Scientists develop a wireless implant that gave paralyzed monkeys the ability to walk again

In a research that might one day help paralyzed people walk again, Swiss scientists working with researchers from Brown University have enabled monkeys with injured spinal cords to regain control of their non-functioning limbs.

The team led by the Swiss Federal Institute of Technology (EPFL) achieved this by treating the monkeys with a neuroprosthetic interface that acted as a wireless bridge between the brain and spine. The device does this by decoding brain activity related to walking and then sending those signals to the spinal cord through electrodes that stimulate neural pathways and activate leg muscles.

This method allowed researchers to use a partial spinal cord lesion to successfully treat two rhesus monkeys each with one leg paralyzed by a partial spinal cord lesion. They gave the monkeys the newly designed spinal implants, and paired them with a simple, wireless BCI (brain-computer interface). This computer is a tiny array of electrodes that sits on the surface animals’ motor cortices and protrudes just slightly from their heads. This BCI registers basic signals from the brain—such as intent to move—and sends them to the spinal implant with virtually no delay and no cumbersome wires restricting movement.

The first monkey regained use of its paralyzed leg within the first week after its injury with no training both on a treadmill and on the ground, while the other took around two weeks to recover to the same point.

“We developed an implantable, wireless system that operates in real-time and enabled a primate to behave freely, without the constraint of tethered electronics,” said Gregoire Courtine, a neuroscientist at the Swiss Federal Institute of Technology (EPFL) which led the work.

“We understood how to extract brain signals that encode flexion and extension movements of the leg with a mathematical algorithm. We then linked the decoded signals to the stimulation of specific hotspots in the spinal cord that induced the walking movement.”

While both the brain and spinal cord can adjust and recover from small injuries, this is the first time they have ever been noted overpowering severe damage. In the past, attempts made to restore spinal cord function have focused either on stem cell therapy or electrical and chemical stimulation of the spinal cord. In contrast, this study creates a path between the decoding of the brain and the stimulation of the spinal cord, reports Reuters.

This new technology has huge implications for the medical field and could be the first step toward helping paralyzed people walk again. The team is already looking at setting up future human trials.

“For the first time, I can imagine a completely paralyzed patient able to move their legs through this brain-spine interface,” said Jocelyne Bloch, a neurosurgeon at the Lausanne University Hospital who surgically placed the brain and spinal cord implants in the monkey experiments.

But, Courtine cautioned that there are major challenges ahead and “it may take several years before this intervention can become a therapy for humans.”

However, the findings have laid a platform for future studies on paralysis rehabilitation in both primates and humans.

“There’s an adage in neuroscience that circuits that fire together wire together,” Borton added. “The idea here is that by engaging the brain and the spinal cord together, we may be able to enhance the growth of circuits during rehabilitation. That’s one of the major goals of this work and a goal of this field in general.”

The study has been published in the journal Nature on Wednesday.

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