A simple optogenetic system for behavioral analysis of freely moving small animals

► We made a simple optogenetic system for tracking behaving C. elegans. ► It consists of a strong LED ring array and a high-resolution CCD camera. ► We expressed ChRGR in the body wall muscle cells. ► The worm's behavior was modified by photo-activation of ChRGR. ► This system would facilitate the behavioral analysis of small genetic model animals.