title: Vascular coupling in resting-state fMRI: evidence from multiple modalities.
abstract: Resting-state functional magnetic resonance imaging (rs-fMRI) provides a potential to understand intrinsic brain functional connectivity. However, vascular effects in rs-fMRI are still not fully understood. Through multiple modalities, we showed marked vascular signal fluctuations and high-level coupling among arterial pressure, cerebral blood flow (CBF) velocity and brain tissue oxygenation at <0.08 Hz. These similar spectral power distributions were also observed in blood oxygen level-dependent (BOLD) signals obtained from six representative regions of interest (ROIs). After applying brain global, white-matter, cerebrospinal fluid (CSF) mean signal regressions and low-pass filtering (<0.08 Hz), the spectral power of BOLD signal was reduced by 55.6% to 64.9% in all ROIs (P=0.011 to 0.001). The coherence of BOLD signal fluctuations between an ROI pair within a same brain network was reduced by 9.9% to 20.0% (P=0.004 to <0.001), but a larger reduction of 22.5% to 37.3% (P=0.032 to <0.001) for one not in a same network. Global signal regression overall had the largest impact in reducing spectral power (by 52.2% to 61.7%) and coherence, relative to the other three preprocessing steps. Collectively, these findings raise a critical question of whether a large portion of rs-fMRI signals can be attributed to the vascular effects produced from upstream changes in cerebral hemodynamics.
authors.affiliation: Departments of Radiology and Psychology, Cognitive Imaging Research Center, Michigan State University, East Lansing, Michigan, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Zhu
authors.affiliation: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA.|Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tarumi
authors.affiliation: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA.|Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Muhammad Ayaz
authors.initials: MA
authors.lastname: Khan
authors.affiliation: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA.|Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000368:Aged; D000465:Algorithms; D001808:Blood Vessels / Q000033:anatomy & histology* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D010100:Oxygen / Q000097:blood / Q000134:cerebrospinal fluid; D010101:Oxygen Consumption; D012146:Rest; D066127:White Matter / Q000033:anatomy & histology / Q000502:physiology
chemical_list: D010100:Oxygen