A transcriptomic atlas of mouse cerebellar cortex reveals novel cell types

The cerebellar cortex is a well-studied brain structure with diverse roles in motor learning, coordination, cognition, and autonomic regulation. Nonetheless, a complete inventory of cerebellar cell types is presently lacking. We used high-throughput transcriptional profiling to profile more than 600,000 nuclei and molecularly define cell types across individual lobules of the adult mouse cerebellum. Purkinje neurons showed considerable regional specialization, with the greatest diversity occurring in the posterior lobules. For multiple types of cerebellar interneurons, the molecular variation within each type was more continuous, rather than discrete. For the unipolar brush cells (UBCs)--an interneuron population previously subdivided into discrete populations--the continuous variation in gene expression was associated with a graded continuum of electrophysiological properties. Most surprisingly, we found that molecular layer interneurons (MLIs) were composed of two molecularly and functionally distinct types. Both show a continuum of morphological variation through the thickness of the molecular layer, but electrophysiological recordings revealed marked differences between the two types in spontaneous firing, excitability, and electrical coupling. Together, these findings provide the first comprehensive cellular atlas of the cerebellar cortex, and outline a methodological and conceptual framework for the integration of molecular, morphological, and physiological ontologies for defining brain cell types. Characterization and annotation of single nuclei transcriptomes from adult and developing mouse cerebella. Nuclei suspensions for adult mouse cerebellum profiles were generated from 2 female and 4 male adult mice (60 days old), from individual dissections across 16 regions. Nuclei suspensions for developing mouse cerebellum profiles were generated from 2 E18 mice, 2 P0 (newborn) mice, 2 P4 (4 days old) mice, 2 P8, 2 male P12 and 2 male P16 mice. >>>Raw data are unavailable for human samples due to patient privacy concerns<<<小脑皮层是一类研究较为充分的脑结构，在运动学习、协调、认知以及自主神经调控中发挥着多样功能。然而，目前学界仍缺乏一套完整的小脑细胞类型分类目录。本研究采用高通量转录谱分析（high-throughput transcriptional profiling）对超过60万个细胞核进行了检测，并对成年小鼠小脑各小叶的细胞类型进行了分子层面的定义。浦肯野神经元（Purkinje neurons）展现出显著的区域特化现象，其中后小叶的细胞多样性最高。针对多种小脑中间神经元类型，每一类内部的分子变异呈现连续分布特征，而非离散的亚型划分。对于单极刷状细胞（unipolar brush cells, UBCs）——这类中间神经元此前被划分为多个离散亚型——其基因表达的连续变异与电生理特性的梯度连续谱密切相关。最令人意外的是，我们发现分子层中间神经元（molecular layer interneurons, MLIs）实际上由两类在分子层面与功能层面均存在显著差异的亚型组成。两类亚型均在分子层的厚度范围内呈现出连续的形态学变异，但电生理记录显示，二者在自发放电、兴奋性以及电耦合特性上存在显著差异。综上，本研究首次构建了小脑皮层的完整细胞图谱，并为整合分子、形态学与生理学本体论以定义脑细胞类型提供了一套方法学与概念性框架。本数据集涵盖成年与发育阶段小鼠小脑的单个细胞核转录组的表征与注释工作。成年小鼠小脑的细胞核悬液样本采集自6只60日龄的小鼠（2只雌性、4只雄性），样本取自16个独立解剖的脑区。发育阶段小鼠小脑的细胞核悬液样本则采集自：2只胚胎18日龄（E18）小鼠、2只新生0日龄（P0）小鼠、2只出生后4日龄（P4）小鼠、2只出生后8日龄（P8）小鼠、2只雄性出生后12日龄（P12）小鼠以及2只雄性出生后16日龄（P16）小鼠。【注】由于患者隐私保护问题，人类样本的原始数据无法公开获取。