Corpus callosum morphology across the lifespan in baboons (Papio anubis): A cross-sectional study of relative mid-sagittal surface area and thickness

René Westerhausen,Adrien Meguerditchian

doi:10.1016/j.neures.2021.03.002

René Westerhausen, Adrien Meguerditchian

Open Access

https://doi.org/10.1016/j.neures.2021.03.002

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Abstract

The corpus callosum enables integration and coordination of cognitive processing between the cerebral hemispheres. In the aging human brain, these functions are affected by progressive axon and myelin deteriorations, reflected as atrophy of the midsagittal corpus callosum in old age. In non-human primates, these degenerative processes are less pronounced as previous morphometric studies on capuchin monkey, rhesus monkeys, and chimpanzees do not find old-age callosal atrophy. In the present study, we extend these previous findings by studying callosal development of the olive baboon (Papio anubis) across the lifespan and compare it to chimpanzee and human data. For this purpose, total relative (to forebrain volume) midsagittal area, subsectional area, and regional thickness of the corpus callosum were assessed in 91 male and female baboons using non-invasive MRI-based morphometry. The studied age range was 2.5–26.6 years and lifespan trajectories were fitted using general additive modelling. Relative area of the total and anterior corpus callosum showed a positive linear trajectory. That is, both measures increased slowly but continuously from childhood into old age, and no decline was observed in old age. Thus, comparable with all other non-human primates studied to-date, baboons do not show callosal atrophy in old age. This observation lends supports to the notion that atrophy of the corpus callosum is a unique characteristic of human brain aging.

Highlights

The corpus callosum as the major white-matter commissure, is a critical channel for the integration of information (e.g., Steinmann et al, 2018; Westerhausen, Gruner, Specht, & Hugdahl, 2009) and coordination of processing in the two cerebral hemisphere (e.g., Davis & Cabeza, 2015; Thiel et al, 2006)
The main finding was that relative area of total corpus callosum follows a linear lifespan trajectory
The present study supplements the findings of a series of previous studies suggesting that the aging trajectories of the corpus callosum differ substantially between primate species

Summary

Introduction

The corpus callosum as the major white-matter commissure, is a critical channel for the integration of information (e.g., Steinmann et al, 2018; Westerhausen, Gruner, Specht, & Hugdahl, 2009) and coordination of processing in the two cerebral hemisphere (e.g., Davis & Cabeza, 2015; Thiel et al, 2006). Morphometric analyses of the midsagittal corpus callosum report a substantial atrophy of callosal surface area (Doraiswamy et al, 1991; Hasan, EwingCobbs, Kramer, Fletcher, & Narayana, 2008; Prendergast et al, 2015; Salat, Ward, Kaye, & Janowsky, 1997; Skumlien et al, 2018) and thickness measures (Danielsen et al, 2020) This atrophy of the corpus callosum is stronger than what would be predicted from the parallel ongoing decline in overall forebrain and white-matter volume, suggesting a progressive decline in structural callosal connectivity in the aging brain (Danielsen et al, 2020; Salat et al, 1997; Skumlien et al, 2018). We examined a possible sexual dimorphism in the corpus callosum, and explored potential differences in the age trajectories between the sexes

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