Quantitative analysis of cerebellar morphology in monotreme, metatherian and eutherian mammals

Ashwell, Ken W.S.

doi:10.1016/j.zool.2020.125753

Cited by 4 publications

(10 citation statements)

References 35 publications

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“…Our results showed two very different groups of phenotypes: those like brain size, that changed over several orders of magnitude, and those like folial width which were much more conserved. We confirm the strong allometry between the size of the cerebellum and the cerebrum across mammals ( Barton and Harvey, 2000 ; Barton, 2002 ; Whiting and Barton, 2003 ; Herculano-Houzel, 2010 ; Barton, 2012 ; Smaers et al, 2018 ; Ashwell, 2020 ; Magielse et al, 2023 ) and show similarly strong relationships for the width of cerebellar folds and the thickness of the molecular layer, although with a much narrower range of variation. This deeply conserved pattern suggests the presence of a common mechanism underlying the development of the cerebellum and cerebellar folding across mammals.…”

Section: Introductionsupporting

confidence: 78%

“…Our cerebellum section area measurement also correlated strongly with their medial cerebellum volume measurement, a fact that could be eventually used in the future for imputing missing data, although we do not use medial cerebellar measurements in our analyses. See Figure 6—figure supplement 1 for correlation with measurements in Ashwell, 2020 .…”

Section: Resultsmentioning

confidence: 99%

“…Most of the data used in this study comes from the Brain Museum website ( https://brainmuseum.org ) – the Comparative Mammalian Brain Collection initiated by Wally Welker, John Irwin Johnson, and Adrianne Noe from the University of Wisconsin, Michigan State University, and the National Museum of Health and Medicine. This is the same eutherian mammal data used by Ashwell, 2020 , through the Neuroscience Library website ( https://neurosciencelibrary.org , offline since June 2022). The human brain data comes from the BigBrain Project ( https://bigbrainproject.org ) led by teams from Forschungszentrum Jülich and McGill University ( Amunts et al, 2013 ).…”

Section: Methodsmentioning

confidence: 99%

“…We used an artificial calibration image to ensure that our algorithms produce the correct measurements. Measurements were not modified to account for shrinkage, and reflect the raw data obtained from the images (see Ashwell, 2020 , for a discussion of shrinkage in the Brain Museum collection). All measurements were log 10 converted to facilitate their comparison.…”

Section: Methodsmentioning

confidence: 99%

“…However, data is only 2D, and sectioning often induces non-trivial deformations which make it challenging to create full 3D reconstructions (see, however, the work of Sereno et al, 2020 , and Zheng et al, 2023 ). Using histological data, Ashwell, 2020 , was able to estimate the surface area in 90 species of marsupials and 57 species of eutherian mammals, but did not study folia, of which the measurement remains challenging.…”

Section: Introductionmentioning

confidence: 99%

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Diversity and evolution of cerebellar folding in mammals

Heuer,

Traut,

de Sousa

et al. 2023

eLife

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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.

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Section: Introductionsupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Diversity and evolution of cerebellar folding in mammals

Heuer,

Traut,

de Sousa

et al. 2023

eLife

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Numerical Analysis of the Cerebral Cortex in Diprotodontids (Marsupialia; Australidelphia) and Comparison with Eutherian Brains

Jyothilakshmi

Gurovich

Ashwell

2020

Zoology

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Clade-specific forebrain cytoarchitectures of the extinct Tasmanian tiger

Haines

Bailey

Nelson

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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The thylacine, or Tasmanian tiger, is the largest of modern-day carnivorous marsupials and was hunted to extinction by European settlers in Australia. Its physical resemblance to eutherian wolves is a striking example of evolutionary convergence to similar ecological niches. However, whether the neuroanatomical organization of the thylacine brain resembles that of canids and how it compares with other mammals remain unknown due to the scarcity of available samples. Here, we gained access to a century-old hematoxylin-stained histological series of a thylacine brain, digitalized it at high resolution, and compared its forebrain cellular architecture with 34 extant species of monotremes, marsupials, and eutherians. Phylogenetically informed comparisons of cortical folding, regional volumes, and cell sizes and densities across cortical areas and layers provide evidence against brain convergences with canids, instead demonstrating features typical of marsupials, and more specifically Dasyuridae, along with traits that scale similarly with brain size across mammals. Enlarged olfactory, limbic, and neocortical areas suggest a small-prey predator and/or scavenging lifestyle, similar to extant quolls and Tasmanian devils. These findings are consistent with a nonuniformity of trait convergences, with brain traits clustering more with phylogeny and head/body traits with lifestyle. By making this resource publicly available as rapid web-accessible, hierarchically organized, multiresolution images for perpetuity, we anticipate that additional comparative insights might arise from detailed studies of the thylacine brain and encourage researchers and curators to share, annotate, and preserve understudied material of outstanding biological relevance.

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Quantitative analysis of cerebellar morphology in monotreme, metatherian and eutherian mammals

Cited by 4 publications

References 35 publications

Diversity and evolution of cerebellar folding in mammals

Diversity and evolution of cerebellar folding in mammals

Numerical Analysis of the Cerebral Cortex in Diprotodontids (Marsupialia; Australidelphia) and Comparison with Eutherian Brains

Clade-specific forebrain cytoarchitectures of the extinct Tasmanian tiger

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