Six years after a diving accident left him paralysed from the neck down, Keith Thomas can move his arms and hands again, and feel touch.
The 48-year-old regained the ability to feel and grasp objects after receiving an experimental brain implant, according to a study published in Nature Medicine on July 16.
Researchers said Thomas kept both the sense of touch and the ability to grasp objects for months after the system was switched off. That suggests the technology may have rewired his nervous system by promoting neuroplasticity.
“We turned everything off completely, for many months, and yet he’s maintained these gains,” study co-author Chad Bouton, a neuroscientist at the Feinstein Institutes for Medical Research in New York, told Christa Lesté-Lasserre at New Scientist. “That’s unheard of.”
Thomas received a double neural bypass surgery in 2023 as part of a clinical trial.
Bouton and his colleagues placed five electrode arrays in Thomas’s brain motor and sensory cortexes. The arrays measure and deliver electric currents. The team also placed stimulation patches on top of his spinal cord and forearm.
When Thomas tried to move his hand or arm, the implanted electrodes detected the related brain activity. A machine learning algorithm decoded that activity and converted it into electrical signals that stimulated his intended movements.
At the same time, pressure sensors built into a custom 3D-printed orthotic measured pressure during grasping and triggered electrical stimulation patterns in the brain’s sensory cortex, creating the feeling of touch.
Overall, the algorithm interpreted his brain signals with 85 percent accuracy.
After 35 weeks with the system, strength increased by 86 percent in his right arm and 62 percent in his left.
“[The study] changed my life dramatically,” Thomas told O. Rose Broderick at STAT. “I’m able to pet my dog, I’m able to do other things, like sometimes feed myself, wipe my face, wipe my mouth.”
The team also developed a “cortical mirroring” technique to recreate the sense of feeling in his hands.
Researchers first recorded Thomas’s brain activity when he imagined being touched. They then recreated those brain signals using electrical stimulation of his sensory cortex while simultaneously stimulating the spinal cord and skin.
After about 25 weeks of that therapy, focused on his right wrist, Thomas regained the ability to feel touch in an area that had previously been completely numb.
He could grab and lift hollow eggshells without breaking them 87 percent of the time, even when blindfolded.
“In a recent follow up, it was found these gains were still present after more than two years,” Bouton said in a statement. “This is incredibly encouraging.”
Outside experts said the result was promising, but it is not clear how it would translate to other patients.
Thomas is just one person, and the complexity of the procedure makes it hard to untangle what caused which effect, John Downey, a neuroscientist at the University of Chicago who was not involved in the study, told STAT.
David McGonigle, a neuroscientist at Cardiff University who was not involved in the work, told Michael Peel at the Financial Times that the study was “a step towards future work, rather than an end in itself.”
He said the signs of nervous system adaptation were “intriguing,” though not yet proven, and the reported motor improvements were “particularly impressive.”
“That’s where the real worth of the study lies, with the participant now able to perform meaningful everyday tasks such as feeding himself and manipulating delicate objects,” McGonigle says.
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