We investigate calcium signaling feedback through calcium-activated potassium channels of a dendritic spine by applying the immersed boundary method with electrodiffusion. We simulate the stochastic gating of such ion channels and the resulting spatial distribution of concentration, current, and membrane voltage within the dendritic spine. In this simulation, the permeability to ionic flow across the membrane is regulated by the amplitude of chemical potential barriers. With spatially localized ion channels, chemical potential barriers are locally and stochastically regulated. This regulation represents the ion channel gating with multiple subunits, the open and closed states governed by a continuous-time Markov process. The model simulation recapitulates an inhibitory action on voltage-sensitive calcium channels by the calcium-activated potassium channels in a stochastic manner as a non-local feedback loop. The model predicts amplified calcium influx with more closely placed channel complexes, proposing a potential mechanism of differential calcium handling by channel distributions. This work provides a foundation for future computer simulation studies of dendritic spine motility and structural plasticity.

我们通过应用具有电扩散的浸入边界方法来研究钙信号反馈通过树突棘的钙激活钾通道。我们模拟了这种离子通道的随机门控以及由此产生的树突棘内浓度、电流和膜电压的空间分布。在这个模拟中，离子流穿过膜的渗透性由化学势垒的幅度调节。通过空间定位的离子通道，化学势垒是局部和随机调节的。该调节代表具有多个亚基的离子通道门控，打开和关闭状态由连续时间马尔可夫过程控制。非本地反馈回路。该模型通过更接近的通道复合物预测放大的钙流入，提出了通过通道分布进行差异钙处理的潜在机制。这项工作为未来树突棘运动和结构可塑性的计算机模拟研究提供了基础。