PDF(Pubmed)
Abstract：
Complex motor skills in vertebrates require specialized upper motor neurons with precise action potential (AP) firing. To examine how diverse populations of upper motor neurons subserve distinct functions and the specific repertoire of ion channels involved, we conducted a thorough study of the excitability of upper motor neurons controlling somatic motor function in the zebra finch. We found that robustus arcopallialis projection neurons (RAPNs), key command neurons for song production, exhibit ultranarrow spikes and higher firing rates compared to neurons controlling non-vocal somatic motor functions (dorsal intermediate arcopallium [AId] neurons). Pharmacological and molecular data indicate that this striking difference is associated with the higher expression in RAPNs of high threshold, fast-activating voltage-gated Kv3 channels, that likely contain Kv3.1 (KCNC1) subunits. The spike waveform and Kv3.1 expression in RAPNs mirror properties of Betz cells, specialized upper motor neurons involved in fine digit control in humans and other primates but absent in rodents. Our study thus provides evidence that songbirds and primates have convergently evolved the use of Kv3.1 to ensure precise, rapid AP firing in upper motor neurons controlling fast and complex motor skills.
摘要：
脊椎动物的复杂运动技能需要具有精确动作电位（AP）激发的专门的上运动神经元。为了检查不同的上运动神经元群体如何发挥不同的功能以及所涉及的离子通道的特定库，我们对斑马雀科控制躯体运动功能的上运动神经元的兴奋性进行了深入研究。我们发现，隆突投射神经元（RAPNs），歌曲制作的关键命令神经元，与控制非声乐躯体运动功能的神经元（AId神经元）相比，表现出超arrow尖峰和更高的放电率。药理学和分子数据表明，这种显著的差异与高阈值的RAPNs中的较高表达有关。快速激活电压门控K+通道，Kv3.1(KCNC1)。RAPNs中的尖峰波形和Kv3.1表达反映了Betz细胞的特性，在人类和其他灵长类动物中参与精细数字控制的专门的上运动神经元，但在啮齿动物中却不存在。因此，我们的研究提供了证据，证明鸣鸟和灵长类动物已经一致进化了Kv3.1的使用，以确保精确，控制快速和复杂运动技能的上运动神经元的快速AP放电。
