Restorative robotics: Paralyzed man experiences sense of touch with mind-controlled arm

For the first time, scientists have helped a paralyzed man experience the sense of touch through the use of a mind-controlled robotic arm.

The groundbreaking experiment, a collaboration between the University of Pittsburgh and the University of Pittsburgh Medical Center, involves electrodes smaller than a grain of sand implanted in the sensory cortex of the young man's brain. Researchers then stimulated this region, which is associated with sensation in the right hand, and effectively bypassed his damaged spinal cord. Because the paralyzed man was already connected to a robotic arm, when a researcher pressed the fingers of the prosthesis, the subject felt the pressure in the right fingers of his paralyzed hand.

The results of the experiment, which have been repeated over several months with the subject, offer a critical breakthrough in the recreation and restoration of function in people with paralyzed limbs: the ability not just to move those limbs, but something much more difficult — to feel them.

Nathan Copeland took the technology for a high-profile spin this month as he shared a handshake with President Obama at a White House Frontiers Conference on advances in science, medicine and technology.

He had "pretty impressive precision," Obama said. "When I'm moving the hand, it is also sending signals to Nathan so he is feeling me touching or moving his arm." The two also fist bumped.

Preparing to show the president how the arm worked, Copeland said he was "circling between excited and nervous every half-hour."

Copeland was 18 years old when his car spun out of control on a rainy winter night in 2004. The western Pennsylvania man was diagnosed with tetraplegia, paralysis of all four limbs. Five years ago, he volunteered for a cutting-edge experiment at the University of Pittsburgh Medical Center.

Copeland, who had been studying nanotechnology before his accident, was the perfect subject. Last spring, surgeons implanted four tiny electrodes into his sensory cortex, specifically the region of the brain that controls the sense of touch in the right hand and fingers. By electrically stimulating this region, the researchers were able to bypass Copeland's damaged spinal cord. Already connected to a mind-controlled robotic arm, Copeland was ready for the experiment to begin. He was blindfolded so that he couldn't see what researchers were doing, but one by one they touched each of the fingers on the robot's right hand, and each time Copeland correctly identified the location of the sensation.

"I can feel just about every finger," Copeland said. "Sometimes it feels electrical, and sometimes it's pressure, but for the most part, I can tell most of the fingers with definite precision. It feels like my fingers are getting touched or pushed."

The research team was quietly ecstatic.

"I was awfully relieved, " said biomedical engineer Robert Gaunt. "Nathan was pretty happy, these were places on the hand that he hasn't felt in 10 years."

Before this experiment, no robotic limb had allowed a paralyzed person to experience the natural sense of touch, a kind of Holy Grail in rehabilitative medicine. For a prosthetic limb to truly mimic the full functionality of a human one, it needed to be endowed with somatosensory feedback from the paralyzed person's brain.

"With Nathan, he can control a prosthetic arm, do a handshake, fist bump, move objects around," Gaunt said. "And in this [experiment] he can experience sensations from his own hand. Now we want to put those two things together so that when he reaches out to grasp an object he can he feel it. … He can he pick something up that's soft and not squash it, or drop it."