Embedded chips in brains help paralysed monkeys to walk

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Two paralysed monkeys have been helped to walk using chips embedded in their brains.

The animals displayed "nearly normal locomotion" as the system decoded nerve activity and wirelessly transmitted signals that stimulated leg muscles.

It is said to be the first time a neural prosthetic device has been used to restore walking movement directly to the legs of non-human primates.

Scientists hope the research will help in the development of similar hi-tech solutions for people with spinal cord injuries.

Dr David Borton, from Brown University in the US, said: "The system we have developed uses signals recorded from the motor cortex of the brain to trigger co-ordinated electrical stimulation of nerves in the spine that are responsible for locomotion.

"With the system turned on, the animals in our study had nearly normal locomotion."

The two rhesus macaques had partial spinal cord injuries that resulted in loss of movement in one leg.

Macaques with this type of injury generally recover over a period of about a month. The scientists tested the wireless neural interface while the animals were till paralysed.

The heart of the system was a pill-sized electrode array implanted in the brain that recorded signals from the motor cortex, the brain region responsible for voluntary movement.

Signals gathered by the brain chip were transmitted to a computer programmed to recognise patterns associated with leg movement.

After decoding the signals the computer beamed them back to an electrical stimulator implanted in the lumbar spine, below the site of injury. This in turn activated intact spinal nerves that controlled muscle contractions necessary for walking.

With the system turned on, the monkeys began spontaneously to move their non-functional leg while supported on a treadmill.

One animal regained some use of its paralysed leg within the first week after injury. The other took two weeks to achieve the same level of mobility.

Dr Borton said: "Doing this wirelessly enables us to map the neural activity in normal contexts and during natural behaviour. 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."

The scientists, whose work is described in the journal Nature, stressed that much more research was needed before such technology could be tested in humans.