K+ channels at the axon initial segment dampen near-threshold excitability of neocortical fast-spiking GABAergic interneurons
K+ channels at the axon initial segment dampen near-threshold excitability of neocortical fast-spiking GABAergic interneurons
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DOI：
10.1016/j.neuron.2008.03.003
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发表时间：
2008-05-08
期刊：
影响因子：
16.2
通讯作者：
Rudy, Bernardo
中科院分区：
文献类型：
--
作者：
Goldberg, Ethan M.;Clark, Brian D.;Rudy, Bernardo
快棘细胞（FS细胞）是新皮层GABA能中间神经元的一个重要亚型，具有重要的功能作用。多个FS单元属性被协调以实现快速响应。在这里，我们描述了一个FS细胞功能，用于门强大的抑制FS细胞活性产生。我们发现，FS细胞在第2/3层桶皮质具有阻尼机制介导的Kv1.1含钾离子通道定位于轴突起始段。这些通道有力地调节动作电位阈值，并允许FS细胞优先响应足够快的大输入，以“超过”Kv 1激活。此外，Kv1.1通道阻断将FS细胞的延迟型放电模式转换为连续快速尖峰放电模式，而不影响定义FS细胞的高频放电。因此，Kv 1通道提供了一个关键的平衡FS细胞的快速反应特性，通过独特的电生理特性和离散的亚细胞定位的组合调节兴奋性。
Fast-spiking cells (FS cells) are a prominent subtype of neocortical GABAergic interneurons with important functional roles. Multiple FS cell properties are coordinated for rapid response. Here, we describe an FS cell feature that serves to gate the powerful inhibition produced by FS cell activity. We show that FS cells in layer 2/3 barrel cortex possess a dampening mechanism mediated by Kv1.1-containing potassium channels localized to the axon initial segment. These channels powerfully regulate action potential threshold and allow FS cells to respond preferentially to large inputs that are fast enough to "outrun" Kv1 activation. In addition, Kv1.1 channel blockade converts the delay-type discharge pattern of FS cells to one of continuous fast spiking without influencing the high-frequency firing that defines FS cells. Thus, Kv1 channels provide a key counterbalance to the established rapid-response characteristics of FS cells, regulating excitability through a unique combination of electrophysiological properties and discrete subcellular localization.