Associations of resting-state fMRI functional connectivity with flow-BOLD coupling and regional vasculature.

Brain Connect. 2014 Nov 11;

Authors: Tak S, Polimeni JR, Wang DJ, Yan L, Chen J

Abstract
There has been tremendous interest in applying fMRI-based resting-state functional connectivity (fcMRI) measurements to the study of brain function. However, a lack of understanding of the physiological mechanisms of fcMRI limits our ability to interpret fcMRI findings. In this work, we examine regional associations between fcMRI estimates and dynamic coupling between the BOLD and cerebral blood flow (CBF) as well as resting macrovascular volume. Resting-state BOLD and CBF data were simultaneously acquired using a dual-echo pseudo-continuous arterial-spin labeling (pCASL) technique, while macrovascular volume fraction was estimated using time-of-flight MR angiography. Functional connectivity within well-known functional networks-including the default-mode, fronto-parietal, and primary sensory-motor networks-was calculated using a conventional seed-based correlation approach. We found functional connectivity strength to be significantly correlated with the regional increase in CBF-BOLD coupling strength and inversely proportional to macrovascular volume fraction. These relationships were consistently observed within all functional networks considered. Our findings suggest that highly connected networks observed using resting-state fcMRI are not likely to be mediated by common vascular drainage linking distal cortical areas. Instead, high BOLD functional connectivity is more likely to reflect tighter neurovascular connections, attributable to neuronal pathways.

PMID: 25384681 [PubMed - as supplied by publisher]