Age effects on low frequency physiological fluctuations in resting BOLD fMRI

Introduction: Studies have shown that low frequency temporal components (<0.1Hz) in resting state BOLD fMRI reflect spontaneous fluctuations of brain physiology and metabolism, which form the basis for the widely adopted “functional connectivity” analysis to characterize the resting state using BOLD fMRI[1]. Studies also found significant linear correlations between activation induced BOLD signal changes and the magnitude of low frequency fluctuations at baseline (<0.1Hz) [2], suggesting a shared mechanism underlying the BOLD contrast and physiological noise in BOLD fMRI. In the present study, we investigated the associations between BOLD activation and low frequency fluctuations at baseline in two groups of young and elderly subjects. Our hypothesis was that the magnitude of low frequency fluctuations in resting BOLD fMRI can be used to study aging effects, in a way similar to BOLD responses to sensorimotor activation.