State-Dependent Subnetworks of Parvalbumin-Expressing Interneurons in Neocortex

SUMMARY

Brain state determines patterns of spiking output that underlie behavior. In neocortex, brain state is reflected in the spontaneous activity of the network, which is regulated in part by neuromodulatory input from the brain stem and by local inhibition. We find that fast-spiking, parvalbumin-expressing inhibitory neurons, which exert state-dependent control of network gain and spike patterns, cluster into two stable and functionally distinct subnetworks that are differentially engaged by ascending neuromodulation. One group is excited as a function of increased arousal state; this excitation is driven in part by the increase in cortical norepinephrine that occurs when the locus coeruleus is active. A second group is suppressed during movement when acetylcholine is released into the cortex via projections from the nucleus basalis. These data establish the presence of functionally independent subnetworks of Parvalbumin (PV) cells in the upper layers of the neocortex that are differentially engaged by the ascending reticular activating system.

Graphical Abstract

In Brief

Fast-spiking interneurons in cortex are generally viewed as functionally homogeneous. Garcia-Junco-Clemente et al. present evidence that across diverse cortical areas there are at least two functionally distinct subnetworks of these interneurons, which can be independently engaged as a function of behavior.