Optogenetics is a research technique that uses light to control selected cells, especially neurons, after they have been genetically engineered to express light-sensitive proteins called opsins.

It gives researchers highly precise control of neural circuits by cell type, location, and millisecond timing. It is used mainly in experimental neuroscience to investigate functions such as sensation, memory, movement, reward, epilepsy, and neurodegenerative disease mechanisms. In some retinal disorders, optogenetic gene therapies are being studied to restore limited light responsiveness.

A basic workflow is: deliver an opsin gene to target cells, implant or direct a light source to that tissue, then observe or manipulate the resulting cellular activity or behavior.