# Pial and White Surfaces

Extraction of T1-weighted MR scans were processed using FreeSurfer [7] to obtain individual pial and white matter surfaces. Homologue vertices between pial/white surfaces and between individuals allow to easily navigate between subjects. Cortex parcellation was done using the aparc.a2009s Destrieux’s atlas [8] defining 152 regions shown on Fig. 2 detailed in the next section.

# Individual Quantitative Maps of Neurite Density

As displayed on Fig. 2, the correspondence of vertices allowed to extract a distribution of *f _{intra}* for each vertex by sampling the matched

*fi„*map along the segment defined by each pair of corresponding (pial, white) vertices. Maps of local distributions of

_{tra}*f*were computed and statistics were inferred to build maps of average, standard deviation (stddev) and median of

_{intra}*f*at the vertex level. In order to get

_{intra}*f*distributions at the scale of cortical areas, the vertex-wise distributions included in the considered area were merged together providing a microstructural signature of this area per subject. Figure 2 summarizes the cortical sampling pipeline developed to extract quantitative features on the cortex at the individual level.

_{intra}Fig. 2 **Cortical sampling pipeline for one subject**