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arXiv 0705.3759q-bio.NC
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高频下神经元膜模型的一种改进的电缆形式

A modified cable formalism for modeling neuronal membranes at high frequencies

Claude Bedard, Alain Destexhe

摘要:

在体内皮层神经元的细胞内记录显示强烈的阈下膜电位(Vm)活动。Vm的功率谱密度(PSD)在高频(>50 Hz)处显示幂律结构,斜率约为-2.5。这种类型的频率缩放不能被传统模型解释,因为单室模型或基于重建细胞形态的模型显示斜率接近-4的频率缩放。该斜率是由于膜电阻被高频电容“短路”的事实,这种情况可能不现实。在这里,我们将非理想电容器集成到电缆方程中,以反映电容不能瞬时充电的事实。我们表明,由此产生的“非理想”电缆模型可以解决分析使用傅立叶变换。使用球杆模型的数值模拟产生与实验中类似的频率缩放的膜电位活动。我们还讨论了使用非理想电容器对其他细胞特性的影响,例如在非理想电缆中提升的高频传输或树突中的电压衰减。这些结果表明,电缆方程的非理想电容器的基础上,应被用来捕捉在高频下的神经元膜的行为。

英文摘要:

Intracellular recordings of cortical neurons in vivo display intense subthreshold membrane potential (Vm) activity. The power spectral density (PSD) of the Vm displays a power-law structure at high frequencies (>50 Hz) with a slope of about -2.5. This type of frequency scaling cannot be accounted for by traditional models, as either single-compartment models or models based on reconstructed cell morphologies display a frequency scaling with a slope close to -4. This slope is due to the fact that the membrane resistance is "short-circuited" by the capacitance for high frequencies, a situation which may not be realistic. Here, we integrate non-ideal capacitors in cable equations to reflect the fact that the capacitance cannot be charged instantaneously. We show that the resulting "non-ideal" cable model can be solved analytically using Fourier transforms. Numerical simulations using a ball-and-stick model yield membrane potential activity with similar frequency scaling as in the experiments. We also discuss the consequences of using non-ideal capacitors on other cellular properties such as the transmission of high frequencies, which is boosted in non-ideal cables, or voltage attenuation in dendrites. These results suggest that cable equations based on non-ideal capacitors should be used to capture the behavior of neuronal membranes at high frequencies.

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