Researchers explore ways to capture brain signals to help restore movement to paralyzed participants

At age 16, German Aldana was riding in the backseat of a car driven by a friend when another car headed straight for them. To avoid a collision, his friend swerved and hit a concrete pole. The others weren’t seriously injured, but Aldana, unbuckled, was tossed around enough to snap his spine just below his neck. For the next five years, he could move only his neck, and his arms a little.

Right after he turned 21 and met the criteria, Aldana signed up for a research project at the University of Miami Miller School of Medicine, near his home.

Researchers with the Miami Project to Cure Paralysis carefully opened Aldana’s skull and, at the surface of the brain, implanted electrodes. Then, in the lab, they trained a computer to interpret the pattern of signals from those electrodes as he imagines opening and closing his hand. The computer then transfers the signal to a prosthetic on Aldana’s forearm, which then stimulates the appropriate muscles to cause his hand to close. The entire process takes 400 milliseconds from thought to grasp.

A year after his surgery, Aldana can grab simple objects, like a block. He can bring a spoon to his mouth, feeding himself for the first time in six years. He can grasp a pen and scratch out some legible letters. He has begun experimenting with a treadmill that moves his limbs, allowing him to take steps forward or stop as he thinks about clenching or unclenching the fingers of his right hand.

But only in the lab. Researchers had permission to test it only in their facility, but they’re now applying for federal permission to extend their study. The hope is that by the end of this year, Aldana will be able to bring his device home — improving his ability to feed himself and open doors, restoring some measure of independence.

Aldana is one of a small number of people with paralysis nationwide who are participating in experimental trials of what are called brain-computer interfaces. Although people like Aldana can no longer move their limbs at will, they still can think about moving them. Scientists are trying to read the brain-cell activity connected to those thoughts and use that to trigger actions — either from a computer cursor, a keypad, or assistive devices — like Aldana’s prosthetic.

Brain-computer interfaces today are about where the personal computer was in the early 1980s, said A. Bolu Ajiboye, an associate professor of biomedical engineering at Case Western Reserve University in Cleveland. In the not-too-distant future, he said, “They’re going to get exponentially better.”

Through efforts like these and others, conditions are slowly changing for the 12,000 to 13,000 people a year who suffer a spinal cord injury, said David Putrino, director of the Abilities Research Center at Mount Sinai Health System in New York.

Long told all the things they would never do again, patients, with the help of technologies like brain-computer interfaces, are now able to imagine resuming many activities, said Putrino, a physical therapist with a Ph.D. in neuroscience.

"People are waking up to this new and wonderful world where there are all these new technologies we can use to trick the nervous system into getting a little bit more out of the body when an injury has occurred," he said.

Researchers are exploring three ways to capture brain signals that can then be used to restore some movement: One approach measures EEG brain waves from outside the brain; the Miami approach embeds electrodes just inside the skull; and a third places them inside the brain, close enough to pick up the activity of individual neurons.

Each approach has its advantages and disadvantages, Ajiboye said. And all of the devices will have to be approved by the Food and Drug Administration before they can be used outside of a research setting, so they are years from being publicly available.

All three approaches share three big challenges, said Jennifer Collinger, a biomedical engineer and assistant professor at the University of Pittsburgh:

— Making the technology more robust so people can do more of the activities they want and gain more independence.

— Shrinking the systems without losing effectiveness, to make them more portable and less intrusive.

— Bringing the technology out of the lab to make it more useful and usable in everyday life.

“The real hope of these technologies is that they’ll provide true independence,” said Leigh Hochberg, a professor of engineering at Brown and a neurologist at Massachusetts General Hospital in Boston, who also works for the Providence VA Medical Center.

Ultimately, the technology should be small enough to fit in someone's pocket, he said, rather than requiring racks of neural signaling processing hardware.

Right after his implant surgery, Aldana said, it took a lot of concentration to control his hand movements, but now all he has to do is imagine.

"I think of squeezing and it closes and stays closed until I'm ready to let go," he said. "It opens quickly, closes faster. It's more accurate."

Aldana said he decided a couple of days after his accident that “I’m going to try my hardest to get as well as I could.” Being in the trial is part of that commitment to himself and to others like him, whom he hopes he is helping by participating in the research.

"I'm doing it for me, but also to help other people," he said. "I saw a lot of people [with similar injuries] who were basically giving up. That wasn't me."