Twelve years ago, a car wreck took away Nathan Copeland's ability to control his hands or sense what his fingers were touching.
A few months ago, researchers at the University of Pittsburgh and the University of Pittsburgh Medical Center gave Copeland a new way to reach out and feel the world around him. It's a mind-controlled robotic arm that has pressure sensors in each fingertip that send signals directly to Copeland's brain.
The scientists published details of their work online Thursday in the journal Science Translational Medicine.
"It's a really weird sensation," Copeland, now 30, says in a video made shortly after he first tried the system. "Sometimes it feels, kind of, like electrical and sometimes it's more of a pressure." But he also describes many of the sensations coming from his robotic hand as "natural."
When Copeland touches an object with the robotic hand, he can tell which finger the sensation is coming from and whether an object feels hard or soft, says Robert Gaunt, a bioengineer and assistant professor in the Department of Physical Medicine & Rehabilitation at the University of Pittsburgh.
"But we're really not at the point where we could, say, get him to feel the difference between silk and burlap," Gaunt says.
The success represents an advance that is "absolutely critical in terms of making prosthetics useful," says Mike McLoughlin, an engineer at the Johns Hopkins University Applied Physics Laboratory.
McLoughlin is part of a team at Hopkins that developed the Modular Prosthetic Limb that Copeland is using. The research at both Hopkins and in Pittsburgh is supported by the government's Defense Advanced Research Projects Agency.
For several years now, people have been able to control robotic arms using thoughts alone. But they have relied entirely on vision to know whether the arm is going in the right direction or grasping an object with the proper amount of force.
That makes it very challenging to perform simple tasks like grasping a foam coffee cup without crushing it, McLoughlin says.
"Without sensory feedback, somebody would have to actually have to look at the prosthetic, look at the cup, start to close the hand, (and) visually see the cup is starting to deform," he says.
Restoring Copeland's sense of touch was a painstaking process, but the Pittsburgh team knew it was possible.
"His hand has been disconnected from his brain because of his spinal cord injury," Gaunt says. "But the brain hasn't lost its ability to feel."
So the team began looking for a way to send touch sensations directly to Copeland's brain. The first step was to monitor his brain activity using a technique called magnetoencephalography.
"We were able to see the parts of his brain that became active when he was watching videos of a hand being touched," Gaunt says.
Next, the researchers placed tiny electrodes in Copeland's brain that could stimulate the areas corresponding to each finger. Then they waited for the brain to heal, as it adjusted to the presence of the electrodes.
It was several weeks before the team was able to send the first tiny pulse of electricity to Copeland's brain. "When it finally happened, he just very calmly said, 'Yep, I felt it on my index finger,' " Gaunt recalls. "But in the background I was breathing a sigh of relief and other people were cheering."
Of course, mind-controlled robots are still years away from consumer applications, McLoughlin says. At the moment, they are still too expensive, too bulky and too finicky to be used outside a laboratory setting. And there's no good way to control them without implanting electrodes in the brain.
Still, the ability to receive touch sensation from a robotic arm has the potential to help not only thousands of people who are paralyzed, but also people with a wide range of physical disabilities, McLoughlin says. For example, robots that provide sensory feedback could eventually help a disabled person cook a meal or clean up things at home.
"We're on the verge of something here that's going to transform lives," he says.
RENEE MONTAGNE, HOST:
And now to a scientific advance - scientists say they have restored a paralyzed man's sense of touch. NPR's Jon Hamilton reports on the technology that's allowing this man to feel again using a robotic hand.
JON HAMILTON, BYLINE: Nathan Copeland has been paralyzed since he was 18.
(SOUNDBITE OF VIDEO)
NATHAN COPELAND: In 2004, I wrecked my car, and I broke my neck.
HAMILTON: That's from a video made by the University of Pittsburgh Medical Center after Copeland agreed to take part in an experiment. Robert Gaunt, a researcher at the University of Pittsburgh, says Copeland was a good candidate because he can't control his fingers or feel what they touch.
ROBERT GAUNT: With Nathan, his hand has been disconnected from his brain because of his spinal cord injury. But the brain hasn't lost its ability to feel.
HAMILTON: It just needs a signal, so researchers began looking for a way to send that signal. Gaunt says the first step was to monitor Copeland's brain activity.
GAUNT: And we were able to see the parts of his brain that became active when he was watching videos of a hand being touched.
HAMILTON: Then the team placed electrodes in his brain that could stimulate those precise areas. Gaunt says it was several weeks before the team sent the first tiny pulse of electricity to the electrodes in Copeland's head.
GAUNT: When it finally happened, he just very calmly said yup, I felt it on my index finger. And he was very calm and nonchalant about it all. But in the background, I was breathing a sigh of relief. And other people were cheering (laughter).
HAMILTON: The real-world test came when the team connected Copeland's brain to a robotic arm that had sensors in each finger. Copeland says he was immediately able to feel something.
COPELAND: It's a really weird sensation. Sometimes, it feels kind of, like, electrical. And sometimes, it's more of a pressure.
HAMILTON: Gaunt says when Copeland is connected to the robotic arm, he now has a rudimentary sense of touch.
GAUNT: He can tell us how intense it is. Does it feel hard? Does it feel soft? But, you know, we're really not at the point where we could say, get him to feel the difference between silk and burlap or anything like that. Even so, any sense of touch is useful. Mike McLoughlin is an engineer at the Johns Hopkins University Applied Physics Laboratory, which made the robotic arm Copeland uses. It's part of a project funded by the military. McLoughlin says we depend on touch every day, though we rarely think about it. He says, imagine using a prosthetic arm to drink coffee from a Styrofoam cup.
MIKE MCLOUGHLIN: Without sensory feedback, somebody would actually, you know, have to look at the prosthetic, look at the cup, start to close the hand, visually see - OK, the cup's starting to deform...
HAMILTON: And relax their grip before crushing it. McLoughlin says adding even a basic sense of touch makes tasks like this much easier.
MCLOUGHLIN: We're on the verge of something here that's going to, you know, transform lives.
HAMILTON: Of people who are paralyzed or who have a wide range of other disabilities. The results appear in the journal Science Translational Medicine.
Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.