Neural activities in local circuits exhibit complex and multilevel dynamic features. Individual neurons spike irregularly, which is believed to originate from receiving balanced amounts of excitatory and inhibitory inputs, known as the excitation–inhibition balance. The spatial-temporal cascades of clustered neuronal spikes occur in variable sizes and durations, manifested as neural avalanches with scale-free features. These may be explained by the neural criticality hypothesis, which posits that neural systems operate around the transition between distinct dynamic states. Here, we summarize the experimental evidence for and the underlying theory of excitation–inhibition balance and neural criticality. Furthermore, we review recent studies of excitatory–inhibitory networks with synaptic kinetics as a simple solution to reconcile these two apparently distinct theories in a single circuit model. This provides a more unified understanding of multilevel neural activities in local circuits, from spontaneous to stimulus-response dynamics.

中文翻译：

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兴奋-抑制平衡、神经临界性和神经元回路活动

局部回路中的神经活动表现出复杂和多层次的动态特征。单个神经元的尖峰不规则，这被认为源于接收平衡量的兴奋性和抑制性输入，称为兴奋-抑制平衡。簇状神经元尖峰的时空级联以不同的大小和持续时间发生，表现为具有无标度特征的神经雪崩。这些可以通过神经临界假说来解释，该假说假设神经系统围绕不同动态状态之间的转换进行操作。在这里，我们总结了兴奋抑制平衡和神经临界性的实验证据和基本理论。此外，我们回顾了最近关于突触动力学的兴奋-抑制网络的研究，作为在单个电路模型中协调这两种明显不同的理论的简单解决方案。这提供了对局部回路中从自发到刺激反应动力学的多级神经活动的更统一的理解。