The Thy1-Brainbow 3.1 transgene was designed by Drs. Dawen Cai and Joshua R.Sanes (Harvard University) with the mouse Thy1 (thymus cell antigen 1, theta) regulatory elements surrounding four fluorescent protein (Yellow fluorescent protein (Phialidium sp); Orange fluorescent protein: Green fluorescent protein; Far-red fluorescent protein) sequences uniquely flanked with pairs of incompatible lox sites. Specifically, this Brainbow 3.1 coding region contained (from 5' to 3') a loxP site, lox2272 site, loxN site, non-fluorescent nuclear localized derivative of phi-YFP (?NFPnls), polyA sequence, loxP site, farnesylated mOrange2, polyA sequence, lox2272 site, farnesylated EGFP, polyA sequence, loxN site, farnesylated mKate2, polyA sequence. This transgene was microinjected into C57BL/6JxCBA hybrid oocytes. Founder line 3 mice were bred with C57BL/6 and CD1 mice. Upon arrival at The Jackson Laboratory, the mice were crossed to C57BL/6J (Stock No. 000664) at least once to establish the colony.