Local Morphological Measures Confirm that Folding within Small Partitions of the Human Cortex Follows Universal Scaling Law

TL;DR

This study develops a method to analyze local cortical folding in small brain regions and confirms that the universal scaling law of cortical morphology applies at this local level, aiding in understanding regional brain differences.

Contribution

It introduces a new approach for local morphological measurement and demonstrates that the universal scaling law holds at small cortical partitions.

Findings

Local cortical folding follows the universal scaling law.

The method enables regional analysis of cortical morphology.

Scaling law covariance is confirmed at small partition levels.

Abstract

The universal scaling law of cortical morphology describes cortical folding as the covariance of average grey matter thickness, pial surface area, and exposed surface area. It applies for mammalian species, humans, and across lobes, however it remains to be shown that local cortical folding obeys the same rules. Here, we develop a method to obtain morphological measures for small regions across the cortex and correct surface areas by curvature to account for differences in patch size, resulting in a map of local morphology. It enables a near-pointwise analysis of morphological variables and their regional changes due to processes such as healthy ageing. We confirm empirically that the theorised covariance of morphological measures still holds at this level of local partition sizes as predicted, justifying the use of independent variables derived from the scaling law to identify regional differences in folding, subject-specific abnormalities, and local effects of ageing.