| Autor: |
Sharaev MG; National Research Centre 'Kurchatov Institute'Moscow, Russia; Faculty of Physics, M.V. Lomonosov Moscow State UniversityMoscow, Russia; Institute for Higher Nervous Activity and Neurophysiology, Russian Academy of SciencesMoscow, Russia., Zavyalova VV; National Research Centre 'Kurchatov Institute'Moscow, Russia; National Research University Higher School of EconomicsMoscow, Russia., Ushakov VL; National Research Centre 'Kurchatov Institute'Moscow, Russia; Department of Cybernetics, National Research Nuclear University 'MEPhI'Moscow, Russia., Kartashov SI; National Research Centre 'Kurchatov Institute'Moscow, Russia; Department of Cybernetics, National Research Nuclear University 'MEPhI'Moscow, Russia., Velichkovsky BM; National Research Centre 'Kurchatov Institute'Moscow, Russia; NBICS-Faculty, Moscow Institute of Physics and TechnologyMoscow, Russia. |
| Abstrakt: |
The Default Mode Network (DMN) is a brain system that mediates internal modes of cognitive activity, showing higher neural activation when one is at rest. Nowadays, there is a lot of interest in assessing functional interactions between its key regions, but in the majority of studies only association of Blood-oxygen-level dependent (BOLD) activation patterns is measured, so it is impossible to identify causal influences. There are some studies of causal interactions (i.e., effective connectivity), however often with inconsistent results. The aim of the current work is to find a stable pattern of connectivity between four DMN key regions: the medial prefrontal cortex (mPFC), the posterior cingulate cortex (PCC), left and right intraparietal cortex (LIPC and RIPC). For this purpose functional magnetic resonance imaging (fMRI) data from 30 healthy subjects (1000 time points from each one) was acquired and spectral dynamic causal modeling (DCM) on a resting-state fMRI data was performed. The endogenous brain fluctuations were explicitly modeled by Discrete Cosine Set at the low frequency band of 0.0078-0.1 Hz. The best model at the group level is the one where connections from both bilateral IPC to mPFC and PCC are significant and symmetrical in strength (p < 0.05). Connections between mPFC and PCC are bidirectional, significant in the group and weaker than connections originating from bilateral IPC. In general, all connections from LIPC/RIPC to other DMN regions are much stronger. One can assume that these regions have a driving role within the DMN. Our results replicate some data from earlier works on effective connectivity within the DMN as well as provide new insights on internal DMN relationships and brain's functioning at resting state. |
