title: Systemic Low-Frequency Oscillations in BOLD Signal Vary with Tissue Type.
abstract: Blood-oxygen-level dependent (BOLD) signals are widely used in functional magnetic resonance imaging (fMRI) as a proxy measure of brain activation. However, because these signals are blood-related, they are also influenced by other physiological processes. This is especially true in resting state fMRI, during which no experimental stimulation occurs. Previous studies have found that the amplitude of resting state BOLD is closely related to regional vascular density. In this study, we investigated how some of the temporal fluctuations of the BOLD signal also possibly relate to regional vascular density. We began by identifying the blood-bound systemic low-frequency oscillation (sLFO). We then assessed the distribution of all voxels based on their correlations with this sLFO. We found that sLFO signals are widely present in resting state BOLD signals and that the proportion of these sLFOs in each voxel correlates with different tissue types, which vary significantly in underlying vascular density. These results deepen our understanding of the BOLD signal and suggest new imaging biomarkers based on fMRI data, such as amplitude of low-frequency fluctuation (ALFF) and sLFO, a combination of both, for assessing vascular density.
authors.affiliation: McLean Imaging Center, McLean HospitalBelmont, MA, USA; Department of Psychiatry, Harvard University Medical SchoolBoston, MA, USA.
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Tong
authors.affiliation: McLean Imaging Center, McLean HospitalBelmont, MA, USA; Department of Radiology, University of CalgaryCalgary, AB, Canada.
authors.forename: Lia M
authors.initials: LM
authors.lastname: Hocke
authors.affiliation: McLean Imaging Center, McLean HospitalBelmont, MA, USA; Department of Psychiatry, Harvard University Medical SchoolBoston, MA, USA.
authors.forename: Kimberly P
authors.initials: KP
authors.lastname: Lindsey
authors.affiliation: McLean Imaging Center, McLean Hospital Belmont, MA, USA.
authors.forename: Sinem B
authors.initials: SB
authors.lastname: Erdoğan
authors.affiliation: McLean Imaging Center, McLean HospitalBelmont, MA, USA; Department of Psychiatry, Harvard University Medical SchoolBoston, MA, USA.
authors.forename: Gordana
authors.initials: G
authors.lastname: Vitaliano
authors.affiliation: McLean Imaging Center, McLean Hospital Belmont, MA, USA.
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Caine
authors.affiliation: McLean Imaging Center, McLean HospitalBelmont, MA, USA; Department of Psychiatry, Harvard University Medical SchoolBoston, MA, USA.
authors.forename: Blaise deB
authors.initials: Bd
authors.lastname: Frederick
keywords: BOLD; amplitude of low-frequency fluctuation; low frequency oscillation; resting state fMRI; vascular density