All-optical observation and control of communication between neuronal cell-types during behavior via structure-guided design of channelrhodopsins

Understanding the nature and role of communication between distinct cellular populations in the brain will require simultaneous measurement and control of activity within those populations during behavior. Current optogenetic tools, present limitations such as spectral incompatibility with sensors and modest efficacy. To address these issues, we engineered novel red-shifted high potent cation-selective channelrhodopsin, rsChRmine, and K+-selective channelrhodopsins (KCRs), KALIs, with enhanced K+ selectivity based on our cryo-EM structures. By integrating these new opsins with multiple genetically-encoded Ca2+ indicators, we can selectively control specific neural circuits while simultaneously observing the responses of other elements within the same network. We applied this method to the mPFC of freely-behaving mice, quantifying dynamic information transmission between excitatory and inhibitory populations. Together, this work lays the foundation for new kinds of investigation into brain function and dysfunction.