Longitudinal changes in grey and white matter during adolescence

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Neuroimaging

Background:

• Adolescence is a critical period for brain maturation.
• Previous MRI studies indicate complex changes in grey matter (GM) and white matter (WM) volumes and microstructure.
• Understanding these dynamic changes is crucial for comprehending adolescent brain development.

Purpose of the Study:

• To investigate age-related structural changes in grey matter (GM) and white matter (WM) during adolescence using longitudinal MRI data.
• To specifically examine microstructural changes in key white matter tracts, the arcuate fasciculus (AF) and corticospinal tract (CST).

Main Methods:

• Longitudinal study of 24 adolescents with a mean follow-up of 2.5 years.
• Voxel-based morphometry (VBM) analysis of T1-weighted images for GM and WM volume changes.
• Tract-based spatial statistics (TBSS) analysis of diffusion tensor imaging (DTI) data and probabilistic tractography for WM microstructure analysis.

Main Results:

• Significant age-related increases in white matter (WM) volume and fractional anisotropy (FA) were observed bilaterally in multiple fiber tracts, including the AF and CST.
• FA increases were primarily associated with enhanced parallel diffusivity, suggesting axonal growth.
• The arcuate fasciculus (AF) showed significant increases in FA, while grey matter (GM) volume decreased across cortical regions.

Conclusions:

• Adolescent brain maturation involves structural enhancements in long-distance white matter (WM) connectivities, particularly in the AF and CST.
• These structural changes occur concurrently with synaptic "pruning" in cortical grey matter (GM).
• The findings provide imaging evidence for concurrent development of WM pathways and GM refinement during adolescence.