Scientists in charge of the trial said a similar approach could be used on human patients with spinal injuries, with a clinical trial possible within one to two years. The study, published in the Science journal, is the first to demonstrate that a severely damaged spinal cord can adapt and recover enough to allow the brain to regain control of the legs. Researchers from the Ecole Polytechnique Fédérale de Lausanne in France experimented on rats with severed sections of spinal cord, which paralysed them by stopping their brain from sending signals to the nerves controlling their legs.
Previous experiments had shown that chemicals and electrodes implanted in the spine could take on the role of the brain and stimulate these nerves, causing the rats' legs to move involuntarily when they were placed on a treadmill. The new study went a step further by teaching the rats to walk voluntarily on solid ground, allowing the brain to grow new nerve connections down to the lower, electrically-stimulated part of their spinal cord below the injuiry. They did this by placing the rats in a special harness which held them upright, tricking their brains into thinking their spines were perfectly healthy, and putting a piece of fine Swiss chocolate a short distance away as an incentive to try to walk.
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Attempting to move towards the chocolate forced the rats' brains to grow new nerve connections to their limbs, and after two to three weeks they were able to walk on their two hind legs while held upright by the harness. Five to six weeks later, the rats had improved so much that they could run, climb stairs and even move around obstacles on two legs while using the harness - a sure sign that their movement was voluntary and therefore being controlled by their brain. Researchers said they were hopeful the same method could be applied to human patients with similar spinal cord injuries and that the first clinical trials could begin at a Zurich clinic within a year or two.
