Gerhardt Ben, Alfken Jette, Reichmann Jakob, Salditt Tim, Brecht Michael
Bernstein Center for Computational Neuroscience Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.
Institut für Röntgenphysik, Universität Göttingen, Göttingen, Germany.
Nat Commun. 2025 Jan 8;16(1):499. doi: 10.1038/s41467-024-55468-4.
Understanding vibrissal transduction has advanced by serial sectioning and identified afferent recordings, but afferent mapping onto the complex, encapsulated follicle remains unclear. Here, we reveal male rat C2 vibrissa follicle innervation through synchrotron X-ray phase contrast tomograms. Morphological analysis identified 5% superficial, ~32 % unmyelinated and 63% myelinated deep vibrissal nerve axons. Myelinated afferents consist of each one third Merkel and club-like, and one sixth Ruffini-like and lanceolate endings. Unsupervised clustering of afferent properties aligns with classic morphological categories and revealed previously unrecognized club-like afferent subtypes distinct in axon diameter and Ranvier internode distance. Myelination and axon diameters indicate a proximal-to-distal axon-velocity gradient along the follicle. Axons innervate preferentially dorso-caudally to the vibrissa, presumably to sample contacts from vibrissa protraction. Afferents organize in axon-arms innervating discrete angular territories. The radial axon-arm arrangement around the vibrissa maps into a linear representation of axon-arm bands in the nerve. Such follicle linearization presumably instructs downstream linear brainstem barrelettes. Synchrotron imaging provides a synopsis of afferents and mechanotransductory machinery.
通过连续切片和识别传入神经记录，对触须转导的理解取得了进展，但传入神经在复杂的、有被膜的毛囊上的映射仍不清楚。在这里，我们通过同步加速器X射线相衬断层扫描揭示了雄性大鼠C2触须毛囊的神经支配情况。形态学分析确定了5%的浅表、约32%的无髓鞘和63%的有髓鞘深部触须神经轴突。有髓鞘传入神经由三分之一的梅克尔氏小体和棒状小体、六分之一的鲁菲尼氏小体样和柳叶状末梢组成。传入神经特性的无监督聚类与经典形态学类别一致，并揭示了以前未被认识的棒状传入神经亚型，其轴突直径和郎飞节间距离不同。髓鞘形成和轴突直径表明沿毛囊存在近端到远端的轴突速度梯度。轴突优先向触须的背尾侧支配，大概是为了从触须伸展中采样接触信息。传入神经在支配离散角状区域的轴突臂中组织起来。触须周围的径向轴突臂排列映射到神经中轴突臂带的线性表示中。这种毛囊线性化大概指导下游的线性脑干小桶状结构。同步加速器成像提供了传入神经和机械转导机制的概述。
