LAYER-SPECIFIC PROGRAMS OF DEVELOPMENT IN NEOCORTICAL PROJECTION NEURONS
LAYER-SPECIFIC PROGRAMS OF DEVELOPMENT IN NEOCORTICAL PROJECTION NEURONS
复制标题
DOI：
10.1073/pnas.92.24.11145
复制
发表时间：
1995-11-21
影响因子：
11.1
通讯作者：
SUR, M
中科院分区：
文献类型：
--
作者：
CLASCA, F;ANGELUCCI, A;SUR, M
在发育过程中，大脑皮层的长距离轴突投射是如何协调的？通过在胎儿和出生后雪貂中使用被动和主动运输的轴突示踪剂，我们分析了从皮质到许多丘脑核的投射的发育。我们报告说，皮质区域到其相应丘脑核的投射遵循高度细胞特异性的发育程序，来自大脑皮层最深层（第 6 层和浅层亚板神经元）细胞的轴突似乎生长非常缓慢，并且在大脑白质中延迟数周，在较长时间内到达丘脑。另一方面，第 5 层神经元的投射速度要快得多；尽管第 5 层神经元是在更深层次的神经元之后出生的，但第 5 层神经元是第一个将轴突延伸出皮质半球并支配丘脑的，第 5 层投射在出生后最初几周内很大，但可能在发育后期部分消除，在数量上被构成主要皮质丘脑投射的第 6 层细胞所取代。第 5 层投射从一开始就是区域特异性的，是作为指向脑干和脊髓的轴突的侧支分支而出现的。我们的研究结果表明，离皮质连接的早期发育不是由皮质神经发生的顺序决定的，而是由每种类型的投射神经元特有的发育程序决定的。此外，他们证明，在大多数丘脑核中，第 5 层神经元（而不是亚板或第 6 层神经元）建立了来自大脑皮层的第一个下降投射。
How are long-range axonal projections from the cerebral Cortex orchestrated during development? By using both passively and actively transported axonal tracers in fetal and postnatal ferrets, we have analyzed the development of projections from the cortex to a number of thalamic nuclei. We report that the projections of a cortical area to its corresponding thalamic nuclei follow highly cell-specific programs of development, Axons from cells in the deepest layers of the cerebral cortex (layer 6 and superficial subplate neurons) appear to grow very slowly and be delayed for several weeks in the cerebral white matter, reaching the thalamus over a protracted period, Neurons of layer 5, on the other hand, develop their projections much faster; despite being born after the neurons of deeper layers, layer 5 neurons are the first to extend their axons out of the cortical hemisphere and innervate the thalamus, Layer 5 projections are massive in the first postnatal weeks but may become partly eliminated later in development, being overtaken in number by layer 6 cells that constitute the major corticothalamic projection by adulthood. Layer 5 projections are area-specific from the outset and arise as collateral branches of axons directed to the brainstem and spinal cord. Our findings show that the early development of corticofugal connections is determined not by the sequence of cortical neurogenesis but by developmental programs specific for each type of projection neuron, In addition, they demonstrate that in most thalamic nuclei, layer 5 neurons (and not subplate or layer 6 neurons) establish the first descending projections from the cerebral cortex.