Pioneer neurons and target selection in cerebral cortical development.
Pioneer neurons and target selection in cerebral cortical development.
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大脑皮层发育中的先锋神经元和目标选择。
DOI：
10.1101/sqb.1990.055.01.046
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Antonini,A
中科院分区：
文献类型：
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作者：
Shatz,CJ;Ghosh,A;McConnell,SK;Allendoerfer,KL;Friauf,E;Antonini,A
从最简单的无脊椎动物到最复杂的哺乳动物的神经系统，任何神经系统的构建都需要解决几个主要问题。神经元必须在适当的数量和位置生成，轴突必须选择通往目标的正确路径，并且，一旦到达目标，必须形成适当的连接模式。在无脊椎动物中，许多观察表明，轴突通路很早就被铺设好了，当时距离很短，因为先锋神经元的轴突在随后由后来产生的轴突的适当子集穿越的地形中导航（Goodman et al. 1984）。许多轴突通路的早期形成也发生在哺乳动物神经系统发育中。例如，在成人视觉系统中，视网膜神经节细胞投射到外侧膝状核（LGN）， LGN又投射到初级视觉皮层第4层的神经元。在发育过程中，神经节细胞和LGN神经元几乎同时产生，两组神经元立即向其目标生长轴突突起（Rakic 1977; Shatz 1983; Walsh et al. 1983; Hickey and Hitchcock 1984; Shatz and Luskin 1986），这表明，在这里，连接也尽可能早地形成，以尽量减少大脑逐渐生长所带来的寻路和目标选择问题。在哺乳动物大脑皮层的发育过程中，除了上面提到的一系列问题外，还增加了一个额外的逻辑复杂性。为了产生成体皮层所需的数百万个神经元，需要很长时间的神经发生，持续时间从几周到几个月不等，这取决于物种（啮齿动物到灵长类动物）。一旦有丝分裂后，神经元也必须迁移越来越长的距离，以到达它们在皮质板内的最终位置（回顾，见Rakic 1975； McConnell 1988）。因此，与视网膜神经节细胞和LGN神经元不同，许多皮质神经元是在发育很晚的时候产生的，通常是在它们的目标形成和轴突输入到达之后。在本文中，我们考虑了大脑皮层神经发生时间延长所带来的后勤问题，我们提出的证据表明，这个问题在一定程度上可以通过在发育早期构建瞬时神经支架来解决。
The construction of any nervous system from that of the simplest invertebrate to that of the most complex mammal requires the solution of several major problems. Neurons must be generated in appropriate numbers and locations, axons must select correct pathways to their targets, and, once there, the appropriate patterns of connections must be formed. In invertebrates, many observations suggest that axonal pathways are laid down very early, when distances are small, as the axons of pioneer neurons navigate terrain traversed subsequently by appropriate subsets of later-generated axons (Goodman et al. 1984). The early formation of many axonal pathways also occurs in mammalian nervous system development. For example, in the adult visual system, retinal ganglion cells project to the lateral geniculate nucleus (LGN), which in turn projects to the neurons of layer 4 of the primary visual cortex. During development, ganglion cells and LGN neurons are generated at about the same time, and both sets of neurons immediately grow axonal projections toward their targets (Rakic 1977; Shatz 1983; Walsh et al. 1983; Hickey and Hitchcock 1984; Shatz and Luskin 1986), suggesting that, here too, connections are formed as early as possible in order to minimize the considerable problems of pathfinding and target selection posed by the progressive growth of the brain. In the development of the mammalian cerebral cortex, an additional logistical complexity is added to the set of problems mentioned above. To produce the millions of neurons required for the adult cortex requires a very prolonged period of neurogenesis, lasting from weeks to months, depending on the species (rodents to primates). Neurons, once postmitotic, must also migrate over increasingly longer distances to reach their final locations within the cortical plate (for reviews, see Rakic 1975; McConnell 1988). Thus, unlike the retinal ganglion cells and LGN neurons, many cortical neurons are generated very late in development, often well after their targets have been formed and their axonal inputs have arrived. In this paper, we consider the logistical problem posed by the prolonged period of neurogenesis in the cortex, and we present evidence that the problem is solved in part by the construction of a transient neural scaffold early in development.