For the first time, scientists have helped a paralyzed man experience the sense of touch in his mind-controlled robotic arm.
For the cutting-edge experiment, a collaboration between the University of Pittsburgh and the University of Pittsburgh Medical Center, electrodes smaller than a grain of sand were implanted in the sensory cortex of the man’s brain. The electrodes received signals from a robot arm. When a researcher pressed the fingers of the prosthesis, the man felt the pressure in the fingers of his paralyzed right hand, effectively bypassing his damaged spinal cord.
The results of the experiment, which have been repeated over several months with 30-year-old Nathan Copeland, offer a breakthrough in the restoration of a critical function in people with paralyzed limbs: the ability not just to move those limbs, but to feel them.
The experiment with Copeland was a featured stop Thursday when President Obama visited Pittsburgh for a White House Frontiers Conference on advances in science, medicine and technology. The researchers described how neuroscience has been able to build a technology where simply imagining a motion translates into motion, in this case a robotic arm.
“It’s amazing. Pretty cool,” Obama said, before asking Copeland to “blow it up” with a handshake, where they each pulled their hand away at the end. “I couldn’t be prouder of all of you.”
Copeland was a teenager when his car spun out of control on a rainy winter night more than a decade ago. The western Pennsylvania man was diagnosed with tetraplegia, paralysis of all four limbs. He has some ability to move his shoulders.
Five years ago, he volunteered for the research at UPMC. There, a team of surgeons, biomedical engineers and doctors of rehabilitative medicine had been toiling with the technology that, they hoped, would enable paralyzed people to again feel sensations — something even more difficult to achieve than movement.
Copeland, who had been studying nanotechnology before his accident, was the perfect subject. Last spring, the surgeons implanted four tiny electrodes in the left hemisphere of his brain, into the sensory cortex area that senses touch in the body’s right hand and fingers. Copeland already had chips implanted in his brain that connect him to a mind-controlled robotic arm. To test whether the new chips could allow him to experience touch, he was blindfolded so that he couldn’t see what the researcher was doing. One by one, the researcher touched each of the fingers on the robot’s right hand, and each time Copeland correctly identified the location of the touch.
“I can feel just about every finger,” Copeland said Wednesday. “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,” biomedical engineer Robert Gaunt acknowledged. “Nathan was pretty happy. These were places on the hand that he hasn’t felt in 10 years.”
Prior to this experiment, no robotic limb had allowed a paralyzed person to experience the natural sense of touch, a top goal in rehabilitative prosthetic medicine. For a prosthetic limb to truly mimic the full functionality of a human one, it needs to be endowed with sensory feedback to and from the paralyzed person’s brain.
Currently, electrical stimulation of nerves in amputees’ bodies offers enough sensation to allow for improvements in the control of artificial limbs, but not true sensation. In paralyzed people without a functioning peripheral nerve system, it has been impossible to experience touch. Mind-controlled robotic arms got them only half way: Being able to move and manipulate objects was an advance, but without the sensation of touch, these prosthetic limb movements tend to be slow and clumsy.
“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 feel it. … He can pick something up that’s soft and not squash it or drop it.”
To even get to this point involved massive collaboration with multiple institutions and researchers, Gaunt said. The microelectrode package and control system were developed by Blackrock Microsystems and the robotic arm by the Applied Physics Lab at Johns Hopkins University. The experiment, published Thursday in the journal Science Translational Medicine, lists 10 authors and 10 departments and institutions.
Four years earlier, Jennifer Collinger, another member of the team, was involved in an experiment that served as a kind of stepping stone. Jan Scheurmann, a 36-year-old mother of two, was the volunteer this time. Scheurmann had been diagnosed with spinocerebellar degeneration, a disease that destroys the connections between the brain and muscles. The Pittsburgh researchers enabled the woman to consistently perform many natural and difficult motions with her arms and hands using a brain chip that controlled a human-like robot arm. Her goal: to eat a piece of chocolate on her own. In 2012 she did.
“We’ve been working since 2010 to get to this point, doing the background research, doing the regulatory work, and the pre-surgical involvement,” Collinger said. “For Nathan, he did this with the greater good in mind. He was willing to be the pioneer, and he’s excited to be the very first person to feel sensation. And now he’s excited to see how far we can take it.”