Abstract
The default mode network (DMN) is one of the most widely studied resting state functional networks. The structural basis for the DMN is of particular interest and has been studied by several researchers using diffusion tensor imaging (DTI). Most of these previous studies focused on a few regions or white matter tracts of the DMN so that the global structural connectivity pattern and network properties of the DMN remain unclear. Moreover, evidences indicate that the DMN is involved in both memory and emotion, but how the DMN regulates memory and anxiety from the perspective of the whole DMN structural network remains unknown. We used multimodal neuroimaging methods to investigate the structural connectivity pattern of the DMN and the association of its network properties with memory and anxiety in 205 young healthy subjects with age ranging from 18 to 29 years old. The Group ICA method was used to extract the DMN component from functional magnetic resonance imaging (fMRI) data and a probabilistic fiber tractography technique based on DTI data was applied to construct the global structural connectivity pattern of the DMN. Then we used the graph theory method to analyze the DMN structural network and found that memory quotient (MQ) score was significantly positively correlated with the global and local efficiency of the DMN whereas anxiety was found to be negatively correlated with the efficiency. The strong structural connectivity between multiple brain regions within DMN may reflect that the DMN has certain structural basis. Meanwhile, the results we found that the network efficiency of the DMN were related to memory and anxiety measures, indicated that the DMN may play a role in the memory and anxiety.
Highlights
Analyzing task-free functional connectivity using temporal correlations has identified several resting-state networks (RSNs)
The medial prefrontal cortex (mPFC)-posterior cingulate cortex (PCC) connectivity in the default mode network (DMN) was found to be immature in children, and a weak positive correlation was demonstrated between the mPFC-PCC connectivity and the fractional anisotropy (FA) value of the cingulum tract, in contrast to adults, who showed a significant positive relationship.When studying the PCC/retrosplenial cortex (RSC) as the region of interest (ROI) using diffusion tensor imaging (DTI) fiber tractography, the mPFC was found to connect to the more rostral aspect(PCC) of the ROI, whereas the medial temporal lobes (MTL) connected to the more caudal aspect (RSC; Greicius et al, 2009)
We found several structural connectivities, such as the connectivities between the PCC and the left temporoparietal regions (TP), the PCC and the right TP, the right HIP and the PCC, the left HIP and the PCC, the mPFC and the PCC, the left superior prefrontal cortices (supF) and the right supF, that were relatively higher than the rest
Summary
Analyzing task-free functional connectivity using temporal correlations has identified several resting-state networks (RSNs). One of these is the default mode network (DMN; Raichle et al, 2001; Raichle and Snyder, 2007), which has been studied extensively and is widely known to be involved in many brain functions, such as self-referential mental activity and introspective thought. Most of the previous studies have focused on a few regions or white matter tracts of the DMN so that the global structural connectivity pattern and network properties of the DMN remain unclear
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