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添加113字节 、 2022年3月30日 (三) 07:25
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In the Hodgkin-Huxley model, the original conductance-based model,
 
In the Hodgkin-Huxley model, the original conductance-based model,
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在‎‎霍奇金-赫胥黎模型‎‎中,基于电导的原始模型,‎
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在‎‎[[霍奇金-赫胥黎模型]]‎‎中,基于电导的原始模型,‎
    
\( <math>I_{ionic} = I_{Na} + I_K + I_L</math> \ .\)
 
\( <math>I_{ionic} = I_{Na} + I_K + I_L</math> \ .\)
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for each j. \( V_j \) is the Nernst potential or reversal potential for current \( j \ ,\) \( (V - V_j) \) is called the driving force for \( j \ ,\) and \( I_{ext} \) is an external current that may be present. \( a, b \) are gating variables raised to small integer powers \( x, y \ ,\) respectively. \( a_{\infty}, b_{\infty} \) are the steady-state gating variable functions that are typically sigmoidal in shape. \( \tau \) is the time constant, which can be voltage-dependent. Further details and equation descriptions can be found in many texts such as Hille (2001) and Koch (1999). Thus, conductance-based models consist of a set of ordinary differential equations (ODEs), as derived from current flow in a circuit representation following Kirchoff's laws. The number of differential equations in the set of model equations depends on the number of different ion channel types being represented with their particular activation and inactivation gating variables. The conductances can depend not only on transmembrane potential \( V \ ,\) but also on concentrations of different ions, for example, the concentration of calcium.
 
for each j. \( V_j \) is the Nernst potential or reversal potential for current \( j \ ,\) \( (V - V_j) \) is called the driving force for \( j \ ,\) and \( I_{ext} \) is an external current that may be present. \( a, b \) are gating variables raised to small integer powers \( x, y \ ,\) respectively. \( a_{\infty}, b_{\infty} \) are the steady-state gating variable functions that are typically sigmoidal in shape. \( \tau \) is the time constant, which can be voltage-dependent. Further details and equation descriptions can be found in many texts such as Hille (2001) and Koch (1999). Thus, conductance-based models consist of a set of ordinary differential equations (ODEs), as derived from current flow in a circuit representation following Kirchoff's laws. The number of differential equations in the set of model equations depends on the number of different ion channel types being represented with their particular activation and inactivation gating variables. The conductances can depend not only on transmembrane potential \( V \ ,\) but also on concentrations of different ions, for example, the concentration of calcium.
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\( <math>V_j</math> \) 是电流的能斯特电位或反转电位 \( <math>j<math> \ ,\) \( (<math>V - V_j</math>) \) 称为 \( <math>j</math> \ ,\) 的驱动力,而 \( <math>I_{ext}</math> \) 是可能存在的外部电流。
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\( <math>V_j</math> \) 是电流的[[能斯特电位]]或[[反转电位]] \( <math>j<math> \ ,\) \( (<math>V - V_j</math>) \) 称为 \( <math>j</math> \ ,\) 的驱动力,而 \( <math>I_{ext}</math> \) 是可能存在的外部电流。
    
\( <math>a</math>, <math>b</math> \) 是分别提升为小整数幂 \( <math>x</math>, <math>y</math> \ ,\) 的门控变量。???
 
\( <math>a</math>, <math>b</math> \) 是分别提升为小整数幂 \( <math>x</math>, <math>y</math> \ ,\) 的门控变量。???
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进一步的细节和方程描述可以在许多文本中找到,如Hille(2001)和Koch(1999)。
 
进一步的细节和方程描述可以在许多文本中找到,如Hille(2001)和Koch(1999)。
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因此,基于电导的模型由一组常微分方程(ODE)组成,根据基尔霍夫定律从电路表示的电流推导得出。
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因此,基于电导的模型由一组常微分方程([[ODE]])组成,根据[[基尔霍夫定律]]从电路表示的电流推导得出。
    
模型方程组中微分方程的数量取决于不同离子通道类型的数量,这些离子通道类型用其特定的激活和失活门控变量表示。
 
模型方程组中微分方程的数量取决于不同离子通道类型的数量,这些离子通道类型用其特定的激活和失活门控变量表示。
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The parameters in conductance-based models are determined from empirical fits to voltage-clamp experimental data (e.g., see Willms 2002), assuming that the different currents can be adequately separated using pharmacological manipulations and voltage-clamp protocols. As shown in the model formulation, the activation and inactivation variables can be raised to a non-unity integer power, and this is dictated by empirical fits to the data.
 
