Multichannel fiber-based simultaneous neural stimulation and signal readout in vivo

Abstract

In order to overcome the depth limitation of light penetration in brain tissue, a promising approach in optogenetics is implanting multimode optical fibers for stimulation and fluorescence imaging. However, traditional fiber photometry can only realize stimulation or recording in a single brain region, so optogenetic stimulation and simultaneous recording at the implantation site cannot be achieved. And there is currently no scheme for synchronization of multiple brain regions, therefore the connection between brain regions cannot be strictly proved. To overcome these issues, we developed a multichannel fiber-based in vivo simultaneous neural stimulation and signal readout system. Different from traditional fiber photometry, our system uses the galvanometer scanning technology and a specially-made optical fiber bundle with 200-μm diameter to realize high-precision multichannel stimulation with up to 1-kHz frequency and simultaneous recording. Combined with the specific light-sensitive proteins such as ChrimsonR and genetically encoded calcium indicator GCamP6s, we realize simultaneous optogenetic stimulation and recording of fluorescence signals representing neural activity in up to 7 brain regions of a mouse in vivo. At the same time, we performed optogenetic stimulation in the SNc/VTA brain region of 3 mice expressing the ChrimsonR light-sensitive protein, and recorded the fluorescence signal of the corresponding site simultaneously. In addition, our scheme is also suitable for stimulation and simultaneous recording of multiple brain regions in a single mouse, as well as signal recording and regulation in social and other behaviors in multiple mice. Our system and experimental method allow acquisition and analysis of functional information about relevant brain regions in specific behaviors, thus providing important data and theoretical support for further understanding and treatment of related diseases.