Cholinergic and adrenergic modulation sculpts parallel inhibition of SST-INs in visual cortex

In layer 2/3 of Mus musculus primary visual cortex (V1), PV- and VIP-expressing interneurons inhibit SST-INs in parallel, with PV driving fast perisomatic inhibition and VIP slower dendritic inhibition.

• Why it matters: Disinhibitory GABAergic circuit motifs involving SST-INs are known, but how diverse inputs to SST-INs are regulated by neuromodulators remains only partially understood.
• What they did: Using widefield and 2-photon optogenetic stimulation of PV- and VIP-INs plus recordings from fluorescently identified SST-INs, the study tested how muscarinic and beta adrenergic modulation changes inhibitory input properties.
• The result: Cholinergic muscarinic modulation strongly suppresses PV-IN output, while adrenergic beta modulation enhances VIP-IN output, and modeling suggests these parallel pathways can differentially regulate circuit gain and network stability across inputs and arousal conditions.