Single Ih channels in pyramidal neuron dendrites:: Properties, distribution, and impact on action potential output
Single Ih channels in pyramidal neuron dendrites:: Properties, distribution, and impact on action potential output
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DOI：
10.1523/jneurosci.3664-05.2006
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发表时间：
2006-02-08
影响因子：
5.3
通讯作者：
Stuart, GJ
中科院分区：
文献类型：
--
作者：
Kole, MHP;Hallermann, S;Stuart, GJ
超极化激活的阳离子电流（I-h）在调节神经元兴奋性中起着重要作用，但其在脑中的天然单通道特性基本上是未知的。在这里，我们使用方差-均值分析来研究单个I-H通道的特性在顶树突的皮质第5层锥体神经元在体外。在这些神经元中，我们发现，I-h通道有一个平均单位电导为680余积30 fS（n=18）。模拟和本地I-h通道的频谱分析表明，在5 kHz以下很少或没有通道闪烁。与均匀分布的单通道电导相反，I-h通道数随距离呈指数增加，在远端树突部位达到类似于550通道/μ m（2）的密度。这些高通道密度产生显著的膜电压噪声。通过将I-H单通道门控的随机模型的第5层神经元的形态学上现实的模型，我们表明，该通道的噪声是较高的远端树突隔室和增加了三倍，增加了10倍的单通道电导（6.8 pS），但恒定的I-H电流密度。此外，我们证明了电压波动归因于随机I-H通道门控对动作电位输出的影响，在具有实验确定的单通道电导的模型中具有更高的尖峰定时精度。这些数据表明，在面对高电流密度，小的单通道电导的I-h是至关重要的保持动作电位输出的保真度。
The hyperpolarization-activated cation current (I-h) plays an important role in regulating neuronal excitability, yet its native single-channel properties in the brain are essentially unknown. Here we use variance-mean analysis to study the properties of single I-h channels in the apical dendrites of cortical layer 5 pyramidal neurons in vitro. In these neurons, we find that I-h channels have an average unitary conductance of 680 coproduct 30 fS (n=18). Spectral analysis of simulated and native I-h channels showed that there is little or no channel flicker below 5 kHz. In contrast to the uniformly distributed single-channel conductance, I-h channel number increases exponentially with distance, reaching densities as high as similar to 550 channels/mu m(2) at distal dendritic sites. These high channel densities generate significant membrane voltage noise. By incorporating a stochastic model of I-h single-channel gating into a morphologically realistic model of a layer 5 neuron, we show that this channel noise is higher in distal dendritic compartments and increased threefold with a 10-fold increased single-channel conductance (6.8 pS) but constant I-h current density. In addition, we demonstrate that voltage fluctuations attributable to stochastic I-h channel gating impact on action potential output, with greater spike-timing precision in models with the experimentally determined single-channel conductance. These data suggest that, in the face of high current densities, the small single-channel conductance of I-h is critical for maintaining the fidelity of action potential output.