In fact, two of the patients can take several steps without electrical stimulation, a sign that there's been growth of new nerve connections, said senior researcher Gregoire Courtine, chair of spinal cord fix at the Swiss Federal Institute of Technology in Lausanne. They even built personalized model spinal cords to lie in an electricity-conducting salty fluid, allowing the team to work out precisely where each electrode needed to be inserted during surgery.
"If you think about cutting the head off a chicken, it can still walk around". None of them can walk efficiently enough to outpace a wheelchair, but he says they are walking nonetheless.
The new study takes the medicine and technology of spinal stimulation even further in two ways. But an important factor in this experiment is the implants aren't working the patients' legs for them. When a command from the brain hits a spinal cord injury, that electrical signal dissipates and becomes too weak to effectively activate muscles. And so the researchers set about understanding how the nervous system responded to movements in every joint in healthy individuals, building up a "map" of what these activation patterns looked like.More news: Federer, Djokovic reach Paris Masters quarterfinals
The most surprising moment occurred, he added, when the implants were switched back off again: some of the patients' recovered abilities persisted, even in the absence of those helpful electrical pulses. "There's a complex network of information coming back into the spinal cord from the leg about where your leg is in space".
Continuous nerve stimulation overloads a person's proprioceptive system, researchers discovered.
"If you stimulate the entire spinal cord, you will activate all the muscles at the same time and block leg movement", Courtine said.More news: Oversupply Concerns Weighing on Prices, US-China Deal is Wildcard
The stimulation begins with a pulse directed at a muscle to prompt the patient to begin movement, for example a step. "After a few months, participants regained voluntary control over previously paralysed muscles without stimulation and could walk or cycle in ecological settings during spatiotemporal stimulation", Fabien Wagner and his colleagues wrote in the study. Because it disrupts the connection between the brain and the spinal cord, injuries can lead to motor and sensory deficits or, sometimes, paralysis.
These sessions helped to trigger activity-dependent plasticity, which is the nervous system's inherent ability to reorganise nerve fibres.
David Mzee, 28, suffered full paralysis of his left leg after an accident in 2010, but after the five-month program, he can walk for up to two hours with a walker using electrical stimulation, or take steps over shorter distances by himself. Within a week, the men were able to leave the treadmill and walk on the ground with continued electrical stimulation. "It's not that we're taking over control of the leg. Our goal is to develop a widely accessible treatment", Courtine said. "They might not walk around, but they will feel better and will have a lot of health benefits associated with this mobilization of their body". 'And [Tobler] needs a walker.' Courtine built a mobile app that allows the patients to turn their stimulators on or off remotely, so they could train at home after the study ended. Moritz says this staccato action might be why Courtine's patients reportedly showed stronger signs of recovery than those in previous studies did.More news: Golf Equipment Market - Continues to Impress as Expansions Gain Momentum