Cable properties of layer V neurons from cat sensorimotor cortex in vitro.
Cable properties of layer V neurons from cat sensorimotor cortex in vitro.
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体外猫感觉运动皮层 V 层神经元的电缆特性。
DOI：
10.1152/jn.1984.52.2.278
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发表时间：
1984
影响因子：
2.5
通讯作者：
Crill,WE
中科院分区：
文献类型：
--
作者：
Stafstrom,CE;Schwindt,PC;Crill,WE
用电流钳技术和单微电极电压钳技术研究了猫新皮质V层神经元的被动电缆性。在存在和不存在几种阻断依赖时间和电压的电导的试剂的情况下，对神经元进行了检查。在所研究的17个电池中，12个电池对注入电流脉冲的充电响应符合单一指数曲线。就其本身而言，这一结果将表明大多数神经元是等电位的。然而，使用两种不同的、独立的方法：应用电压钳阶跃和电流脉冲，在所有被检查的神经元中都证明了非等电位区的存在。电压钳制步骤后电容充电瞬变的衰减仅反映了非等电位区的电荷再分布，其平均时间常数约为膜时间常数taum的17%。电流脉冲后的电压衰减总是用(至少)两个指数来拟合，其中较短的指数约为taum的9%。这些结果表明，存在一个非等电位区，但电性较短，输入电导相对较低，或两者都有，与特定的神经元模型无关。采用Rall(23，24)理想神经元模型(固定在有限长的均匀电缆上的等电室)，由电压钳数据得到的非等电室的等效电渗性长度(L)的平均值为0.72空间常数，由脉冲响应数据得到的空间常数的平均值为1.21。无论采用哪种工艺，都可以得到2-4的枝晶-胞体电导比(P)。正常细胞和存在电导阻滞剂的细胞之间的电缆参数没有显著差异。通过假定文献中报道的比膜电容的值，估计了从2,300到11,700 omega X cm2的比膜电阻(Rm)。我们的结论是，在静息电位附近的电压范围内，在没有明显的紧张性突触输入的情况下，体外培养的大V层新皮质神经元是电张力致密的。在这方面，它们的电紧张性电缆的特性类似于其他哺乳动物神经元的体外培养。
The passive cable properties of neurons from layer V of cat neocortex were studied in an in vitro slice preparation using current-clamp techniques and a single-microelectrode voltage clamp. Neurons were examined in the presence and absence of several agents that block time- and voltage-dependent conductances. The charging response to an injected current pulse was well fitted by a single exponential in 12 of 17 cells examined. By itself, this result would suggest that most of the neurons are isopotential. However, the existence of a nonisopotential region was demonstrated in all neurons examined using two alternative, independent methods: application of voltage-clamp steps and current impulses. The decay of the capacitive charging transient following a voltage-clamp step reflects charge redistribution solely in the nonisopotential region and had a mean time constant about 17% of the membrane time constant, tau m. The voltage decay following a current impulse was always fitted by (at least) two exponentials, the shorter of which was about 9% of tau m. These results suggest that a nonisopotential region exists but is electrotonically short, of relatively low-input conductance, or both, independent of a particular neuron model. Adopting Rall's (23, 24) idealized neuron model (isopotential compartment attached to a finite-length uniform cable) resulted in a mean value for the equivalent electrotonic length (L) of the nonisopotential compartment of 0.72 space constants from voltage-clamp data and 1.21 space constants from impulse-response data. A dendrite-to-soma conductance ratio (p) of 2-4 was obtained from either procedure. There were no significant differences in the cable parameters between normal cells and those where conductance-blocking agents were present. A specific membrane resistance (Rm) ranging from 2,300 to 11,700 omega X cm2 was estimated by assuming values of specific membrane capacitance reported in the literature. We conclude that large layer V neocortical neurons in vitro are electrotonically compact in the voltage range near resting potential and in the absence of significant tonic synaptic input. In this respect, their electrotonic cable properties resemble those of other mammalian neurons in vitro.