Optogenetics in Caenorhabditis elegans.

With a compact neural circuit consisting of entirely mapped 302 neurons, Caenorhabditis elegans plays an important role in the development and application of optogenetics. Optogenetics in C. elegans offers the opportunity that drastically changes experimental designs with increasing accessibility for neural activity and various cellular processes, thereby accelerating the studies on the functions of neural circuits and multicellular systems. Combining optogenetics with other approaches such as electrophysiology increases the resolution of elucidation. In particular, technologies like patterned illumination specifically developed in combination with optogenetics provide new tools to interrogate neural functions. In this chapter, we introduce the reasons to use optogenetics in C. elegans, and discuss the technical issues raised, especially for C. elegans by revisiting our chapter in the first edition of this book. Throughout the chapter, we review early and recent milestone works using optogenetics to investigate a variety of biological systems including neural and behavioral regulation.