Just by Thinking About it


Brain Power May Give Paralyzed Motion Control
by Guy Webster

Source: Fox News

June 9, 2000

TEMPE, Ariz. - A paralyzed person could steer an arm to maneuver a spoon or a pencil just by thinking about it, if a promising partnership of engineering and neuroscience pans out.

ASU Associate professor of bioengineering Daryl Kipke with the robotic arm that can be controlled with brain power.

In one Arizona State University laboratory, a robotic arm already mimics movements of a monkey whose brain signals are read by electrodes and used to guide the artificial arm. The monkey moves its arm upward and to the left, and the mechanical arm in the next room simultaneously moves up and to the left.

Human applications are likely within five years, says researcher Andrew Schwartz of ASU and the Neurosciences Institute in La Jolla, Calif.

"The whole program is engineering," he said. "The science is already established." The strategy relies on surgically implanting a polymer microchip with dozens or hundreds of electrodes, each reading the signals of a different brain cell. The need for surgery would restrict application to people with severe paralysis.

"If you or I could put on some kind of cap and could control a robotic arm, that would be pretty neat, but we're a long way from that," said biomedical engineer Daryl Kipke, another leader of the 30-person ASU team.

Some patients with otherwise total paralysis, or "locked-in" syndrome, can blink an eye. Their eye blinks can answer yes-or-no questions, or select from a list of choices, such as letters or directions of movement.

Jean-Dominique Bauby, former editor of the French edition of Elle magazine, wrote a widely praised book, The Diving Bell and the Butterfly, by blinking his eye as someone recited a sequence of letters. It was published in 1997, two years after a brain-stem stroke left him locked in.

But some other locked-in quadriplegics can't even move an eyelid. "If they can't even blink their eyes, they can do it with brain waves," said neuroscientist Emanuel Donchin, of the University of Illinois. His research group and others in Albany, N.Y., and Tubingen, Germany, are using electroencephalogram readings from external electrodes to enable patients to select characters from a virtual keyboard or array.

Donchin hopes for a communication speed of eight to nine characters per minute. "That's not enough for a typist, but if you're locked in, that's not bad."

Researchers at Emory University in Atlanta have had some success testing implanted electrodes in a few paralyzed patients. In these tests brain signals control a computer cursor and spell out messages.

Implantable electrodes with nerve contacts already have therapeutic uses in treating Parkinson's disease and the pain associated with spinal injuries. But, there's also another type of electrode that produces instead of reads signals. It stimulates muscles to move.

For locked-in patients, brain-implanted electrodes will be necessary to give them control over a robotic arm, predicts neuroscientist Apostolos Georgopoulos, director of the Brain Science Center at the Veterans Administration Medical Center in Minneapolis. External electrodes don't give detailed enough information about what's happening in the brain.

"The only way to have specificity in movement is to have electrodes in the brain," he said.

Designing software capable of deciphering implanted electrodes' signals is an area where the ASU researchers have made important progress, Georgopoulos said. "That's a big advance," he claims, "It's really impressive."

The signals detected from the monkey's brain as he moves his arm are transmitted to a computer that begins to recognize patterns of neuron activity that are consistently associated with particular movements. The computer instructs the robot arm to make those movements. The next step is to make the movement intentional, Schwartz said. The monkey doesn't even know about the robot arm in the other room.

In expected use by humans, a patient would know that something in his brain controlled the arm. That knowledge would add the brain's learning power to the computer power, Schwartz said. The patient's ability to steer the arm could improve with practice.

The ASU group has begun using a 3-D virtual reality setup to help the monkeys learn that they control the movement of something not attached to them. At first, the image of a ball floating in space moves parallel to the monkey's arm. Then the monkey's arm is restrained, but the its brain signals still control the ball's movement. When the animal successfully moves the ball to a target he wins a food treat.

The next step will be to replace the virtual ball with a real robot arm that the monkey can see and control.

"We'll drop a grape into the cup at the end of the arm," says Schwartz, "and the animal will have to get its neurons firing the right way to get the cup to its mouth to get the grape.

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