Monkeys in study learn to control robotic arms with brain
11/5/2005 15:08
In a latest study, monkeys have learnt to use their brain signals to
control a robotic arm just as if it were their own appendage, US scientists
reported yesterday.
The findings, showing extraordinary adaptability of the
primate brains, may lead to clinical success of brain-operated devices to give
the handicapped the ability to control their environment, said the researchers
at Duke University Medical School.
Led by neurobiologist Miguel Nicolelis,
the researchers published their findings in the May 11, 2005, issue of the
Journal of Neuroscience.
They performed detailed analysis of the mass of
neural data that emerged from experiments reported in 2003, in which the
researchers discovered for the first time that monkeys were able to control a
robot arm with only their brain signals.
But after these experiments, a major
question remained about how the animals' brains adapted to control an robotic
appendage, according to Nicolelis.
Thus, drawing on the extensive data from
these experiments, the researchers analyzed very carefully what happens
functionally to the brain cells and the brain cell ensembles in multiple brain
areas during this transition.
And they found clearly that a large percentage
of the neurons become more correlated to the operation of the robot arm than to
the animal's own arm.
The analysis revealed that, while the animals were
still able to use their own arms, some brain cells formerly used for that
control shifted to control of the robotic arm. The animal was simultaneously
doing one thing with its own arm and something else with the robotic
arm.
"So, our hypothesis is that the adaptation of brain structures allows
the expansion of capability to use an artificial appendage with no loss of
function, because the animal can flip back and forth between using the two.
Depending on the goal, the animal could use its own arm or the robotic arm, and
in some cases both.
This finding supports the theory that the brain has
extraordinary abilities to adapt to incorporate artificial tools, whether
directly controlled by the brain or through the appendages, Nicolelis said in a
statement.
"Our brain representations of the body are adaptable enough to
incorporate any tools that we create to interact with the environment. This may
include a robot appendage, but it may also include using a computer keyboard or
a tennis racket. In any such case, the properties of this tool become
incorporated into our neuronal space."
The analysis suggested that a
fundamental trait of higher primates, in particular apes and humans, is the
ability to incorporate these tools into the very structure of the brain. These
findings also have important clinical significance, the researchers
said.
"This latest analysis shows that the device is incorporated very
intimately as a natural extension of the brain," Nicolelis said, "this is a
fundamentally important property if brain-machine interface technology is to
have any clinical future."
In the future, truly useful "neuroprosthetic"
devices will have to be dextrous enough to give patients a full range of
mobility in robot arms, hands or other appendages, he said.
Xinhua
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