He is unable to move or breathe on his own after his spinal cord was severed in a knife attack five years ago. But thanks to a dramatic scientific advance, Matthew Nagle, 25, can now pick up objects, open e-mails, change the channel on the television and play computer games. And, incredibly, he does it all using the power of thought alone.
The quadraplegic - paralysed from the neck down - is part of an experiment at the cutting edge of neural implants research that enables him to operate a computer and a robotic arm with his brain. Scientists led by Professor John Donoghue, an expert in neurotechnology at Brown University in Rhode Island describe in the journal Nature, published today, how they implanted an electrode array into Mr Nagle's brain which converted the hubbub of electrical activity produced by a million sparking neurons into brain signals that operated devices outside his body.
He was able to use his thoughts to move a cursor around a computer screen, open e-mails, change channels on a television and operate a robotic arm to pick up an object and move it, as well as playing simple computer games such as neural pong, a computer version of ping pong. During all these activities he was able to talk just as an able-bodied person would.
A second patient, aged 55, who had been paralysed since 1999, also had the implant, and successfully used his thoughts to operate devices, though with less effect than Mr Nagle. After 11 months, signals from his brain were abruptly lost for reasons researchers are still investigating.
Professor Donoghue, whose company Cyberkinetics developed the implant called Braingate, said: "The results hold promise that we will one day be able to activate limb muscles with these brain signals, effectively restoring brain-to-muscle control via a physical nervous system." Three months ago, the American Association of Anatomists unveiled its vision for a bionic man, based on advances in microelectronics that have led to the development of a robotic arm capable of playing the piano, and a powerful "exoskeleton" that would allow the wearer to carry heavy loads over long distances. The association named the project the "$6bn human" after the 1970s television series.
These are not the first patients to have brain implants but they are the most successful. Previous attempts at linking brains to computers have had limited success, enabling patients to move a cursor to the left and right, and have been slow and laborious to operate. Experiments have also been conducted with less invasive techniques attaching electrodes to the scalp, but these take months of training to use.
Some experts have warned that the rapidly developing technology could have a more sinister application. There are at least a dozen laboratories in the US working on brain computer interfaces, many funded by more than $25m in grants from the US military which is interested in developing "killer robots" that could be controlled by soldiers, warriors with the brains of humans and the invincibility of machines.
Implants might also be used to control challenging behaviour in individuals with mental problems caused by Alzheimer's disease or other conditions, by inhibiting anti-social tendencies and programming in "acceptable" responses.
British scientists hailed the advance as a landmark yesterday that could bring hope to hundreds of thousands of people disabled by accidents, stroke or other diseases. Francisco Sepulveda, Reader in brain-computer interfaces at Essex University, said: "The paper in Nature is important in that it shows the first commercial attempt to use implanted technology that uses brain signals to control devices just by thinking. This technology will have immense impact for disabled individuals in the future but it will eventually be used by the able-bodied as well. It shows the sort of technology we could be exploring in the UK if there was more support for responsible animal experimentation."
Maria Stokes, professor of neuromuscular rehabilitation at the University of Southampton, said: "This is the first report showing that this specific brain computer interface technology can be used successful in humans. Even though only one person was [fully] studied, the findings are impressive, especially when you can use the system while talking."
It was not known until the experiment on Mr Nagle, whether someone paralysed years before could still produce the brain signals necessary for movement. But almost from the first test it was clear that the implanted electrodes could record patterns of neural signals, which could be filtered and interpreted by the computer, and that his brain was not broadcasting mere "noise."
The researchers were also excited by the speed with which he was able to react, 10 times faster than previous brain implants. A second team of scientists whose work with monkeys was also published in Nature today has made headway speeding the interface between brain and machine, showing it is possible to communicate information at a rate equal to typing 15 words per minute on a keyboard.
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."
Mr Nagle mastered the art of moving the computer cursor in days, a skill that had taken months for patients with electrodes fixed to their scalps. Initially, he pictured himself physically moving the computer mouse but he quickly adapted to imagining moving the cursor itself. The cursor became an extra limb, as much a part of him as his arms and legs
The success of the technology depended on its capacity to decipher the brain's electrical activity and convert it into useful action. The researchers found certain actions were accompanied by a corresponding pattern of neurons firing, but the sensor picked up only a tiny fraction of the total activity. Even a simple movement like raising an arm involved signals from many regions of the brain. Professor Donoghue likened it to dropping a microphone into a crowded room and trying to pick up the gist of all the conversations. The result was jerky, imprecise movements as Mr Nagle struggled to turn imprecise thoughts into precise action, but over time his control improved and he was eventually able to draw a rough circle with the computer cursor.
In the long term, Professor Donoghue says it should be possible to do away with heavy cables connecting patients heads to large quantities of electronic kit. Miniaturisation should lead to smaller devices that can be inserted in the brain, and the skull closed over them, like a heart pacemaker. Signals would be transmitted wirelessly from the brain to a processor worn on the belt that trigger the computer, robotic arm or other device.
Implants have drawbacks and some scientists believe they are not the best answer for people with total disability. Some objected to the experiment on Mr Nagle, saying the risks of brain damage were too great. If his brain rejects the implant, it may dissuade other researchers from pursuing the technique. Implanted electrodes are prone to cause inflammation and infection which could render them useless. Professor Donoghue is convinced the only way to give paralysed people full interaction with their environment is through electrodes embedded in their brains. "No other method gives you the power and clarity you need to transform this noisy signal into something that a patient can use," he says.
Other researchers have greater ambitions. Miguel Nicolelis, a neurobiologist at Duke University in North Carolina who taught a monkey with 86 microwires implanted in its brain to move a cursor on a screen to get a sip of juice, believes it should be possible to help the disabled walk again. He is developing an exoskeleton that could be worn like The Wrong Trousers in the Wallace and Grommit film, but with better control.
He is also working on a technique of "shared control" to overcome the problem caused by the sensor inserted in the brain picking up only a fraction of the neuronal firing that is going on. Using this technique, a robotic limb would be triggered by a basic command from the brain but the movement would be refined and performed by pre-programmed intelligence. The challenge is to develop better prosthetics controlled by more sophisticated software.
There are long years of development ahead and many hurdles to be overcome, such as the great variation in individual responses to the implants, and a tendency for the electrodes to become less efficient over time. Patients with spinal cord injuries are often young and would need to use the technology for many decades.
But the idea of using thoughts to control the world around us was once the realm of science fiction. With the development of the latest generation of brain implants, it has moved an important step closer to reality.Reuse content