Online sculpting of the functional cortical circuit. A. Activity of GCamp6-expressing VIP interneurons in primary visual cortex of an awake behaving mouse around the time of locomotion onset (L-on) as compared to a preceding quiescent period, quantified as a modulation index. The majority of VIP cells exhibit increased activity during locomotion, and some cells also show anticipatory activity preceding motor output. Adapted from [50]. B. Schematic of a local cortical circuit with PV (orange), SST (blue), and VIP (purple) -expressing interneurons and a pyramidal neuron (green). Under quiescent conditions, VIP interneurons may be minimally participatory in the local circuit. Upon arousal, VIP cells are robustly recruited into the functional local circuit, potentially altering the balance of dendrite- and soma-targeting inhibition and increasing pyramidal neuron output.