Parvalbumin interneurons mediate spontaneous hemodynamic fluctuations

Resting-state hemodynamic fluctuations are closely linked to gamma-band neural activity, yet the cellular drivers of this neurovascular coupling remain unclear. Given their established contribution in generating gamma oscillations, parvalbumin (PV) interneurons are prime candidates for regulating spontaneous cerebral blood flow (CBF) dynamics. Using chemogenetic tools in awake PV-Cre mice, we modulated PV interneuron activity and measured effects on neural network activity, local field potentials (LFP), and hemodynamics. Two-photon (2P) calcium imaging confirmed effective PV modulation, which affected excitatory neuron activity. PV suppression reduced high-gamma power, increased low-frequency LFP activity, and elevated basal CBF. 2P vessel imaging showed increased basal arterial diameter and significantly greater diameter fluctuation power in deeper cortical layers enriched with PV cells, but not in superficial layers. PV suppression also significantly weakened the correlation between gamma LFP power and CBF. Despite increased apparent neuronal synchrony during PV suppression, its relationship to arterial dynamics remained stable, possibly due to compensatory regulation by subsets of PV-positive and PV-negative cells. These findings provide causal evidence that PV interneuron contribute to spontaneous neurovascular dynamics and mediate the link between gamma oscillations and resting-state hemodynamic signals, revealing their significant role in maintaining functional connectivity and vascular regulation during non-task-engaged brain states.