FIG. 4.

Associations between functional connectivity strength, CBF-BOLD coupling, and macrovascular volume fraction in multiple functional networks. Functional connectivity was estimated using the conventional seed-based correlation approach. The scatter plots depict the spatial correlation between samples of two variables (connectivity strengths and either CBF-BOLD coupling or resting blood volume fraction) averaged across ROIs involved in (a) the default mode network, (b) the frontoparietal network, and (c) the primary sensory-motor (motor, auditory and visual) network. (d) As control ROIs, we selected additional ROIs outside main regions of resting-state networks. Each data point represents one ROI from one participant. The degree of functional connectivity among all network regions significantly increased as the BOLD-CBF coupling increased. In contrast, functional connectivity strength was significantly reduced as the macrovascular volume fraction increased. These associations between connectivity strength and neurovascular factors were consistently observed within the regions of resting-state networks, but not statistically significant outside of these networks.