Optogenetic actuators are proteins that modify the activity of the cell in which they are expressed when that cell is exposed to light.
These actuators can be used to induce single or multiple action potentials, suppress neural activity, or modify biochemical signaling pathways, with millisecond control over the timing of events. The most powerful and widely used actuators are opsins, which are naturally occurring light-sensitive transmembrane proteins found in a variety of organisms ranging from microbes to primates.
Optogenetic actuators can be used as found in nature or engineered to optimize functioning in neuroscientific experiments.[1]