A Paralyzed Man Can Touch Again, Thanks to Brain Chips
This discovery will help design better neuroprostetic limbs.
On a rainy night in 2004, Nathan Copeland was in a terrible car crash. The accident snapped his neck and injured his spinal cord. Doctors said he would never be able to feel or move his lower arms and legs again.
But now, 12 years later, Copeland has regained his sense of touch with the help of a robotic arm and a brain-computer interface (BCI).
The brain chips — four microelectrode arrays, each the size of a shirt button — were placed in Copeland’s brain in areas that corresponded to the feelings of touch in fingers and in the palm. In a paper published Thursday in Science Translational Medicine, researchers from the University of Pittsburgh explain that when light pressure is applied to the robotic fingers, that feeling is converted into electrical signals that feed back into Copeland’s somatosensory cortex.
“I can feel just about every finger — it’s a really weird sensation,” Copeland says in a statement. “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.”
While Copeland cannot tell whether a substance is hot or cold with the BCI, he was able to describe 93 percent of the stimuli (like the feeling of a cotton swab on skin) as feeling “possibly natural” at the end of the six-month study. He also can correctly identify which prosthetic finger is being touched while blindfolded 84 percent of the time.
The BCI is the newest improvement of mind-controlled prosthetics, which have steadily emerged as the most promising way to provide a wider range of motion. This research, first announced to the public in September 2015 and is now peer reviewed, was funded by the Defense Advanced Research Projects Agency (DARPA).
“DARPA has previously shown that a brain interface can be used to direct the movements of a robotic arm,” explains Justin Sanchez, director of DARPA’s Biological Technologies Office in a video released on Thursday by DARPA. “With this new development … we have closed the loop between human and machine.”
This is a huge breakthrough in health robotics: In order to experience full functionality of a native limb, a person has to be able to experience somatosensory feedback. Not being able to feel is problematic for more than the obvious: It creates severe deficits in motor control while also damaging the ability to manipulate objects. For the more than 1.6 million people in the United States who have some type of limb loss, the ability to experience touch would be revolutionary.
While researchers acknowledge that more research is necessary to understand the stimulation patterns of touch, they believe that this iteration of the BCI is a crucial first step.
“The ultimate goal is to create a system which moves and feels just like a natural arm would,” lead author Robert Gaunt said in a statement. “We have a long way to go to get there, but this is a great start.”