来源：《新科学家》
原文见刊日期：2022年2月26日
Adults may not be able to create new neurons in the brain – contrary to previous findings. The question of whether adults can form new neurons, called neurogenesis, has long been a source of controversy. While researchers have discovered adult neurogenesis in mice, the evidence for this ability in humans is less clear.
与之前的发现相反，成年人可能无法在大脑中创造新的神经元。成人是否能形成新的神经元，称为神经发生，这个问题长期以来一直存在争议。虽然研究人员已经在老鼠身上发现了成年神经发生，但在人类身上发现这种能力的证据还不太明确。
The hippocampus, which has been linked with adult neurogenesis, is vulnerable to Alzheimer’s disease and other neurodegenerative conditions. This has led to arguments that adult neurogenesis may hold the key to treating these conditions.
海马体与成人神经发生有关，易受到阿尔茨海默病和其他神经退行性疾病的影响。这导致了成人神经发生可能是治疗这些疾病的关键的争论。
Jon Arellano and Pasko Rakic at Yale University and their colleagues examined the brains of six dead people, with an average age of 53, who had donated the organ to science. They also studied the brains of 18 pigs, and looked at data from studies of mouse brains.
耶鲁大学的乔恩·阿雷利亚诺、帕斯卡·拉基奇和他们的同事对6名平均年龄为53岁的死者的大脑进行了检查，这些人都将器官捐献给了科学研究。他们还研究了18头猪的大脑，并查看了老鼠大脑研究的数据。
“There are two regions where neurogenesis occurs in non-human animals,” says Arellano. “One is the olfactory bulb and the other is the hippocampus.” The human olfactory bulb, which is vital for our sense of smell, is considered incapable of adult neurogenesis, says Arellano, but there is still debate when it comes to the hippocampus.
阿雷亚诺说：“非人类动物有两个神经发生区域，嗅球和海马体。”阿雷利亚诺说，人类的嗅球，对我们的嗅觉至关重要，被认为不存在成年神经发生，但至于海马体仍有争议。
The researchers used a technique called single-nucleus RNA sequencing to study the hippocampal cells in the brain samples. This method targets the nuclear RNA molecules that help turn DNA code into proteins and can characterise the cell, which can help establish its age.
研究人员使用一种被称为单核RNA测序的技术来研究大脑样本中的海马细胞。这种方法以核RNA分子为目标，核RNA分子有助于将DNA编码转化为蛋白质，并能对细胞进行特征分析，从而帮助确定细胞的年龄。
They found that just 0.003 percent of their human sample cells had a nuclear RNA profile that suggested they were newly created neurons. For comparison, about 6.6 per cent of the cells in the same region in mice could be new neurons.
他们发现，只有0.003%的人类样本细胞具有核RNA谱，表明它们是新创造的神经元。相比之下，老鼠体内同一区域的大约6.6%的细胞可能是新的神经元。
The researchers also looked in their brain samples for DCX, a protein marker for newly formed neurons. Other studies have found DCX in the human adult hippocampus, but Arellano argues their methods were unreliable. Using a more fine-tuned technique, he and his team didn’t find any of this protein in their samples. Combined with the nuclear RNA data, this suggests to them that adult neurogenesis doesn’t exist in humans.
研究人员还在他们的大脑样本中寻找DCX，这是一种新形成神经元的蛋白质标记。其他的研究已经在成人海马中发现了DCX，但是阿雷利亚诺认为他们的方法是不可靠的。使用一种更精细的技术，他和他的团队在他们的样本中没有发现任何这种蛋白质。结合核RNA数据，他们认为成人神经发生在人类身上并不存在。
If they are right, that makes the human brain truly remarkable, says Rakic. “I’m over 88 years old and I have billions of neurons that have lasted a lifetime,” he says. “That’s more impressive to me than the idea that mice can make new neurons. Everything that I’ve learned is still there in my brain.”
拉基奇说，如果他们是对的，那人类的大脑就真的非同寻常了。他说：“我已经88岁了，我有数十亿个神经元，这些神经元持续了一生。对我来说，这比老鼠能制造新神经元的想法更令人印象深刻。我所学到的一切仍然存在于我的大脑中。”