Fig. 2.

Potential integration of optogenetics and fNIRS.

Activity of neurons in a cortical (left panels) or a subcortical (right panels) region can be manipulated by expressing a light-responsive protein called an opsin (such as channelrhodopsin-2) and delivering photostimulation using a fiber-optic cable installed just above the target region (top panels) in the rodent brain. Using the same fiber-optic cable, a combination of wavelengths of near-infrared light can be delivered to the target brain region alternately (bottom panels). The neighboring fiber-optic cable, which is connected to the photodetector, captures the returning photons. Thus, it would be possible to perform targeted optogenetic manipulation and fNIRS imaging simultaneously in the same animal.