Cross-species cortical alignment identifies different types of neuroanatomical reorganization in higher primates

Abstract Evolutionary adaptations can affect different aspects of brain architecture, including areal expansion, relocation, or changes in connectivity profiles. Distinguishing between different types of reorganization is critical for our understanding of brain evolution. We propose to address this using a computational neuroanatomy approach. We investigate the extent to which between-species cortical alignment based on myelin can predict changes in connectivity patterns across macaque, chimpanzee and human brains. We show that expansion and relocation of brain areas as predicted by the myelin-based alignment are sufficient to predict reorganization of several white matter tracts and their terminations in temporal, frontal and parietal cortex. A notable exception is the arcuate fasciculus, in which we found extensive tract expansion into new territories that cannot be explained by cortical expansion. The presented approach can flexibly be extended to include other features of cortical organization and other species, which allows us to directly test and quantify evolutionary hypotheses.