Integration of new neurons into adult hippocampal circuits is a process coordinated by local and long-range synaptic inputs. To achieve stable integration and uniquely contribute to hippocampal function, immature neurons are endowed with a critical period of heightened synaptic plasticity, yet it remains unclear which mechanisms sustain this form of plasticity during neuronal maturation. We found that as new neurons enter their critical period, a transient surge in fusion dynamics stabilizes elongated mitochondrial morphologies in dendrites to fuel synaptic plasticity. Conditional ablation of fusion dynamics to prevent mitochondrial elongation selectively impaired spine plasticity and synaptic potentiation, disrupting neuronal competition for stable circuit integration, ultimately leading to decreased survival. Despite profuse mitochondrial fragmentation, manipulation of competition dynamics was sufficient to restore neuronal survival but left neurons poorly responsive to experience at the circuit level. Thus, by enabling synaptic plasticity during the critical period, mitochondrial fusion facilitates circuit remodeling by adult-born neurons.

中文翻译：

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在成年神经元突触可塑性的关键时期增强线粒体融合


新神经元整合到成人海马回路中是一个由局部和远程突触输入协调的过程。为了实现稳定的整合并对海马功能做出独特的贡献，未成熟的神经元被赋予了突触可塑性增强的关键时期，但目前尚不清楚在神经元成熟过程中哪种机制维持这种形式的可塑性。我们发现，当新神经元进入关键期时，融合动力学的短暂激增会稳定树突中细长的线粒体形态，从而增强突触可塑性。有条件地消融融合动力学以防止线粒体伸长，选择性损害脊柱可塑性和突触增强，扰乱神经元对稳定电路整合的竞争，最终导致存活率下降。尽管线粒体大量破碎，但竞争动态的操纵足以恢复神经元的存活，但使神经元对回路水平的经验反应不佳。因此，通过在关键时期实现突触可塑性，线粒体融合促进了成年神经元的回路重塑。