Table_1.docx

A key parameter to constrain predictive, bottom-up circuit models of a given brain domain is the number and position of the neuronal populations involved. These include not only the neurons whose bodies reside within the domain, but also the neurons in distant regions that innervate the domain. The mouse visual cortex receives its main subcortical input from the dorsal lateral geniculate nucleus (dLGN) and the lateral posterior (LP) complex of the thalamus. The latter consists of three different nuclei: lateral posterior lateral (LPL), lateral posterior medial rostral (LPMR), and lateral posterior medial caudal (LPMC), each exhibiting specific patterns of connections with the various visual cortical areas. Here, we have determined the number of thalamocortical projection neurons and interneurons in the LP complex and dLGN of the adult C57BL/6 male mouse. We combined Nissl staining and histochemical and immunolabeling methods for consistently delineating nuclei borders, and applied unbiased stereological cell counting methods. Thalamic interneurons were identified using GABA immunolabeling. The C57BL/6 dLGN contains ∼21,200 neurons, while LP complex contains ∼31,000 total neurons. The dLGN and LP are the only nuclei of the mouse dorsal thalamus containing substantial numbers GABA-immunoreactive interneurons. These interneurons, however, are scarcer than previously estimated; they are 5.6% of dLGN neurons and just 1.9% of the LP neurons. It can be thus inferred that the dLGN contains ∼20,000 and the LP complex ∼30,400 thalamocortical projection neurons (∼12,000 in LPL, 15,200 in LPMR, and 4,200 in LPMC). The present dataset is relevant for constraining models of mouse visual thalamocortical circuits, as well as for quantitative comparisons between genetically modified mouse strains, or across species.

约束特定脑区预测性自下而上环路模型的关键参数之一，是其所涉及的神经元群体的数量与空间分布。此类群体不仅包括胞体位于该脑区内的神经元，亦包括来自远端脑区并支配该脑区的神经元。小鼠视觉皮层的主要皮层下输入来自背外侧膝状体核（dorsal lateral geniculate nucleus，dLGN）与丘脑后外侧复合体（lateral posterior，LP）。后者包含三个不同的亚核：后外侧丘脑外侧亚核（LPL）、后外侧丘脑嘴侧内侧亚核（LPMR）以及后外侧丘脑尾侧内侧亚核（LPMC），每个亚核均与不同视觉皮层区域存在特异性连接模式。本研究明确了成年雄性C57BL/6小鼠后外侧丘脑复合体与背外侧膝状体核内的丘脑皮层投射神经元及中间神经元数量。我们结合尼氏染色、组织化学与免疫标记技术实现了核团边界的一致性划定，并采用无偏体视学细胞计数法进行定量分析；通过γ-氨基丁酸（GABA）免疫标记鉴定丘脑中间神经元。C57BL/6小鼠的背外侧膝状体核约含21200个神经元，而后外侧丘脑复合体总神经元数约为31000个。背外侧膝状体核与后外侧丘脑复合体是小鼠背侧丘脑中唯一含有大量GABA免疫反应性中间神经元的核团，不过此类中间神经元的数量较此前预估更为稀少：其占背外侧膝状体核神经元总数的5.6%，仅占后外侧丘脑复合体神经元总数的1.9%。由此可推断，背外侧膝状体核内约含20000个丘脑皮层投射神经元，后外侧丘脑复合体则约含30400个（其中LPL约12000个、LPMR约15200个、LPMC约4200个）。本数据集可用于约束小鼠视觉丘脑皮层环路模型，亦适用于不同转基因小鼠品系间或跨物种的定量比较研究。