A wireless implant enabled injured macaques to walk again

Monkey walks again with wireless brain implant

Image credit: EPFL

A wireless brain implant has been used to successfully bridge a spinal cord injury of two rhesus macaques, allowing the monkeys to regain the ability to walk.

The accomplishment, described in the journal Nature, represents the first time researchers were able to use neural prosthetics to restore walking in primates, a major step towards a future possible application in humans.

“The system we have developed uses signals recorded from the motor cortex of the brain to trigger coordinated electrical stimulation of nerves in the spine that are responsible for locomotion,” said David Borton, assistant professor of engineering at Brown University, the USA, who led the team developing the implant. “With the system turned on, the animals in our study had nearly normal locomotion.”

The brain implant used in the study consists of a pill-sized electrode array, which gathers signals and sends them wirelessly into a computer that decodes and relays them to an electrical spinal simulator implanted in the lumbar spine. The signals can’t pass directly, as the spine between the brain and the lumbar region is damaged.

The team has previously used to same implant to allow tetraplegics to operate a robotic arm with their thoughts. The team hopes they will be able to run similar experiments with humans as they’ve done with the macaques.

“There is evidence to suggest that a brain-controlled spinal stimulation system may enhance rehabilitation after a spinal cord injury,” Borton said. “This is a step toward further testing that possibility.”

The researchers collaborated with scientists from the Swiss Ecole Polytechnique Federale Lausanne, the German, Fraunhofer ICT-IMM and Medtronic.

The ability to transmit the signals wirelessly is key for future usability of the invention as wired brain sensing systems limit the patient’s ability to move. It also enabled the researchers to gather more data. To calibrate the system, they implanted the sensor into brains of healthy macaques to understand what types of signals are generated by different types of locomotion.

“Doing this wirelessly enables us to map the neural activity in normal contexts and during natural behaviour,” Borton said. “If we truly aim for neuroprosthetics that can someday be deployed to help human patients during activities of daily life, such untethered recording technologies will be critical.”

In future, the researchers would like to enhance the system to be able to also relay signals from the spine back to the brain.

“There's an adage in neuroscience that circuits that fire together wire together,” Borton said. “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.”


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