- ARLINGTON, Va. - The long-sought
ability to control the movement of prosthetic limbs with brain waves has
edged a little closer to reality.
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- In experiments published in the June 7 issue of the journal
Science, monkeys were able to move balls around in 3D space on a computer
screen just by thinking about it. With a little practice, they got even
better at it.
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- "They achieved nearly the same accuracy and speed
as normal arm movements," said senior author Andrew Schwartz, Ph.D.,
of the Department of Bioengineering at Arizona State University and the
Neurosciences Institute in San Diego.
-
- To begin with, two monkeys learned a computer game that
required moving balls around in 3D space on the screen. The balls moved
in response to the monkeys' arm movements. The monkeys were rewarded for
playing and were allowed to stop when they tired of it.
-
- Then tiny electrodes were painlessly implanted in the
monkeys' brains to record the motor control signals emitted when they moved
their arms to play the game. The recorded signals were matched against
specific arm/ball movements.
-
- Finally, the monkeys were encouraged to play the game
without using their arms. They had to move the balls on the screen using
brain signals that corresponded with the appropriate arm movements.
-
- At first they tried to use their arms. But as they realized
they could move the balls without moving their arms, they relaxed their
arms and continued the game using thought control. As they played, their
game skills improved.
-
- Controlling the movement of a prosthetic limb, however,
would require learning a wider range of movements, so the two monkeys were
given new tasks and 180-degree changes in directions.
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- "There was no significant difference between the
novel and trained target hit rates in either animal, and both monkeys improved
their performance with daily practice," the researchers reported.
-
- Even when the monkeys were not allowed to first practice
the movements with their arms, they still learned through visual feedback
to control the computer images with their brain waves. This suggests that
people who are paralyzed and have not had a chance to practice with their
arms could still learn to move objects with thought control.
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- Schwartz's group cited recent case studies indicating
that motor control centers are still active in the brain even after years
of paralysis. This activity might be harnessed to control a prosthesis,
but the technique and the electrodes used in the current experiments are
not yet ready for human testing.
-
- Schwartz's group is working in the relatively new area
of neuroprosthetics. His earlier research in this area was supported by
a Special Opportunity Award from The Whitaker Foundation. The lead author
on the current paper is Whitaker graduate fellow Dawn Taylor of Arizona
State's Department of Bioengineering.
-
- Other groups have reported some early successes in neuroprosthetic
research, mostly in animal experiments. Two years ago, researchers at Case
Western Reserve University reported activating a prosthetic implant using
human brain waves. The experiments did not require implanting electrodes
in the brain.
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- A quadriplegic wearing a hat dotted with electrodes gained
mental control of an arm prosthesis after a series of training sessions
in which he learned to regulate his beta-rhythm through biofeedback.
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- He learned to move a cursor up or down on a computer
screen just by thinking about it. Then he was connected to the neuroprosthesis.
By thinking about moving the cursor up, he opened his hand, and by thinking
"down," his hand closed. He demonstrated using the device to
pick up and hold objects like a drinking glass and a fork.
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- Editor's Note: The original
news release can be found at http://www.whitaker.org/news/schwartz.html
-
- Note: This story has been
adapted from a news release issued by Whitaker Foundation for journalists
and other members of the public. If you wish to quote from any part of
this story, please credit Whitaker Foundation as the original source. You
may also wish to include the following link in any citation: http://www.sciencedaily.com/releases/2002/06/020618073233.htm
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