This story is from the category The Brain
Date posted: 10/02/2005
No need for invasive BCI any more?
Researchers from the New York State Department Of Health and the Massachusetts Institute of Technology have shown that it is possible to use brainwaves picked up by electrodes attached to the outside of the scalp to move a cursor around a computer screen.
The Noninvasive Brain-Computer Interface allows people to learn to move a cursor around a two-dimensional computer screen by controlling the electrical noise that the brain makes as it functions, said Jonathan Wolpaw, chief of the Laboratory of Nervous System Disorders at the Wadsworth Center of the New York State Department of Health.
Recent improvements in signal processing and an algorithm that adjusts to the way an individual controls brainwave oscillations have allowed for a leap in this non-surgical roue to interface.
In a four-person study of the interface, the researchers showed that it is possible for people to learn to move a cursor to one of 16 areas of a computer screen by changing the idling oscillations of the electric field of the brain.
The oscillations are not part of the brain's operations as far as we understand, said Wolpaw. "It's like the noise a car engine makes when a car is operating."
Different areas of the brain produce a variety of rhythms that reflect brain activity. "The question is how much control can people develop over them," said Wolpaw. "In our case we're giving the brain the opportunity to learn how to use the brainwaves we record for communication control,"
A person learning to use the control might start out thinking about walking or moving a hand, said Wolpaw. The right sensory motor cortex controls the left side of the body and vice versa. "If you think about moving your right hand, generally sensory motor rhythms will tend to get smaller over the left side of your brain." Relaxing increases the amplitude of the rhythm.
The rhythm amplitude gets converted into movement of the cursor on a screen, said Wolpaw. If the rhythm gets larger the cursor goes up the screen and if it gets smaller the cursor goes down the screen, and he said. "People start out with various kinds of motor imagery until they find what's best for moving the cursor in one direction verses the other."
Although the cursor is controlled using the signals from two electrodes, the researchers' subjects wear a cap of sixty-four electrodes during the training sessions. This is so the researchers can find ways to get the most out of the signals. "We look... to see where the control is on the head and what frequencies they're controlling and we can adjust the program off-line to focus on those rhythms," he said.
The researchers are also working on a selection, or grasp function. This will make it possible to move the cursor over an object without selecting it, and will also enable the method to be used with robotic arms, said Wolpaw. They are also working on three-dimensional cursor control.
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