Inhibitory Interneurons Modulate Neurovascular Coupling Primarily Through Indirect Circuit Mechanisms

Neurovascular coupling (NVC) links neuronal activity to local hemodynamics, underlies functional imaging signals such as fMRI, and is often disrupted in neurological disorders. Although inhibitory interneurons can directly signal to blood vessels, their relative contribution to NVC during sensory processing remains unclear. Here, we combined mesoscale cell-type-specific calcium imaging, hemodynamic imaging, and chemogenetic silencing to determine how parvalbumin-expressing (PV) and somatostatin-expressing (SOM) interneurons shape functional hyperemia in the mouse barrel cortex. During single-whisker stimulations, PV and SOM activity exhibited strong spatial co-variation with local hemodynamic responses across the barrel field. Silencing PV interneurons produced variable changes in local hemodynamic responses that closely tracked excitatory activity while disproportionately broadening the spatial spread of the hemodynamic response, whereas SOM silencing exerted comparatively modest effects. Together, these findings suggest that NVC predominantly reflects overall circuit activity, even when inhibitory signaling is broadly impaired.