Control of Phasic Firing by a Background Leak Current in Avian Forebrain Auditory Neurons
Control of Phasic Firing by a Background Leak Current in Avian Forebrain Auditory Neurons
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DOI：
10.3389/fneel.2015.00471
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发表时间：
2015-12-10
影响因子：
5.3
通讯作者：
Leao, Ricardo M.
中科院分区：
文献类型：
--
作者：
Dagostin, Andre A.;Lovell, Peter V.;Leao, Ricardo M.
中枢神经元表达多种神经元类型和离子通道，这些神经元类型和离子通道促进其不同神经元群体之间的放电异质性。低阈值电压激活钾电流（VAKC）产生的动作电位（AP）相位放电是哺乳动物脑干神经元中常见的参与声音信息时间特性处理的现象。鸟类尾内侧巢皮层（NCM）是一个类似于哺乳动物听觉皮层的听觉区，参与鸟鸣声的知觉辨别和记忆，对听觉刺激有复杂的反应。（Taeniopygia guttata），并观察到一半的NCM神经元发射AP相位响应膜去极化，而其余的火灾短暂或紧张。相神经元发射AP的速度更快，时间精度比紧张和瞬态神经元。这些神经元具有相似的膜静息电位，但相位神经元具有较低的膜输入电阻和时间常数。令人惊讶的是，阶段性神经元不表达低阈值VAKC，这减少了阶段性哺乳动物脑干神经元的放电，具有与其他NCM神经元相似的VAKC。相性放电不是由VAKC决定的，而是由钾背景漏电导决定的，钾背景漏电导在相性神经元中表达得更显著，这一结果得到了药理学、动态钳和建模实验的证实。这些结果揭示了一个新的作用，漏电流产生放电多样性的中央神经元。
Central neurons express a variety of neuronal types and ion channels that promote firing heterogeneity among their distinct neuronal populations. Action potential (AP) phasic firing, produced by low-threshold voltage-activated potassium currents (VAKCs), is commonly observed in mammalian brainstem neurons involved in the processing of temporal properties of the acoustic information. The avian caudomedial nidopallium (NCM) is an auditory area analogous to portions of the mammalian auditory cortex that is involved in the perceptual discrimination and memorization of birdsong and shows complex responses to auditory stimuli We performed in vitro whole cell patch clamp recordings in brain slices from adult zebra finches (Taeniopygia guttata) and observed that half of NCM neurons fire APs phasically in response to membrane depolarizations, while the rest fire transiently or tonically. Phasic neurons fired APs faster and with more temporal precision than tonic and transient neurons. These neurons had similar membrane resting potentials, but phasic neurons had lower membrane input resistance and time constant. Surprisingly phasic neurons did not express low-threshold VAKCs, which curtailed firing in phasic mammalian brainstem neurons, having similar VAKCs to other NCM neurons. The phasic firing was determined not by VAKCs, but by the potassium background leak conductances, which was more prominently expressed in phasic neurons, a result corroborated by pharmacological, dynamic-clamp, and modeling experiments. These results reveal a new role for leak currents in generating firing diversity in central neurons.