Rats with a spinal cord injury that left their hind legs completely paralyzed 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 program.

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.