A paralyzed man with a small sensor implanted in his brain was able to control a computer, a television and a robot using only his thoughts, scientists reported today. The development offers hope that in the future, people with spinal cord injuries, Lou Gehrig’s disease or other ailments that impair movement might be able to better communicate with or control their world. “If your brain can do it, we can tap into it,’’ said John P. Donoghue, a professor at Brown University who led the development of the system and was the senior author of a report published today in...