Optogenetics

Optogenetics is a biological technique to control the activity of neurons or other cell types with light. This is achieved by expression of light-sensitive ion channels, pumps or enzymes specifically in the target cells. On the level of individual cells, light-activated enzymes and transcription factors allow precise control of biochemical signaling pathways. In systems neuroscience, the ability to control the activity of a genetically defined set of neurons has been used to understand their contribution to decision making, learning, fear memory, mating, addiction, feeding, and locomotion. In a first medical application of optogenetic technology, vision was partially restored in a blind patient. Optogenetic techniques have also been introduced to map the functional connectivity of the brain. By altering the activity of genetically labelled neurons with light and using imaging and electrophysiology techniques to record the activity of other cells, researchers can identify the statistical dependencies between cells and brain regions. In a broader sense, optogenetics also includes methods to record cellular activity with genetically encoded indicators. 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. At the same time, optogenetics was highlighted in the article on "Breakthroughs of the Decade" in the academic research journal Science. In 1979, Francis Crick suggested that controlling all cells of one type in the brain, while leaving the others more or less unaltered, is a real challenge for neuroscience. Francis Crick speculated that a technology using light might be useful to control neuronal activity with temporal and spatial precision but at the time there was no technique to make neurons responsive to light. By early 1990s LC Katz and E Callaway had shown that light could uncage glutamate. Heberle and Büldt in 1994 had already shown functional heterologous expression of a bacteriorhodopsin for light-activated ion flow in yeast.