An unexpected group of nerves ensures that paraplegics can run again after electrotherapy. This is the result of an examination of nine with the epidural electrostimulation (EES) of the spinal cord treated paralyzed as well as on the same mice. As a team led by Grégoire Courtine from Lausanne University Hospital in Switzerland reports, a specific group is crucial for the success of the EES. If you destroy this cell population before therapy, the EES will remain unsuccessful, the working group writes in its publication in "Nature". It is noteworthy that the internal internals involved are not involved in movements in healthy people - they are apparently misused. The experts expect the findings to help further improve epidural electrostimulation.
It has been known for several years that paralysis caused by severe spinal cord injuries can be partially reversed by electrically stimulating the spinal cord below the injury. At the EES, an electrostimulator is implanted, which stimulates the dorsal roots - those leads that transport sensory signals to the spinal cord. At the same time, the paralyzed are hung in a stretcher so that their legs can move. In the Swiss study, the patients underwent a five–month training, after which they were able to walk independently again with a walker - four of them even without electrostimulation. So far, however, it was completely unclear how this healing works in detail.
In order to find out which neurons are involved in restoring the function of the legs, the team first created a detailed atlas of the nerve cells in the lower spinal cord of the mouse. The group then determined with a machine learning algorithm, which show neurons during EES increased gene activity. In doing so, she came across a group of interneturons. These cells usually belong to neuronal circuits that process signals instead of forwarding stimuli. By the EES, however, they apparently received a new function and now connected the nerve cells of the muscles with the signals from the brain, so that the limbs are deliberately controlled again. So far, however, therapy has only been experimental. In clinical practice, epidural electrostimulation is currently being used to treat chronic pain.
