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LIKE any other 25-year-old male, Matt Nagle loves to channel surf. The stocky former high school American football player flicks up and then down through the channels of his television, before adjusting the volume from the comfort of his chair. He then turns his attention to his computer, moving the mouse cursor across the screen to open an e-mail that has been waiting for him. The message "you're doing well" visibly delights him.
But Nagle has one crucial difference from most other young men his age - he is paralysed from the neck down, unable to move any of his limbs. His pale hands are strapped to the armrests of his wheelchair, unable to use a remote control or a computer mouse. Instead he has been controlling his computer and television using only the power of his mind.
Nagle, from Weymouth, Massachusetts, is the first patient to be fitted with a pioneering brain implant that uses the tiny electrical impulses produced by his brain to control electronic equipment. Simply by thinking "move left" and "move right" he can play computer games, open e-mails and even operate a prosthetic hand to grasp and move objects.
For 13 months he took part in a remarkable clinical trial where his brain was linked to a computer that interpreted the electrical signals via a 4mm square electronic chip. Tiny electrodes on the chip interpreted the electrical activity in his brain as he imagined moving his hand, converting it into the movement of the mouse cursor.
He said: "Now that I think back on it, it was kind of a trip that my brain signals were controlling a mouse, changing channels on my TV, adjusting the volume and opening e-mails.
"Maybe in a couple of years we can start moving our limbs."
Nagle's spinal cord was severed in 2001 by a stab wound in his neck after being caught up in a brawl on a beach. Since then he has been unable to move, totally reliant upon nurses to do even the simplest of tasks for him. His inspiring involvement in the BrainGate trial has now given hope to millions of paralysed people around the world who hope one day to be able to independently operate artificial, or even their own limbs.
The technology harnesses the unique power of the human brain for the first time by tapping in to the minute electrical signals, known as neurons, which brains use to communicate. In movement, an electrical pulse from a cluster of neurons will normally pass through a string of other neurons to the muscle and spark it into action. The implant uses around 100 electrodes, each thinner than a human hair, to pick up this electrical brain activity from a particular part of the brain and transmit it to a computer instead, which interprets the signal into a movement.
Scientists are also looking beyond the immediate clinical benefits of the ground-breaking research that enabled Nagle to regain some of his independence. They believe as the technology grows more sophisticated, it could be adopted by able-bodied people to control everything from computers to mobile phones.
Already the researchers behind the BrainGate implant are developing ways of making it wireless, eliminating the need to be directly connected to a computer by using infrared light to transmit the brain signals.
"The electrodes only need to come close to neurons to pick up their signals," said Professor John Donoghue, director of the brain science programme at Brown University and chief scientific officer of Cyberkinetics, the company behind the implant. "A device that transmits the signals from a small capsule inside the body will send signals wirelessly through the skin using infrared light similar to a TV remote control."
Other groups are hoping to take the technology even further. At Glasgow University, researchers have developed the first mind-controlled typewriter together with a team based in Berlin. The device uses a cap filled with sensors that pick up the electrical signals from the brain through the scalp and a computer associates these with certain movements. By "training" the computer so that it recognises the brain impulses when the wearer imagines moving their right hand and their left hand, it is possible to control an arrow that then selects letters.
Professor Roderick Murray-Smith, from Glasgow's department of computer science, claims the device is more user friendly as it does not require potentially dangerous surgery like the brain implant. He believes this could see it eventually being adapted to control mobile phones and other portable devices.
At a recent computer fair in Germany, the mind-controlled keyboard attracted a huge amount of attention from the electronics industry.
"It takes about half an hour to calibrate the device to a new user," said Murray-Smith. "It doesn't need the months of operant condition training that other interfaces need.
"It uses machine learning to make the task easier for the user, rather than the user learning how to use it. People seem to be variable as to how much they can control it, and a lot seems to be about relaxing appropriately.
"Obviously more sensitivity can be gained by implants, as you can tap in to much more specific groups of neurons, but direct implants have health risks."
In Germany, neuroscientists believe the scalp cap approach to brain sensing will even have benefits in the car industry. They are already able to control basic computer games with the brainwaves detected by their cap.
Professor Gabriel Curio, a member of the Berlin Brain-Computer Interface group at the Bernstein Centre for Computational Neuroscience in Berlin, said: "This is not just useful for helping people to control computer games. In able-bodied people it could help in reaction situations such as emergency braking while driving.
"While we don't expect the computer to brake for a driver, it may detect when a driver is about to brake by recognising the brainwaves they create before they brake. The computer can then change the layout of the car mechanics by tightening the seat belt and making the car body stiffer than before.
"It is something we are talking about with the car industry in Germany, so if a driver is about to break in half a second the car can be better prepared for that."
