Cell type-specific targeting strategies for optogenetics

Optogenetic techniques allow versatile, cell type-specific light-based control of cellular activity in diverse set of cells, circuits, and brain structures. Optogenetic actuators are genetically encoded light-sensitive membrane proteins that can be selectively introduced into cellular circuits in the living brain using a variety of genetic approaches. Gene targeting approaches used in optogenetic studies vary greatly in their specificity, their spatial coverage, the level of transgene expression and their potential adverse effects on neuronal cell health. Here, we describe the major gene targeting approaches utilized in optogenetics and provide a simple set of guidelines through which these approaches can be evaluated when designing an in vitro or in vivo optogenetic study.