Scientists make paralysed rats run again
Paralysed rats whose spinal cords had been severed from their brains
were made to run again using a technique that scientists say can work
for people, according to a study released Sunday.
Consistent electrical stimulation and drugs enabled the rats to walk
on their hind legs on a treadmill - bearing the full weight of the body
- within a week of being paralysed.
With the addition of physical therapy, the rodents were able after
several weeks to walk and run without stumbling for up to 30 minutes,
reported the study, published in the journal Nature Neuroscience.
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With the addition of physical therapy, the rodents were able
after several weeks to walk and run without stumbling. |
Remarkably, the animals could adjust their movements in response to
stimuli despite the lack of signals to and from the brain: when the
treadmill was reversed, for example, the rats walked backwards.
"This means that the spinal network is almost capable of cognitive
processing," explained Gregoire Courtine, a professor at Zurich
University.
"It can understand that the external world is changing, and interpret
this information to modify the way it activates muscle," he told AFP by
phone.
Earlier studies had shown that nerve networks in the spinal cord can
produce limited motion in the muscles independent of the brain or
sensory organs.
But this is the first time that researchers have been able to restore
normal or nearly normal functions.
"We can optimise the use of the circuitry in the spinal cord to the
point where the animals can sustain full weight-bearing locomotion,"
said Courtine.
"In some cases they actually walked with more consistent locomotive
patterns than non-injured animals."
The next step is to develop devices that can be implanted inside the
body.
"We are now designing neuro-prostheses, arrays of electrodes that fit
like a second skin between the vertebrae and the spinal cord," Courtine
explained.
A strip measuring three centimetres (1.2 inches) long and one
hundredth of a centimetre thick, the device is described as "minimally
invasive" because it does not penetrate into the spinal cord.
Courtine and colleagues are currently testing the neuro-prostheses on
rats, and expect to have an interface for humans within four years.
The new technique is designed to help patients with incomplete but
severe injuries, such as those who cannot walk independently. "For these
people, it is highly likely that this approach will improve their
function," he said.
The mix of electrical stimulation and physical therapy may be enough
to restore significant mobility in many patients, but the addition of
drugs "would be extremely beneficial," he added.
In the rat experiments, the researchers injected so-called
serotonergic agonists, a compound that mimics the effect of the
neurotransmitter serotonin and activates receptors in the central and
peripheral nervous system. AFP |
