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Numerical Analysis of the Cerebral Cortex in Diprotodontids (Marsupialia; Australidelphia) and Comparison with Eutherian Brains
Zoology ( IF 2 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.zool.2020.125845
T.K. Jyothilakshmi , Yamila Gurovich , Ken W.S. Ashwell

Diprotodontids are a diverse group of Australian metatherians, which occupy a range of ecological niches from nectar and pollen-feeders to grazers and folivores. The group encompasses small-brained nectar-feeding species (Tarsipes) and large-brained grazing and browsing species (macropods). This group of Australian metatherians therefore represents an opportunity to examine how the cerebral cortex has expanded in an adaptive radiation quite independent of that occurring among eutherians. We have used the Nelson Brain Collection and online resources to perform a quantitative analysis of the isocortex, hippocampal formation and olfactory structures in diprotodontids. We found that the scaling relationship between iso- and periallocortical grey matter and brain size, and between subcortical white matter and iso- and periallocortex grey matter, are both almost identical among diprotodontids and eutherians. By contrast, the relationship between gyrification and brain size is strikingly different between diprotodontids and eutherians, with gyrification being much lower for a given brain size among the diprotodontids, although gyrification is much more varied among macropods than other diprotodontids. The scaling of iso- and periallocortical volume with dorsal striatal and dorsal thalamic volume is almost identical among the diprotodontids and eutherians, but the claustrum is smaller, and amygdala larger, for a given brain size among diprotodontids than eutherians. The hippocampal formation and central olfactory areas (anterior olfactory region and piriform cortex) both scale more steeply with brain size among diprotodontids compared to eutherians. Our findings suggest that, although white matter scaling is identical among all therians, there are significant differences between diprotodontids and eutherians in the way that cortical folding and expansion of allocortical structures occurs with brain enlargement.

中文翻译:

Diprotodontids (Marsupialia; Australidelphia) 大脑皮层的数值分析和与 Eutherian 大脑的比较

Diprotodontids 是一个多样化的澳大利亚 metatherians 群体,它们占据了从花蜜和花粉饲养者到食草动物和食叶动物的一系列生态位。该组包括小脑花蜜喂养物种(Tarsipes)和大脑放牧和浏览物种(巨足类)。因此,这组澳大利亚超兽类动物提供了一个机会,可以检查大脑皮层如何在适应性辐射中扩展,而完全独立于真兽类动物中发生的辐射。我们使用 Nelson Brain Collection 和在线资源对双原齿动物的同皮质、海马结构和嗅觉结构进行了定量分析。我们发现等皮质和皮质周围灰质与大脑大小之间,以及皮质下白质与等皮质和皮质周围灰质之间的比例关系,diprotodontids 和eutherians 之间几乎相同。相比之下,双原齿类和真齿类动物之间的回旋化和大脑大小之间的关系截然不同,尽管巨足类之间的回旋化比其他双齿类动物的变化更大,但对于给定的大脑大小而言,双齿类动物的回旋化程度要低得多。在双原齿类动物和真牙类动物中,等量和周围皮质体积与背侧纹状体和背侧丘脑体积的比例几乎相同,但对于给定的大脑尺寸,双原齿类动物的闭锁骨更小,杏仁核更大。与真齿兽类相比,海马体的形成和中央嗅觉区(前嗅觉区和梨状皮层)在双原齿类动物中随着大脑大小的变化更加陡峭。我们的研究结果表明,
更新日期:2020-12-01
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