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Study: Monkey brains move cursor
Technique still a long way from human use
June 6, 2002 Posted: 2:03 PM EDT (1803 GMT)

CAPTION FOR PHOTO: Scientists say brain experiments carried out on rhesus
monkeys could one day help paralyzed people work a computer using only their
thoughts.

WASHINGTON (Reuters) -- Monkeys implanted with special electrodes moved a
cursor on a computer screen just by thinking about it, and learned how to do
it better with practice, scientists reported on Thursday.

The experiment could eventually lead to the development of better prosthetic
limbs for amputees and might even offer a way for paralyzed patients to move
again.

"They were able to move balls around, by thinking about it, in
three-dimensional space," said Andrew Schwartz, a neural physiologist at
Arizona State University who led the study.

The new field, called neuroprosthetics, is small but active. In March, a
team at Brown University in Rhode Island reported similar research in the
journal Nature.

In Schwartz's experiment, each tiny electrode was attached to a single
neuron in the motor cortex, the part of the brain where movement is
controlled.

Two rhesus macaque monkeys were fitted with 50 to 100 electrodes, which
consisted of minuscule wires about half the width of a human hair.

The monkeys had been trained to play a computer game, at first using their
arms, in which they had to move virtual balls around a three-dimensional
virtual space.

After the appropriate neurons were mapped, they were fitted with electrodes
that sent signals to the computer. "We basically strapped the animals' arms
down so they couldn't use their arms," Schwartz said.

At first the monkeys strained to use their arms but as they learned their
thoughts alone could move the cursor on the screen, they stopped trying to
move.

Writing in the journal Science, Schwartz's team said what was new in the
latest experiment was the addition of a "feedback loop" that helped the
monkeys, and the computers, learn how to make the virtual movements more
accurate. "They learn to get better and better at this," Schwartz said.

This means fewer electrodes are needed to achieve more precise movement.

"Their performance is approaching that of what we can get when they move
their own arms," Schwartz said.

Monkeys feel no pain
Schwartz said the monkeys do not feel pain from the electrodes and have been
trained to work in return for a simple drink of water. "They get used to it
and they work at it until they get tired. (Then) they stop working and just
sit there," Schwartz said.

Schwartz said it will be a long time before the technique can be tried out
in people.

"Right now the electrodes we are using are not really appropriate for human
use," Schwartz said. "They don't work every time."

The electrodes also cause some scarring that may eventually affect their
performance.

Although patients likely to want to try the method first may be desperate,
Schwartz said regulators would not be willing to approve major brain surgery
unless it was clear it was safe.

If he were paralyzed, Schwartz said, he would overlook the risk. "If I had
my druthers, I'd do it," he said.

At least one person has. Dr. Phil Kennedy, chief executive officer of Neural
Signals in Atlanta, Georgia, implanted two glass electrodes into the brain
of a quadriplegic man.

The patient was able to move a cursor across a computer screen. But it took
great effort and weeks of training.

Copyright 2002 Reuters. All rights reserved. This material may not be
published, broadcast, rewritten, or redistributed.

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