Brainbow technique

Individual neurons and glia in the living brain can be made to express specific fluorescent proteins using genetic engineering techniques. The cells can be imaged in brain sections with confocal microscopy, making it possible to map each one because it has a distinctive color. The importance of this brainbow technique is that it allows detailed studies of neural connectivity and circuitry.

Differential expression of five protein fluorophores—yellow, orange, red, green, and cyan derivatives of the original green fluorescent protein (GFP)—allows upwards of 90 distinct hues to color individual cells. The technique was invented in 2007 and originally allowed mapping of only a few neurons, but currently over 100 neurons can be mapped simultaneously.The brainbow technique relies on the cre/loxP genetic engineering system which has been used extensively in brain research since 1998 to control gene expression in particular cell types.