Table 1.
MRI studies of structural brain networks in development.
Figure 1.
Maturation of the “baby connectome”: examples of brain networks at four different ages.
(A) Anatomic MRI images (3T, T2-weighted fast spin-echo pulse sequence, echo train length 16, TR/TE = 5000/120 ms, 512×512 matrix, in-plane resolution 0.4×0.4 mm2, slice thickness 3 mm, 2 averages). (B) Tractograms reconstructed based on DTI data. Visualization: minimum length 15 mm, skip 90%. (C) Brain networks represented as weighted graphs. The size of the nodes is proportional to the node degree. The edge weights are proportional to the streamline count. (D) Binary connectivity matrices, reordered in a way that maximizes the number of connections close to the main diagonal (1,000,000 reordering attempts). Note: the 6 days and 6 months networks were mapped in the same infant longitudinally.
Figure 2.
Distribution of physical connection lengths in cortical networks averaged across subjects within each group.
Figure 3.
Group analysis of scaled network metrics (scaled clustering coefficient and scaled characteristic path length), modularity, and small-world index.
*p<0.05.
Figure 4.
Group analysis of absolute network metrics: clustering coefficient C, characteristic path length L, and edge density.
The dependence of C and L on the edge density can be appreciated.
Figure 5.
Intersubject variability of graphs within the adult age group.
The size of the nodes is proportional to the node degree. The edge weights are proportional to the streamline count.
Figure 6.
Node degree distribution averaged across subjects within each group.
Figure 7.
Network-driven segmentation of the cortex into five modules for subjects from all age groups that showed a similar pattern.
Top row: dorsal view, bottom row: ventral view. No prior anatomical information was used to find the modules.
Table 2.
Subject and group description.