Rhesus monkey and human share a similar topography of the corpus callosum as revealed by diffusion tensor MRI in vivo.

A recent study of the corpus callosum (CC) in humans revealed a new topographical arrangement of the cortical connectivity pattern. To explore the CC topography in nonhuman primates, we applied magnetic resonance diffusion tensor imaging and tract tracing techniques in individual rhesus monkeys in vivo. The results demonstrate that the CC topography of primates and humans is surprisingly similar. In particular, the relatively large representation and caudal extension of commissural frontal fibers in the CC is observed in both the monkey and human brain. If evolutionary changes in relative brain volumes are reflected in the arrangement of related fibers crossing the CC, the current study is in line with the fact that the relative volume of the frontal lobe did not significantly increase after the split of the hominid line from other primates.