Voltage-modulated membrane resistance in coupled leech neurons.
Voltage-modulated membrane resistance in coupled leech neurons.
复制标题
耦合水蛭神经元中的电压调节膜电阻。
DOI：
10.1152/jn.1979.42.2.465
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发表时间：
1979
影响因子：
2.5
通讯作者：
B. Zipser
中科院分区：
文献类型：
--
作者：
B. Zipser
1.研究了水蚤中枢神经系统第6节中两对大型可识别神经元之间的阻性相互作用，它们被称为侧细胞和吻细胞。两者都是导致阴茎外翻的运动神经元。2.外侧神经元和吻侧神经元具有不同的膜电阻特性。外侧神经元的输入电阻几乎是恒定的。相反，吻部神经元的膜电阻高度依赖于电压。当从静息电位去极化到放电水平时，吻部神经元的输入电阻可以增加10倍，从30 Momega到300 Momega。3.吻侧神经元的电压依赖性膜特性导致与外侧神经元的阻性相互作用是非线性的。在侧部细胞中诱发的DC电位被传递到吻部细胞，效率在10倍的范围内变化。超极化耦合较弱，耦合因子约为0.03。去极化耦合因子随侧向神经元去极化程度的增加而递增，最高可达0.3。4.吻侧细胞与吻侧细胞相互作用时，吻侧神经元的膜电阻发生变化。输入电阻在去极化过程中增大，在超极化耦合势过程中减小。从吻侧到外侧的细胞连接阻力很高且不变，从吻侧到外侧神经元的反向均匀弱耦合证明了这一点。5.综上所述，外侧至吻侧细胞相互作用的不对称性是基于突触后阻力的变化，而不是基于连接阻力的变化。侧向对嘴细胞兴奋性的影响除了通常的线性加法外，还包含一个非线性分量。在传统的阻性耦合中，去极化耦合电位使吻部神经元更接近其电压阈值。但更重要的是，去极化耦合电位降低了吻部神经元的电流阈值，因为电阻的增加会按比例减少达到放电水平所需的兴奋电流量。因此，电阻变化起到放大输入信号效率的作用。除了电流阈值的静态变化外，动态区神经元也会发生动态变化。膜电阻的增加导致空间常数的增加，缩小了神经元的电长度。6.对网络的其他性质进行了分析。外侧神经元对是强耦合的，而吻部神经元对是弱耦合的，耦合因子分别为0.3和0.05。外侧神经元和吻侧神经元的超极化膜时间常数估计在100-200ms之间。去极化的吻部神经元的时间常数明显较大。
1. Resistive interactions have been studied between two pairs of large identifiable neurons in ganglion 6 of the leech CNS, called the lateral and rostral cells. Both are motor neurons causing penile eversion. 2. Lateral and rostral neurons have different membrane resistance properties. Input resistances of lateral neurons are virtually constant. By contrast, membrane resistances of rostral neurons are highly voltage dependent. When depolarized from resting potential to firing level, a rostral neuron's input resistance can increase 10-fold, from 30 to 300 Momega. 3. Voltage-dependent membrane characteristics of rostral neurons cause resistive interactions with lateral neurons to be nonlinear. DC potentials evoked in lateral cells are transmitted to rostral cells with an efficiency varying over a 10-fold range. Hyperpolarizing coupling is weak, with coupling factors of about 0.03. Depolarizing coupling factors increase progressively with increasing lateral neuron depolarization, reaching values of up to 0.3. 4. Membrane resistance changes in rostral neurons accompany lateral to rostral cell interactions. Input resistances increase during depolarizing and decrease during hyperpolarizing coupling potentials. The lateral to rostral cell junctional resistance is high and invariant, as evidenced by uniformly weak coupling in the reverse direction, from rostral to lateral neurons. 5. In conclusion, asymmetries in lateral to rostral cell interaction are based on postsynaptic rather than junctional resistance changes. The impact of the lateral onto the rostral cell's excitability contains a nonlinear component besides the usual linear additive one. As in conventional resistive coupling, depolarizing coupling potentials raise the rostral neuron closer to its voltage threshold. But more significantly, depolarizing coupling potentials lower the rostral neuron's current threshold because increases in resistance proportionately reduce the amount of excitatory current needed to reach firing level. Thus, the resistance change acts to amplify the input signal efficiency. In addition to the static changes in current threshold, the reostral neuron also changes dynamically. Membrane resistance increases lead to increases in space constant shrinking the neuron's electrical lenght. 6. Other properties of the network have been analyzed. The pair of lateral neurons is strongly coupled, whereas the pair of rostral neurons is weakly coupled, the coupling factors are 0.3 and 0.05, respectively. Hyperpolarizing membrane time constants for the lateral and rostral neurons are estimated to be between 100 and 200 ms. Time constants of depolarized rostral neurons are significantly larger.