Author: By Steve Connor, Science Editor
The astonishing feat is being seen as a major breakthrough in the development
of robotic prosthetic limbs and other automated devices that can be
manipulated by paralysed patients using mind control alone.
Scientists eventually plan to use the technology in the development of
prosthetics for people with spinal cord injuries or conditions such as motor
neurone disease, where total paralysis leaves few other options for
controlling artificial limbs or wheelchairs. They hope one day to develop
robotic machines that feel like a natural extension of the human body, which
would enable the technology to be adapted for a wide variety of purposes,
from driving a car to operating a fork-lift truck.
Andrew Schwartz, professor of neurobiology at the University of Pittsburgh,
said that the monkeys were able to move the robot arm to bring pieces of
marshmallow or fruit to their mouths in a set of “fluid and
“Now we are beginning to understand how the brain works using
brain-machine interface technology,” said Dr Schwartz, whose study is
published online in the journal Nature.
Video courtesy of Andrew Schwartz/ Univerisity of Pittsburgh
“The more we understand about the brain, the better we’ll be able to
treat a wide range of brain disorders, everything from Parkinson’s disease
and paralysis to, eventually, Alzheimer’s disease and perhaps even mental
illness,” he said.
The study is part of a larger effort to find ways of tapping into the brain’s
complicated electrical activity that controls the movement of muscles.
Eventually, scientists hope to develop a way of detecting brain patterns
that signify a person’s intentions regarding the movement of a limb.
The technology is known as the “brain-machine interface” which hopes
to connect the silicon hardware of the microprocessor with the carbon-based “software”
of the human nervous system so that machines can be controlled by the mind.
“Our immediate goal is to make a prosthetic device for people with total
paralysis. Ultimately, our goal is to better understand brain complexity,”
Dr Schwartz said.
The monkeys in the experiment had been initially trained to control the robot
arm with a joystick operated by the animals’ own hands. Later on, the
monkeys’ arms were gently restrained and they were trained to use electrical
patterns in the motor centre of their brain ? which controls muscle
movements ? to operate the robotic arm.
The scientists said that they were astonished to find how easy it was for them
to train the monkeys to move the robotic arm, which appeared to be readily
accepted by the animals as a useful eating tool.
The scientists used electrodes that monitored a representative sample of about
100 brain cells out of the many millions that are activated when the motor
centre is involved in muscular movement. The electrical patterns were sent
to a computer which had been programmed to analyse the patterns and use them
to control the movement of the robotic arm, which consisted of a shoulder
joint, an elbow joint and a claw-like gripper “hand”.
“The monkey learns by first observing the movement, which activates the
brain cells as if he were doing it. It’s a lot like sports training, where
trainers have athletes first imagine that they are performing the movements
they desire,” Dr Schwartz said.
The robotic arm used in the experiment had five degrees of freedom ? three at
the shoulder, one at the elbow and one at the hand, which was supposed to
emulate the movement of the human arm. The training of the monkeys took
several days using food as rewards.
Previous work by the group has concentrated on training monkeys to move
cursors of a computer screen but the latest study using a robotic arm
involved a more complicated system of movements, the scientists said.
John Kalaska, of the University of Montreal, said that the experiment is the
first demonstrated use of “brain-machine interface technology” to
perform a practical behavioural act such as feeding. “It represents the
current state of the art in the development of neuroprosthetic controllers
for complex arm-like robots that could one day, in principle, help patients
perform many everyday tasks such as eating, drinking from a glass or using a
tool,” Dr Kalaska said.
“One encouraging finding was how readily the monkeys learnt to control
the robot… Equally encouraging was how naturally the monkeys controlled
and interacted with the robot,” he said.
“They made curved trajectories of the gripper through space to avoid
obstacles, made rapid corrections in the trajectory when the experimenter
unexpectedly changed the location of the food morsel, and even used the
gripper as a prop to push a loose treat from their lips into their mouth,”
Dr Kalaska said.
In 2000, scientists at the Massachusetts Institute of Technology were the
first to show that it is possible to record the neural activity in a
monkey’s brain and send it over the internet to control the movement of a
remotely controlled robotic arm in a laboratory 600 miles away. The team
also used microelectrodes implanted into the monkey’s brain but it did not
involve using the robot arm for a useful task such as feeding.
Dr Kalaska said the next task was to develop a way of sending sensory
information back to the monkey through the robotic arm so that the animal
knows how hard to grip an object, which is essential for human interactions.
“For physical interactions with the environment, the subject must also be
able to sense and control the forces exerted by the robot on any object or
surface so that, for instance, they can pick up an object with a strong
enough grip to prevent it slipping from the robotic hand but not so strong
as to crush it,” he said. “These and other technical issues are
challenging, but not insurmountable.”
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