Evolutionary conservation of neocortical neurogenetic program in the mammals and birds.
Evolutionary conservation of neocortical neurogenetic program in the mammals and birds.
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DOI：
10.4161/bioa.21032
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发表时间：
2012-07
期刊：
影响因子：
--
通讯作者：
Hirata T
中科院分区：
文献类型：
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作者：
Suzuki IK;Hirata T
层状新皮质在哺乳动物进化中的独特创新被认为通过提供高信息处理能力来促进哺乳动物物种对各种生态环境的适应辐射。从非哺乳动物的简单大脑到哺乳动物的多层新皮质并没有过渡状态，因此，到目前为止，这种大脑结构是如何在进化过程中获得的完全是一个谜。在我们最近的研究中，我们发现有证据表明，新皮质神经元亚型的进化起源早于层结构的实际出现。我们对与哺乳动物新皮质同源的雏鸡大脑皮层的比较发育分析表明，哺乳动物和鸟类基本上共享新皮质神经元亚型及其产生机制，这表明它们的共同祖先已经拥有相似的神经元库。我们进一步证明，新皮质层特异性神经元亚型在雏鸡中以内侧分离的区域排列，而在哺乳动物新皮质中不是以层的形式排列。这些动物群体特有的神经元排列是通过神经遗传学程序的空间调节来完成的，这表明了一个进化假说，神经遗传学程序中的调节变化创新了哺乳动物特有的分层新皮质。
The unique innovation of the layered neocortex in mammalian evolution is believed to facilitate adaptive radiation of mammalian species to various ecological environments by furnishing high information processing ability. There are no transitional states from the non-mammalian simple brain to the mammalian multilayered neocortex, and thus it is totally a mystery so far how this brain structure has been acquired during evolution. In our recent study, we found the evidence showing that the evolutionary origin of the neocortical neuron subtypes predates the actual emergence of layer structure. Our comparative developmental analysis of the chick pallium, homologous to the mammalian neocortex, revealed that mammals and avians fundamentally share the neocortical neuron subtypes and their production mechanisms, suggesting that their common ancestor already possessed a similar neuronal repertory. We further demonstrated that the neocortical layer-specific neuron subtypes are arranged as mediolaterally separated domains in the chick, but not as layers in the mammalian neocortex. These animal group-specific neuronal arrangements are accomplished by spatial modulation of the neurogenetic program, suggesting an evolutionary hypothesis that the regulatory changes in the neurogenetic program innovated the mammalian specific layered neocortex.