The parameters in conductance-based models are determined from empirical fits to voltage-clamp experimental data (e.g., see Willms 2002), assuming that the different currents can be adequately separated using pharmacological manipulations and voltage-clamp protocols. As shown in the model formulation, the activation and inactivation variables can be raised to a non-unity integer power, and this is dictated by empirical fits to the data.
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基于电导的模型中的参数是通过经验拟合和电压钳实验数据确定的(例如,参见Willms 2002),假设可以使用药理学操作和电压钳方案充分分离不同的电流。如模型公式所示,激活和失活变量可以提高到(非单位整数幂)(???),这是由对数据的经验拟合决定的。
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基于电导的模型中的参数是通过经验拟合和[[电压钳]]实验数据确定的(例如,参见Willms 2002),假设可以使用药理学操作和[[电压钳]]方案充分分离不同的电流。如模型公式所示,激活和失活变量可以提高到(非单位整数幂)(???),这是由对数据的经验拟合决定的。
    
Since (i) it is rarely possible to obtain estimates of all parameter values in a conductance-based mathematical model from experimental data alone, and (ii) the model construct is necessarily a simplification of the biological cell, it is important to consider various optimization techniques to help constrain the problem for which the conductance-based model was developed to address.
 
Since (i) it is rarely possible to obtain estimates of all parameter values in a conductance-based mathematical model from experimental data alone, and (ii) the model construct is necessarily a simplification of the biological cell, it is important to consider various optimization techniques to help constrain the problem for which the conductance-based model was developed to address.
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由于(i)仅从实验数据中很难获得基于电导的数学模型中所有参数值的估计,并且(ii)模型构建必然是生物细胞的简化,因此重要的是要考虑各种优化技术,以帮助约束建立基于电导的模型以解决的问题。(???)
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由于(i)仅从实验数据中很难获得基于电导的数学模型中所有参数值的估计,并且(ii)模型构建必然是生物细胞的简化,因此重要的是要考虑各种[[优化技术]],以帮助约束建立基于电导的模型以解决的问题。(???)
    
In summary, the basic assumptions in conductance-based models are:
 
In summary, the basic assumptions in conductance-based models are:
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* Hodgkin-Huxley model (1952): Original conductance-based model based on the giant axon of the squid producing action potentials. There is a sodium current with activation and inactivation variables, a potassium current with only an activation variable, and a (passive) leak current.
 
* Hodgkin-Huxley model (1952): Original conductance-based model based on the giant axon of the squid producing action potentials. There is a sodium current with activation and inactivation variables, a potassium current with only an activation variable, and a (passive) leak current.
* 霍奇金-赫胥黎模型(1952年):原始的基于电导的模型,建立在产生动作电位的乌贼巨大轴突的基础上。模型中有具有激活和失活变量的钠电流,仅具有激活变量的钾电流,以及(被动)漏电流。
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* [[霍奇金-赫胥黎模型]](1952年):原始的基于电导的模型,建立在产生[[动作电位]]的乌贼巨大轴突的基础上。模型中有具有激活和失活变量的钠电流,仅具有激活变量的钾电流,以及(被动)漏电流。
 
* Connor-Stevens model (1971): Extended action potential generating model using gastropod neuron somas. There is a sodium, potassium and leak current as in the Hodgkin-Huxley model, and in addition, another potassium current that is transient, the so-called A-current, is included. This current has an activation and an inactivation variable.
 
* Connor-Stevens model (1971): Extended action potential generating model using gastropod neuron somas. There is a sodium, potassium and leak current as in the Hodgkin-Huxley model, and in addition, another potassium current that is transient, the so-called A-current, is included. This current has an activation and an inactivation variable.
* Connor-Stevens模型(1971):使用腹足纲神经元体建立的扩展动作电位生成模型。与霍奇金 - 赫胥黎模型一样,有钠离子项、钾离子项和漏电流项,此外,还包括另一个瞬态钾电流,即所谓的A电流。此电流项具有激活和失活变量。
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* Connor-Stevens模型(1971):使用[[腹足纲神经元体]]建立的扩展动作电位生成模型。与[[霍奇金-赫胥黎模型]]一样,有钠离子项、钾离子项和漏电流项,此外,还包括另一个瞬态钾电流,即所谓的[[A电流]]。此电流项具有激活和失活变量。
 
* Morris-Lecar model (1981): Based on the barnacle muscle fiber. There is a calcium current with an instantaneous activation, a potassium current with an activation variable, and a (passive) leak current.
 
* Morris-Lecar model (1981): Based on the barnacle muscle fiber. There is a calcium current with an instantaneous activation, a potassium current with an activation variable, and a (passive) leak current.
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* Morris-Lecar模型(1981年):基于藤壶肌纤维建立模型。模型中有具有瞬时激活的钙电流、具有激活变量的钾电流和(被动)漏电流。
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* [[Morris-Lecar模型]](1981年):基于[[藤壶肌纤维]]建立模型。模型中有具有瞬时激活的钙电流、具有激活变量的钾电流和(被动)漏电流。
    
Conductance-based models are the most common formulation used in neuronal models and can incorporate as many different ion channel types as are known for the particular cell being modeled.  
 
