- NEW YORK (Reuters Health) - It may seem like science fiction,
but scientists say they have developed a technology that enables a monkey
to move a cursor on a computer screen simply by thinking about it.
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- The breakthrough could someday help totally
paralyzed, ''locked-in'' patients ``operate external devices such as a
robot arm, or a computer to surf the Internet,'' explained researcher Daniella
Meeker of the California Institute of Technology in Pasadena.
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- Meeker described her team's findings
at a recent meeting of the Society for Neuroscience.
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- Their work focuses on a section of the
primate brain known as the posterior parietal cortex. Using high-tech brain
scans, the researchers determined that small clumps of cells in this region--as
few as 16--were active in the formation of the desire to carry out specific
body movements.
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- Armed with this knowledge, Meeker's group
implanted sensitive electrodes in the posterior parietal cortex of a rhesus
monkey trained to play a simple video game. The monkey's brain was first
analyzed on high-tech MRI as it used its hand to touch dots on a touch-sensitive
computer screen.
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- ``After the monkey has done this task
several times, we are able to determine, for the particular neuron, the
different patterns of electrical activity when he is planning reaches in
different directions,'' Meeker said.
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- Going one step further, her team then
trained the monkey to simply think about a movement, without reaching out
and touching the screen. A computer program, hooked up to the implanted
electrodes, interpreted the monkey's thoughts by tracking flare-ups of
brain cell activity. The computer then moved a cursor on the computer screen
in accordance with the monkey's desires--left or right, up or down, wherever
``the electrical (brain) pattern tells us the monkey is planning to reach,''
according to Meeker.
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- ``In fact,'' she said, ``we found that
he became quite reluctant to move his arm to the reach command once the
cursor was introduced into the game. Apparently it was easier just to think
about reaching.''
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- Speaking with Reuters Health, Meeker
said her group's work differs from previous research in that it seeks to
replicate the brain-motor connection ``at the level of the first inclination
to make a movement.''
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- She added, ``This supposes that much
of the downstream function--which would be normally implemented by the
rest of the brain, the spinal cord and muscles--can be relegated to intelligent
machines.''
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- Giving completely paralyzed patients
full mental control of robotic limbs or communication devices has long
been a dream of those working to free such individuals from their locked-in
state.
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- ``These patients are completely paralyzed
and cannot speak, yet they are fully conscious and aware,'' Meeker said.
Brainstem strokes, injury to the upper spinal cord or diseases such as
ALS (Lou Gehrig's disease) condemn tens of thousands of patients to such
an existence.
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- ``Restoring even the most rudimentary
communication or motor function to such patients will drastically improve
their quality of life,'' she said.
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- Of course, roadblocks remain and the
technology remains crude. Still, Meeker said her group ``can achieve over
90% accuracy'' in carrying out the simple commands the monkey has been
trained to perform so far. A technology that could replicate more complex
movements--such as handwriting a letter or playing games with a robot arm--could
still be years or decades away.
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- Even more challenging are ``Terminator''-type
applications that would allow the minds of healthy individuals to meld
with machines--allowing drivers to ``think'' their way through traffic,
for example, or granting pilots the ability to navigate the skies with
their mind.
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- ``The largest difficulty that I see with
this kind of sci-fi application is the current risk that brain surgery
presents,'' Meeker said. ``This kind of technology could save the life
of a locked-in patient, but has the potential to kill a healthy pilot if
something went wrong.''
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- However, several groups are currently
working to develop methods of tracking brain signals without the use of
surgically implanted electrodes. Such a breakthrough could lay these types
of safety concerns to rest and ``revolutionize'' the field, Meeker said.
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