Walking after spinal injury
June 5, 2012
SWISS researchers are giving
hope to the sufferers of spinal cord
injury, following their breakthrough
in “waking-up” the “spinal brain” of
rats with spinal cord injuries.
Published in Science, the study
involved rats with spinal cord
injuries and severe paralysis and
found that a severed section of the
spinal cord is able to make a
comeback when its own innate
intelligence and regenerative
capacity, or what study lead author
Grégoire Courtine calls the “spinal
brain”, is awakened.
“After a couple of weeks of
neurorehabilitation with a combination
of a robotic harness and electricalchemical
stimulation, our rats are
not only voluntarily initiating a
walking gait, but they are soon
sprinting, climbing up stairs and
avoiding obstacles,” Courtine said.
During the research the rats were
injected with a chemical solution of
monoamine agonists to trigger cell
responses by binding to specific
dopamine, adrenaline, and serotonin
receptors on the spinal neurons.
This chemical mix replaced
neurotransmitters released by
brainstem pathways in healthy
subjects, and excited neurons
readying them to coordinate lower
body movement.
Shortly after the injection, the
rats’ spinal cords were stimulated
electronically.
“This localised epidural stimulation
sent continuous electrical signals
through nerve fibers to the
chemically excited neurons that
control leg movement,” said
researcher Rubia van den Brand.
“All that is left was to initiate that
movement,” Brand added.
The research found that the
stimulated spinal column,
physically isolated from the brain
from the lesion down, started
taking over the task of modulating
leg movement, allowing previously
paralyzed rats to walk involuntarily
over treadmills.
According to the researchers,
these experiments revealed that
the movement of the treadmill
created sensory feedback that
initiated walking: the spinal brain
took over, and walking essentially
occurred without any input from
the rat’s actual brain.
From here, researchers replaced
the treadmill with a robotic device
that supported the subjects and
only came into play when they lost
balance, giving them the impression
of having a healthy and working
spinal column, which in turn
encouraged them to will themselves
toward a chocolate reward on the
other end of the platform.
“What they deemed will powerbased
training translated into a
fourfold increase in nerve fibers
throughout the brain and spine—a
regrowth that proves the
tremendous potential for
neuroplasticity even after severe
central nervous system injury,” said
researcher Janine Heutschi.
The researchers then found that
the newly formed fibers bypassed
the original spinal lesion and allowed
signals from the brain to reach the
spine, and that the signal was
sufficiently strong to initiate
movement over ground, without
the treadmill, meaning the rats
began to walk voluntarily towards
the reward, entirely supporting
their own weight.
“This is the world-cup of
neurorehabilitation,” said Courtine.
“Our rats have become athletes
when just weeks before they were
completely paralyzed.
“I am talking about 100%
recuperation of voluntary
movement,” he added.
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