Rats with a spinal cord injury that left their hind legs completely paralysed learned to walk again on their own after an intensive training course that included electrical stimulation of the brain and the spine,scientists reported on Thursday.
Researchers have known for some time that stimulation and training can improve muscle control somewhat after such injuries in animals. And last year,an international team of scientists reported the case of a 23-year-old paraplegic who regained the ability to stand for a few minutes at a time after a similar programme.
But the new study is the most comprehensive and rigorous presentation to date of what is possible,and the Swiss research team is already working on technology to test the techniques in humans.
The report,published online on Thursday in the journal Science,provides a striking demonstration of what until recently few scientists thought possible: complete rehabilitation after a disabling blow to the spinal cord. After weeks of training,many of the rats could walk as well as before the injury,and some could run.
The findings do not apply to all spinal injuries. The animals spinal columns were cut without being completely severed; there were still some nerve connections. But this is also the case for a substantial proportion perhaps a quarter to a third of people whose injuries are severe enough to confine them to a wheelchair.
In the study,a research team led by Grégoire Courtine of the Federal Institute of Technology in Lausanne,gave a group of 10 rats the same surgical injury,cutting all direct nerve connections to the hind legs but stopping short of severing the spinal cord. The rats lost the use of their hind legs,but not their front legs. The rats then began a daily regimen. With tiny vests,held upright on their back legs but left to bear their full weight,the rats tried to move toward a piece of cheese.
The scientists provided stimulation in three places: electrically,in the motor area of the brain and in the spinal cord below the injury,and chemically,infusing the wound area with drugs thought to promote growth.
And growth is what they got. After two to three weeks of 30-minute daily sessions,the rats began to take their first voluntary steps. After six weeks,all of them could walk on their own,some could run and climb stairs.