Multi-scale hierarchical brain regions detect individual and inter-species variations of structural connectivity in macaque monkeys and humans

Macaques are representative animal models in translational research. However, the distinct shape and location of the brain regions between macaques and humans prevents us from comparing the brain structure directly. Here, we calculated structural connectivity (SC) with multi-scale hierarchical regions of interest (ROIs) to parcel out human and macaque brain into 4 (level 1 ROIs) or 13 (level 2 ROIs) regions, which consist of anatomically and functionally defined level 3 ROIs (around 100 parcellation of the brain) and similar function. The SC with the level 1 ROIs showed lower individual and inter-species variation in macaques and humans. SC with level 2 ROIs shows that the temporal lobe has high individual and inter-species variation in macaques and humans, while the prefrontal and sensory cortices show low individual and inter-species variation. These results provide insights into the suitability of macaques as animal models for humans.