Microstructural and functional gradients are increasingly dissociated in transmodal cortices

Area of Science:

• Neuroscience
• Cognitive Science
• Neuroimaging

Background:

• Cortical microstructure organizes neural function, but its link to cognitive flexibility is poorly understood in humans.
• Previous studies relied on post-mortem analyses, limiting direct correlation with functional data.
• Nonhuman primate research shows structure-function links, but human data is scarce.

Purpose of the Study:

• To develop a novel method for modeling microstructural similarity in the direction of cortical columns in humans.
• To investigate the relationship between microstructural and functional gradients across the human brain.
• To explore how structural-functional dissociations relate to higher-level cognitive processes.

Main Methods:

• Developed a novel approach to model microstructural profile similarity along cortical columns.
• Applied the method to ultra-high-resolution 3D histological reconstruction of a human brain.
• Translated the approach to myelin-sensitive magnetic resonance imaging (MRI) data in a large cohort of healthy adults.

Main Results:

• Identified a system-level gradient of microstructural differentiation from sensory to limbic regions.
• Observed that microstructural and functional gradients largely aligned but dissociated in transmodal networks (default mode, fronto-parietal).
• Meta-analytic decoding linked these dissociations to cognitive control and social cognition.

Conclusions:

• Demonstrated a relative decoupling of macroscale functional from microstructural gradients in human transmodal regions.
• This decoupling likely underlies the flexible role of these regions in complex human cognition.
• The novel MRI-based method provides a powerful tool for studying brain structure-function relationships in vivo.