The six-layered neocortex of the mammalian pallium has no clear homolog in birds or non-avian reptiles. Recent research indicates that although these extant amniotes possess a variety of divergent and nonhomologous pallial structures, they share a conserved set of neuronal cell types and circuitries. These findings suggest a principle of brain evolution: that natural selection preferentially preserves the integrity of information-processing pathways, whereas other levels of biological organization, such as the three-dimensional architectures of neuronal assemblies, are less constrained. We review the similarities of pallial neuronal cell types in amniotes, delineate candidate gene regulatory networks for their cellular identities, and propose a model of developmental evolution for the divergence of amniote pallial structures.

中文翻译：

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同源性、新皮质和发育机制的进化


哺乳动物大脑皮层的六层新皮质在鸟类或非鸟类爬行动物中没有明显的同源物。最近的研究表明，尽管这些现存的羊膜动物具有各种不同且非同源的大脑皮层结构，但它们共享一组保守的神经元细胞类型和电路。这些发现表明了大脑进化的一个原则：自然选择优先保留信息处理路径的完整性，而其他层次的生物组织，例如神经元组件的三维结构，则受到较少的限制。我们回顾了羊膜动物中大脑皮层神经元细胞类型的相似性，描绘了其细胞特性的候选基因调控网络，并提出了羊膜动物大脑皮层结构差异的发育进化模型。