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”的关键区域，新神经元就已经停止生长了。
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（海马区的一个部分）中有新神经细胞生长的证据。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.
这一发现与之前的研究结果相矛盾，以往的研究显示，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，就像它们在其他哺乳动物身上一样。
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.
科学家们发现，在猕猴身上，新海马神经元的发育也逐渐减少。而海豚和鲸鱼则被认为缺乏海马体的再生。

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。该文章总结道，“在成年人中，齿状回中的神经元再生不会继续，或者非常罕见。”
'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。”
In an accompanying News And 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。”