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| In the context of neurophysiology, '''balance of excitation and inhibition''' (E/I balance) refers to the relative contributions of excitatory and inhibitory synaptic inputs corresponding to some neuronal event, such as oscillation or response evoked by sensory stimulation. | | In the context of neurophysiology, '''balance of excitation and inhibition''' (E/I balance) refers to the relative contributions of excitatory and inhibitory synaptic inputs corresponding to some neuronal event, such as oscillation or response evoked by sensory stimulation. |
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− | 在神经生理学背景下,'''兴奋-抑制平衡E/I balance'''指的是对应于某些神经元事件的兴奋性和抑制性突触输入的相关贡献,如由感觉刺激引起的振荡或反应。 | + | 在神经生理学背景下,'''兴奋-抑制平衡 E/I balance'''指的是对应于某些神经元事件的兴奋性和抑制性突触输入的相关贡献,如由感觉刺激引起的振荡或反应。 |
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| In the current literature, owing to the extremely wide range of conditions in which the term is applied, it has several different, albeit related, meanings. | | In the current literature, owing to the extremely wide range of conditions in which the term is applied, it has several different, albeit related, meanings. |
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| In the cortex, interneurons responsible for inhibition comprise just a small fraction of the neurons, yet they have an important function in regulating activity of principal cells. | | In the cortex, interneurons responsible for inhibition comprise just a small fraction of the neurons, yet they have an important function in regulating activity of principal cells. |
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− | 在皮层中,负责抑制的中间神经元只占神经元的一小部分,但它们对调节主细胞的活动具有重要功能。
| + | 在皮层中,负责抑制的'''<font color="#ff8000"> 中间神经元interneurons </font>'''只占神经元的一小部分,但它们对调节'''<font color="#ff8000"> 主细胞 principal cells </font>'''的活动具有重要功能。 |
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| When inhibition is blocked pharmacologically, cortical activity becomes epileptic (Dichter and Ayala, 1987), and neurons may lose their selectivity to different stimulus features (Sillito, 1975). | | When inhibition is blocked pharmacologically, cortical activity becomes epileptic (Dichter and Ayala, 1987), and neurons may lose their selectivity to different stimulus features (Sillito, 1975). |
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| Our understanding of the relationships between these two opposing forces has advanced significantly during the recent years, mainly due to the growing use of in-vivo intracellular recording techniques. | | Our understanding of the relationships between these two opposing forces has advanced significantly during the recent years, mainly due to the growing use of in-vivo intracellular recording techniques. |
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− | 近年来,得益于体内的胞内记录技术的日益普及,我们对这两种对立力量之间的关系的理解有了显著的进步。
| + | 近年来,得益于体内的'''<font color="#ff8000"> 胞内记录intracellular recording </font>'''技术的日益普及,我们对这两种对立力量之间的关系的理解有了显著的进步。 |
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| // | | // |
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| However, spike trains extracellularly recorded from single cortical neurons exhibit high variability. | | However, spike trains extracellularly recorded from single cortical neurons exhibit high variability. |
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− | 然而,从单个皮质神经元记录的胞外尖峰序列表现出高度的<font color="#32CD32">可变性</font>。
| + | 然而,从单个皮质神经元记录的胞外'''<font color="#ff8000"> 尖峰序列spike trains </font>'''表现出高度的<font color="#32CD32">可变性</font>。 |
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| For instance, the coefficient of variation of the inter-spike intervals (ISIs) of neurons firing in response to a sensory input for a period of several seconds, is approximately equal to 1, as expected from a Poisson process (Softky and Koch, 1993). | | For instance, the coefficient of variation of the inter-spike intervals (ISIs) of neurons firing in response to a sensory input for a period of several seconds, is approximately equal to 1, as expected from a Poisson process (Softky and Koch, 1993). |
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− | 例如,响应于数秒内的感觉输入而放电的神经元的放电间隔(ISIs)的<font color="#32CD32">变化系数</font>大约等于1,正如泊松过程所预期的那样(Softky和Koch,1993)。 | + | 例如,响应于数秒内的感觉输入而放电的神经元的放电间隔(ISIs)的<font color="#32CD32">变化系数</font>大约等于1,正如'''<font color="#ff8000"> 泊松过程Poisson process </font>'''所预期的那样(Softky和Koch,1993)。 |
