ABSTRACT
Recently, genetic technologies combined with optics have emerged and become necessary tools for life science. For example, green fluorescence protein (GFP) [1] is widely used as an optical tag for a target protein, and channel rhodopsin 2 (ChR2) is an effective tool for optically stimulating specific cells, which is called “Optogenetics” [2]. This can be used in transgenic mice or introduced by a virus such as an adeno-associated virus (AAV). Since “Optogenetics” is an established word for optical stimulation with a light sensitive protein, we define the technology that combines genetic technology and photonic device technology as “Photogenetics” in this chapter. Photogenetics includes fluorescent proteins such as GFP, as well as light sensitive proteins. The most important feature of photogenetics is its specific reaction with light: in GFP, a specific protein can be detected through fluorescence, and in ChR2, specific cells can be evoked through blue light. Electrical methods do not have such features, and hence are nonspecific. Figure 15.1 shows a comparison between the electrical and optical methods for measuring and stimulating biological functions.
