Is sedation-induced BOLD fMRI low-frequency fluctuation increase mediated by increased motion?

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Physiology

Background:

• Low-frequency fluctuations (LFF) in the BOLD fMRI signal increase during sedation and sleep.
• Head motion is a potential confound in neuroimaging studies, particularly during altered states of consciousness.

Purpose of the Study:

• To investigate whether increased head motion mediates the observed increases in LFF during sedation.
• To examine the relationship between sedation, head motion, and LFF in functional brain networks.

Main Methods:

• Healthy volunteers underwent resting-state fMRI scans during baseline and midazolam sedation.
• LFF power was calculated from time series data in 14 regions of interest across 5 functional networks.
• Mediation analysis was used to assess the indirect effects of head motion on sedation-induced LFF.

Main Results:

• Sedation significantly increased LFF power across all analyzed functional networks.
• Increased head motion significantly mediated the effect of sedation on LFF in all networks.
• Head motion was strongly correlated with LFF even at baseline, independent of sedation.

Conclusions:

• Conscious sedation increases LFF, but this effect is predominantly mediated by concurrent increases in head motion.
• Researchers should exercise caution when designing and interpreting fMRI studies that compare conditions with differential head motion.
• Head motion is a critical factor to consider in fMRI research, especially when studying altered states of consciousness.