Paraplegic rats walk again after therapy, now we know why

Paraplegic rats walk again in response to neuroprosthetic rehabilitation that allows the brain to elaborate new routes so that motor commands about walking, swimming and even climbing staircases reach spinal cord execution centers below the injury. With the help of robot-assisted rehabilitation and electrochemical spinal cord stimulation, rats with clinically-relevant spinal cord injury regain control of their otherwise paralyzed limbs. But how do brain commands - about walking, swimming and stair-climbing - bypass the injury and still reach the spinal cord to execute these complex tasks' EPFL scientists have observed for the first time that the brain reroutes task-specific motor commands through alternative pathways originating in the brainstem and projecting to the spinal cord. The therapy triggers the growth of new connections from the motor cortex into the brainstem and from the brainstem into the spinal cord, thus reconnecting the brain with the spinal cord below the injury. The results are published March 19^th . "The brain develops new anatomical connections through regions of the nervous system that are still intact after injury," says EPFL scientist Grégoire Courtine. "The brain essentially rewires circuits from the cerebral cortex, brainstem and spinal cord-an extensive rewiring that we exposed to unprecedented detail using next-generation whole brain-spinal cord microscopy." "The recovery is not spontaneous," furthers EPFL scientist and lead author Léonie Asboth.