Optogenetics is a biological technique which involves the use of light to control cells in living tissue, typically
neurons, that have been genetically modified to
express light-sensitive
ion channels. It is a
neuromodulation method employed in
neuroscience that uses a combination of techniques from
optics and
genetics to control and monitor the activities of individual
neurons in
living tissue—even within freely-moving animals—and to precisely measure the effects of those manipulations in real-time. The key reagents used in optogenetics are light-sensitive proteins. Spatially-precise neuronal control is achieved using
optogenetic actuators like
channelrhodopsin,
halorhodopsin, and
archaerhodopsin, while temporally-precise recordings can be made with the help of
optogenetic sensors for calcium (
Aequorin,
Cameleon,
GCaMP), chloride (Clomeleon) or membrane voltage (Mermaid).