[monkeywire] Monkeys Control Robotic Arm With Brain Implants
francisco at tweakfilms.com
Mon Oct 13 13:01:42 EDT 2003
Monkeys Control Robotic Arm With Brain Implants
By Rick Weiss
Washington Post Staff Writer
Monday, October 13, 2003; Page A01
Scientists in North Carolina have built a brain implant that lets
monkeys control a robotic arm with their thoughts, marking the first
time that mental intentions have been harnessed to move a mechanical
The technology could someday allow people with paralyzing spinal cord
injuries to operate machines or tools with their thoughts as naturally
as others today do with their hands. It might even allow some paralyzed
people to move their own arms or legs again, by transmitting the
brain's directions not to a machine but directly to the muscles in
those latent limbs.
The brain implants could also allow scientists or soldiers to control,
hands-free, small robots that could perform tasks in inhospitable
environments or in war zones.
In the new experiments, monkeys with wires running from their brains to
a robotic arm were able to use their thoughts to make the arm perform
tasks. But before long, the scientists said, they will upgrade the
implants so the monkeys can transmit their mental commands to machines
"It's a major advance," University of Washington neuroscientist
Eberhard E. Fetz said of the monkey studies. "This bodes well for the
success of brain-machine interfaces."
The experiments, led by Miguel A.L. Nicolelis of Duke University in
Durham, N.C., and published today in the journal PLoS Biology, are the
latest in a progression of increasingly science fiction-like studies in
which animals -- and in a few cases people -- have learned to use the
brain's subtle electrical signals to operate simple devices.
Until now, those achievements have been limited to "virtual" actions,
such as making a cursor move across a computer screen, or to small
two-dimensional actions such as flipping a little lever that is wired
to the brain.
The new work is the first in which any animal has learned to use its
brain to move a robotic device in all directions in space and to
perform a mixture of interrelated movements -- such as reaching toward
an object, grasping it and adjusting the grip strength depending on how
heavy the object is.
"This is where you want to be," said Karen A. Moxon, a professor of
biomedical engineering at Drexel University in Philadelphia. "It's one
thing to be able to communicate with a video screen. But to move
something in the physical world is a real technological feat. And
Nicolelis has taken this work to a new level by quantifying the
neuroscience behind it."
The device relies on tiny electrodes, each one resembling a wire
thinner than a human hair. After removing patches of skull from two
monkeys to expose the outer surface of their brains, Nicolelis and his
colleagues stuck 96 of those tiny wires about a millimeter deep in one
monkey's brain and 320 of them in the other animal's brain.
The surgeries were painstaking, taking about 10 hours, and ended with
the pouring of a substance like dental cement over the area to
substitute for the missing bits of skull.
The monkeys were unaffected by the surgery, Nicolelis said. But now
they had tufts of wires protruding from their heads, which could be
hooked up to other wires that ran through a computer and on to a large
Then came the training, with the monkeys first learning to move the
robot arm with a joystick. The arm was kept in a separate room -- "If
you put a 50-kilogram robot in front of them, they get very nervous,"
Nicolelis said -- but the monkeys could track their progress by
watching a schematic representation of the arm and its motions on a
The monkeys quickly learned how to use the joystick to make the arm
reach and grasp for objects, and how to adjust their grip on the
joystick to vary the robotic hand's grip strength. They could see on
the monitor when they missed their target or dropped it for having too
light a grip, and they were rewarded with sips of juice when they
performed their tasks successfully.
While the monkeys trained, a computer tracked the patterns of
bioelectrical activity in the animals' brains. The computer figured out
that certain patterns amounted to a command to "reach." Others, it
became clear, meant "grasp." Gradually, the computer learned to "read"
the monkeys' minds.
Then the researchers did something radical: They unplugged the joystick
so the robotic arm's movements depended completely on a monkey's brain
activity. In effect, the computer that had been studying the animal's
neural firing patterns was now serving as an interpreter, decoding the
brain signals according to what it had learned from the joystick games
and then sending the appropriate instructions to the mechanical arm.
At first, Nicolelis said, the monkey kept moving the joystick, not
realizing that her own brain was now solely in charge of the arm's
movements. Then, he said, an amazing thing happened.
"We're looking, and she stops moving her arm," he said, "but the cursor
keeps playing the game and the robot arm is moving around."
The animal was controlling the robot with its thoughts.
"We couldn't speak. It was dead silence," Nicolelis said. "No one
wanted to verbalize what was happening. And she continued to do that
for almost an hour."
At first, the animals' performance declined compared to the sessions on
the joystick. But after just a day or so, the control was so smooth it
seemed the animals had accepted the mechanical arm as their own.
"It's quite plausible that the perception is you're extended into the
robot arm, or the arm is an extension of you," agreed the University of
Washington's Fetz, a pioneer in the field of brain-controlled devices.
John P. Donoghue, a neuroscientist at Brown University developing a
similar system, said paralyzed patients would be the first to benefit
by gaining an ability to type and communicate on the Web, but the list
of potential applications is endless, he said. The devices may even
allow quadriplegics to move their own limbs again by sending signals
from the brain to various muscles, leaping over the severed nerves that
caused their paralysis.
"Once you have an output signal out of the brain that you can
interpret, the possibilities of what you can do with those signals are
immense," said Donoghue, who recently co-founded a company,
Cyberkinetics Inc. of Foxboro, Mass., to capitalize on the technology.
Both he and Nicolelis hope to get permission from the Food and Drug
Administration to begin experiments in people next year. Nicolelis also
is developing a system that would transmit signals from each of the
hundreds of brain electrodes to a portable receiver, so his monkeys --
or human subjects -- could be free of external wires and move around
while they turn their thoughts into mechanical actions.
"It's like multiple cellular phone lines," Nicolelis said. "As my
mother said, 'You can dial your brain now.' "
Significant challenges remain if the technology is to find widespread
application in people. Although earlier experiments suggest the
electrodes are safe and able to continue functioning for three years or
more, longer-term safety studies are needed, and implants with far more
electrodes may be required to accomplish anything more than the
"For something basic like grasping a cup of coffee or brushing your
teeth, apparently you could do almost all of this with this kind of
prosthesis," said Idan Segev, director of the center for
neurocomputation at Hebrew University in Jerusalem. "If you were a
pianist and had a spinal cord injury and you wanted to play Chopin
again, then 500 neurons is not enough."
Still, Segev expressed astonishment at how much the monkeys were able
to do with signals from only a few hundred of the brain's 100 billion
or so nerve cells -- evidence, he said, that "the brain uses a lot of
backup and a lot of redundancy."
That may explain one of the more interesting findings of the Duke
experiments, he and others said: that neurons not usually involved in
body movements, including those usually involved in sensory input
rather than motor output, were easily recruited to help operate the
robotic arm when electrodes were implanted there.
Asked if the monkeys seemed to mind the experiments, Nicolelis answered
with an emphatic "No."
"If anything, they're enjoying themselves playing these games. It
enriches their lives," he said. "You don't have to do anything to get
these guys into their chair. They go right there. That's play time."
© 2003 The Washington Post Company
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