Artificial limbs controlled by mind power

Brain implants offer hope to the severely disabled

Ian Sample, science correspondent
Tuesday October 14, 2003
The Guardian

Brain implants that could allow severely disabled people to control prosthetic limbs with their minds could be ready for use within two years, according to a team of scientists. Their claim comes after tests with monkeys showed that the animals could control a robotic arm using just their thoughts.

The brain implants could have a wider use, enabling people to operate machinery if they are unable to do so by any other means.

The scientists from Duke University in North Carolina implanted hundreds of fine electrodes into the brains of rhesus monkeys. They then got the monkeys to play a simple video game.

Using a joystick, the monkeys had to steer a cursor towards a circle on a computer screen. When the cursor was positioned over the circle, they had to squeeze the joystick until the cursor grew in size to cover the circle.

By reading the electrical signals from the monkeys' brains, the scientists were able to work out what thoughts gave rise to different movements, whether it was up, down, side to side or gripping. To make the task more difficult, the scientists wired up the joystick so that it controlled a robot arm in another room.

This time, the movements of the robot arm, rather than the joystick, controlled where the cursor moved on the screen. The point was to see how the monkeys coped with the time delay that the robot arm introduced - an issue someone with a real robotic arm would have to learn to deal with.

After a period of training on the game, the researchers took away the joystick to see if the monkeys could still play the game.

For a while, the monkeys continued trying to play the game with their arms flailing around. But then, the monkeys suddenly realised that they were trying too hard.

"The most stunning thing is that the monkey realised he didn't have to move his arm at all; he stopped moving his arm, but could still play the game," said Professor Miguel Nicolelis, who led the team.

The monkey had realised that just thinking about moving its arms was enough to control the robot arm and the cursor on the screen. The computer linked up to the electrodes in the monkey's brain could work out what movements the monkey was trying to do and turn them into actions.

"I thought it would take a decade to achieve something like this," said Prof Nicolelis, whose study is published in the new Public Library of Science biology journal. "Today I'm much more optimistic about the possibility of using signals from the brain to control robotic arms for people who have lost limbs or are severely paralysed.

"We already have preliminary clinical data suggesting this works in humans."

The results of tests on humans will be announced in the next few months.

Professor Mandayam Srinivasan, an expert in biorobotics at MIT in Massachusetts, said: "This is a very important step towards our ultimate goal, which is for paralysed people to have brain implants to control prostheses or any other kind of device with their minds.

"If we can do it, it would improve their quality of life immeasurably."

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