Department of Bioinformatics, Graduate School of Engineering, Hachioji, Tokyo, 192-8577, Japan.
Department of Science and Engineering for Sustainable Innovation, Faculty of Science and Engineering, Hachioji, Tokyo, 192-8577, Japan.
J Comp Neurol. 2018 Oct 1;526(14):2257-2284. doi: 10.1002/cne.24481. Epub 2018 Aug 25.
Proper formation of laminar structures in sensory cortexes is critical for sensory information processing. Previous studies suggested that the timing of neuronal migration and the laminar position of cortical neurons differ among sensory cortexes. How they differ during postnatal development has not been systematically investigated. Here, identifying laminas using transcription factors, we examined postnatal changes in neuronal density and distribution in presumptive primary auditory (ACx), visual (VCx), and somatosensory cortexes (SCx) in a strain of mice using immunofluorescence techniques. Development of laminar thickness and its cortical proportion differed among the sensory cortexes. Layers 2-4 defined by Cut-like homeobox 1 (Cux1)-expressing neurons were narrower, and layer 5 was wider in ACx compared to those in VCx or SCx, while Forkhead-box protein P2 (Foxp2)-defined layer 6 was wider in SCx than the other two sensory cortexes throughout postnatal development. Meanwhile, thalamocortical input layers identified by Cux1-expressing neurons formed later in ACx than in the other two cortical regions. The cell densities of ETS-related protein 81-expressing neurons increased in both lower and upper layers but at distinct timing, while those of COUP-TF-interacting protein 2 expressing neurons in the lower layers changed bidirectionally (i.e., increased or decreased) both in layer- and cortical region-specific manners. Foxp2-expressing cells in layer 6 distributed differently and declined at different timing among the sensory cortexes. Overall, we demonstrate that the maturational timing of lamina differs among the sensory cortexes and that postnatal age-dependent changes in neuronal distribution are unique to each of the sensory cortexes.
层状结构在感觉皮层中的正确形成对于感觉信息处理至关重要。先前的研究表明，神经元迁移的时间和皮质神经元的层状位置在不同的感觉皮层中有所不同。在出生后发育过程中它们如何不同尚未得到系统研究。在这里，我们使用转录因子来识别层，通过免疫荧光技术检查了一种小鼠中假定的初级听觉（ACx）、视觉（VCx）和体感皮层（SCx）中神经元密度和分布的出生后变化。感觉皮层之间的层厚度和皮质比例的发育不同。与 VCx 或 SCx 相比，由 Cut-like homeobox 1（Cux1）表达神经元定义的 2-4 层较窄，而 5 层较宽，而由 Forkhead-box protein P2（Foxp2）定义的 6 层在整个出生后发育过程中在 SCx 中比在其他两个感觉皮层中更宽。同时，由 Cux1 表达神经元识别的丘脑皮质输入层在 ACx 中形成的时间晚于其他两个皮质区域。ETS 相关蛋白 81 表达神经元的细胞密度在较低和较高层中均增加，但时间不同，而下层中 COUP-TF 相互作用蛋白 2 表达神经元的细胞密度以层和皮质区域特异性的方式双向变化（即增加或减少）。Foxp2 表达的 6 层细胞在感觉皮层中的分布不同，并且在不同的时间以不同的方式减少。总的来说，我们证明了感觉皮层之间的层状成熟时间不同，并且神经元分布的出生后年龄依赖性变化在每个感觉皮层中都是独特的。
