For the first time, a paralyzed man with an experimental brain implant bypassed his damaged spine to manipulate an artificial limb and a computer program using only his imagination. This ScienCentral News video has more. Movin' on His Mind Americans celebrate their freedom every year on the same day that Matthew Nagle lost almost all of his. As Fourth of July fireworks flashed over Wessagussett Beach in Weymouth, Massachusetts nearly four years ago, Nagle found himself in a sea of flying fists and within minutes, Nicholas Cirignano, a man with a lengthy criminal past, plunged a hunting knife into Nagle's neck, severing his spine. Doctors had two more pieces of bad news for Nagle: He'd never walk again and his daily activity would be severely limited. But Brown University neuroscientist John Donoghue has another life in mind for people like Nagle, whose paralysis renders him highly dependent on others. Since the 1990’s, Donoghue's been working on a brain implant that can route brain signals to machines that process the signals and issue commands. Now, just by thinking about the action of opening and closing his own paralyzed hand, Nagle is able to do the same to an artificial hand.
Donoghue targets a region under the head's crown called the motor cortex where billions of nerve fibers carry commands through the spinal cord to single cells called axons. When these fire, an impulse travels down the axon to the muscle, releasing a chemical that prompts muscle to move. Donoghue developed a sensor that instead of sending signals to the severed axons feeds them into an amplifier and then a computer.
"They first go into an amplifier system that takes these very tiny voltages and makes them much bigger so they're easy to process once they're amplified," he explains. "Then they go through a computer that sorts out signals from the various noise that's embedded in the signals…and then they are passed through a mathematical decoder that takes the neural signals and converts them into a useful command. So what you eventually see is that the thought of moving is translated into the motion of the cursor on the screen." Using a special computer, Nagle can control some of his environment by pointing to different commands. He can change channels on a television, turn lights on or off and even draw. The research is part of a fast growing field called BMI, or Brain Machine Interface. Universities around the country are working on technology similar to Donoghue's---mostly in monkeys---but Donoghue was the first to find success in a person, Matthew Nagle. He's now running clinical trials in others. That may be encouraging news for the two million Americans the Christopher Reeve Paralysis Foundation estimates are living with paralysis of the extremities. Donoghue says he hopes his research will one day bring full movement back into the lives of people physically limited by paralysis. "We are developing means to truly restore function and assemble, reassemble the nervous system when it's been damaged," he says. That's still years away. For now, Donogue's next step is to take the implant wireless. This February, Nicholas Cirignano, the man who attacked Nagle, was sentenced to 10 years behind bars, not nearly enough time to satisfy the Nagles. The Patriot Ledger reported that Matthew's brother Michael gave this victim impact statement to a packed courtroom: "Some say we are put here for a purpose in life. For you, Mr. Cirignano, ask yourself, what is yours?" This research was funded by National Institutes of Health, the Neurology Institute, the W.M. Keck Foundation, and Defense Advanced Research Projects Agency (DARPA) and appeared in the January, 2005 issue of Discover Magazine. |
Click Picture for 
