Optogenetic Dissection of Cell Types and Circuits in Mouse Visual Cortex

While many observations make it clear that cell types and specificity of connections matter, we still lack a mechanistic understanding of how cell types and their specific pattern of connectivity might contribute uniquely to cortical computations. To understand the contributions of cell types and circuits in mouse visual cortex we have taken advantage of multi-feature Boolean logical expression of light sensitive cationic channel (channelrhodopsin-ChR2) and whole cell dual patch recordings in living brain slices. Using these tools, we have identified unique electrophysiology and connectivity patterns of vasoactive intestinal peptide (VIP) expressing interneuron subtypes (Chapter 2). We have also introduced methods that will enable single cell resolution mapping of inhibitory inputs in the future (Chapter 3). Finally in Appendix A, we identified three layer 5 pyramidal cell types in mouse visual cortex based on intrinsic electrophysiology, visual responses, and long range connectivity. Better understanding of highly specific cell types and circuits in mouse models will help us better classify and treat psychiatric disorders in humans where inhibitory circuit dysfunctions have been implicated