Brain Implant helps Paralysed man operate a Computer by Thoughts

Toronto -- Scientists have for the first time developed a brain implant that will allow people to control electronic devices by thought alone.

This remarkable breakthrough offers hope that people who are paralyzed will one day be able to independently operate artificial limbs, computers or wheelchairs.

The implant, called BrainGate, has allowed Matthew Nagle, a 25-year-old Massachusetts man, who has been paralysed from the neck down since 2001, to control a cursor on a screen and to open and close the hand on a prosthetic limb just by thinking about the relevant actions.

These movements were his first since he was stabbed five years ago. The attack severed his spinal cord.

"The results hold out the promise to one day be able to activate limb muscles with these brain signals, effectively restoring brain to muscle control via a physical nervous system," said John Donoghue, director of the brain science programme at Brown University, Rhode Island, and chief scientific officer of Cyberkinetics, the company behind the brain implant.

Professor Donoghue, in his publicaton, has described how, after a few minutes spent calibrating the implant, Nagle could read emails and play the computer game Pong. He was able to draw circular shapes using a paint programme and could also change channel and turn up the volume on a television, even while talking to people around him. After several months, he could also operate simple robotic devices such as a prosthetic hand, which he used to grasp and move objects.

The BrainGate system uses a 4-square-millimetre electronic chip, called the neuromotor prosthesis, inserted into the motor cortex of the brain, the area that controls voluntary movement.

The chip has 100 electrodes, each thinner than a single human hair, which penetrate 1 millimetre into the surface of the brain, where they pick up the electrical activity of the cells. The resulting signals are fed into a computer, which interprets the meaning in real time and then controls objects such as artificial limbs, computer cursors or wheelchairs.

"What is also encouraging is the immediate response from the brain," said Donoghue. "When asked to 'think right' or 'think left,' patients were able to change their neural activity immediately. And their use of the device is seemingly easy.

Patients can control the computer cursor and carry on a conversation at the same time, just as we can simultaneously talk and use our computers."

The brain's 100 billion neurons fire between 20 and 200 times a second, and convert the buzz of electrical activity in the brain into meaningful instructions.

Donoghue's research team also found that the brain cells in Nagle's motor cortex were still active, several years after his spinal cord injury had severed their connection to the rest of the nervous system.

"The movement-related signals are still there," said Leigh Hochberg, a neurologist at Massachusetts general hospital and a co-author of the new research.