Optogenetics, chosen as the "Method of the Year" in 2010 by Nature Methods and highlighted in the article on “Breakthroughs of the Decade” in Science, has revolutionized the way neuroscientists study the function of neural circuits underlying behaviors. Optogenetic approach is a powerful research approach to map neural circuits and study their functional roles. It is the combination of genetic and optical methods to allow reversibly control neuronal activity in targeted cells or circuits of living brain in the millisecond timescale. The field of optogenetics has made remarkable progress in mapping functional neural circuits and shown tremendous impact on behavioral neuroscience research. The course aims to enable students to understand the concepts of research questions, methodology and experimental designs through reading important optogenetic research literature focusing on the behavioral functions of neural circuits.