New algorithms can quickly adjust electrical signals needed for complex movement, such as walking.
In the past few years, there have been some pretty impressive breakthroughs for those suffering from partial paralysis, but a frustrating lack of successes when it comes to those who are fully paralyzed. But a new technique pioneered by scientists working on project NEUWalk at the Swiss Federal Institute for Technology (EPFL) have figured out a way to reactivate the severed spinal cords of fully paralyzed rats, allowing them to walk again via remote control.
And, the researchers say, their system is just about ready for human trials.
Previous studies have had some success in using epidural electrical stimulation (EES) to improve motor control in rodents and humans with spinal cord injuries. However, electrocuting neurons in order to get allow natural walking is no easy task, and it requires extremely quick and precise stimulation.
As the researchers wrote in a study published in Science Translational Medicine, "manual adjustment of pulse width, amplitude, and frequency" of the electrical signal being supplied to the spinal cord was required in EES treatment, until now.
Manual adjustments don't exactly work when you're trying to walk.
The team developed algorithms that can generate and accommodate feedback in real-time during leg movement, making motion natural. Well, sort of. We're talking about rats with severed spinal cords hooked up to electrodes being controlled by advanced algorithms, after all.
"We have complete control of the rat's hind legs," EPFL neuroscientist Grégoire Courtine said in a statement. "The rat has no voluntary control of its limbs, but the severed spinal cord can be reactivated and stimulated to perform natural walking. We can control in real-time how the rat moves forward and how high it lifts its legs."
The first step was to tune the EES pulses accurately enough to control the fine motor functions of a normal gait. To do this, the researchers put paralyzed rats onto a treadmill and supported them with a robotic harness. After several weeks of testing, the researchers had mapped out how to stimulate the rats' nervous systems precisely enough to get them to put one paw in front of the other.
Next, the team developed a robust algorithm that could monitor a host of factors like muscle action and ground reaction force in real-time. By feeding this information into the algorithm, EES impulses could be precisely controlled, extremely quickly.
The result, the researchers say, is a closed-loop system that can make paralyzed subjects mobile.
Courtine is quick to note in the above EPFL video that while his team hasn't found the cure for spinal cord injury-related paralysis, they've developed a system that can, and will be scaled to human size.
According to the researchers, human trials are scheduled to begin during summer 2015. The trials will take place at the EPFL, in a specially-designed Gait system, which includes a treadmill, harness support for the subjects, and myriad cameras and sensors to measure their performance.
The EPFL team's research is very exciting, and it could even be huge, but there are months, perhaps even years, of trials and experimentation ahead of them before they can make a person walk again.
It's anyone's guess when something like this could become portable and effective enough to become practical, for instance.
George Church, Harvard's mad geneticist, once told me that any new technology is a lot like a baby: It has to learn to crawl before it can walk. You don't want to oversell it. In this case, that sentiment almost couldn't be any more literal.