  Human brain maturation is characterized by the prolonged development of
structural and functional properties of large-scale networks that extends into
adulthood. However, it is not clearly understood which features change and
which remain stable over time. Here, we examined structural connectivity based
on diffusion tensor imaging (DTI) in 121 participants between 4 and 40 years of
age. DTI data were analyzed for small-world parameters, modularity, and the
number of fiber tracts at the level of streamlines. First, our findings showed
that the number of fiber tracts, small-world topology, and modular organization
remained largely stable despite a substantial overall decrease in the number of
streamlines with age. Second, this decrease mainly affected fiber tracts that
had a large number of streamlines, were short, within modules and within
hemispheres; such connections were affected significantly more often than would
be expected given their number of occurrences in the network. Third, streamline
loss occurred earlier in females than in males. In summary, our findings
suggest that core properties of structural brain connectivity, such as the
small-world and modular organization, remain stable during brain maturation by
focusing streamline loss to specific types of fiber tracts.
