A pioneering brain implant has allowed a paralyzed man to feel a robotic arm. The implant is capable of unimaginable sensitivity, and the carrier can even identify which finger is feeling pressure. The limited sense of touch is part of the work of a team from the University of Pittsburgh that installed the implant 17 months ago.
This is a milestone for science because no one else had previously succeeded in brain implants that allow people to feel again. Nathan Copeland is the fortunate man that is experimenting sensitivity again after he had a car accident when he was 18 years old. Now he is 30, and even when the accident snapped his neck and injured his spinal cord, science is letting him feel pressure-like sensations.
Copeland cannot move his legs nor lower his arms. He can feel the robotic arm thanks to the implant that was put into his brain. The device electrically stimulates the brain region that receives sensory information from the rest of the body. That area is called the somatosensory cortex, and it produces touch-like sensations. Similar experiments have taken place in brain surgery but compared to the implant; those are crude efforts.
“I can feel just about every finger- it’s a really weird sensation. 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,” said Copeland after a month of having the implant installed in his brain.
Elizabeth Tyler-Kabara, the co-author of the study and a neurological surgeon at the University of Pittsburgh, explains that people under brain surgery had experienced a buzz or a vibrating sensation, but neither of the described feelings is natural.
Robert Gaunt, a biomedical engineer at the University of Pittsburgh and lead author of the study, installed two microelectrode arrays into Copeland’s somatosensory cortex. Then, two other electrodes were also installed but this time into Copeland’s motor cortex, which controls hand and arm movements.
Brain implants are controlled by a computer with a robotic arm that transmits sensations to Copeland’s brain
The electrodes are activated through the computer, which is controlled by the team. Once the electrodes are stimulated, Copeland starts to feel touch-like sensations. The robotic arm is linked to Copeland’s implants, and when its fingers are touched, the implants send the message to Copeland’s brain and allow him to identify which finger is being touched, and sometimes, even which region.
The results have been gratifying and have passed the most difficult test: time. Copeland has had the implants for 17 months, and his sensitivity has been stable, which means that the electrodes and their electrical stimulation are not damaging the brain.
Dustin Tyler, a biomedical engineer at Case Western Reserve University, said the results are a significant advance in restoring sensation in people with paralysis, according to the journal Nature.
There have been previous experiments trying to achieve what Dr. Gaunt and his team managed to do; the difference is that the attempts were made to improve prosthetic arms adding them sensitivity. Those experiments are different from the one performed on Copeland, because amputated people still have functioning nerves to attach the prosthesis, making Gaunt’s effort a pioneering work.
Brain implants in paralyzed people have their limitations
Although Copeland can feel most of the robot’s fingers, he cannot feel the thumb nor the fingertips of the robotic hand. Regarding other sensations, the electrodes allow Copeland to feel pressure but not sensations of movement, temperature or pain.
To make Copeland feel movement is a harder task since the brain regions in charge of arms movements are less accessible. The other brain regions that control other body parts are less accessible than the areas in charge of sensation and movements corresponding to arms.
But there is still hope. There’s a chance of manufacturing the implants with flexible materials to make it possible to install them deeper in the brain. Wireless connections are also part of future works based on Gaunt’s achievements with Copeland.
It will take a while to create and test new brain implants, but so far, reinstating the basic sense of touch in a paralyzed person is a significant success for science.
Source: Nature