MRI signatures of cortical microstructure in human development align with oligodendrocyte cell-type expression

Area of Science:

• Neuroscience
• Developmental Biology
• Biophysics

Background:

• Adolescent cortical development shows age-related thinning and volume loss via MRI.
• Cellular mechanisms driving these macroscopic changes are not well understood.
• Diffusion MRI and biophysical models offer new insights into cellular microstructure.

Purpose of the Study:

• To investigate in vivo cortical neurite and soma microstructure changes in adolescents.
• To correlate microstructural findings with gene expression patterns during development.
• To elucidate the cellular basis of adolescent cortical maturation.

Main Methods:

• Utilized ultra-strong gradient MRI for high-resolution in vivo imaging of cortical microstructure.
• Analyzed diffusion MRI data with biophysical models to estimate neurite and soma parameters.
• Examined developmental gene expression patterns from two independent post-mortem databases.

Main Results:

• Cortical neurite signal fraction increased with age (11.91% over age).
• Apparent soma radius decreased with age (1% over age).
• Gene expression analysis revealed increased oligodendrocyte and excitatory neuron markers, with decreased astrocyte and microglia markers, aligning with microstructural changes and adolescent development.

Conclusions:

• Adolescent cortical development is characterized by increasing neurite density and decreasing soma size.
• Gene expression patterns indicate a significant role for oligodendrocytes and myelination.
• Intra-cortical myelination is a key cellular process driving cortical maturation throughout adolescence and into adulthood.