Fri, Jul 14, 2006 - Page 1 News List

Chip implanted in the brain offers hope to paralyzed


Scientists have for the first time developed a brain implant that allows people to control electronic devices by thought alone, it emerged on Wednesday.

The 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, allowed Matthew Nagle, a 25-year-old Massachusetts man who has been paralyzed 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.

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

"The results hold 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 program at Brown University, Rhode Island, and chief scientific officer of Cyberkinetics, the company behind the brain implant.

Donoghue's work was published yesterday in Nature. He describes how, after a few minutes spent calibrating the implant, Nagle could read e-mails and play the computer game Pong. He was able to draw circular shapes using a paint program 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 4mm2 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 1mm 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," Donoghue said. "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 converting the buzz of electrical activity in the brain into meaningful instructions proved a tough task.

"We had a general idea what they were doing but in a spinal cord injury person, we weren't sure they would be behaving in a normal way," Donoghue said.

His research team 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.

"Some researchers might have predicted that this part of the brain would alter its function dramatically after the spinal cord was injured. But that doesn't seem to be the case. The movement-related signals are still there," said Leigh Hochberg, a neurologist at Massachusetts general hospital and a co-author of the new research.

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