Two people with paralysis were able to feel objects again thanks to electrical brain stimulation. By implanting electrodes in the brain, researchers simulated sensations like texture and motion. This allowed the participants to control a robotic arm and feel as though it was part of their own body, even guiding it successfully.
Mind-controlled robotic arm lets people with paralysis touch and feel
Author: Carissa Wong
TWO people with paralysis of their hands were able to temporarily regain their sense of touch and feel the shape of objects after receiving electrical brain stimulation.
There have been previous efforts to restore touch through brain stimulation, but they were fairly crude. “These were very basic sensations of contact and no contact,” says Giacomo Valle at the Chalmers University of Technology in Gothenburg, Sweden. “But when you touch a surface, you feel the texture, the edges, the curvature. You feel the motion of your hand relative to the surface.”
To evoke richer sensations, Valle and his colleagues worked with two people with spinal cord injuries that had led to partial paralysis, including the loss of most of their ability to move and feel with their hands. The researchers asked the pair to imagine wiggling their fingers and feeling sensations in them while scanning their brains with an MRI machine. Guided by which areas of their brains lit up during these exercises, the team then implanted dozens of tiny electrodes into corresponding regions.
By using the implants to zap brain cells linked to hand movements and sensations, the researchers identified signals that made the participants feel like they were holding a can, pen or ball. They also identified signals that mimicked the motion of objects across their fingers. “It blew me away,” says Scott Imbrie, one of the participants. He hadn’t felt objects so clearly for decades, he says.
To see if the approach could help with everyday tasks, the researchers attached Imbrie’s electrodes to a robotic arm that held onto a steering wheel and got him to watch a virtual car travelling along a straight road. They transmitted electrical signals into his brain to mimic sudden movements of the wheel against his hand to the left or right, then asked Imbrie to keep the car on track by counteracting these with his mind, sending his brain signals to the robotic arm.
Imbrie kept the car on track 80 per cent of the time (Science, doi.org/g8z7tq). He says it felt like the arm was an extension of himself. “It was like, ‘oh my god, this arm is part of me’.” The team plans to carry out the same task with the second participant.
Credits: TCA, LLC.