Cheetham Claire E J, Park Una, Belluscio Leonardo
Developmental Neural Plasticity Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, Maryland 20892, USA.
Nat Commun. 2016 Feb 22;7:10729. doi: 10.1038/ncomms10729.
Incorporation of new neurons enables plasticity and repair of circuits in the adult brain. Adult neurogenesis is a key feature of the mammalian olfactory system, with new olfactory sensory neurons (OSNs) wiring into highly organized olfactory bulb (OB) circuits throughout life. However, neither when new postnatally generated OSNs first form synapses nor whether OSNs retain the capacity for synaptogenesis once mature, is known. Therefore, how integration of adult-born OSNs may contribute to lifelong OB plasticity is unclear. Here, we use a combination of electron microscopy, optogenetic activation and in vivo time-lapse imaging to show that newly generated OSNs form highly dynamic synapses and are capable of eliciting robust stimulus-locked firing of neurons in the mouse OB. Furthermore, we demonstrate that mature OSN axons undergo continuous activity-dependent synaptic remodelling that persists into adulthood. OSN synaptogenesis, therefore, provides a sustained potential for OB plasticity and repair that is much faster than OSN replacement alone.
新神经元的整合能够实现成年大脑回路的可塑性和修复。成年神经发生是哺乳动物嗅觉系统的一个关键特征，新的嗅觉感觉神经元（OSN）在一生中都会连接到高度有组织的嗅球（OB）回路中。然而，出生后产生的新OSN何时首次形成突触，以及成熟后OSN是否仍保留突触形成能力，目前尚不清楚。因此，成年出生的OSN如何促进OB的终身可塑性尚不清楚。在这里，我们结合电子显微镜、光遗传学激活和体内延时成像技术，表明新生成的OSN形成高度动态的突触，并且能够在小鼠OB中引发神经元强烈的刺激锁定放电。此外，我们证明成熟的OSN轴突会经历持续的依赖活动的突触重塑，这种重塑会持续到成年期。因此，OSN突触形成提供了一种持续的OB可塑性和修复潜力，其速度比单独的OSN替换要快得多。
