Pfeuty Benjamin, Mato Germán, Golomb David, Hansel David
Neurophysique et Physiologie du Système Moteur, Université René Descartes, 75270 Paris Cedex 06, France.
Neural Comput. 2005 Mar;17(3):633-70. doi: 10.1162/0899766053019917.
Recent experimental results have shown that GABAergic interneurons in the central nervous system are frequently connected via electrical synapses. Hence, depending on the area or the subpopulation, interneurons interact via inhibitory synapses or electrical synapses alone or via both types of interactions. The theoretical work presented here addresses the significance of these different modes of interactions for the interneuron networks dynamics. We consider the simplest system in which this issue can be investigated in models or in experiments: a pair of neurons, interacting via electrical synapses, inhibitory synapses, or both, and activated by the injection of a noisy external current. Assuming that the couplings and the noise are weak, we derive an analytical expression relating the cross-correlation (CC) of the activity of the two neurons to the phase response function of the neurons. When electrical and inhibitory interactions are not too strong, they combine their effect in a linear manner. In this regime, the effect of electrical and inhibitory interactions when combined can be deduced knowing the effects of each of the interactions separately. As a consequence, depending on intrinsic neuronal properties, electrical and inhibitory synapses may cooperate, both promoting synchrony, or may compete, with one promoting synchrony while the other impedes it. In contrast, for sufficiently strong couplings, the two types of synapses combine in a nonlinear fashion. Remarkably, we find that in this regime, combining electrical synapses with inhibition amplifies synchrony, whereas electrical synapses alone would desynchronize the activity of the neurons. We apply our theory to predict how the shape of the CC of two neurons changes as a function of ionic channel conductances, focusing on the effect of persistent sodium conductance, of the firing rate of the neurons and the nature and the strength of their interactions. These predictions may be tested using dynamic clamp techniques.
最近的实验结果表明，中枢神经系统中的γ-氨基丁酸能中间神经元经常通过电突触相互连接。因此，根据区域或亚群的不同，中间神经元通过抑制性突触或仅通过电突触相互作用，或者通过两种类型的相互作用进行交互。本文提出的理论工作探讨了这些不同相互作用模式对中间神经元网络动力学的意义。我们考虑了在模型或实验中可以研究此问题的最简单系统：一对神经元，通过电突触、抑制性突触或两者进行相互作用，并通过注入有噪声的外部电流来激活。假设耦合和噪声较弱，我们推导了一个解析表达式，将两个神经元活动的互相关（CC）与神经元的相位响应函数联系起来。当电相互作用和抑制性相互作用不太强时，它们以线性方式组合其效应。在这种情况下，知道每种相互作用的单独效应后，就可以推导出电相互作用和抑制性相互作用组合时的效应。因此，根据神经元的内在特性，电突触和抑制性突触可能相互协作，都促进同步，或者可能相互竞争，其中一个促进同步而另一个阻碍同步。相反，对于足够强的耦合，两种类型的突触以非线性方式组合。值得注意的是，我们发现在这种情况下，将电突触与抑制相结合会放大同步，而仅电突触会使神经元的活动去同步。我们应用我们的理论来预测两个神经元的CC形状如何随离子通道电导而变化，重点关注持续钠电导的影响、神经元的放电率以及它们相互作用的性质和强度。这些预测可以使用动态钳技术进行测试。
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