Christian Wentz from MIT has designed a hat that wouldn’t look out of place at a horse race or a royal wedding. It consists of two circuit boards and an antenna, and it’s being modelled by a mouse. Wentz has wired the hat directly to the mouse’s brain and he can use it to control the animal’s behaviour with flashes of light. And most importantly, he can do it from afar.

The wireless helmet is the latest innovation in the exciting field of optogenetics, where scientists can use light to control the behaviour of both cells and entire animals. The typical set up involves loading cells – usually neurons – with a light-sensitive gatekeeper protein. When the protein sees