生物谷报道： 成年脑中稳定形成的新生脑细胞，在脑中可能远不止是扮演替补角色，一项新的研究表明。这些新生脑细胞可能具有让成年脑获得拓宽的学习本领，而这与已存在的成熟的脑中电路并不冲突。Hongjun Song和同事于2007年5月24日《Neuron》杂志上发表的研究性文章，详细地描述了这一惊人的发现。
在实验过程中，研究者运用荧光蛋白选择性地标记海马区的新生脑细胞，而这个区域正是成年鼠脑中学习和记忆的中心。他们的结论是“成年脑中的神经形成，并不只是替代损失的神经元，而很有可能让神经系统保持不断更新，从而在之后的生命过程中，不断保持可塑性。”
原始出处：
Neuron, Vol 54, 559-566, 24 May 2007
Article
A Critical Period for Enhanced Synaptic Plasticity in Newly Generated Neurons of the Adult Brain
Shaoyu Ge,1,2,3 Chih-hao Yang,1,2,4 Kuei-sen Hsu,4 Guo-li Ming,1,2,3 and Hongjun Song1,2,3,
1 Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
2 Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
3 The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
4 Department of Pharmacology, College of Medicine, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan
Corresponding author
Hongjun Song
shongju1@jhmi.edu
Active adult neurogenesis occurs in discrete brain regions of all mammals and is widely regarded as a neuronal replacement mechanism. Whether adult-born neurons make unique contributions to brain functions is largely unknown. Here we systematically characterized synaptic plasticity of retrovirally labeled adult-born dentate granule cells at different stages during their neuronal maturation. We identified a critical period between 1 and 1.5 months of the cell age when adult-born neurons exhibit enhanced long-term potentiation with increased potentiation amplitude and decreased induction threshold. Furthermore, such enhanced plasticity in adult-born neurons depends on developmentally regulated synaptic expression of NR2B-containing NMDA receptors. Our study demonstrates that adult-born neurons exhibit the same classic critical period plasticity as neurons in the developing nervous system. The transient nature of such enhanced plasticity may provide a fundamental mechanism allowing adult-born neurons within the critical period to serve as major mediators of experience-induced plasticity while maintaining stability of the mature circuitry.
