Master monkey's brain controls sedated 'avatar'
The brain of one monkey has been used to control the movements of another, "avatar", monkey, US scientists report.
Brain scans read the master monkey's mind and were used to
electrically stimulate the avatar's spinal cord, resulting in controlled
movement.
The team hope the method can be refined to allow paralysed people to regain control of their own body.
The findings, published in Nature Communications, have been described as "a key step forward".
Damage to the spinal cord can stop the flow of information
from the brain to the body, leaving people unable to walk or feed
themselves.
The researchers are aiming to bridge the damage with machinery.
Match electrical activity
The scientists at Harvard Medical School said they could not
justify paralysing a monkey. Instead, two were used - a master monkey
and a sedated avatar.
The master had a brain chip implanted that could monitor the activity of up to 100 neurons.
During training, the physical actions of the monkey were matched up with the patterns of electrical activity in the neurons.
The avatar had 36 electrodes implanted in the spinal cord and
tests were performed to see how stimulating different combinations of
electrodes affected movement.
The two monkeys were then hooked up so that the brain scans in one controlled movements in real time in the other.
The sedated avatar held a joystick, while the master had to think about moving a cursor up or down.
In 98% of tests, the master could correctly control the avatar's arm.
One of the researchers, Dr Ziv Williams, told the BBC: "The
goal is to take people with brain stem or spinal cord paralysis and
bypass the injury.
"The hope is ultimately to get completely natural movement, I
think it's theoretically possible, but it will require an exponential
additional effort to get to that point."
He said that giving paralysed people even a small amount of movement could dramatically alter their quality of life.
Reality or science fiction?
The idea of one brain controlling an avatar body is the stuff of blockbuster Hollywood movies.
However, Prof Christopher James, of the University of
Warwick, dismissed a future of controlling other people's bodies by
thought.
He said: "Some people may be concerned this might mean
someone taking over control of someone else's body, but the risk of this
is a no-brainer.
"Whilst the control of limbs is sophisticated, it is still
rather crude overall, plus of course in an able-bodied person their own
control over their limbs remains anyway, so no-one is going to control
anyone else's body against their wishes any time soon."
Instead, he said this was "very important research" with
"profound" implications "especially for controlling limbs in spinal cord
injury, or controlling prosthetic limbs with limb amputees".
Realising that goal will face additional challenges. Moving a
cursor up and down is a long way from the dextrous movement needed to
drink from a cup.
There are also differences in the muscles of people after
paralysis; they tend to become more rigid. And fluctuating blood
pressure may make restoring control more challenging.
Prof Bernard Conway, head of biomedical engineering at the
University of Strathclyde, said: "The work is a key step forward that
demonstrates the potential of brain machine interfaces to be used in
restoring purposeful movement to people affected by paralysis.
"However, significant work still remains to be done before
this technology will be able to be offered to the people who need it."