BiPOLES: a tool for bidirectional dual-color optogenetic control of neurons

We report BiPOLES, an optogenetic tool for balanced excitation and inhibition of neurons with light of two different colors. BiPOLES consists of the blue-light-sensitive anion-conducting channelrhodopsin ACR2 fused to the red-light-sensitive cation-conducting channelrhodopsin Chrimson in a single, trafficking-optimized tandem protein. BiPOLES enables multiple applications including potent dual-color spiking and silencing of the same neurons and dual-color optogenetic control of two independent neuronal populations.