Technology‎ > ‎

Brain waves trigger movement in paralysed monkeys

posted 20 Jun 2012, 11:15 by Mpelembe   [ updated 20 Jun 2012, 11:17 ]

Scientists from Northwestern University in Chicago are making significant advances in paralysis research. The team have been successful in restoring a paralysed monkey's ability to control its muscles through a brain-computer interface. Katharine Jackson, reports.
REUTERS/ NORTHWESTERN UNIVERSITY FEINBERG SCHOOL OF MEDICINE - Spike, the rhesus monkey, picks up a ball and slides it into a slot. Rewarded with sips of sweet fruit juice, he repeats the process again and again.

He is one of several monkeys taking part in groundbreaking research at Chicago's Northwestern University.

The study is aimed at finding a new way for people paralysed by spinal cord injury to move their limbs again.

To simulate spinal cord injury, scientists numb the monkey's arm with anaesthetic. Try as he might, the monkey can't put the ball in the slot.

That is, until they switch on a connection between electrodes in the monkey's brain, a computer, and electrodes in the monkey's arm muscles.

Neuroscientist Emily Oby.


"We can give him back the ability to activate those muscles in a quite natural way so he's still able to pick up a ball under his control."

Neuroscientist Christian Ethian says the experiment shows it's possible to bypass the spinal cord…connecting thoughts to muscle movements through a computer.

The monkey's movement begins with a 4-mm square implant inside its brain.


"It's a tiny silicone chip that has 100 very small hair-thin electrodes. And it sits right on the surface of the motor cortex, the part of the brain that controls the movements. All the electrodes pick up the activity from neurons in the cortex."

The electrodes detect impulses from 100 neurons and transmit the data along wires to an amplifier on the monkey's head. The amplified data is then sent to a computer, showing up as waves on a screen that emit a crackling noise.

Neuroscience Professor Lee Miller is leading the study.


"The computer is really the heart of the matter. It takes these hundred signals coming from the brain extracts the information from them related to what the muscles are doing and does this conversion from brain signals into muscle signals."

To turn brain waves into motion, the computer uses an equation the scientists developed while the monkey's arm was functioning normally.

He thinks about moving his hand and neurons fire, sending signals to his muscles that allow him to grab the ball and drop it into the slot.

Then when the monkey's arm is temporarily paralysed, the computer records the neuron firings and uses the equation to determine the corresponding muscle signals. The signals are sent to the electrodes implanted in the monkey's arm muscles, triggering their movement.

Ethian says a neuroprosthesis like this could allow people with spinal cord injury to move their bodies using only their thoughts.


"It's controlled from the brain, so it's a much more natural way of controlling the stimulation and the muscle activation. And also, we hope that it's going to provide a signal that's a lot more precise to restore dexterous movement too."

The system can't yet capture the complexity of brain activity that produces movement. And the monkey does not grab and drop the ball perfectly every time. But the scientists say over time, the monkey improves, learning to move his hand with his brain.

And if a rhesus monkey like Spike can do it, so can a human.

Katharine Jackson, Reuters.