Diversity and evolution of cerebellar folding in mammals
- Institut Pasteur, Falkland Islands (Malvinas)
- Institut Pasteur, France
- Bath Spa University, United Kingdom
- Max Planck Institute for Human Cognitive and Brain Sciences, Germany
- Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023, France
Abstract
The process of brain folding is thought to play an important role in the development and organisation of the cerebrum and the cerebellum. The study of cerebellar folding is challenging due to the small size and abundance of its folia. In consequence, little is known about its anatomical diversity and evolution. We constituted an open collection of histological data from 56 mammalian species and manually segmented the cerebrum and the cerebellum. We developed methods to measure the geometry of cerebellar folia and to estimate the thickness of the molecular layer. We used phylogenetic comparative methods to study the diversity and evolution of cerebellar folding and its relationship with the anatomy of the cerebrum. Our results show that the evolution of cerebellar and cerebral anatomy follows a stabilising selection process. We observed 2 groups of phenotypes changing concertedly through evolution: a group of 'diverse' phenotypes - varying over several orders of magnitude together with body size, and a group of 'stable' phenotypes varying over less than 1 order of magnitude across species. Our analyses confirmed the strong correlation between cerebral and cerebellar volumes across species, and showed in addition that large cerebella are disproportionately more folded than smaller ones. Compared with the extreme variations in cerebellar surface area, folial anatomy and molecular layer thickness varied only slightly, showing a much smaller increase in the larger cerebella. We discuss how these findings could provide new insights into the diversity and evolution of cerebellar folding, the mechanisms of cerebellar and cerebral folding, and their potential influence on the organisation of the brain across species.
Data availability
All data analysed during this study is openly available at https://microdraw.pasteur.fr/project/brainmuseum-cb. Code for reproducing our analyses and our figures is openly available at https://github.com/neuroanatomy/comp-cb-folding
Article and author information
Author details
Funding
European Commission (101033485)
- Katja Heuer
Agence Nationale de la Recherche (ANR-19-DATA-0025)
- Katja Heuer
- Nicolas Traut
- Roberto Toro
Agence Nationale de la Recherche (ANR-21-CE45-0016)
- Katja Heuer
- Nicolas Traut
- Roberto Toro
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: The human dataset used has been made openly available through the BigBrain project.
Copyright
© 2023, Heuer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Diversity and evolution of cerebellar folding in mammals
eLife 12:e85907.
https://doi.org/10.7554/eLife.85907
