Fig. 5. Relevance to cortical measures. The relationships between callosal fiber length scaling and cortical functional lateralization (A), myelin content (B), evolutionary cortical expansion of the primate brain (C), and developmental cortical expansion of the human brain (D). Top row is the averaged cortical functional lateralization map across cognitive terms, averaged myelin content map across HCP subjects, evolutionary cortical expansion map, and developmental cortical expansion map, respectively. Middle row is the cortical measures of the midsagittal CC at the voxel and segment level. Bottom row is the Spearman correlation between the cortical measures and callosal fiber length scaling coefficient across midsagittal CC voxels and segments. Black: HCP, Gray: UKB. Solid lines represent empirical Spearman correlation coefficients; dashed lines represent the null distribution of Spearman correlation coefficients derived from 10,000 permutations.