Proprioception is governed by highly diverse and versatile sensory neuron types

Proprioceptive neurons (PNs) are essential for the proper execution of all our movements by providing muscle sensory feedback to the central motor network. Here, using deep single cell RNAseq of adult PNs coupled with advanced virus- and genetic tracings, we have molecularly identified the 3 main types of PNs (Ia, Ib and II) and unexpectedly found that they segregate into 8 subgroups. Our data further reveal a highly sophisticated organization of PNs into discrete sensory input channels with distinct spatial distribution, innervation patterns and molecular profiles, that together contribute to the sensory monitoring of complex motor behavior. Moreover, while Ib- and II-PN subtypes are specified around birth, Ia-PN subtypes diversify later along with increased motor activity and show versatility in the adult following exercise training, suggesting adaptive proprioceptive function. Exploring the molecular heterogeneity of mouse proprioceptors at different developmental stages (E16.5, P5 and P54)本体感觉神经元（Proprioceptive neurons, PNs）通过向中枢运动网络传递肌肉感觉反馈，对所有运动的正常执行至关重要。本研究通过对成年PNs开展深度单细胞RNA测序（single cell RNAseq），并结合先进的病毒示踪与遗传示踪技术，在分子层面鉴定出PNs的3种主要类型（Ia、Ib及II型），且意外发现它们可进一步分为8个亚群。研究数据进一步揭示，PNs以高度复杂的组织形式构建为多个独立的感觉输入通道，这些通道具备独特的空间分布、神经支配模式与分子特征，共同参与复杂运动行为的感觉监测过程。此外，尽管Ib型与II型PN亚群在出生前后即已定型，但Ia型PN亚群则随着运动活动的增加在后续阶段发生分化，且成年个体在接受运动训练后其Ia型PN亚群表现出功能可塑性，这提示本体感觉功能具有适应性。本研究还针对不同发育阶段（E16.5、P5及P54）的小鼠本体感觉神经元的分子异质性展开了探究。