Goychuk Igor, Hänggi Peter, Vega Jose L, Miret-Artés Salvador
Institute of Physics, University of Augsburg, Universitätsstrasse 1, D-86135 Augsburg, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Jun;71(6 Pt 1):061906. doi: 10.1103/PhysRevE.71.061906. Epub 2005 Jun 16.
Stochastic resonance in single voltage-dependent ion channels is investigated within a three-state non-Markovian modeling of the ion channel conformational dynamics. In contrast to a two-state description one assumes the presence of an additional closed state for the ion channel which mimics the manifold of voltage-independent closed subconformations (inactivated "state"). The conformational transition into the open state occurs through a domain of voltage-dependent closed subconformations (closed "state"). At distinct variance with the standard two-state and also the three-state Markovian approach, the inactivated state is characterized by a broad, nonexponential probability distribution of corresponding residence times. The linear response to a periodic voltage signal is determined for arbitrary distributions of the channel's recovery times. Analytical results are obtained for the spectral amplification of the applied signal and the corresponding signal-to-noise ratio. Alternatively, these results are also derived by use of a corresponding two-state non-Markovian theory which is based on driven integral renewal equations [I. Goychuk and P. Hänggi, Phys. Rev. E 69, 021104 (2004)]. The non-Markovian features of stochastic resonance are studied for a power law distribution of the residence time intervals in the inactivated state which exhibits a large variance. A comparison with the case of biexponentially distributed residence times possessing the same mean value, i.e., the simplest non-Markovian two-state description, is also presented.
在离子通道构象动力学的三态非马尔可夫模型中研究了单电压依赖性离子通道中的随机共振。与二态描述不同，假设离子通道存在一个额外的关闭状态，该状态模拟了与电压无关的关闭子构象的集合（失活“状态”）。向开放状态的构象转变通过一个电压依赖性关闭子构象的区域（关闭“状态”）发生。与标准的二态以及三态马尔可夫方法明显不同的是，失活状态的特征是相应停留时间的广泛的、非指数概率分布。对于通道恢复时间的任意分布，确定了对周期性电压信号的线性响应。获得了关于施加信号的频谱放大和相应信噪比的分析结果。另外，这些结果也通过使用基于驱动积分更新方程的相应二态非马尔可夫理论得出[I. Goychuk和P. Hänggi，《物理评论E》69，021104（2004）]。研究了失活状态下停留时间间隔的幂律分布的随机共振的非马尔可夫特征，该分布具有很大的方差。还给出了与具有相同平均值的双指数分布停留时间的情况的比较，即最简单的非马尔可夫二态描述。
