In the new study, the brain-spine interface, as the researchers called it, took advantage of an artificial intelligence thought decoder to read 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, as Courtine described it, was the digital bridge spanning 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. You’re continuing to blur the philosophical boundary between what’s the brain and what’s the technology.”
Jackson added that scientists in the field had been theorising about connecting the brain to spinal cord stimulators for decades but that this represented the first time they had achieved such success in a human patient. “It’s easy to say; it’s much more difficult to do,” he said.
“For 12 years I’ve been trying to get back my feet,” Oskam said. “Now I have learned how to walk normal, natural.”Credit: Jimmy Ravier/EPFL via The New York Times
To achieve this result, the researchers first implanted electrodes in Oskam’s skull and spine. The team then used a machine-learning program to observe which parts of the brain lit up as he tried to move different parts of his body. This thought decoder was able to match the activity of certain electrodes with particular intentions: One configuration lit up whenever Oskam tried to move his ankles, another when he tried to move his hips.
Then the researchers used another algorithm to connect the brain implant to the spinal implant, which was set to send electrical signals to different parts of his body, sparking movement. The algorithm was able to account for slight variations in the direction and speed of each muscle contraction and relaxation. And because the signals between the brain and spine were sent every 300 milliseconds, Oskam could quickly adjust his strategy based on what was working and what wasn’t. Within the first treatment session, he could twist his hip muscles.
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Over the next few months, the researchers fine-tuned the brain-spine interface to better fit basic actions like walking and standing. Oskam gained a somewhat healthy-looking gait and was able to traverse steps and ramps with relative ease, even after months without treatment. Moreover, after a year in treatment, he began noticing clear improvements in his movement without the aid of the brain-spine interface. The researchers documented these improvements in weight-bearing, balancing and walking tests.
Now Oskam can walk in a limited way around his house, get in and out of a car and stand at a bar for a drink. For the first time, he said, he feels like he is the one in control.
The researchers acknowledged limitations in their work. Subtle intentions in the brain are difficult to distinguish, and although the current brain-spine interface is suitable for walking, the same probably cannot be said for restoring upper-body movement. The treatment is also invasive, requiring multiple surgeries and hours of physical therapy. The current system does not fix all spinal cord paralysis.
But the team was hopeful that further advances would make the treatment more accessible and more systematically effective. “This is our true objective,” Courtine said, “to make this technology available across the world for all the patients who need it.”
This article originally appeared in The New York Times.
