生物系統的電傳導性質

Abstract

我們在這裡主要探討的生物系統是神經系統。過去五十年來，神經系統的建模已經幫助、解釋並建構出神經科學許多重要的理論 [1]. 豐富的動態行為一直不斷地被發現。神經的傳導之中，在實驗與數值模擬中都可以看的到向後倒傳現象(back-propagation) [2-6]。向後倒傳是說神經的電訊號可能可以倒傳回去發出源的那一端。離子通道在空間上的分佈與突觸(dendrite)的構形皆有可能會影響神經有向後倒傳的現象發生 [2-6]。在數值上去控制在神經上的離子通道濃度已經有不少研究 [7-13]。雖然許多模型都已被模擬並應用在各種神經網路上，目前仍需要更有系統或更簡化的研究。 在以下的三章，我們會簡單的介紹神經傳導的基本理論與實驗。在第四章時，我們會討論更有系統性的控制鉀離子通道的濃度的案例。當我們忽略漏電流離子通道(leakage ion channel)的影響時，我們在其中找到了非常豐富的動態行為，像是神經傳導電訊號波包的二分化(dichotomy)、電訊號的向後傳導、還有類似於神經系統中常見的急切傳導 ( bursting) 現象。

Neuron modeling has helped to explain and construct the theory of neuronscience for over fifty years. Large amount of models has been constructed and many phenomena have been explained [1]. Interesting dynamical behaviors have been reported without a break. Back-propagation is the behavior that the action potential will go in the reverse direction of the axon, which has been observed both experimentally and numerically [2-6]. Distribution of ion channel densities and the morphology of the dendrite might affect the behavior of back-propagation [2-6]. Controlling the densities of ion channel has been simulated in various neuron models [7-13]. Although several models have been simulated and applied in various neuron networks, it still lacks a more systematic and simplified analysis. In the following three chapters, basic theories of neuron transport and experiments are introduced. In chapter four, we discussed the case when we manipulated the spatial distribution of ion channels. Rich dynamics have been found when we blocked the leakage ion channel and altered the distribution of potassium ion channel, such as dichotomy of action potential, back-propagation, and bursting-like behavior. Many phenomena were demonstrated and analyzed.