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The brain is bidirectional: it takes in information while it sends signals to the rest of the body, telling it to act. A movement that seems as easy as taking a glass also calls to the brain to control the muscles in the hand and listen to the nerves of the fingers.
Since Copeland’s brain was not injured in the accident, he could still, in theory, handle this input and output conversation. But most of the electrical messages from the nerves in his body did not reach the brain. When the Pittsburgh team hired him for his studies, they wanted to design a solution. They believed that the brain of a paralyzed person could stimulate the robotic arm and could be stimulated by the electrical signals received from it, ultimately interpreting that stimulation as feeling touched in their hands. The challenge was to make everything natural. The robotic wrist would have to be twisted when Copeland wanted to twist it; he had to close when he intended to catch her hands; and when the robotic pinkie touched a hard object, Copeland should feel his pinkie.
Two of the four microelectrode enrollments placed in Copeland’s brain read two networks from his motor cortex to command the robotic arm to command the robot, and both networks stimulate his sensory system. From the outset, the research team learned that they could use the BCI to create a tactile sensation in Copeland by giving these electrodes an electrical current — no real touch or robotics required.
To build the system, the researchers took advantage of the fact that Copeland stores some sensations in his right index finger, index finger, and middle finger. The researchers rubbed a Q-tip while sitting on a magnetic scanner in the brain and found that the exact contour of the brain corresponded to those fingers. The researchers decoded their intentions to move from individual electrodes by recording brain activity while imagining specific movements. And when the current was turned on at specific electrodes in his sensory system, he felt it. For him, the sensation seems to come from the base of his fingers, near the top of his right palm. You may feel natural pressure or heat or a strange bite, but it has never hurt. “Actually, I just happened to look at my hand:‘ Man, I really feel like someone can poke right there, ’” Copeland says.
Once Copeland could experience these sensations and the researchers knew which areas of the brain were stimulated to create feelings in the various places in their hands, the next step was simply to get used to controlling Copeland’s robot arm. He and the research team set up a training room in the lab, hanging posters of Pac Man and cat memes. Three days a week, a researcher connected the electrode connector from the scalp to a set of cables and computers, and then took time to block the blocks and spheres, moving them from left to right. Over the course of a couple of years, it put up pretty well. He too he proved the system For then-President Barack Obama.
But then, Collinger says, “because of his high level of performance.” A non-paralyzed person would need about five seconds to complete a task of moving objects. Copeland could sometimes do it in six seconds, but the average time was around 20.
To get over the wall, it was time to try to give real-time feedback from the robot’s arm.
The human fingers feel the pressure, and the resulting electrical signals pass wire-shaped axons from the hand to the brain. The group reflected this sequence by placing sensors on the robotic fingertip. Objects do not always touch the fingertips, so a more reliable signal had to come from other places: moment sensors at the base of mechanical digits.
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