研究发现：人类的记忆细胞在13岁后就停止再生

　　New neurons stop growing in a key region of the brain’s ’memory center’ as early as 13 years old, according to a controversial new study.

　　一项有争议的新研究显示，早在人类13岁时，大脑“记忆中心”一个关键区域的新神经细胞就停止生长了。

　　Scientists looking at brain tissue samples found no evidence of new nerve cell growth in the dentate gyryus, a part of the hippocampus vital to memory formation, after the age of 13.

　　研究脑组织样本的科学家没有发现人类在13岁后齿状回中有新神经细胞生长的证据。齿状回是海马区的一个部分。海马区对于记忆的形成至关重要。

　　The discovery contradicts previous findings suggesting that hippocampal neurons replenish themselves throughout adulthood, as they do in many other mammals.

　　该结论同先前的发现相左。以往研究显示，人类大脑海马区的神经元在整个成年时期都会不断自我补充，就像很多其他哺乳动物一样。

　　The newly found pattern seems to be a hallmark of big complex brains.

　　这种新发现似乎显示了复杂大脑的特征。

　　New hippocampus neuron development also dwindled over time in macaque monkeys, the scientists found. And hippocampus regeneration was thought to be lacking in big-brained dolphins, porpoises and whales.

　　科学家发现，在猕猴身上，新海马神经元生长也会随时间减弱。科学家认为，在有着大型脑的海豚和鲸中间，也缺少海马神经元再生的情况。

　　Writing in the journal Nature, the authors led by Dr Arturo Alvarez-Buylia, from the University of California at San Francisco, concluded: ’Neurogenesis in the dentate gyrus does not continue, or is extremely rare, in adult humans.

　　该研究由加利福尼亚大学旧金山分校的阿图罗?阿尔瓦雷斯-拜利亚博士领导，发表在英国《自然》周刊上。他总结道，“在成年人中，齿状回中的神经元再生不会继续，或极其稀少。”

　　The early decline in hippocampal neurogenesis raises questions about how the function of the dentate gyrus differs between humans and other species in which adult hippocampal neurogenesis is preserved.’

　　“海马区神经再生的早期衰退提出了人类和其他物种之间齿状回功能如何不同的问题。其他物种在成年期仍可再生海马神经元。”

　　The scientists used marker antibodies to ’flag up’ neural precursor cells and immature neurons in 59 human brain tissue samples.

　　科学家们使用标记抗体来“指示”59个人类脑组织样本中的神经前体细胞和不成熟神经元。

　　The post-mortem and post-surgery samples spanned all life stages from the foetus to older adulthood.

　　这些死后和手术后获得的样本横跨从胎儿到老年的所有生命阶段。

　　The number of developing neurons in the dentate gyrus reduced with age and the oldest sample in which any were found was from a 13-year-old. No young neurons were detected in samples from people aged 18 to 77.

　　在齿状回中，生长中的神经元数量会随年龄增长而减少。包含生长中神经元的最老样本来自一个13岁的人。从18到77岁的人的脑样本中没有发现年轻的神经元。

　　The scientists added: ’Interestingly, a lack of neurogenesis in the hippocampus has been suggested for aquatic mammals (dolphins, porpoises and whales), species known for their large brains, longevity and complex behaviour.’

　　科学家还说：“有趣的是，水栖哺乳动物(海豚和鲸)的海马体也缺乏神经元再生现象。这些物种以大规模的脑、长寿和复杂行为而闻名。”

　　Previous studies may have wrongly reported the detection of immature hippocampal neurons because the marker proteins used to disclose them do not work the same way in humans and animals, said the researchers.

　　研究人员说，过去的研究可能错误报道了不成熟海马神经元的发现，因为用于指示它们的标记蛋白质在人类和动物身上以不同方式工作。

　　In an accompanying News & Views commentary, Dr Jason Snyder from the University of British Columbia, Canada, wrote: ’These findings are in stark contrast to the prevailing view that human hippocampal neurogenesis extends throughout adult life.’

　　加拿大英属哥伦比亚大学的杰森斯奈德博士在一篇相关的新闻与观察评论中写道：“这些发现与人们普遍认为的人类海马神经发生贯穿成年期的观点形成了鲜明的对比。”