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Even a simple task like buttoning a shirt relies on more than dexterity. It requires a sense of touch. NPR's Jon Hamilton reports on an effort to restore this sense in people who are paralyzed from a stroke or spinal cord injury.
JON HAMILTON, BYLINE: In 2014, an engineer named Chad Bouton got a lesson on the importance of touch. Bouton, who's at The Feinstein Institutes for Medical Research on Long Island, had developed a brain computer interface that allowed a man living with paralysis to move one hand.
CHAD BOUTON: He was trying to pick something up, and he was doing it. But then he turned around, and he said to us, you know, Chad, I can't feel this object. And so, at that moment, we realized, wow, that's what we need to work on next.
HAMILTON: More than a decade later, that work is paying off for a man named Keith Thomas. A diving accident in 2020 left Thomas paralyzed and with no sensation from the chest down. In 2023, the team at Feinstein, a part of Northwell Health, implanted two sets of computer chips in his brain. One set detects signals in areas that control movement, the other delivers signals to areas that process touch and pressure. Thomas described the result during a video call from his home.
KEITH THOMAS: They hooked me up to the machine and then, like, it was the first time I felt my index finger. I was like, whoa.
HAMILTON: After more than a year of practice and lots of tweaks to the equipment, Thomas can pick up an object and tell researchers something about it.
THOMAS: I feel, like, it's a tennis ball, or something heavier or something lighter.
HAMILTON: Thomas is the first patient to receive what researchers call a double neural bypass. Bouton says the first branch bypasses the damaged area of the spinal cord.
BOUTON: We're literally rerouting signals from the brain to, say, muscles that are affected by a spinal cord injury, in this case.
HAMILTON: That allows Thomas to move his hand. At the same time, Bouton says, sensors on his palm, thumb and index finger are sending signals back to the brain about what he's touching.
BOUTON: And then we have a second branch that reconnects the brain to the spinal cord, and as someone thinks about moving again, we stimulate the spinal cord based on their thoughts.
HAMILTON: That amplifies and strengthens the remaining natural connections between the brain and an affected limb. It takes a lot of people and equipment to animate Keith Thomas' right hand for just a few hours. I get a quick overview from Erona Ibroci, Dana Fried, Aniket Jangam, Zeev Elias and Santosh Chandrasekaran.
ERONA IBROCI: First thing we do is greet him with a smile.
DANA FRIED: We do mobility testing. We do strength testing.
ANIKET JANGAM: We have this pedestal that helps to collect the data from the motor cortex region.
ZEEV ELIAS: And then we plug in a cable to the pedestal.
SANTOSH CHANDRASEKARAN: And that talks to the signal processor over there and the computer, eventually.
HAMILTON: Once Thomas is wired up, the real work begins. Chandrasekaran points to a monitor showing two animated hands. One indicates the motion Thomas is supposed to carry out. The other is controlled by Thomas' brain.
CHANDRASEKARAN: He cannot move his own hand, but he's trying to do that. The decoder figures out what he's thinking about and then controls the other hand on the screen to produce the output that he's thinking about.
HAMILTON: The decoder also sends signals to the muscles controlling Thomas' actual hand, so it moves in sync with its onscreen avatar. Chandrasekaran says Thomas has much better control of his hand when it's fitted with the tiny sensors that add a sense of touch.
CHANDRASEKARAN: What we are measuring is the force levels on the sensor, and then appropriately stimulating the right electrodes in the brain so that we can make him feel a sensory percept at the right location on the hand.
HAMILTON: That allowed Thomas to feel his sister's hand when she made a visit to the lab. Bouton says another milestone came when they put a cup of water in front of him.
BOUTON: He lifted that cup up for the first time to his mouth, took a drink, and then set it back down all on his own, without any help, any assistance from anyone.
HAMILTON: At first, the improvements were only present in the lab, but over time, benefits like increased arm strength have persisted when he goes home. I asked Thomas if he does things now he couldn't do before.
THOMAS: Yeah, like pet my dog and stuff like that.
HAMILTON: When you do pet your dog, do you feel anything?
THOMAS: I do, actually. My wrist - I can feel a little bit of the fur.
HAMILTON: Thomas says eventually, he hopes to be able to do things like brush his own teeth without assistance. Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.
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