'Bionic man' can control robotic arm with his mind
Daily Mail | July 13, 2006
A man paralysed from the neck down has shown he can open email, control a TV and move objects with a robotic arm by thought alone.
The 25-year-old American patient, Matthew Nagle, had a computer-linked implant placed in his brain that enabled him to operate devices just by thinking about it.
Brain-computer interfaces have been demonstrated before, in humans and animals. But this is the biggest step taken so far towards developing "bionic" systems that can restore motor function in people who have lost control of their limbs.
In the 1970s TV series "The Six Million Dollar Man", scientists rebuilt the body of crash victim Steve Austin with bionic prosthetics controlled by his mind.
At the time the concept was pure fantasy, but in future thought-controlled replacement limbs could be made real.
The results described today in the journal Nature represent the culmination of decades of work.
However the scientists involved in the research stress that the technology is still in its infancy.
Mr Nagle, from Massachusetts, whose spinal cord was severed in 2001, received his implant at Rhode Island Hospital in 2004.
Known as the BrainGate Neural Interface System, it consists of an array of electrodes that record neural activity from the motor cortex of the brain.
Signals from the implant are decoded and processed by a computer, allowing them to be translated into movement commands.
First, Mr Nagle learned to move a computer cursor by focusing his thoughts on the task.
Later, during 57 trial sessions at the New England Sinai Hospital and Rehabilitation Centre in Massachusetts, he greatly expanded his repertoire of thought control.
He was able to open simulated e-mail, draw circular shapes on the computer screen, play a simple video game called "neural Pong", and change the channel and adjust the volume on a television.
Ultimately, he could open and close the fingers of an artificial hand and use a robotic arm to grasp and move objects.
A second patient, aged 55, who had a sensor implanted by surgeons at the University of Chicago in April 2005, was able to move a computer cursor for three months until his implant malfunctioned.
Professor John Donoghue, who led the research and heads the brain science programme at Brown University in Rhode Island, said: "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."
Prof Donoghue is chief scientific officer at Cyberkinetics Neurotechnology Systems Inc, based in Foxborough, Massachusetts, which developed the implant.
Previous attempts at linking brains to computers have only had limited success, such as getting patients to move a cursor to the left and right. Experiments have also been conducted with less invasive techniques using sensors attached to the scalp, but these take months of training to use.
Mr Nagle adapted to the BrainGate system in minutes, and was able to talk while using it.
The implant consists of a pill-sized sensor measuring just four millimetres across containing 100 tiny electrodes, each thinner than a human hair.
It is placed on the surface of the motor cortex, the area of the brain responsible for voluntary movement. The hair-like electrodes penetrate about one millimetre into the brain, where they pick up electrical signals from nearby neurons. These are transmitted through thin gold wires to a titanium pedestal protruding about an inch above the patient's scalp. A cable connects the pedestal to the computer.
In future it is hoped that "wi-fi" systems will avoid the problem of having to use invasive and bulky wires and cables.
The patient learns how to operate devices simply by imagining a particular task being carried out.
Dr Richard Penn, the University of Chicago neurosurgeon who implanted the sensor in the second patient, said: "This is the strangest, most interesting surgery I've ever done. Not the technical stuff, but the data that we get from the neurons firing in different patterns when you're thinking in different ways. And seeing it is only the beginning."
Experts had not been certain that the brain's limb-control signals could still be found years after a paralysing spinal injury.
But such doubts were put to rest by the success with Mr Nagle, who was injured three years before his surgery.
"We're finding that, even years after spinal cord injury, the same signals that originally controlled a limb are available and can be utilised," said Dr Leigh Hochberg, a neurologist from Massachusetts General Hospital, who was a member of the research team.
Major technical obstacles remain, such as the great variation in individual responses to the implants, and a tendency for the sensors to become less efficient over time.
To restore limb function in any meaningful way scientists must also work out how the body tells the brain where its limbs are positioned in space. This is done through a little-understood sense called "proprioception".
However, enormous challenges have already been overcome - in particular, being able to "listen" to large groups of brain cells firing together between 20 and 200 times a second.
A second team of scientists whose work with monkeys was also published in Nature today has made headway speeding up the interface between brain and machine.
Dr Krishna Shenoy, from Stanford University in California, and colleagues, showed that it is possible to communicate information at a rate equal to typing 15 words per minute on a keyboard
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