So far both the brain implants and the skull cap are in relatively early stages of development and it could be years before they develop the kind of sensitivity that will see them being offered commercially. The implant has the potential to produce the most dramatic results, giving the precision needed to operate robotic limbs. By using more than one implant in different parts of the brain could also be possible to carry out multiple tasks.
Brain implants could also be linked up with separate technology being developed at Glasgow University's mechanical engineering department that sends electrical impulses directly into the leg muscles of paralysed patients to help them to walk again. By linking this to the brain implant, it could allow disabled patients to realise their dreams.
But Curio insists it is unlikely implants will be used in able-bodied consumers. He said: "They do have a potential drawback due to the risk involved in the operation needed to implant them. There is a danger of infection, blood loss and the potential for developing epilepsy due to scarring of the cortical tissue in the brain."
And the technology has sparked deeper ethical fears that it could be abused. While implants could be used to help people control machines, they could also potentially be used in reverse to control humans.
Researchers at State University in New York have developed remote controlled rats, known as Roborats, by implanting electrodes into the living animals' brains that allow them to be guided with a joystick.
The scientists behind the project were able to guide the radio-controlled rats through obstacles and mazes. They hope it could one day be used to help search for survivors in collapsed buildings.
Curio, however, warned that this technology was now also a real possibility in human beings.
"There are ethical issues that must be answered as this work develops," he said. "Implants could be used in reverse by sending electrical signals instead of receiving them. It is extremely important that this is realised.
"This technology is now moving from rats to being available in humans. Obviously this is not on the agenda for patients, but it is by all means possible.
"The issue is how it is used. A knife, for example can be used to spread butter on bread or to stab someone - it all depends on the user."
Remote controlled humans do not just require implants either. Like something from Dr Who, Japanese telephone company Nippon Telegraph and Telephone Corporation is reported to have created earphone-style headsets that can control human movement.
By sending low electrical currents through the back of the ears, the headsets can make the wearer perform involuntary actions. Demonstrations of the device showed volunteers being turned either left or right with the flick of a joystick.
Dr Paul Wolpe, from the centre for bioethics at the University of Pennsylvania, said: "In the broader scheme of things, a lot of the neuroscience technologies we are developing now do have the potential to cause mischief in a variety of ways.
"What we are seeing is an increased knowledge of brain function that is going to allow a variety of technologies that may actually end up having some chilling implications for the way in which we treat each other."
In the shorter term, other neuroscience developments have the potential to infringe other human rights, Wolpe warns. He claims that as brain imaging technology develops using MRI scanning, people will find it increasingly hard to keep their own thoughts to themselves.
He said the US government is already funding research into developing better lie detectors through brain imaging. "Brain imaging is going to get there long before implantable brain technology in areas such as lie detection," he said.
"There is a threat to liberty from these brain imaging techniques that can tell quite a bit about what we are thinking and whether we are deceiving. These are much closer to coming to any kind of market and have serious ethical implications."
In the meantime, however, researchers are concentrating on finding ways of helping the millions of people left disabled by stroke and spinal cord injuries who could benefit from this research. Every day at least three people in the UK suffer a spinal cord injury.
Andy MacLeod, liaison officer at Spinal Injuries Scotland, said: "People with a high level of paralysis are entirely reliant on other people and even something as simple as needing to itch your nose can be maddening.
"This kind of technology in the future could help them regain some independence, but it must be emphasised that it will be many years before this is available as a treatment.
"It is also worth remembering that while the implant worked in one participant in the trial, it did not work at all for another, so it obviously has a long way to go."
But for Matt Nagle, the experience of being able to carry out tasks he had once taken for granted has transformed his life and given him new hope.
"I just thought it and I had control of the cursor on the screen," he said. "It meant more independence as far as changing my television, opening up my shades and turning on my lights which right now the nurse has got to come down and do for me. I can't put it into words. I used my brain."
BRAIN POWER
THE average human brain weighs around three pounds and contains more than 100 billion neurons that communicate with each other through tiny electrical signals. The power it generates is thought to be enough to power a 10-watt lightbulb.
The human brain is capable of subconsciously controlling 'lower' or involuntary activities such as heartbeat, respiration and digestion, together with 'higher' order activities such as conscious thought, reasoning and movement. It is generally regarded as being more capable of these higher order activities than any other species.
Humans have evolved the biggest brains compared with body size in the animal kingdom, accounting for 2% of the human body weight. This has created extra capacity to carry out advanced brain functions such as speech, emotions and social interaction.
To power this , the human brain uses about 20% of all the oxygen and energy taken in by the body. About 750ml of blood pumps through the human brain, which consists of over 78% water, every minute. Processes such as sleeping and dreaming are also believed to be crucial in helping to store memories and brain development.
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