Experience-dependent neuronal plasticity is a fundamental substrate of learning and memory. Intrinsic excitability is a form of neuronal plasticity that can be altered by learning and indicates the pattern of neuronal responding to external stimuli (e.g. a learning or synaptic event). Associative fear conditioning is one form of learning that alters intrinsic excitability, reflecting an experience-dependent change in neuronal function. After fear conditioning, intrinsic excitability changes are evident in brain regions that are a critical part of the fear circuit, including the amygdala, hippocampus, retrosplenial cortex, and prefrontal cortex. Some of these changes are transient and/or reversed by extinction as well as learning-specific (i.e. they are not observed in neurons from control animals). This review will explore how intrinsic neuronal excitability changes within brain structures that are critical for fear learning, and it will also discuss evidence promoting intrinsic excitability as a vital mechanism of associative fear memories. This work has raised interesting questions regarding the role of fear learning in changes of intrinsic excitability within specific subpopulations of neurons, including those that express immediate early genes and thus demonstrate experience-dependent activity, as well as in neurons classified as having a specific firing type (e.g. burst-spiking vs. regular-spiking). These findings have interesting implications for how intrinsic excitability can serve as a neural substrate of learning and memory, and suggest that intrinsic plasticity within specific subpopulations of neurons may promote consolidation of the memory trace in a flexible and efficient manner.

中文翻译：

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内在兴奋性的调节与恐惧调节回路中学习的关系。

依赖于经验的神经元可塑性是学习和记忆的基本基础。内在兴奋性是神经元可塑性的一种形式，可以通过学习来改变，并指示神经元对外部刺激（例如学习或突触事件）作出反应的模式。联想恐惧调节是改变内在兴奋性的一种学习形式，反映了神经元功能的经验依赖性变化。经过恐惧调节后，内在的兴奋性变化在恐惧回路的关键部分-包括杏仁核，海马，脾后皮质和前额叶皮质-中很明显。这些改变中的一些是由于灭绝而短暂的和/或逆转的，以及因学习而异的（即在对照动物的神经元中未观察到）。这篇综述将探讨对于恐惧学习至关重要的大脑结构内在神经元兴奋性的变化，还将讨论促进内在兴奋性作为关联恐惧记忆的重要机制的证据。这项工作提出了有关恐惧学习在特定神经元亚群内内在兴奋性变化中的作用的有趣问题，这些亚群包括那些表达立即早期基因从而表现出经验依赖性活动的神经元，以及被归类为具有特定放电类型的神经元。 （例如突发突发与常规突发）。这些发现对内在兴奋性如何充当学习和记忆的神经基础具有有趣的意义，