Paralyzed monkeys have been able to walk again using a brain implant that transmits signals wirelessly to stimulators in their legs, researchers reported Wednesday.
It's another step forward in a field that has helped people and monkeys alike to control robotic arms and hands using brain implants. But this is the first time an implant has helped a primate walk.
It's years away from being used in people, but the implant worked without months or even weeks of training, the team reported in the journal Nature.
"The primate was able to walk immediately once the brain-spine interface was activated. No physiotherapy or training was necessary," Erwan Bezard of Bordeaux University, who led the tests in the monkeys, said in a statement.
The animals had two implants — one in the brain and one in the lower part of the spinal cord. The team first trained a computer to decode the brain signals that corresponded to leg movements in healthy monkeys. Then they partly cut the spinal cord of one to see if the system could allow movement.
"This is the first time that neurotechnology (has restored) locomotion in primates," said neuroscientist Grégoire Courtine of the Swiss Federal Institute of Technology in Lausanne, who led the study.
"But there are many challenges ahead and it may take several years before all the components of this intervention can be tested in people," Courtine said.
For one thing, they only partly injured the spinal cords because of ethical concerns. A real injury might completely sever the spinal cord, or crush it in a way that would make recovery harder, they noted.
But this kind of technology tends to move quickly from monkeys to people, said Dr. Andrew Jackson of Britain's Newcastle University.
"The pace at which neural interfaces are being translated from initial experiments in monkeys to human trials has been rapid," Jackson, who was not involved in the research, wrote in a commentary.
"For the first time, I can imagine a completely paralyzed patient able to move their legs through this brain-spine interface," said Dr. Jocelyne Bloch of the Lausanne University Hospital, the neurosurgeon who installed the brain and spinal cord implants.
The device was developed by the BrainGate collaboration, which includes the Department of Veterans Affairs, Brown University, Massachusetts General Hospital, Harvard Medical School, and the German Aerospace Center. It was made by medical device company Medtronic.
"With the system turned on, the animals in our study had nearly normal locomotion," said David Borton, assistant professor of engineering at Brown.