BrainBow is a technique where cells are made to express several fluorescent proteins, in essentially random amounts. The randomness derives from feedback loops in gene expression. Mixing of fluorescence wavelengths yields a remarkable colour contrast on the single-neuron level.

The method was originally developed by Jeff W. Lichtman and Joshua R. Sanes at the Department of Neurobiology, Harvard Medical School.

Read more about BrainBow on Wikipedia or an introduction at the Harvard Gazette.

Source