查看Ch12 Physiology of Neurons的源代码

=== 本征发射模式由动力学相对较慢的各种离子流决定 ===
<b style=color:#0ae>Intrinsic firing patterns are determined by a variety of ion currents with relatively slow kinetics</b>

What determines the variety of spiking patterns in each type of neuron, and why do neurons differ in their intrinsic patterns? The key is a large set of ion channel types that have variable and often relatively slow kinetics compared with the quick Na+ and K+ channels that shape the spike. For a discussion of the properties of such channels, see p. 182. Each neuron expresses a different complement of these slow channels and has a unique spatial arrangement of them on its dendrites, soma, and axon initial segment. The channels are gated primarily by membrane voltage and [Ca2+]i, and a neuron’s ultimate spiking pattern is determined by the net effects of the slow currents that it generates. We provide three examples of systems that have been studied in detail.

是什么决定了每种类型神经元中脉冲模式的多样性，为什么神经元的内在模式不同？关键是大量的离子通道类型，与形成加标的快速 Na+ 和 K+ 通道相比，这些离子通道具有可变且通常相对较慢的动力学。有关此类通道特性的讨论，请参见第 182 页。每个神经元表达这些慢通道的不同补充，并在其树突、体细胞和轴突初始段上具有独特的空间排列。通道主要由膜电压和 [Ca2+]i 门控，神经元的最终尖峰模式由它产生的慢电流的净效应决定。我们提供了三个已详细研究的系统示例。


1. A neuron with only fast voltage-gated Na+ channels and delayed-rectifier K+ channels will generate repetitive spikes when it is presented with a long stimulus. The pattern of those spikes will be quite regular over time, as for the particular type of cerebral cortical interneuron that we have already seen in Figure 12-4A.

1. 只有快速电压门控 Na+ 通道和延迟整流器 K+ 通道的神经元在受到长刺激时会产生重复的尖峰。随着时间的推移，这些尖峰的模式将非常有规律，正如我们在图 12-4A 中已经看到的特定类型的大脑皮层中间神经元。


2. If the neuron also has another set of K+ channels that activate only very slowly, the spiking pattern becomes more time dependent: the spiking frequency may initially be very high, but it adapts to progressively lower rates as a slow K+ current turns on to counteract the stimulus, as shown for the small pyramidal cell in Figure 12-4B. The strength and rate of adaptation depend strongly on the number and properties of the fast and slow K+ channels.

2. 如果神经元还有另一组激活速度非常慢的 K+ 通道，则尖峰模式将变得更加依赖于时间：尖峰频率最初可能非常高，但随着缓慢的 K+ 电流打开以抵消刺激，它会适应逐渐降低的速率，如图 12-4B 中的小锥体细胞所示。适应的强度和速率在很大程度上取决于快速和慢速 K+ 通道的数量和特性。


3. A neuron, by exploiting the interplay between two or more voltage-gated currents with relatively slow kinetics, can generate spontaneous rhythmic bursting—as in the case of the large pyramidal neuron in Figure 12-4C—even without ongoing synaptic activity to drive it.

3. 神经元通过利用两个或多个动力学相对较慢的电压门控电流之间的相互作用，可以产生自发的有节奏的爆发——如图 12-4C 中的大锥体神经元一样——即使没有持续的突触活动来驱动它。

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