Automatic analysis of cross‐sectional cerebral asymmetry on 3D in vivo MRI scans of human and chimpanzee

Abstract

One prominent feature of human brain asymmetry is the cerebral torque. To investigate whether this characteristic is shared with chimpanzees who are our closest extant relative, we developed an automatic method to compute cerebral hemisphere width and perimeter length on consecutive 2D sections through 3D MR images obtained in vivo for 91 human and 78 chimpanzee brains. In brief, contiguous inter‐hemispheric width and perimeter asymmetries were calculated on coronal sections, which in profile allow us to examine asymmetry in relation to speciation. The right frontal and left occipital asymmetry (greater posteriorly in females) distinguishes humans from chimpanzees. This result is consistent with a major saltational (discontinuity) event occurring at some point after the separation of humanity and the great apes in the last 6 million years.

Comparison of Surface Area and Cortical Thickness Asymmetry in the Human and Chimpanzee Brain

“…However, relevant application on the chimpanzee brain is very few in the literature. In our previous brain morphology study (Xiang, Crow, & Roberts, 2019a, 2019b, we adopted Greve's approach to compare the interhemispheric positional brain asymmetry between humans and chimpanzees under the same framework. The findings suggested absence of cerebral torque in the chimpanzee brain, contradict to the previous literature Hopkins & Marino, 2000;LeMay, 1982).…”