Walking on a treadmill is no great feat, unless your legs are being moved by a robotic device connected to your brain. A new brain-computer interface allows a person to walk using a pair of mechanical leg braces controlled by brain signals (above), as reported on arXiv. The device has only been tested on able-bodied people, and while it has limitations, it lays a foundation for helping people with paralysis walk again. Its an important step toward helping people with lower limb paralysis, said biomedical engineer Matt Fifer of Johns Hopkins University, who has done similar work but was not involved with the study. But there are lots of challenges still, he said.