Brain-wide functional connectivity artifactually inflates throughout functional magnetic resonance imaging scans

Area of Science:

• Neuroimaging
• Neuroscience
• Biomedical Engineering

Background:

• Functional magnetic resonance imaging (fMRI) is crucial for studying brain function, organization, and diseases.
• Standard fMRI analysis may be susceptible to artifacts that distort brain connectivity maps.

Purpose of the Study:

• To identify and characterize artifactual inflation in fMRI-based functional brain connectivity estimates.
• To investigate the underlying causes of this artifact, specifically the role of systemic low-frequency oscillations (sLFOs).
• To evaluate the effectiveness of a specialized sLFO denoising procedure in mitigating these artifacts.

Main Methods:

• Analysis of resting-state and task-based fMRI data to assess functional connectivity.
• Investigation of the temporal dynamics of non-neuronal systemic low-frequency oscillations (sLFOs) in blood flow signals.
• Application and evaluation of a novel sLFO denoising technique within fMRI processing pipelines.

Main Results:

• fMRI-based functional connectivity estimates were artifactually inflated at spatially heterogeneous rates.
• This artifact was driven by temporal inflation of sLFOs, linked to physiological changes during scanning (e.g., respiration, heart rate) and reduced arousal.
• Standard denoising methods did not address this sLFO-related artifact.

Conclusions:

• Artifactual inflation of functional connectivity is a significant issue in fMRI, potentially leading to false positives and spatial distortions.
• A specialized sLFO denoising procedure effectively mitigates this artifact, enhancing the validity and reliability of fMRI findings.
• This improved processing approach is vital for accurate interpretation of brain connectivity in research and clinical applications.