For the first time a brain implant has given a paralyzed man the sense of touch through a robotic arm that he controls with his brain.
In 2004, 28-year-old Nathan Copeland was in a car accident that snapped his neck and injured his spinal cord, leaving him paralysed from the upper chest down.
Right after the accident he had enrolled as a participant in a clinical trial but it took nearly a decade before he actually took part in the experimental study.
Before the surgery, a team of researchers from the University of Pittsburgh and UPMC used imaging techniques to identify the exact regions in Nathan's brain that corresponded to feelings in each of his fingers and his palm.
Then they implanted four tiny electrodes, each about half the size of a shirt button, in Nathan's brain.
These brain chips can electrically stimulate neurons, bypassing his spinal cord injury, to recreate the perception of touch, a technique known as intracortical microstimulation.
The results, , showed their efforts were largely successful.
Nathan described 93 per cent of the stimuli (such as pressing a cotton swab on the surface of the skin) as feeling "possibly natural."
He was also able to get a tactile feeling when connected to a prosthetic limb, correctly identifying 84 per cent of the time which individual prosthetic finger was being touched while blindfolded.
"I can feel just about every finger -- it's a really weird sensation," Nathan said about a month after surgery. "Sometimes it feels electrical and sometimes its 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."
Study co-author Andrew Schwartz said: "The most important result in this study is that microstimulation of sensory cortex can elicit natural sensation instead of tingling."
The findings suggest that electrical brain stimulation can help re-establish realistic touch in paralyzed and potentially amputee patients, which may guide the design of better neuroprosthetic limbs.
"The ultimate goal is to create a system which moves and feels just like a natural arm would," said Robert Gaunt, the team’s lead researcher. "We have a long way to go to get there, but this is a great start."
