Axonal tension contributes to consistent fold placement

Area of Science:

• Neuroscience
• Developmental Biology
• Computational Biology

Background:

• Cortical folding is crucial for brain development, creating species- and individual-specific brain structures.
• Existing computational models, primarily based on differential growth, struggle to explain the precise locations of cortical folds.
• The axon tension hypothesis offers a potential explanation, but its role in gyrification remains controversial.

Purpose of the Study:

• To investigate the role of axonal tension in cortical folding by developing a novel computational model.
• To integrate the axon tension hypothesis with the differential growth theory to better understand gyrification.
• To determine if axonal tension can influence the location and pattern of cortical folds.

Main Methods:

• Developed a novel bi-layered finite element model.
• Incorporated both differential cortical growth and characteristic axonal tension in the subcortex.
• Simulated the effects of axonal tension and geometric perturbations on cortical folding patterns.

Main Results:

• Axon tension acts as a perturbation that can trigger buckling and determine fold locations.
• Axon tension can overpower typical thickness perturbations, dictating fold placement.
• Heterogeneity in axon stiffness significantly alters cortical folding patterns, highlighting the importance of white matter connectivity.

Conclusions:

• Axon tension is a critical factor in determining the location of cortical folds, complementing differential growth theories.
• Computational models incorporating axon tension provide new insights into the mechanisms of gyrification.
• Further research into the role of axon connectivity in brain development and folding is warranted.