Visualizing cortical laminar architecture in the living human brain using next-generation ultra-high-gradient...

Area of Science:

• Neuroimaging
• Human Brain Anatomy
• Advanced MRI Techniques

Background:

• Understanding the human brain's layered structure (cortical laminar cytoarchitecture and myeloarchitecture) is crucial.
• Current methods often rely on invasive histological analysis, limiting in vivo studies.

Purpose of the Study:

• To characterize in vivo cortical laminar microstructure using advanced diffusion MRI.
• To demonstrate the feasibility of noninvasive mapping of the brain's laminar architecture.

Main Methods:

• Utilized a next-generation Connectome MRI scanner with high gradient strength and slew rate.
• Applied soma and neurite density imaging (SANDI) metrics derived from 1 mm diffusion MRI.
• Performed cortical depth-dependent analyses to assess laminar profiles.

Main Results:

• SANDI revealed distinct laminar profiles matching known histological patterns, with intra-soma signal fraction peaking at ~55% cortical depth.
• Visual cortex showed higher intra-soma signal fraction than motor cortex in deeper layers.
• Correlations between intra-soma signal fraction and cortical curvature were layer-specific.

Conclusions:

• Noninvasive mapping of cortical laminar architecture is feasible using high-performance gradient MRI.
• SANDI provides a potential in vivo surrogate for histological analysis of brain microstructure.
• This technique enables future studies on cortical laminar organization.