Hierarchy of transcriptomic specialization across human cortex captured by structural neuroimaging topography

Area of Science:

• Neuroscience
• Human Brain Anatomy
• Cortical Organization

Background:

• Cortical hierarchy is a key principle for macroscale brain organization, but microscale specialization in humans remains unclear.
• Conventional methods for assessing anatomical hierarchy, like tract-tracing, are invasive and not suitable for humans.
• Understanding gene expression patterns across the cortex is crucial for deciphering microcircuitry specialization.

Purpose of the Study:

• To identify a noninvasive method for indexing anatomical hierarchy in the human cortex.
• To investigate the relationship between anatomical hierarchy and gene expression patterns.
• To explore the role of hierarchical gene expression gradients in cortical microcircuitry and function.

Main Methods:

• Utilized magnetic resonance imaging (MRI)-derived T1-weighted/T2-weighted (T1w/T2w) mapping as a proxy for anatomical hierarchy.
• Analyzed gene expression data across the human cortex.
• Correlated T1w/T2w mapping with transcriptional variation and microcircuitry-related gene expression profiles.

Main Results:

• MRI-derived T1w/T2w mapping reliably indexes anatomical hierarchy in the human cortex.
• This neuroimaging measure captures the dominant pattern of transcriptional variation across the cortex.
• Hierarchical gradients in gene expression related to microcircuit function were identified, consistent with primate microanatomy and implicated in neuropsychiatric disorders.

Conclusions:

• A hierarchical axis links cortical transcription and anatomy in the human brain.
• Gradients of microscale properties along this axis contribute to the macroscale specialization of cortical function.
• Noninvasive MRI-based T1w/T2w mapping provides a valuable tool for studying cortical organization and transcriptional variation in humans.