In vivo mapping of the deep and superficial whitematter connectivity in the chimpanzee brain

Mapping the chimpanzee brain connectome, and comparing it to humans, is key to our understanding of similarities and differences in primate evolution that occurred after the split from their common ancestor around 6 million years ago. In contrast with macaque species brain studies, less studies have specifically addressed the structural connectivity of the chim-panzee brain and its comparison with the human brain. Most comparative studies in the liter-ature focus on the anatomy of the cortex and deep nuclei to evaluate how their morphometry and asymmetry differs from that of the human brain, and some studies have emerged concern-ing the study of brain connectivity between primates. In this work, we established a new white matter atlas of the deep and superficial white matter structural connectivity in chimpanzees. In vivo anatomical and diffusion weighted magnetic resonance imaging (MRI) data were collected on a 3 Tesla magnetic resonance imaging (MRI) system in 39 chimpanzees. These datasets were subsequently processed using a dedicated fiber clustering pipeline adapted to the chimpanzee brain enabling us to create two novel deep and superficial white matter connectivity atlases representative of the chimpanzee brain. These atlases provide the scientific community with an important and novel set of reference data for understanding the commonalities and differ-ences of the structural connectivity between the human and chimpanzee brains, which will contribute to a better understanding of the hominin brain evolution.