Quadriplegic moves objects with thoughts

A brain implant allows a paralyzed man to open his email, move a prosthetic hand or adjust a TV setThe thought-capturing technology offers hope for people with spinal cord injuries, Joseph Hall writes
Jul. 13, 2006. 05:54 AM
JOSEPH HALL
STAFF REPORTER

In a medical breakthrough worthy of an illusionist's act, a U.S. quadriplegic has been able to move objects around him through the power of thought.
Usng a tiny sensor implanted on his brain, the paralyzed Massachusetts man was able to open email, control a prosthetic hand and adjust the volume on a television just by thinking about doing so, according to a cover article in this week's edition of the journal Nature.
And researchers say the thought-capturing technology could soon lead to profound improvements in the lives of people with spinal cord injuries — even to the point where arms and legs could be made to move at will.
"We've found that merely imagining action is sufficient to cause a particular activity," says John Donoghue, a neuroscientist at Rhode Island's Brown University and a lead study author.
"We're reading the neural activity related to that imagined action ... and using it to control devices."
Known as BrainGate, the technology includes an electrode array, about the size of a baby Aspirin, that's implanted on the surface of the brain's motor cortex. Located directly beneath the top of the skull, the motor cortex controls voluntary limb and body movements.
Brain impulses detected by the BrainGate array are sent up via a set of fine wires that pierce the skull and scalp. These are attached by cable to a computerized system that can amplify these neurological impulses or "spikes" and translate them, in real time, into the desired actions.
"Brain cells have a language called spikes, which are basically impulses," Donoghue says.
"And the change in the number of those impulses over time is really the way the brain carries around information from one spot to another."
For example, Donoghue says, neurons in the part of the motor cortex regulating hand movements might fire a series of 10 rapid spikes to indicate right and 20 spikes to indicate left.
"What we're trying to do is read the impulses when they occur and count them up," he says.
"And in the future, if we saw 10 impulses (from the hand centre of the cortex), we'd know that means right."
Paper co-author Leigh Hochberg, a neurologist at Massachusetts General Hospital, says that simply imagining a movement in your mind creates these neurological spikes.
And importantly, the study found, the motor cortex spikes continue to operate properly long after the signal path to their target limbs have been severed, through spinal injuries, amputations or disease.
"One of the very encouraging aspects of these initial findings is that this part of the brain, which normally sends its signals down through the spinal cord and ultimately out through the muscles, can still be used," says Hochberg.
As well, Hochberg says, the BrainGate equipment was able to learn the meaning of the test subject's spike sequences rapidly — often within minutes — and translate them accurately into external action commands.
"It was encouraging to see how quickly he (the test subject) was able to gain control over these physical alternative devices," he says.
Matthew Nagle, the main test subject in the Nature paper, is a quadriplegic who was stabbed in the neck in the summer of 2001 after coming to the defence of a friend in a fight.
The 6-foot-2 Boston-area native, a former high school football standout, was paralyzed from the neck down after the 20-centimetre blade severed his spinal cord.
So far, the 26-year-old man has been able to open and close a prosthetic hand, move a robotic arm and play Pong on a computer screen by simply thinking the necessary movements.
Currently, however, the BrainGate electronics Nagle used to run these devices are the size of a small refrigerator. As well, it's attached by wires to a penny-sized plug on his skull, so his mobility and the activities he can participate in are severely limited when he's hooked up.
But Donoghue says the equipment's Foxborough, Mass., manufacturer, Cyberkinetics Neurotechnology Systems Inc., is working to miniaturize the device and give it remote-control functions.
"We're taking something that's larger than two or three desk-top computers and reducing it down to something that's the size of a cellphone," says Donoghue, who is also Cyberkinetics' chief scientific officer.
Ultimately, Donoghue says, the technology, which has shown a 70 to 90 per cent thought-to-movement accuracy, could reconnect the motor cortex to muscle nerves, allowing people to use their own hands to grasp or move things.
Already, he says, there are devices that can allow paralyzed people to open and close their hands through electronic impulses.
Donoghue says such devices might be integrated into his thought-controlled system to create a virtual neurological connection.
Kevin Rogers, a spokesman for the Canadian Paraplegic Association, says the technology has enormous potential to improve the lives of people with spinal cord injuries.
"It's huge, especially for somebody who is a high-level quadriplegic," says Rogers, who himself has only limited movement in his arms. "That you could think, and it reads your thought patterns, you could have so much more independence."
While Rogers says the idea of a brain implant might give many people pause, he also sees possibilities for the technology to help people beyond those with spinal injuries.
He says people suffering from spastic disorders like cerebral palsy, for example, might use the system to gain easier access to computers and other electronic devices.
And Cyberkinetics president Tim Surgenor foresees many applications beyond prosthetic and rehabilitation functions — including some with military potential.
"There is an opportunity down the road ... to have people be able to use these products who are not disabled," Surgenor says.
"People who want to be able to control a computer by thinking, or who want to have an extra output that they don't have today."
He says military applications "are not a fantasy" and could, for example, allow pilots to plug their minds into their planes.
As well, he says, the system might be able to monitor brain signals for such things as epilepsy, pain or depression, as well as to bring signals into the brain to compensate for the loss of a particular function.