Brain Hemispheric Structural Efficiency and Interconnectivity Rightward Asymmetry in Human and Nonhuman Primates

Evidences of inter-regional structural asymmetries have been previously reported for brain anatomic regions supporting well described functional lateralization. Here we aimed to investigate whether the two brain hemispheres demonstrate dissimilar general structural attributes implying different principles on information flow management. Common left/right hemisphere structural network properties are estimated and compared for right-handed healthy human subjects and a non-human primate, by means of three different probabilistic diffusionweighted MRI fiber tractography algorithms and a graph theory framework. In both the human and non-human primate the data support the conclusion that the right hemisphere is significantly more efficient and interconnected than the left hemisphere, whereas the left hemisphere presents more indispensable regions for the whole brain structural network than the right hemisphere. In terms of functional principles, this pattern could be related with the fact that the left hemisphere has a leading role for highly demanding specific process, such as language, which may require dedicated specialized networks, whereas the right hemisphere has a leading role for more general process, such as integration tasks, which may require a more general level of interconnection