Structural maturation of neural pathways in children and adolescents: In vivo study

Structural maturation of fiber tracts in the human brain, including an incr ease in the diameter and myelination of axons, may play a role in cognitive development during childhood and adolescence. A computational analysis of structural magnetic resonance images obtained in 111 children and adolescen ts revealed age-related increases in white matter density in fiber tracts c onstituting putative corticospinal and frontotemporal pathways. The maturat ion of the corticospinal tract was bilateral. whereas that of the frontotem poral pathway was found predominantly in the left (speech-dominant) hemisph ere. These findings provide evidence for a gradual maturation, during late childhood and adolescence, of fiber pathways presumably supporting motor an d speech functions.