AnalyzeDirect

Research focusing on developmental changes of the human brain over time has dramatically advanced due to the improvement of novel imaging techniques. Diffusion tensor imaging (DTI) allows for an accurate analysis of the morphological modifications of white matter tracts connecting different brain regions.
This technique provides for the visualization and quantification of the diffusion of water molecules in biological tissues. As molecular diffusion is affected by interactions with various obstacles, water molecule diffusion patterns can provide valuable information about the orientation and integrity of neural fibers in the region of interest.

Using DTI, scientists from the University of Toyama, Japan, recently quantified the development of white matter fibers in 52 subjects ranging in age from 2 months to 25 years. From DTI scans, Analyze software was used to segment regions of interest such as the corpus callosum, cingulum hippocampus, inferior longitudinal fasciculus and superior longitudinal fasciculus. The researchers investigated 4 DTI parameters: fractional anisotropy (direction of the molecular motion of water), apparent diffusion coefficient (the amount of water molecule distribution) and axial and radial diffusivity (diffusivity parallel and orthogonal to white matter tracts). Analyze software was also used to calculate fractional anisotropy maps for all subjects.

The study indicated that each region of interest followed a different developmental pattern in terms of direction of chronological maturation (central-to-peripheral or peripheral-to-central). However, all the structures investigated showed that fractional anisotropy increased with age, while all the other parameters decreased over time. The trend of these values was persistent until 6 years of age. In fact, this age can be considered a turning point, as a great amount of neural tracts are by then fully matured. White matter undergoes important changes until 6 years of age, after that DTI parameters remain stable in adulthood and start changing again in senescence.

Changes in these values over time are due to white matter development, which includes decreasing water quantity, myelination and thickening diameters of fibers. Findings from this study are vital for our understanding of cerebral maturation and normal long-term cerebral degeneration.

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Tags: Aging, Brain Studies