Table 1.

Overview of optogenetic tools indicating opsin name, family, type and optimal wavelength, ion permeability, and defining properties

Opsin	Family	Opsin type	Optimal wavelength	Ion permeability	Defining properties and references
ChR2	Channelrhodopsin	Ion channel	460 nm	Mono and divalent cations	Depolarizing Single spike precision from 5 to 30 Hz [87]
ChETA	Channelrhodopsin	Ion channel	490 nm	Mono and divalent cations	Depolarizing Single spike precision up to 200 Hz Rapid recovery from inactivation [88]
NpHR	Halorhodopsin	Ion pump	580 nm	Chloride	Hyperpolarizing Single spike precision [89]
eNpHR3.0	Halorhodopsin	Ion pump	590 nm	Chloride	Hyperpolarizing Single spike precision Enhanced membrane localization Large photocurrent No ER accumulation [90]
Jaws	Cruxhalorhodopsin	Ion pump	600 nm	Chloride	Hyperpolarizing Also sensitive to red light & non-invasive stimulation through intact skull [91]
Arch	Archaerhodopsin	Ion pump	575 nm	Proton	Hyperpolarizing Quicker inactivation than NpHR [92]
ArchT	Archaerhodopsin	Ion pump	575 nm	Proton	Hyperpolarizing Greater light sensitivity than Arch [93]
Chrimson	Channelrhodopsin	Ion channel	625 nm	Mono and divalent cations	Red shifted Supports two color stimulation in combination with Chronos [94]
Chronos	Channelrhodopsin	Ion channel	470 nm	Mono and divalent cations	Faster kinetics light sensitivity Used in combination with Chrimson for two color stimulation [94]
iC1C2	Channelrhodopsin	Ion channel	470 nm	Chloride	Hyperpolarizing Optogenetic silencing more efficient & physiological than conventional ion pumps [95]
Step Function Opsins (SFO)	Channelrhodopsin	Ion channel	460 nm ON 546 nm OFF	Mono and divalent cations	Bistable opsin discretely activated by 460 nm and inactivated by 546 nm allowing stable steps in membrane potential with ms precision [96]