When Ian Burkhart was 19, he accidentally dove into a sandbar while in the water with friends and quickly realized what had happened: He was paralyzed. Today, Burkhart is still paralyzed—but he can move his hand by controlling it with his mind.
In June, Burkhart, now 23, became the first person to use Neurobridge, a technology that bypasses the spinal cord and uses brain signals to directly stimulate muscle movement. Developed by R&D company Battelle, Neurobridge consists of a pea-sized chip that's implanted in the brain and connected to a muscle stimulation sleeve. The chip, which contains an an array of 96 electrodes, allows researchers to look at detailed signals and neural activity emanating from the motor cortex of Ian's brain.
When Burkhart thinks about moving his hand, the chip sends those signals to the limb in less than a tenth of a second. The technology, while promising, is still in its infancy.
Battelle has been working on neurosensing technology for almost a decade. "We were having such success in decoding brain activity, we thought, 'Let’s see if we could remap the signals, go around something like a spinal cord injury and then translate the signals into something that the muscles could understand and help someone paralyzed regain control of their limb,'" explains Chad Bouton, the leader of the Neurobridge project at Battelle.
Burkhart became involved with the study after his doctor mentioned it to him. It turned out that Ian was the perfect candidate. He had the exact level of injury the researchers were looking for, he's young and otherwise healthy, and he lives about 20 minutes away from the Ohio State University Wexner Medical Center, where the research is being conducted.
Even with the tantalizing promise of moving a paralyzed limb, Burkhart had to think hard before agreeing to the surgery. "Mainly, it was just the fact that I would have to have brain surgery for something that wasn’t needed," he says. He also knew that the surgery wouldn't magically give him movement again. He would have to undergo rigorous training to regain even basic hand function. Mainly, his experience would help move along future technological advances.
Post-surgery, Burkhart still had a lot of thinking to do—this time, in order to move his hand. "Anyone able bodied doesn’t think about moving their hand, it just happens. I had to do lots of training and coaching."
The hand can make innumerable complex movements with the wrist, the fingers, and the fist. In order for Battelle's software to read Ian's mind, it has to look for subtle changes in the signals coming from Ian's brain. As Bouton explains it, the process is like walking into a crowded room with hundreds of people trying to talk to each other, and you're trying to isolate one particular conversation in a language that you don't understand.
Over time, as Burkhart thinks about doing various tasks, the chip in his brain sends messages to machine learning software, which over time understands the patterns of his brain activity. One pattern will correspond to Burkhart closing his hand; another, for moving it up and down. "We're creating a virtual spinal cord," says Bouton.
At this point, Burkhart can perform a handful of movement patterns, including moving his hand up and down, opening and closing it, rotating it, and drumming on a table with his fingers. All of this can only be done while he's in the hospital, hooked up to the researchers' equipment. When he leaves, his hand is back to being completely paralyzed.
This isn't the only research looking into bringing movement back to the paralyzed. In the past, paralyzed patients have been given brain-computer interfaces—but they have only been able to control artificial limbs. Participants in an epidural stimulator implant study have been able to regain some movement in their limbs, but this technology works best on patients with incomplete spinal cord injuries.
Burkhart is confident that he can regain even more movement back from his hand, and the researchers are approved to try the technology out on four more patients. Ultimately, the system will only be workable commercially with a wireless neural implant, or an EEG headset (kind of like the Emotiv).
The technology could be used in stroke rehabilitation as well. "In that case, we think potential applications may come sooner rather than later," says Bouton.