Diffusion tensor imaging of neurodevelopment in children and young adults.

Diffusion tensor magnetic resonance imaging (DTI) was used to study regional changes in the brain's development from childhood (8-12 years, mean 11.1 +/- 1.3, N = 32) to young adulthood (21-27 years, mean 24.4 +/- 1.8, N = 28). Mean diffusivity (Trace/3 apparent diffusion coefficient, ADC) and fractional anisotropy (FA) were measured in 30 regions of interest (ROIs) in 13 distinct brain structures. Correlational analysis was performed to detect changes within 8-12 years and within 21-27 years, and group analysis to compare childhood diffusion properties with young adult values. Increases of fractional anisotropy were seen in the genu of the corpus callosum, splenium of the corpus callosum, corona radiata, putamen, and head of the caudate nucleus within 8-12 years, and also between childhood and young adulthood. Reductions in Trace/3 ADC were observed in 9 of 13 structures within 8-12 years and into young adulthood as well. DTI demonstrates more widespread changes in the brain's microstructure with maturation than previous reports using conventional T1-weighted MRI scans. These findings suggest a continuation of the brain's microstructural development through adolescence.

Imaging brain connectivity in children with diverse reading ability.

Reading is a complex cognitive skill that requires the coordination of multiple brain regions. Although functional neuroimaging studies highlight the cortical brain regions associated with a specific cognitive task like reading, they do not directly address the underlying neural connections necessary for efficient performance of this task. Adults with reading disability have demonstrated lower regional white matter connectivity, but it is not known whether this relationship between neuronal wiring and reading performance also holds in younger readers. Using diffusion tensor magnetic resonance imaging (DTI) that highlights the structural integrity of the brain wiring, we show that regional brain connectivity in the left temporo-parietal white matter correlates with a wide range of reading ability in children as young as 8-12 years old. Diffusion tensor tractography suggests that the posterior limb of the internal capsule is consistent with the location of the largest cluster of correlation between reading ability (Word Identification subtest) and fractional anisotropy. The maturation of the white matter may play a key role in the development of cognitive processes such as reading.