Optogenetics is a technique that grants the manipulation of neuronal activity. This method allows for targeted excitation and/or inhibition of specific neuronal populations.

A particular protein of interest is expressed in the targeted cells. This protein – called the optogenetic actuator - has the unique characteristic to be a light-sensitive ion channel. When illuminated with the corresponding wavelength, the channel allows the flow of ions through the cell membrane. This method offers spatiotemporal control of neuronal excitability in living tissue.

For use in vivo, optogenetics requires the implant of an optical fiber (stereotaxic surgery) - to provide the illumination necessary to control the neuronal activity. With most available solutions, the optical fiber is connected to a stimulation unit that provides the light. This technique has the disadvantage of requiring invasive implantation of equipment such as the optical fiber in the animal’s brain.

However, a new channelrhodopsin developed by Deisseroth’s lab allows for the activation of specific neural populations at unprecedented depths of up to 7 mm with millisecond precision. This tool would make possible implant-free deep brain optogenetics.

More information following this link: https://www.nature.com/articles/s41587-020-0679-9.