On the Stability of BOLD fMRI Correlations

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) measures correlations between brain regions, known as functional connectivity, to study brain organization.
• Dynamic functional connectivity (dFC) analysis of resting-state BOLD fMRI has gained recent attention.

Purpose of the Study:

• To investigate the sources of observed dynamic changes in functional connectivity during resting-state BOLD fMRI.
• To determine if resting-state functional connectivity truly exhibits moment-to-moment variability or if observed dynamics are artifacts.

Main Methods:

• Simulations were used to model BOLD signal dynamics.
• Multiple sets of empirical resting-state BOLD fMRI data were analyzed.
• The influence of task states, sampling variability, head motion, and sleep state on functional connectivity was assessed.

Main Results:

• Task states can alter BOLD activity correlation structures.
• Observed "dynamic" BOLD correlations during rest are largely explained by sampling variability.
• Head motion and fluctuating sleep state contribute significantly to the observed "dynamics" during rest.
• A single correlation structure may adequately describe the resting state, excluding artifactual influences.

Conclusions:

• Observed dynamic functional connectivity in resting-state BOLD fMRI is predominantly driven by technical factors and physiological variations, not cognitive content.
• Resting-state BOLD correlations may primarily reflect the maintenance of long-term brain functional organization stability.