State-Dependent Subnetworks of Parvalbumin-Expressing Interneurons in Neocortex

摘要

Brain state determines patterns of spiking outputthat underlie behavior. In neocortex, brain state is reflectedin the spontaneous activity of the network,which is regulated in part by neuromodulatory inputfrom the brain stem and by local inhibition. We findthat fast-spiking, parvalbumin-expressing inhibitoryneurons, which exert state-dependent control ofnetwork gain and spike patterns, cluster into two stableand functionally distinct subnetworks that aredifferentially engaged by ascending neuromodulation.One group is excited as a function of increasedarousal state; this excitation is driven in part by theincrease in cortical norepinephrine that occurswhen the locus coeruleus is active. A second groupis suppressed during movement when acetylcholineis released into the cortex via projections fromthe nucleus basalis. These data establish the presenceof functionally independent subnetworks ofParvalbumin (PV) cells in the upper layers of theneocortex that are differentially engaged by theascending reticular activating system.