Negative relationship between inter-regional interaction and regional power: a resting fMRI study

ABSTRACT Background Regional neural response and network property used to be treated separately. However, evidence has suggested an intimate relationship between the regional and inter-regional profiles. This research aimed to investigate the influence of functional connectivity on regional spontaneous activity. Methods Thirty-six and sixty datasets of structural magnetic resonance imaging (sMRI) and resting state functional MRI (rsfMRI) were selected from the NKI and CAN-BIND database, respectively. The cerebral cortex in rsfMRI was parcellated by MOSI (modular analysis and similarity measurements), which enables multi-resolution exploration. For each parcellated cluster, the mean amplitude of low-frequency fluctuation (ALFF) and its average functional connectivity strength with the remaining cortical analogs were computed. Correlation analyses were exploited to examine their relationship. Supplementary analysis was applied to CAN-BIND EEG data (1 to 30 Hz). Results Negative correlation coefficients between inter-regional interaction and regional power were noticed in both MRI datasets. One-sample t-tests revealed robust statistics across different analytic resolutions yielded by MOSI, with individual P values at the level 10^-4 to 10^-5. The results suggested that the more intense crosstalk a neural node is embedded in, the less regional power it manifests, and vice versa. The negative relationship was replicated in EEG analysis but limited to delta (1 to 4 Hz) and theta (4 to 8 Hz) frequencies. Conclusions We postulate that inhibitory coupling is the mechanism that bridges the local and inter-regional properties, which is more prominent in the lower spectra. The interpretation warrants particular caution since noise may also contribute to the observation.