TY - JOUR TI - Motor cortex analogue neurons in songbirds utilize Kv3 channels to generate ultranarrow spikes AU - Zemel, Benjamin M AU - Nevue, Alexander A AU - Tavares, Leonardo ES AU - Dagostin, Andre AU - Lovell, Peter V AU - Jin, Dezhe Z AU - Mello, Claudio V AU - von Gersdorff, Henrique A2 - Huguenard, John R A2 - Forsythe, Ian D VL - 12 PY - 2023 DA - 2023/05/09 SP - e81992 C1 - eLife 2023;12:e81992 DO - 10.7554/eLife.81992 UR - https://doi.org/10.7554/eLife.81992 AB - 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. KW - patch-clamp electrophysiology KW - zebra finch KW - excitability KW - potassium channels KW - action potential KW - vocal/motor cortex JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -