Light shows fMRI works as advertised

Optogenetic method validates assumption underlying brain imaging technique

A quick flash of light has confirmed the key assumption justifying the use of functional magnetic resonance imaging to reveal the inner workings of living brains. In a study appearing online May 16 in Nature, researchers used light to activate nerve cells and then saw the telltale fMRI signal, demonstrating that nerve cell activity is indeed responsible for the colorful splotches appearing on fMRI images.