Researchers explore ways to capture brain signals that can then be used to restore some movement to paralyzed participants
At age 16, German Aldana was riding in the back seat 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, open doors and restoring some measure of independence.
Aldana is one of a small number of people with paralysis nationwide participating in experimental trials of what are called brain-computer interfaces. Although people like him 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 PhD 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 different ways to capture brain signals that can then be used to restore some movement to paralyzed participants: 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.
The first approach is like listening to a concert while standing across the street from the concert hall, Ajiboye said. You might be able to hear some music, but it would be hard to discern the tune. The Miami approach – reading brain waves from under the skull – is like standing in the lobby of the theater, where you can make out the music, but not individual instruments. And the third approach is like sitting on the stage, where you can pick out the notes an instrument plays.
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 advantage of using a simple EEG to read brain waves from outside the body is clear: no need for brain surgery. But it’s nearly impossible to get any precision from EEG readings, Ajiboye said, so it’s unlikely to support many movements.
In May 2019, Carnegie Mellon University in Pittsburg received a $19 million federal grant to hopefully improve on this noninvasive type of brain-computer interface, using light and ultrasound, perhaps in conjunction with EEG.
Ajiboye’s own approach – similar to Miami’s – uses recording technologies with electrodes that penetrate the brain, he said. In 2017, his team showed that by implanting electrodes shallowly in the brain and inside paralyzed arm muscles, they were able to get a 53-year-old volunteer with paralysis to reach out, grasp and hold an object, feed himself and bring a cup to his face.
Miami’s innovation is that there’s no need to plug Aldana in. The brain wave reading technology in his head can “speak” remotely to a computer, meaning it should be easier to get him out of the lab and into the outside world.
The third approach, which puts the electrodes right onto the stage, to use Ajiboye’s metaphor, was pioneered at Brown University in Providence, in 2004 with a project called BrainGate. BrainGate, which has had a total of 14 volunteer participants, can read more complex thoughts than the other approaches, such as which key to type on a keyboard. In late 2018, BrainGate researchers demonstrated that they could enable people with ALS, also known as Lou Gehrig’s disease, to control a typical tablet computer simply with their thoughts.
Participants have been using BrainGate at home, but one near-term goal is to get the technology to work when a trained technician or even a caregiver isn’t around to help, said Leigh Hochberg, a professor of engineering at Brown and a neurologist at Massachusetts General Hospital in Boston, who helps lead BrainGate.
“The real hope of these technologies is that they’ll provide true independence,” said Hochberg, 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.
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The Miami experiment appealed to Aldana, now 23 and a sophomore at Miami Dade College majoring in computer science.
Jonathan Jagid, a neurosurgeon and associate professor at the University of Miami, has been working for about a decade on the technology now implanted just underneath Aldana’s skull.
“We truly believe this type of device is going to get somebody much more quickly to a therapeutic use rather than a laboratory use,” Jagid said, citing its versatility, longevity and that it doesn’t require Aldana to be plugged in.
Abhishek Prasad, assistant professor of biomedical engineering at the University of Miami, said the system works in near real-time, taking about 400 milliseconds for the signal being recorded in the brain to be transmitted to the computer. That compares to about 60 to 120 milliseconds for a normal person’s thought to be transmitted from the brain down the spinal cord to their muscles to cause natural movement, he said.
Right now, Prasad said, the signal processing is done by a nearby laptop, but he hopes eventually to enable the system to work with a cellphone.
Prasad and Jagid said the work could not progress without Aldana, who comes into the lab several days a week, and is a great collaborator.
Brain-computer interface research cannot involve a lot of volunteers because of the complexity of the work and risks involved with surgery, but the learning process can be intense.
At the University of Pittsburgh, for instance, Collinger said she works with research volunteers three times a week for four hours a time – roughly 600 hours of testing per year. “We’re really indebted to the people who are willing to be the early pioneers,” she said.
Hard work is a necessary part of the process of retraining the brain, said Putrino of Mount Sinai. The technology is important, he said, but “in every single case, it comes down to really awesome technology paired with intensive work on the patient’s end.”
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.”
His goal is to work with researchers as a participant – and once he has his degree – as a peer, to improve brain-computer interfaces and related devices. Eventually, he thinks, they could enable people with paralysis to do nearly everything an able-bodied person can.
Aldana said he’s satisfied with the progress he and the brain-computer interface have been able to make together so far.
“It’s gotten a lot better, so I’m happy,” he said, “and I’m waiting to see what other things come our way, what more stuff we can do with it.”