频率依赖性细胞外阻抗的细胞内外电位传递函数证据
Evidence for frequency-dependent extracellular impedance from the transfer function between extracellular and intracellular potentials
摘要：
本文研究了大脑皮层细胞内膜电位（V_m）与局部场电位（V_{LFP}）之间的传递函数F_T = V_m / V_{LFP}的性质。我们首先从理论上证明，在阈下区，细胞外介质和膜电位的频率依赖性对F_T有明显的影响。对于各个电流源可视为独立的非相干态，可由实验计算F_T，并与理论公式相匹配。使用平均场近似，我们得到了一种方法来估计细胞外介质的阻抗，而无需注入电流。我们研究了双极（差分）LFPs的传递函数，并比较了在大鼠桶状皮质去兴奋状态下同时记录的V_m和V_{LFP}。只有当假设细胞外介质的阻抗是频率依赖性的，并且对于3和500 Hz之间的频率为1/sqrt（Ω）（Warburg阻抗）变化时，实验得出的F_T才与理论得出的F_T相匹配。这构成了细胞外介质是非抗性的间接证据，这对于LFP建模具有许多可能的后果。
英文摘要：
We examine the properties of the transfer function F_T = V_m / V_{LFP} between the intracellular membrane potential (V_m) and the local field potential (V_{LFP}) in cerebral cortex. We first show theoretically that, in the subthreshold regime, the frequency dependence of the extracellular medium and that of the membrane potential have a clear incidence on F_T. The calculation of F_T from experiments and the matching with theoretical expressions is possible for desynchronized states where individual current sources can be considered as independent. Using a mean-field approximation, we obtain a method to estimate the impedance of the extracellular medium without injecting currents. We examine the transfer function for bipolar (differential) LFPs and compare to simultaneous recordings of V_m and V_{LFP} during desynchronized states in rat barrel cortex in vivo. The experimentally derived F_T matches the one derived theoretically, only if one assumes that the impedance of the extracellular medium is frequency-dependent, and varies as 1/sqrt(omega) (Warburg impedance) for frequencies between 3 and 500 Hz. This constitutes indirect evidence that the extracellular medium is non-resistive, which has many possible consequences for modeling LFPs.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