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| This apparent paradox between simple probabilistic considerations and the observed statistics of cortical spike trains led to several proposed resolutions. | | This apparent paradox between simple probabilistic considerations and the observed statistics of cortical spike trains led to several proposed resolutions. |
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| Simulations, based on the random walk model of (Gerstein and Mandelbrot, 1964) demonstrated that under such a regime of synaptic inputs the ISI variability is in agreement with experimental observations (Shadlen and Newsome, 1994, 1998). | | Simulations, based on the random walk model of (Gerstein and Mandelbrot, 1964) demonstrated that under such a regime of synaptic inputs the ISI variability is in agreement with experimental observations (Shadlen and Newsome, 1994, 1998). |
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− | 基于的随机游走模型(Gerstein和Mandelbrot,1964)的模拟表明,在这种突触输入的机制下,ISI的变异性与实验观察结果一致(Shadlen和Newsome,1994,1998)。
| + | 基于的'''<font color="#ff8000">随机游走模型random walk model</font>'''(Gerstein和Mandelbrot,1964)的模拟表明,在这种突触输入的机制下,ISI的变化与实验观察结果一致(Shadlen和Newsome,1994,1998)。 |
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| Furthermore, computational studies of spontaneous activity in neuronal networks showed that E/I balance emerges naturally if the network is sparsely connected (van Vreeswijk and Sompolinsky, 1996; Vogels et al., 2005). | | Furthermore, computational studies of spontaneous activity in neuronal networks showed that E/I balance emerges naturally if the network is sparsely connected (van Vreeswijk and Sompolinsky, 1996; Vogels et al., 2005). |
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| 膜电位的行为是用神经元的被动单隔室的基于电导的模型近似的,描述如下 | | 膜电位的行为是用神经元的被动单隔室的基于电导的模型近似的,描述如下 |
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− | CdV/dt = -G_{leak}(V(t)-E_{leak}) - G_{ex}(t)(V(t)-E_{ex}) - G_{in}(t)(V(t)-E_{in})+I_{inj} (1) | + | <math>CdV/dt = -G_{leak}(V(t)-E_{leak}) - G_{ex}(t)(V(t)-E_{ex}) - G_{in}(t)(V(t)-E_{in})+I_{inj}</math> (1) |
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| where \(E_{leak}\) is the resting membrane potential of the neuron, \(C\) is its capacitance, \(G_{leak}\) is the mean conductance in absence of stimulation (the inverse of input resistance), \(E_{ex}\) and \(E_{in}\) are the reversal potentials of excitation and inhibition, and \(I_{inj}\) is the current injected through the recording pipette. | | where \(E_{leak}\) is the resting membrane potential of the neuron, \(C\) is its capacitance, \(G_{leak}\) is the mean conductance in absence of stimulation (the inverse of input resistance), \(E_{ex}\) and \(E_{in}\) are the reversal potentials of excitation and inhibition, and \(I_{inj}\) is the current injected through the recording pipette. |
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− | 其中E_{leak}是神经元的静息膜电位,C是其电容,\(G_{leak}\)是在没有刺激的情况下的平均电导(输入电阻的倒数),E_{ex}和E_{in}是兴奋和抑制的反转电位,I_{inj}是通过记录移液管注入的电流。
| + | 其中<math>E_{leak}</math>是神经元的静息膜电位,C是其电容,<math>G_{leak}</math>是在没有刺激的情况下的平均电导(输入电阻的倒数),<math>E_{ex}</math>和<math>E_{in}</math>是兴奋和抑制的反转电位,<math>I_{inj}</math>是通过记录移液管注入的电流。 |
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| By fitting equation (1) to the average responses at different holding potentials, the synaptic conductances evoked by the stimulus, \(G_{ex}(t)\) and \(G_{in}(t)\ ,\) can be computed (see Figure 1). | | By fitting equation (1) to the average responses at different holding potentials, the synaptic conductances evoked by the stimulus, \(G_{ex}(t)\) and \(G_{in}(t)\ ,\) can be computed (see Figure 1). |
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− | 通过将方程(1)拟合到不同保持电位下的平均响应,可以计算出由刺激G_{ex}(t)和G_{in}(t)引起的突触电导(见图1)。
| + | 通过将方程(1)拟合到不同保持电位下的平均响应,可以计算出由刺激<math>G_{ex}(t)</math>和<math>G_{in}(t)</math>引起的突触电导(见图1)。 |
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| For an in-depth review of the method and its caveats an interested reader is referred to (Monier et al., 2008). | | For an in-depth review of the method and its caveats an interested reader is referred to (Monier et al., 2008). |