Fear extinction, an inhibitory learning that suppresses a previously learned fear memory, is diminished during adolescence. Earlier studies have shown that this suppressed fear extinction during adolescence involves an altered glutamatergic plasticity in infralimbic medial prefrontal cortical (IL-mPFC) pyramidal neurons. However, it is unclear whether the excitability of IL-mPFC pyramidal neurons plays a role in this development-dependent suppression of fear extinction. Therefore, we examined whether fear conditioning and extinction affect the active and passive membrane properties of IL-mPFC layer 5 pyramidal neurons in preadolescent, adolescent and adult mice. Both preadolescent and adult mice exhibited a bidirectional modulation of the excitability of IL-mPFC layer 5 pyramidal neurons following fear conditioning and extinction, i.e., fear conditioning reduced membrane excitability, whereas fear extinction reversed this effect. However, the fear conditioning-induced suppression of excitability was not reversed in adolescent mice following fear extinction training. Neither fear conditioning nor extinction affected GABAergic transmission in IL-mPFC layer 5 pyramidal neurons, suggesting that GABAergic transmission did not play a role in experience-dependent modulation of neuronal excitability. Our results suggest that the extinction-specific modulation of excitability is impaired during adolescence.

中文翻译：

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青春期下肢内侧前额叶皮层缺乏经验依赖的固有可塑性。

恐惧的灭绝是一种抑制性学习，它抑制了先前学习的恐惧记忆，在青春期会减弱。较早的研究表明，这种在青春期抑制的恐惧消退涉及改变下肢内侧前额叶皮层（IL-mPFC）锥体神经元的谷氨酸能可塑性改变。但是，尚不清楚IL-mPFC锥体神经元的兴奋性是否在这种依赖发展的恐惧绝灭抑制中起作用。因此，我们检查了恐惧条件和灭绝是否会影响青春期前，青春期和成年小鼠的IL-mPFC层5锥体神经元的主动和被动膜特性。青春期之前和成年小鼠均表现出恐惧调节和消退后IL-mPFC第5层锥体神经元兴奋性的双向调节，即 恐惧调理降低了膜的兴奋性，而恐惧消退则扭转了这种效应。但是，恐惧消除训练后，在青春期小鼠中没有逆转恐惧条件引起的兴奋性抑制。恐惧条件和灭绝都不会影响IL-mPFC第5层锥体神经元中的GABA能传递，这表明GABA能传递在经验依赖的神经元兴奋性调节中不起作用。我们的结果表明，在青春期，消光特异性的兴奋性调节受到损害。恐惧条件和灭绝都不会影响IL-mPFC第5层锥体神经元中的GABA能传递，这表明GABA能传递在经验依赖的神经元兴奋性调节中不起作用。我们的结果表明，在青春期，消光特异性的兴奋性调节受到损害。恐惧条件和灭绝都不会影响IL-mPFC第5层锥体神经元中的GABA能传递，这表明GABA能传递在经验依赖的神经元兴奋性调节中不起作用。我们的结果表明，在青春期，消光特异性的兴奋性调节受到损害。