It
has finally been done. Neuron signals are been successfully
converted as usable data able to drive neuron excitation and control
in a paralyzed muscle. It will never be the optimum solution and it
will not replace damaged tissue but it will allow organs and muscles
to function almost naturally after damage.
Just
allowing a quadriplegic to restore motor function is a huge first
step and important in terms of preparing for eventual cures that are
no longer far away.
We
should expect to see the young and middle aged who retain cognitive
function able to get out of their wheel chairs pretty completely just
from this work. It is very good news.
Neuroprosthesis
restores hand movement in paralyzed monkeys
By Darren Quick
01:31 April 20, 2012
Researchers have
developed a neuroprosthesis that restores hand movement in paralyzed
monkeys (Photo: Shutterstock)
Researchers at
Northwestern University have developed a neuroprosthesis that
restores complex movement in the paralyzed hands of monkeys. By
implanting a multi-electrode array directly into the brain of the
monkeys, they were able to detect the signals that generate arm and
hand movements. These signals were deciphered by a computer and
relayed to a functional electrical stimulation (FES) device,
bypassing the spinal cord to deliver an electrical current to the
paralyzed muscles. With a lag time of just 40 milliseconds, the
system enabled voluntary and complex movement of a paralyzed hand.
The experiments were
carried out on two healthy monkeys, whose electrical brain and muscle
signals were recorded by the implanted electrodes when they grasped,
lifted and released a ball into a small tube. Using these recordings,
the researchers developed an algorithm to decode the monkeys’ brain
signals and predict the patterns of muscle activity that occurred
when they wanted to move the ball.
The monkeys were then
given an anesthetic to locally block nerve activity at the elbow,
resulting in temporary paralysis of the hand. The multi-electrode
array and FES device – which combine to form the neuroprosthesis –
allowed the monkeys to regain movement in the paralyzed hand and pick
up and move the ball with almost the same level of dexterity as they
did before the paralysis.
“The monkey won’t
use his hand perfectly, but there is a process of motor learning that
we think is very similar to the process you go through when you learn
to use a new computer mouse or a different tennis racquet. Things are
different and you learn to adjust to them,” said Lee E. Miller, the
Edgar C. Stuntz Distinguished Professor in Neuroscience at
Northwestern University Feinberg School of Medicine and the lead
investigator of the study.
Dr. Miller’s team
also performed grip strength tests, and found that the
neuroprosthesis enabled voluntary and intentional adjustments in
force and grip strength – key factors in successfully performing
everyday tasks naturally.
The multi-electrode
array implant detects the activity of about 100 neurons in the brain,
which is just a fraction of the millions of neurons involved in
making the hand movements. However, Miller points out that the
neurons they are detecting are output neurons normally responsible
for sending signals to the muscles.
“Behind these
neurons are many others that are making the calculations the brain
needs in order to control movement. We are looking at the end result
from all those calculations,” Miller said.
Miller added that,
while the temporary nerve block used in the study is a useful model
of paralysis, it doesn’t replicate the chronic changes that occur
after prolonged brain and spinal cord injuries. For this reason, the
next test for the system will be in primates suffering long-term
paralysis to study how the brain changes as it continues to use the
device.
However, the ultimate
aim for the team is for the system to restore movement in human
paralysis sufferers. “This connection from brain to muscles might
someday be used to help patients paralyzed due to spinal cord injury
perform activities of daily living and achieve greater independence,”
said Miller.
The results of the
Northwestern University team’s study, which was funded by the
National Institutes of Health (NIH), appears in the journal Nature.
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