nNOS-expressing interneurons control basal and behaviorally evoked arterial dilation in somatosensory cortex of mice

Cortical neural activity is coupled to local arterial diameter and blood
flow. However, which neurons control the dynamics of cerebral arteries is
not well understood. We dissected the cellular mechanisms controlling the
basal diameter and evoked dilation in cortical arteries in awake,
head-fixed mice. Locomotion drove robust arterial dilation, increases in
gamma band power in the local field potential (LFP), and increases calcium
signals in pyramidal and neuronal nitric oxide synthase (nNOS)-expressing
neurons. Chemogenetic or pharmocological modulation of overall neural
activity up or down caused corresponding increases or decreases in basal
arterial diameter. Modulation of pyramidal neuron activity alone had
little effect on basal or evoked arterial dilation, despite pronounced
changes in the LFP. Modulation of the activity of nNOS-expressing neurons
drove changes in the basal and evoked arterial diameter without
corresponding changes in population neural activity.