Systemic Low-Frequency Oscillations in BOLD Signal Vary with Tissue Type

Area of Science:

• Neuroimaging
• Physiology
• Biomarkers

Background:

• Blood-oxygen-level dependent (BOLD) signals in functional magnetic resonance imaging (fMRI) are standard for measuring brain activity.
• BOLD signals are influenced by physiological factors, particularly in resting-state fMRI.
• Previous research links resting-state BOLD amplitude to regional vascular density.

Purpose of the Study:

• To investigate the relationship between temporal fluctuations in BOLD signals and regional vascular density during resting states.
• To identify and characterize systemic low-frequency oscillations (sLFOs) within resting-state BOLD signals.
• To explore the potential of sLFOs and related metrics as imaging biomarkers for vascular density.

Main Methods:

• Identification of blood-bound systemic low-frequency oscillations (sLFOs) in resting-state fMRI data.
• Assessment of voxel-wise correlations with identified sLFOs.
• Analysis of the relationship between sLFO distribution and tissue types with varying vascular densities.

Main Results:

• sLFOs are prevalent in resting-state BOLD signals across the brain.
• The proportion of sLFOs in each voxel correlates with underlying tissue type and vascular density.
• A significant relationship exists between sLFO presence and regional vascularity.

Conclusions:

• Temporal fluctuations in BOLD signals, specifically sLFOs, are linked to regional vascular density.
• sLFOs represent a promising imaging biomarker for assessing vascular density.
• Combining metrics like amplitude of low-frequency fluctuation (ALFF) and sLFO may offer enhanced assessment of vascular density using fMRI.