Maybe the parents of neurons can tell their progeny apart, but researchers have a harder time disentangling one brain cell from the horde as they try to tease apart the inner workings of the brain's subsystems. A new labeling technique published in Nature may go a long way toward sorting out the chatter between cells. Researchers engineered neurons to randomly express one of nearly 90 different combinations of red, cyan and yellow fluorescent proteins, resulting in "brainbows" such as this set of multicolored axons projecting from the oculomotor nerve of a mouse.