Paralysed man uses mind control to walk again

https://www.youtube.com/watch?v=P6gai4SbRIU

A 26-year-old man who is paralysed in both legs has walked for the first time in five years – just by thinking about it. He is the first person to have his brain activity recorded and used to control a muscle-stimulating device in his legs.

Every year, 250,000 to 500,000 people worldwide suffer spinal cord injuries, which can leave them partially or completely paralysed below the site of damage.

Many rehabilitation clinics already offer functional electric stimulation (FES) devices, which activate the nerves that innervate leg muscles at the push of a button. But people with upper-body paralysis are not always able to operate the FES in this way. The new system bypasses the button and returns control to the brain.

“We want to re-establish the connection between the brain and the leg muscles, to bring back the function that was once present,” says Zoran Nenadic at the University of California Irvine. To do that, Nenadic and his colleagues combined an FES system with a brain-computer interface.

The team developed an electrode cap that picks up the brainwaves created when a person thinks specifically about walking or standing still. They tailored the device to pick up brain signals from their volunteer – a man who has had little sensation below his shoulder blades for five years.
Virtual training

The group created an algorithm to translate the two patterns of brain activity into signals that would switch an FES device attached to the man’s legs on or off. Before they tested the device in a real-world setting, the group trained their volunteer to use the device in virtual reality. At the start of training, the man could control whether the device was on or off with his thoughts 70 per cent of the time. “We got this up to about 99 per cent accuracy,” says Nenadic. Throughout the training period, the man also underwent physical exercises to strengthen his leg muscles.

When the team felt the man was ready, they taught him to walk in the real world. “When we told him to, he could start walking,” says Nenadic. “He walked 1.8 metres to a traffic cone, could stop for 30 seconds, and then continue the length of a 3.6 metre course.”

With practice, the man was able to walk the course six times in a row. During the test, the man was supported by a harness, to catch him if he fell. But he never did fall, says Nenadic.

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