can also tell the di erence between rubbing something rough, like sandpaper, and smooth, like glass, by how fast the rods vibrate. "I go up to Chicago to experiment with it, and I love it," she says. "I want them to give it to me already so I can take it home. But it's a lot more com- plicated than my take-home arm, so they don't have it completely reliable yet." , , doesn't need arti- cial hands. He just needs his natural ones to work. ey haven't done that on their own since Schremp broke his neck in 1992, leaving him a quadriplegic. Now, however, the 40-year-old Ohio man can grip a knife or a fork. He can do this because of an implanted device developed by Hunter Peckham, a bio- medical engineer at Case Western Reserve University in Cleveland. "Our goal is to restore hand grasping," Peckham says. "Hand use is key to independence." Schremp's nger muscles and the nerves that control them still exist, but the signals from his brain have been cut o at the neck. Peckham's team ran eight micro-thin electrodes from Schremp's chest under the skin of his right arm, ending at the nger muscles. When a muscle in his chest twitches, it triggers a signal that's sent via a radio transmitter to a small computer hang- ing from his wheelchair. e computer interprets "The day they turned on the implant, a month after surgery, we noticed he responded to sound," says Aiden's mother, Tammy Kenny. "He turned at the sound of my voice."