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Abstract
Functional and structural maturation of networks comprised of discrete regions is
an important aspect of brain development. The default-mode network (DMN) is a prominent
network which includes the posterior cingulate cortex (PCC), medial prefrontal cortex
(mPFC), medial temporal lobes (MTL), and angular gyrus (AG). Despite increasing interest
in DMN function, little is known about its maturation from childhood to adulthood.
Here we examine developmental changes in DMN connectivity using a multimodal imaging
approach by combining resting-state fMRI, voxel-based morphometry and diffusion tensor
imaging-based tractography. We found that the DMN undergoes significant developmental
changes in functional and structural connectivity, but these changes are not uniform
across all DMN nodes. Convergent structural and functional connectivity analyses suggest
that PCC-mPFC connectivity along the cingulum bundle is the most immature link in
the DMN of children. Both PCC and mPFC also showed gray matter volume differences,
as well as prominent macrostructural and microstructural differences in the dorsal
cingulum bundle linking these regions. Notably, structural connectivity between PCC
and left MTL was either weak or non-existent in children, even though functional connectivity
did not differ from that of adults. These results imply that functional connectivity
in children can reach adult-like levels despite weak structural connectivity. We propose
that maturation of PCC-mPFC structural connectivity plays an important role in the
development of self-related and social-cognitive functions that emerge during adolescence.
More generally, our study demonstrates how quantitative multimodal analysis of anatomy
and connectivity allows us to better characterize the heterogeneous development and
maturation of brain networks.
Copyright 2010 Elsevier Inc. All rights reserved.