Optogenetics is the combination of genetic and optical methods to control specific events in targeted cells of living tissue, even within freely moving mammals and other animals, with the temporal precision (millisecond-timescale) needed to keep pace with functioning intact biological systems.

In 2010, optogenetics was chosen as the Method of the Year across all fields of science and engineering by the interdisciplinary research journal Nature Methods (Primer on Optogenetics, EditorialCommentary). At the same time, optogenetics was highlighted in the article on “Breakthroughs of the Decade” in the scientific research journal Science Breakthrough of the Decade ; these journals also referenced recent public-access general-interest video Method of the year video and textual SciAm summaries of optogenetics.

The theoretical utility of selectively controlling precise neural activity (action potential) patterns within subtypes of cells in the brain (for example, using light to control optically-sensitized neurons) had been articulated by Francis Crick in his Kuffler Lectures at the University of California in San Diego . An early use of light to activate neurons was carried out by Richard Fork and later Rafael Yuste, who demonstrated laser activation of neurons within intact tissue, although not in a genetically-targeted manner. The earliest genetically targeted photostimulation method was demonstrated by Boris Zemelman and Gero Miesenbock, who employed Drosophila multiple-protein cascades initiated by G protein-coupled rhodopsin photoreceptors for controlling neural activity in cultured neurons. Miesenbock later employed a combination chemical-and-G-protein coupled receptor method to modulate the behavior of fruit flies with light, and the Kramer and Isacoff groups likewise employed synthesized organic photoswitches or “caged” compounds that could interact with genetically-introduced ion channels ,