What determines the frequency of fast network oscillations with irregular neural discharges? I. Synaptic dynamics and excitation-inhibition balance
What determines the frequency of fast network oscillations with irregular neural discharges? I. Synaptic dynamics and excitation-inhibition balance
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DOI：
10.1152/jn.01095.2002
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发表时间：
2003-07-01
影响因子：
2.5
通讯作者：
Wang, XJ
中科院分区：
文献类型：
--
作者：
Brunel, N;Wang, XJ
当皮层网络的局部场电位显示出相干的快速振荡（类似于40-Hz伽马或类似于200-Hz尖波波纹）时，组成神经元的尖峰序列通常是不规则和稀疏的。节律性局部场和随机性锋电位序列的二分法对耦合振子框架下的脑节律理论提出了挑战。先前的研究表明，当噪声很大且复发性抑制很强时，可以产生连贯的网络节律，而单个神经元以与振荡频率相比较低的速率间歇性地放电。然而，这些研究使用了过于简化的突触动力学，使人口节律频率的定量预测。在这里，我们展示了如何定量地推导出一个随机连接的网络的泄漏集成和消防神经元与现实的突触参数的相干振荡频率。在噪声主导的神经元间网络中，振荡频率更多地取决于最短的突触时间常数（延迟和上升时间），而不是更长的突触衰减时间，并且类似于200 Hz的频率可以用取自切片数据的突触时间常数来实现。在由中间神经元和兴奋性细胞组成的网络中，节律发生是两种情况之间的折衷：快速的纯粹的中间神经元机制和较慢的反馈机制（依赖于兴奋性抑制回路）。节律的性质基本上由兴奋性电流和抑制性电流的时间尺度之比以及平均周期性兴奋和抑制之间的平衡决定。比抑制更快的兴奋，或更高的兴奋/抑制比，有利于反馈回路和更慢的振荡（通常在伽马范围内）。
When the local field potential of a cortical network displays coherent fast oscillations (similar to40-Hz gamma or similar to200-Hz sharp-wave ripples), the spike trains of constituent neurons are typically irregular and sparse. The dichotomy between rhythmic local field and stochastic spike trains presents a challenge to the theory of brain rhythms in the framework of coupled oscillators. Previous studies have shown that when noise is large and recurrent inhibition is strong, a coherent network rhythm can be generated while single neurons fire intermittently at low rates compared to the frequency of the oscillation. However, these studies used too simplified synaptic kinetics to allow quantitative predictions of the population rhythmic frequency. Here we show how to derive quantitatively the coherent oscillation frequency for a randomly connected network of leaky integrate-and-fire neurons with realistic synaptic parameters. In a noise-dominated interneuronal network, the oscillation frequency depends much more on the shortest synaptic time constants (delay and rise time) than on the longer synaptic decay time, and similar to200-Hz frequency can be realized with synaptic time constants taken from slice data. In a network composed of both interneurons and excitatory cells, the rhythmogenesis is a compromise between two scenarios: the fast purely interneuronal mechanism, and the slower feedback mechanism (relying on the excitatory-inhibitory loop). The properties of the rhythm are determined essentially by the ratio of time scales of excitatory and inhibitory currents and by the balance between the mean recurrent excitation and inhibition. Faster excitation than inhibition, or a higher excitation/inhibition ratio, favors the feedback loop and a much slower oscillation (typically in the gamma range).