Optogenetics (Microbial Opsin Photostimulation)

Millisecond-precision control of genetically targeted neurons and signaling pathways using light-gated microbial opsins.

Specifications & Metrics

type: Neuromodulation & Circuit Mapping
organism: Genetically targeted neurons, cardiomyocytes, and behaving animals (C. elegans, Drosophila, rodents, primates)
control mechanism: Fiber-optic or two-photon illumination of microbial rhodopsins (Channelrhodopsin-2, Halorhodopsin, Archaerhodopsin)
pioneer: Peter Hegemann, Georg Nagel, and Karl Deisseroth (ChR2 characterization 2003, neuronal control 2005)

Following Peter Hegemann and Georg Nagel's 2003 demonstration that green-algal Channelrhodopsin-2 (ChR2) from Chlamydomonas reinhardtii functions as a light-gated cation channel, Karl Deisseroth, Ed Boyden, Feng Zhang, and Nagel demonstrated millisecond optical spike control in mammalian neurons in 2005.
Blue light (~470 nm) opens cation-conducting Channelrhodopsin-2 to depolarize and fire neurons, whereas yellow/green light activates chloride-pumping halorhodopsins (NpHR) or proton-pumping archaerhodopsins to hyperpolarize and silence firing.
Pairing cell-type-specific Cre-driver mouse lines with viral opsin delivery allows neuropharmacologists to map causal circuit connections underlying reward, fear memory, locomotion, and Parkinsonian motor symptoms in freely moving animals.