Department of Cell Physiology, Max Planck Institute for Medical Research, D-69120 Heidelberg, Germany.
Cereb Cortex. 2010 Oct;20(10):2287-303. doi: 10.1093/cercor/bhq069. Epub 2010 Jun 9.
This is the concluding article in a series of 3 studies that investigate the anatomical determinants of thalamocortical (TC) input to excitatory neurons in a cortical column of rat primary somatosensory cortex (S1). We used viral synaptophysin-enhanced green fluorescent protein expression in thalamic neurons and reconstructions of biocytin-labeled cortical neurons in TC slices to quantify the number and distribution of boutons from the ventral posterior medial (VPM) and posteromedial (POm) nuclei potentially innervating dendritic arbors of excitatory neurons located in layers (L)2-6 of a cortical column in rat somatosensory cortex. We found that 1) all types of excitatory neurons potentially receive substantial TC input (90-580 boutons per neuron); 2) pyramidal neurons in L3-L6 receive dual TC input from both VPM and POm that is potentially of equal magnitude for thick-tufted L5 pyramidal neurons (ca. 300 boutons each from VPM and POm); 3) L3, L4, and L5 pyramidal neurons have multiple (2-4) subcellular TC innervation domains that match the dendritic compartments of pyramidal cells; and 4) a subtype of thick-tufted L5 pyramidal neurons has an additional VPM innervation domain in L4. The multiple subcellular TC innervation domains of L5 pyramidal neurons may partly explain their specific action potential patterns observed in vivo. We conclude that the substantial potential TC innervation of all excitatory neuron types in a cortical column constitutes an anatomical basis for the initial near-simultaneous representation of a sensory stimulus in different neuron types.
这是一项研究的总结文章，该研究共包含 3 个部分，旨在探讨丘脑皮质（TC）输入到大鼠初级体感皮层（S1）皮质柱兴奋性神经元的解剖学决定因素。我们使用病毒突触素增强型绿色荧光蛋白在丘脑神经元中的表达以及 TC 切片中生物胞素标记的皮质神经元的重建，来定量分析潜在地支配位于大鼠体感皮层皮质柱 L2-6 层的兴奋性神经元树突丛的来自腹后内侧核（VPM）和后内侧核（POm）的纤维末梢的数量和分布。我们发现：1）所有类型的兴奋性神经元都可能接受大量的 TC 输入（每个神经元 90-580 个末梢）；2）L3-L6 的锥体细胞接受来自 VPM 和 POm 的双重 TC 输入，对于厚树突锥体细胞（约 300 个末梢）来说，这种输入的可能性大小相等；3）L3、L4 和 L5 锥体细胞具有多个（2-4 个）亚细胞 TC 支配域，与锥体细胞的树突隔室相匹配；4）一种厚树突 L5 锥体细胞亚型在 L4 中具有额外的 VPM 支配域。L5 锥体细胞的多个亚细胞 TC 支配域可能部分解释了它们在体内观察到的特定动作电位模式。我们得出结论，皮质柱中所有兴奋性神经元类型的大量潜在 TC 支配构成了初始近同时代表不同神经元类型的感觉刺激的解剖学基础。
