Running repairs

THE past few months have been a busy time for research into ways to help people paralysed by spinal injury use signals from their brains to control mechanical limbs. If that could be done routinely, it would be an enormous boon to the disabled. But not, perhaps, as enormous as what is being proposed by Grégoire Courtine, of the Federal Institute of Technology in Lausanne, Switzerland. For he and his colleagues have just published a paper in Science in which they explain how they coaxed the paralysed to walk again. And not just to walk, but to run, avoid obstacles and even sprint up a staircase. Unfortunately for those crippled by injury, the paralysed creatures in question were rats. But the results are so extraordinary that they should give hope to human sufferers.

Dr Courtine paralysed his rats by cutting their spinal cords in two places, so that the animals could no longer move their hind legs. The cuts he made did not completely sever the cord, so some nerve fibres still ran from the rats' brains to their lower bodies, but the signals transmitted by these fibres were not powerful enough to allow a rat to use its hind legs. These injuries are similar to those of many people who have suffered spinal damage.