Type-I nNOS neurons orchestrate cortical neural activity and vasomotion

It is unknown how the brain orchestrates the coordination of global neural
and vascular dynamics. We sought to uncover the role of a sparse but
unusual population of genetically-distinct interneurons known as type-I
nNOS neurons, using a novel pharmacological strategy to unilaterally
ablate these neurons from the somatosensory cortex of mice.
Region-specific ablation produced changes in both neural activity and
vascular dynamics, decreased power in the delta-band of the local field
potential, reduced sustained vascular responses to prolonged sensory
stimulation, and abolished the post-stimulus undershoot in cerebral blood
volume. Coherence between the left and right somatosensory cortex
gamma-band power envelope and blood volume at ultra-low frequencies was
decreased, suggesting that type-1 nNOS neurons integrate long-range
coordination of brain signals. Lastly, we observed decreases in the
amplitude of resting-state blood volume oscillations and decreased
vasomotion following the ablation of type-I nNOS neurons. This
demonstrates that a small population of nNOS-positive neurons is
indispensable for regulating both neural and vascular dynamics in the
whole brain and implicates disruption of these neurons in diseases ranging
from neurodegeneration to sleep disturbances.