Bifurcation diagram globally underpinning neuronal firing behaviors modified by SK conductance

作     者：陈梦娇 令恒莉 刘一辉 屈世显 任维 

作者机构：Key Laboratory of MOE for Modern Teaching Technology and College of Life SciencesShaanxi Normal University Institute of Theoretical & Computational PhysicsSchool of Physics and Information TechnologyShaanxi Normal University 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2014年第23卷第2期

页      面：575-582页

核心收录：

学科分类：0710[理学-生物学] 07[理学] 071006[理学-神经生物学] 

基　　金：Project supported by the National Natural Science Foundation of China (Grant No.30900443) the Fundamental Research Funds for the Central Universities,China (Grant Nos.GK201302052 and GK261001007) 

主　　题：neuron Hopf bifurcation SK channel excitability 

摘      要：Neurons in the brain utilize various firing trains to encode the input signals they have received. Firing behavior of one single neuron is thoroughly explained by using a bifurcation diagram from polarized resting to firing, and then to depolarized resting. This explanation provides an important theoretical principle for understanding neuronal biophysical behaviors. This paper reports the novel experimental and modeling results of the modification of such a bifurcation dia- gram by adjusting small conductance potassium （SK） channel. In experiments, changes in excitability and depolarization block in nucleus accumbens shell and medium-spiny projection neurons are explored by increasing the intensity of injected current and blocking the SK channels by apamin. A shift of bifurcation points is observed. Then, a Hodgkin-Huxley type model including the main electrophysiological processes of such neurons is developed to reproduce the experimental results. The reduction of SK channel conductance also shifts the bifurcations, which is in consistence with experiment. A global bifurcation paradigm of this shift is obtained by adjusting two parameters, intensity of injected current and SK channel con- ductance. This work reveals the dynamics underpinning modulation of neuronal firing behaviors by biologically important ionic conductance. The results indicate that small ionic conductance other than that responsible for spike generation can modify bifurcation points and shift the bifurcation diagram and, thus, change neuronal excitability and adaptation.