By Clare Wilson

The brain is a complex network of some 86 billion neurons. To find out how they operate, we need to be able to record the activity of these cells. That is why the methods developed by neuroscientist Ed Boyden are so crucial. His breakthrough came in 2004 when, as a graduate student, he flashed a blue light at a nerve cell to see how it would react. Instantly, it fired. This was the birth of optogenetics, a technology that has revolutionised the study of brains and behaviour. We caught up with him to find out more.