Optogenetics Tools

Optogenetics is a technology that integrates multiple disciplines such as optics, software control, gene manipulation technology, and electrophysiology. The main principle is to use gene manipulation technology to transfer optical-sensing genes (such as ChR2, eBR, NaHR3.0, Arch or OptoXR, etc.) into specific types of cells in the nervous system. optical sensitive ion channels will be selective for the passage of cations or anions under different wavelengths of optical stimulation, such as Cl-, Na+, H+, K+, which will cause changes in the membrane potential on both sides of the cell membrane to achieve selective excitement to the cell or the purpose of suppression.

Fig.1 The concepts of different actuators for activation and inhibition of cells.

Optic-sensitive proteins can be used to activate neurons, inhibit neurons and control G protein coupling signals in vivo. The typical optic-sensitive channel protein used to activate neurons is ChR2 (channelrhodopsin). ChR2 is an ion channel protein, which will induce the opening of cation channels after the excitation of blue optic (the maximum excitation peak is around 470nm wavelength), thereby promoting the depolarization of neurons, inducing action potentials, and activating neurons. A typical optic-sensitive protein that inhibits neuronal activity is NpHR (halorhodopsin), which will induce the opening of chloride channels under the excitation of yellow-green optic (the maximum excitation peak is near 590nm wavelength), and the influx of chloride ions causes Hyperpolarization of neurons, thereby inhibiting the generation of neuronal action potentials. In addition, there is Arch (paleopurin), which is found in Salinasodium sphaeroides. Under the excitation of yellow-green optic (the maximum excitation peak is around 566nm wavelength), this protein induces the outflow of protons, thereby generating hyperpolarized signals, and further inhibits the activity of neurons.