Mechanisms underlying the response of mouse cortical networks to\n optogenetic manipulation

Abstract

GABAergic interneurons can be subdivided into three subclasses: parvalbumin\npositive (PV), somatostatin positive (SOM) and serotonin positive neurons. With\nprincipal cells (PCs) they form complex networks. We examine PCs and PV\nresponses in mouse anterior lateral motor cortex (ALM) and barrel cortex (S1)\nupon PV photostimulation in vivo. In layer 5, the PV response is paradoxical:\nphotoexcitation reduces their activity. This is not the case in ALM layer 2/3.\nWe combine analytical calculations and numerical simulations to investigate how\nthese results constrain the architecture. Two-population models cannot account\nfor the results. Networks with three inhibitory populations and V1-like\narchitecture account for the data in ALM layer 2/3. Our data in layer 5 can be\naccounted for if SOM neurons receive inputs only from PCs and PV neurons. In\nboth four-population models, the paradoxical effect implies not too strong\nrecurrent excitation. It is not evidence for stabilization by inhibition.\n