Circuit mechanisms underlying cortical communications

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In order to understand the principles of long-range connectivity in cortical communication, our efforts have focused on the following two projects during FY20. Functional connectivity of diverse long-range inputs to sensory cortex is aimed at achieving a mechanistic understanding of the functional connectivity of feedback / top-down projections to the primary sensory cortex. We have systematically examined the synaptic strength from different brain areas to diverse neuronal types in the primary somatosensory cortex (S1) and determined how the primary sensory cortex uses input-area-dependent, preferential recruitment of specific types of GABAergic interneurons to parse information from diverse feedback projections. The results of this study are currently under review. The second project, The structural organization of cortical subnetworks, is aimed at understanding the principles that govern the functional heterogeneity of principal neurons in sensory cortex. Neuronal activity in the superficial layer of the primary sensory cortex is highly heterogenous in relation to various aspects of the animals behavior. We asked whether functionally heterogeneous subnetworks are constrained by specific long-range and local presynaptic ensembles. This study provides the circuit-based mechanism for the organization of cortical subnetworks. Using single cell-initiated, monosynaptic rabies virus tracing combined with calcium imaging, we found that behavior state-encoding (spontaneous movement) neurons show characteristic long-range and local presynaptic networks. Our results reveal connectivity rules that support functional heterogeneity of cortical principal cells. We are currently preparing a manuscript on this study.