The superficial dorsal horn (SDH, LI-II) of the spinal cord receives and processes multimodal sensory information from skin, muscle, joints, and viscera then relay it to the brain. Neurons within the SDH fall into two broad categories, projection neurons and interneurons. The later can be further subdivided into excitatory and inhibitory types. Traditionally, interneurons within the SDH have been divided into overlapping groups according to their neurochemical, morphological and electrophysiological properties. Recent clustering analyses, based on molecular transcript profiles of cells and nuclei, have predicted many more functional groups of interneurons than expected using traditional approaches. In this study, we used electrophysiological and morphological data obtained from genetically-identified excitatory (vGLUT2) and inhibitory (vGAT) interneurons in transgenic mice to cluster cells into groups sharing common characteristics and subsequently determined how many clusters can be assigned by combinations of these properties. Consistent with previous reports, we show differences exist between excitatory and inhibitory interneurons in terms of their excitability, nature of the ongoing excitatory drive, action potential (AP) properties, sub-threshold current kinetics, and morphology. The resulting clusters based on statistical and unbiased assortment of these data fell well short of the numbers of molecularly predicted clusters. There was no clear characteristic that in isolation defined a population, rather multiple variables were needed to predict cluster membership. Importantly though, our analysis highlighted the appropriateness of using transgenic lines as tools to functionally subdivide both excitatory and inhibitory interneuron populations.

中文翻译：

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抑制性和兴奋性中间神经元群体的转基因交叉参考以剖析背角神经元异质性。

脊髓的浅表背角 (SDH, LI-II) 接收并处理来自皮肤、肌肉、关节和内脏的多模态感觉信息，然后将其传递给大脑。SDH 内的神经元分为两大类，投射神经元和中间神经元。后者又可进一步细分为兴奋型和抑制型。传统上，SDH 内的中间神经元根据其神经化学、形态学和电生理学特性分为重叠组。最近的聚类分析基于细胞和细胞核的分子转录谱，预测了比使用传统方法预期的更多的中间神经元功能组。在这项研究中，我们使用从转基因小鼠中遗传鉴定的兴奋性 (vGLUT2) 和抑制性 (vGAT) 中间神经元获得的电生理学和形态学数据将细胞聚类成具有共同特征的组，然后确定可以通过这些特性的组合分配多少个簇。与之前的报告一致，我们发现兴奋性和抑制性中间神经元在兴奋性、持续兴奋性驱动的性质、动作电位 (AP) 特性、亚阈值电流动力学和形态学方面存在差异。基于这些数据的统计和无偏分类得到的聚类远远低于分子预测的聚类数量。没有明确的特征可以孤立地定义一个群体，需要多个变量来预测集群成员。但重要的是，我们的分析强调了使用转基因品系作为工具在功能上细分兴奋性和抑制性中间神经元群体的适当性。