Conductance-based models are the most common formulation used in neuronal models and can incorporate as many different ion channel types as are known for the particular cell being modeled.  
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基于电导的模型是神经元模型中最常用的公式,它可以包含在要建模的特定细胞中已知的那么多的不同离子通道类型。
 
基于电导的模型是神经元模型中最常用的公式,它可以包含在要建模的特定细胞中已知的那么多的不同离子通道类型。
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建立在许多基于电导的模型中的一个常见扩展为将钙动力学方程包含在内。
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建立在许多基于电导的模型中的一个常见扩展为将钙[[动力学]]方程包含在内。
    
离子电流除了对钙离子依赖,还依赖于电压,由钙离子电流、离子泵和(交换器???)控制的钙离子浓度。(???)
 
离子电流除了对钙离子依赖,还依赖于电压,由钙离子电流、离子泵和(交换器???)控制的钙离子浓度。(???)
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此外,随着各种离子通道的细节确定,已经建立了基于电导的模型的变体,以更好地适应实验数据。
 
此外,随着各种离子通道的细节确定,已经建立了基于电导的模型的变体,以更好地适应实验数据。
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例如,从霍奇金 - 赫胥黎模型派生的标准基于电导的形式体系,已经扩展到解释快速钠通道和Kv3钾通道中没有电压依赖性的状态依赖性失活(Marom和Abbott 1994)。
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例如,从[[霍奇金-赫胥黎模型]]派生的标准基于电导的形式体系,已经扩展到解释快速钠通道和[[Kv3]]钾通道中没有电压依赖性的状态依赖性失活(Marom和Abbott 1994)。
    
The simplest conductance-based model formulation from a spatial perspective consists of a single, isopotential compartment.  
 
The simplest conductance-based model formulation from a spatial perspective consists of a single, isopotential compartment.  
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离子运动严格地在细胞内和细胞外之间进行。
 
离子运动严格地在细胞内和细胞外之间进行。
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然而,为了结合细胞的空间复杂性,可以连接几个房室来表示细胞的复杂形态(参见区室模型)。
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然而,为了结合细胞的空间[[复杂性]],可以连接几个房室来表示细胞的复杂形态(参见[[区室模型]])。
    
然后,基于电导的模型公式可以用在每个房室,并在方程中添加其他项以表示连接。
 
然后,基于电导的模型公式可以用在每个房室,并在方程中添加其他项以表示连接。
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In turn, these intrinsic characteristics affect behaviors in neuronal networks.
 
In turn, these intrinsic characteristics affect behaviors in neuronal networks.
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建立基于电导的可兴奋细胞模型,来帮助理解促进动作电位的产生、重复放电和爆裂(?)(即振荡模式)等的潜在原理。
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建立基于电导的可兴奋细胞模型,来帮助理解促进动作电位的产生、重复放电和[[爆裂]](?)(即[[振荡]]模式)等的潜在原理。
    
反过来,这些内在特征会影响神经元网络中的行为。
 
反过来,这些内在特征会影响神经元网络中的行为。
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然而,随着基于电导的模型中包含的电流项数量的增加,由于微分方程数量的增加,对由此产生的模型的动力学行为的理解和预测变得更加困难。
 
然而,随着基于电导的模型中包含的电流项数量的增加,由于微分方程数量的增加,对由此产生的模型的动力学行为的理解和预测变得更加困难。
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例如,最初的霍奇金-赫胥黎模型是一个 4 阶ODE系统。
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例如,最初的[[霍奇金-赫胥黎模型]]是一个 4 阶[[ODE]]系统。
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人们不仅努力建立基于电导的模型的定性动力学(例如,FitzHugh-Nagumo模型),而且还降低了系统的复杂性(例如,Kepler等人,1992年)。
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人们不仅努力建立基于电导的模型的定性动力学(例如,[[FitzHugh-Nagumo模型]]),而且还降低了系统的复杂性(例如,Kepler等人,1992年)。
    
Mathematical distinctions in conductance-based models using dynamical system and bifurcation analyses are available. Details are described in Izhikevich (2007).
 
Mathematical distinctions in conductance-based models using dynamical system and bifurcation analyses are available. Details are described in Izhikevich (2007).
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在使用动力系统和分岔分析的基于电导的模型中,可以进行数学区分。(???)细节在Izhikevich(2007)中有所描述。
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在使用动力系统和[[分岔理论|分岔]]分析的基于电导的模型中,可以进行数学区分。(???)细节在Izhikevich(2007)中有所描述。
    
== 参考文献 ==
 
== 参考文献 ==
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