Spinal cord injuries can be devastating. Depending on where along the spine the injury happens, a person’s ability to move can be seriously affected — or even obliterated completely, resulting in paralysis. That’s because the spinal cord houses motor neurons, which carry signals from the brain to the body’s muscles. Doctors have long thought that reversing paralysis is impossible, but new research in the journal Nature shows that the body can relearn how to move.

In the new paper, a team of scientists led by Grégoire Courtine, Ph.D., of the Center for Neuroprosthetics and Brain Mind Institute in Lausanne, Switzerland, shows that paraplegic patients can learn to move again. And it’s all thanks to the help of spinal cord implants that send out waves of electrical activity to the neighboring motor neurons. Research in this field is moving at an impressive pace, with more and more scientists showing that paralysis can be reversed.

The video above shows the remarkable progress of the three paralyzed men involved in the study as the neuroelectrical signals retrained their bodies.

Nervous Tissue: Spinal Cord Motor Neuron
Motor neurons in the spinal cord transmit signals from the brain to muscles, telling them to move.

The researchers took advantage of the fact that the brain communicates through electrical signals and that its neurons can even be reorganized by them, depending on which signals are most often used. This idea is known as brain “plasticity” — the notion that its cells are constantly making new connections and forming new pathways to accommodate new inputs. If the injured parts of the spinal cord could be “activated” using electricity in the same way they would if they were inducing a specific movement, the team thought, then maybe pairing those external signals with certain movements could help the brain reorganize so that it eventually could move without that external stimulation.

So, using a technique called epidural electric stimulation (EES), the team used an implanted pulse generator to shoot out carefully-timed jolts of electricity to the parts of the spinal cord known to be involved with certain movements.

“Within one week,” they write, “this spatiotemporal stimulation had reestablished adaptive control of paralysed muscles during overground walking.”

Clearly, the ability for the brain to communicate via the spinal cord’s neurons with the body’s muscles had improved. After a few months, the team writes, “the participants regained voluntary control over previously paralysed muscles without stimulation and could walk or cycle in ecological settings during spatiotemporal stimulation.”

University of Washington rehabilitation medicine expert Chet Moritz, Ph.D., who was not involved in the research, published a related news article in Nature Neuroscience alongside the new paper. “Rather than a complete disconnection between the brain and the spinal cord,” he wrote, “it now appears that many people can regain the ability to control their paralyzed limbs and even walk again through the innovative combination of spinal stimulation and rehabilitation practice.”

The fact that the patients’ ability to control movement continued even after treatment, he continued, “suggests that this stimulation combined with rehabilitation is actually helping to direct plasticity and healing of the nervous system around the injury.” In other words, Courtine and his team have accomplished, using a couple of well-timed jolts, what was long thought to be impossible.