Brain implants allow paralyzed man to walk with his mind
Gert-Jan Oskam was living in China in 2011 when he was involved in a motorcycle accident that left him paralyzed from the waist down. Now scientists have given him back control of his lower body using a combination of devices.
“I’ve been trying to get back on my feet for 12 years,” Mr Oskam said in a press conference on Tuesday. “Now I’ve learned to walk normally and naturally.”
In a study published Wednesday in the journal Nature, Swiss researchers described implants that formed a “digital bridge” between Mr Oskam’s brain and his spinal cord, bypassing injured sections. The discovery enabled Mr Oskam, 40, to stand, walk and climb a steep ramp with only the help of a walker. More than a year after the implant was placed, he has retained these abilities and has actually shown signs of neurological recovery, allowing him to walk on crutches even when the implant was off.
“We captured Gert-Jan’s thoughts and translated those thoughts into a spinal cord stimulation to restore voluntary movement,” said Grégoire Courtine, a spinal cord specialist at the Swiss Federal Institute of Technology in Lausanne who helped lead the research the press conference.
Jocelyne Bloch, a neuroscientist at the University of Lausanne who implanted the implant in Mr. Oskam, added: “It was pretty science fiction to me at first, but today it has come true.”
In the last few decades there have been a number of technological advances in the treatment of spinal cord injuries. In 2016, a group of scientists led by Dr. Courtine to restore the ability to walk in paralyzed monkeys, and another group helped a man regain control of his paralyzed hand. In 2018, another group of scientists, also led by Dr. Courtine, a way to stimulate the brain with electrical pulse generators, allowing partially paralyzed people to walk and cycle again. Last year, more advanced brain stimulation techniques allowed paralyzed subjects to swim, walk and cycle in a single day of treatment.
Mr. Oskam had undergone stimulation procedures in recent years and was even able to walk to some extent, but eventually his improvement stagnated. At the press conference, Mr. Oskam said that these stimulation technologies made him feel like locomotion was something alien, an alien distance between his mind and his body.
The new interface changed that, he said: “The stimulation before controlled me, and now I control the stimulation.”
In the new study, what the researchers called the brain-spine interface used an artificial intelligence thought decoder to read Mr Oskam’s intentions – detectable as electrical signals in his brain – and match them to muscle movements. The etiology of natural movement, from thought to intention to action, was preserved. The only addition was, as Dr. Courtine described it as the digital bridge that spanned the injured parts of the spine.
Andrew Jackson, a neuroscientist at Newcastle University who was not involved in the study, said, “It raises interesting questions about autonomy and the source of commands.” They continue to blur the philosophical line between what the brain is and what it is what the technology is.”
dr Jackson added that while scientists in the field have theorized about connecting the brain to spinal cord stimulators for decades, this is the first time they have had such success in a human patient. “It’s easy to say, it’s much more difficult to implement,” he said.
To achieve this result, the researchers first implanted electrodes in Mr. Oskam’s skull and spine. The team then used a machine learning program to observe which parts of the brain lit up when he tried to move different parts of his body. This thought decoder was able to match the activity of certain electrodes to specific intentions: one configuration lit up when Mr. Oskam tried to move his ankles, another when he tried to move his hips.
Then the researchers used a different algorithm to connect the brain implant to the spinal implant, which would send electrical signals to different parts of his body, triggering movements. The algorithm was able to account for slight variations in the direction and speed of each muscle contraction and relaxation. And because the signals were sent between the brain and spine every 300 milliseconds, Mr. Oskam was able to quickly fine-tune his strategy based on what worked and what didn’t. Already in the first treatment session he was able to twist his hip muscles.
Over the next few months, the researchers optimized the interface between the brain and the spine to better adapt to basic actions like walking and standing. Mr. Oskam regained a reasonably healthy-looking gait and was able to negotiate stairs and ramps with relative ease, even after months without treatment. In addition, after a year of treatment, he noticed significant improvements in his movements without the help of the brain-spine interface. The researchers documented these improvements on stress, balance and walking tests.
Now, on a limited basis, Mr. Oskam can walk around his house, get in and out of a car and have a drink at a bar. For the first time, he said, he felt like he was the one in control.
The researchers acknowledged limitations in their work. Subtle intentions in the brain are difficult to discern, and while the current brain-spine interface is appropriate for walking, the same probably cannot be said for upper body movement recovery. The treatment is also invasive, requiring multiple surgeries and hours of physical therapy. The current system does not fix all spinal cord paralysis.
However, the team hoped that further advances would make the treatment more accessible and systematic. “That is our true goal,” said Dr. Courtine, “to make this technology available worldwide to any patient who needs it.”