National Geographic : 2017 Sep
One man, one robotic arm, dozens of electrodes—these are the elements of a breakthrough experiment that’s restoring the sense of touch to a paralyzed man. Scientists have long known that the brain retains the sense of an amputated or paralyzed limb. “The brain contin- ues to have the capacity to do what it always did,” says bioengineer Robert Gaunt. “Even after injury.” That’s why researchers have recently been able to help people control robotic limbs with their minds. Gaunt and his colleagues at the Uni- versity of Pittsburgh and the University of Pittsburgh Medical Center aim to go even further. They’re experimenting with ways to make a robotic limb “em- bodied,” as Gaunt puts it—to make it actually feel like a part of the body and not just a tool. Nathan Copeland, mostly paralyzed from the chest down in a car accident in his teens, participated in the experi- ment. The team implanted tiny sensors in his brain—in the motor cortex, which controls voluntary movement, and in the part of the sensory cortex that pro- cesses feeling in the hand. The robotic arm is then wired to send and receive signals from those sensors. Now 31, Copeland can identify— with 84.3 percent accuracy and while blindfolded—which of his arm’s pros- thetic fingers are being pressed, find- ings reported in Science Translational Medicine. Copeland says he’s also felt warmth and tingling sensations in the robot fingers, making him “happy, re- lieved, and hopeful.” The end goal, says Gaunt, is a simple one: to develop technologies so that pa- ralysis and limb loss are “not a disability.” REWIRING THE SENSE OF TOUCH By Eve Conant PHOTO: REBECCA HALE, NGM STAFF | EXPLORE | HEALTH The Johns Hopkins Applied Physics Labo ratory created this modular prosthetic limb and the one used in the Pittsburgh experi ment. Both have more than 100 sensors.