Optogenetics — a tool that enables researchers to control neurons with light — has transformed neuroscience. But the technique is invasive. Light is typically delivered via a fiber optic cable implanted in an animal’s brain. Researchers have developed a noninvasive alternative: a genetic system for controlling neurons that uses radio waves or magnetic fields instead of light. These signals can freely penetrate tissue, meaning the technique can be used on awake, behaving animals without invasive delivery systems.