To understand how the cerebellar cortex transforms mossy fiber (MF) inputs into Purkinje cell (PC) outputs, it is vital to delineate the elements of this circuit. Candelabrum cells (CCs) are enigmatic interneurons of the cerebellar cortex that have been identified based on their morphology, but their electrophysiological properties, synaptic connections and function remain unknown. Here, we clarify these properties using electrophysiology, single-nucleus RNA sequencing, in situ hybridization and serial electron microscopy in mice. We find that CCs are the most abundant PC layer interneuron. They are GABAergic, molecularly distinct and present in all cerebellar lobules. Their high resistance renders CC firing highly sensitive to synaptic inputs. CCs are excited by MFs and granule cells and are strongly inhibited by PCs. CCs in turn primarily inhibit molecular layer interneurons, which leads to PC disinhibition. Thus, inputs, outputs and local signals converge onto CCs to allow them to assume a unique role in controlling cerebellar output.

要了解小脑皮层如何将苔藓纤维 (MF) 输入转换为浦肯野细胞 (PC) 输出，描述该回路的元素至关重要。烛台细胞 (CCs) 是小脑皮质的神秘中间神经元，已根据其形态学进行鉴定，但其电生理特性、突触连接和功能仍然未知。在这里，我们使用小鼠的电生理学、单核 RNA 测序、原位杂交和连续电子显微镜来阐明这些特性。我们发现 CC 是最丰富的 PC 层中间神经元。它们是 GABAergic，分子结构不同，存在于所有小脑小叶中。它们的高电阻使 CC 放电对突触输入高度敏感。CCs 被 MFs 和颗粒细胞激发，并被 PCs 强烈抑制。CC 反过来主要抑制分子层中间神经元，从而导致 PC 去抑制。因此，输入、输出和局部信号会聚到 CC 上，使它们在控制小脑输出方面发挥独特的作用。