A recent study by researchers from McLean Hospital, Harvard Medical School, and the National Institute on Drug Abuse revealed that changes in arousal levels during fMRI scans can lead to distorted brain connection maps.
During fMRI scans, when people’s arousal decreases and they become more relaxed or sleepy, changes in breathing and heart rates can falsely indicate neuronal activity in the brain.
Research fellow Cole Korponay, PhD, explained that the monotonous and passive conditions of fMRI scans can create a misleading impression of increasing brain connection strengths.
fMRI scans are commonly used to map brain connectivity in various situations, but they rely on detecting changes in brain blood oxygen levels, which can be affected by factors like breathing and heart rates tied to arousal levels.
The researchers identified a signal called the “systemic low frequency oscillation” (sLFO) that tracked the decline in arousal levels and the artificial increase in brain connection strengths during scans. They developed a method called RIPTiDe to remove this noise signal from fMRI data and correct the distortion.
According to Korponay, by using the sLFO denoising procedure in future studies, researchers can improve the accuracy and reliability of fMRI findings by eliminating the effects of arousal changes during brain scans.
This study was supported by grants from the National Institutes of Health, including the National Institute on Drug Abuse, the National Institute of Mental Health, and the National Institute on Aging.
