Optogenetics Dissection of Sleep Circuits and Functions

Abstract Defining the sufficiency and necessity of neuronal circuits in promoting natural behavior is central in modern neuroscience. Optogenetics allows modulation and observation of cellular physiology for acute and chronic interventions with millisecond precision. Microbial opsins now include a large variety of genetically encoded, light-sensitive proteins for modulating cellular physiology, from biochemical pathways, enzymatic activity, and gene expression to neuronal excitability and firing. Intrinsic activity patterns are recorded with genetically encoded indicators of cellular activity to identify behaviorally relevant motifs. Newly developed gene-targeting strategies and light-targeting devices allow for robust and selective targeting of single neurons or brain-wide ensembles. Thus, optogenetics provides ideal tools for building a bridge between neuronal identities, neuronal physiology, and behavior, as they combine high spatial and genetic selectivity with high temporal precision for controlling neural activity in the investigation of central mechanisms supporting brain functions and behaviors. Here, we will summarize optogenetic strategies and further elucidate how this technique has been used to unravel sleep circuits and sleep function.