An fMRI Analysis of Reproducible Brain Activity under Natural Stimulation

Abstract

Functional magnetic resonance imaging (fMRI) is a functional neuroimaging method to measure brain activity by detecting changes of blood flow in the brain. The analysis of fMRI time series during real-world experience is methodological challenging because of the human brain processing a variety of features simultaneously in multiple-uncontrolled and -dynamic stimuli. Previous studies have used block designs to localize the activated brain regions. Those experimentally defined control-states hardly exist in the real world. The reproducibility analysis is an approach to investigating event-free spontaneous brain activity. Here we designed an experiment engaging long-term auditory stimulation reflecting a real world experience. The reproducible brain activity is estimated between multiple experimental runs within a participant and across a group of participants were calculated using the proposed intraclass correlation (ICC) statistic, which is directly applicable to pre-processed fMRI time series. An agreement between within- and between-participant analysis results elucidates the possible inter-individual variability in BOLD responses during the experimental stimulation. The results showed that the auditory network in the temporal cortex reflects the experimental stimulation along with other networks such as those associated with imitation, memory, and emotions. We suggested that the proposed ICC statistic as well as agreement between within- and between-participant analyses can be used to investigate functional networks in real-world fMRI experiments.