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A general overview of the current state of medical brain-computer interface technology has been posted recently by It tells the story of Matt Nagle who made history by moving the mouse cursor on his computer screen entirely with his mind in June 2004. When he went on to open e-mails and use a TV remote control, it sent waves of excitement through the neuroscience research community. Nagle’s accomplishments were doubly sensational: not only was he the first almost fully paralyzed person to do this, but he was also the first to do it entirely with his mind.

Desperate to regain normalcy, the 25-year-old paraplegic — a former football star from Massachusetts who was stabbed trying to help his friends in a brawl — agreed to take part in a study using the BrainGate Neural Interface System. After surgeons implanted 96 tiny electrical sensors into Nagle’s brain, a computer decoded the information in his brain cells, allowing him to use a simple detached robotic arm to manipulate a mouse cursor. Within a year, his decoded “thoughts” could make the arm move physical objects, making him BrainGate’s glowing success story.

Almost seven years later, however, the technology is still experimental, and the ultimate goal of restoring movement to deadened human limbs or attached prosthetic arms remains out of reach. To finally achieve it, researchers will need a deeper understanding of how the brain controls limb movements. They’ll also need to learn how to build and implant electrical sensors sturdy enough to last for years in our hostile brain matter. But there has been major progress overcoming these and other barriers recently, and as a result researchers are embarking on a new round of experiments in which paraplegics are using robot arms to do much more complex movements than Nagle could — perhaps even including picking up a cup of water and taking a sip.

“Progress is booming,” says John Donoghue, a neuroscientist on the BrainGate team and director of the Brown University Brain Institute. “But this [technology] takes time and patient research, and we don’t want to push ahead without doing things properly.”

Brain-machine interface research is more than a century old, having started when British and German doctors began stimulating the brain with electricity, according to Daofen Chen, a program director for neurological diseases and motor coordination at the National Institutes of Health. But it wasn’t until a decade ago that this field was transformed by technology.

To explain the high-tech robotic tools we have today, Chen draws a simple analogy: Imagine there is a building with many rooms, filled with people. You’ve been trying to eavesdrop on their conversations for a while, but you’ve never had good microphones to record their voices. Now, advances in nanotechnology allow you to stick in a bunch of small, high-quality microphones into these rooms and record everything. This is what neuroengineers have done by implanting micro-electrodes into a patient’s brain and recording its electrical impulses.

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