Fast 3D imaging in the auditory cortex of awake mice reveals that astrocytes control neurovascular coupling responses at arteriole-capillary junctions.

Neurovascular coupling (NVC) increases blood flow, assuring adequate supply to active cortical regions by local redistribution via penetrating arterioles (PA) and branching capillaries. Astrocyte end-feet enwrapping these vascular structures possess machinery to regulate blood flow, but their participation in NVC is controversial. Via a new 3D+t two-photon imaging approach we visualized PA and capillaries simultaneously during naturally-occurring and tone-evoked dilations in the auditory cortex of awake mice. We observed that dilations occurred bidirectionally, and a fraction of them extended between compartments across the interconnecting sphincter, depending on the animal activity states. These multi-compartment dilations were preceded by rapid astrocyte end-foot Ca2+ signals around the sphincter. Reduction of this astrocytic Ca2+ activity in IP3R2KO mice suppressed multi-compartment dilations, revealing a pivotal role of pre-capillary sphincters in their bidirectional spread between vascular compartments under local control by astrocytes. This novel mechanism contributes to physiological regulation of laminar blood flow during NVC.