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Can your brain grow new neurons? How researchers are solving a century-old puzzle
Mariana Lenharo is a reporter for Nature in New York City.
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For a long time, it was a truism in science that the human brain is born with all of the neurons it will ever have. But truisms can crumble, and this one is looking shaky.
The brain struggles to make new neurons in people with depression
A tantalizing body of evidence suggests that the human brain produces new nerve cells throughout a person’s life. If that’s true, then our brains could have an enduring ability to repair and regenerate.
That concept sounds very appealing to neuroscientist Arturo Alvarez-Buylla at the University of California, San Francisco, who has spent years investigating this topic. “If someone shows it clearly, I’ll be the first to be super happy and say, well, I didn’t waste my life studying a mechanism that is not present in humans.”
The problem is, when he looks at the data, he just doesn’t see it.
The question of whether the human brain can generate nerve cells after childhood has been controversial for decades. Influential papers have come down on both sides of the argument over the years, and the concept has captured public interest well beyond academia.
Part of the reason for the prominence of the debate is that it involves the giants in the field, says Hongjun Song, a neuroscientist at the University of Pennsylvania in Philadelphia. “The people who have positive and negative data are the top researchers,” he says, “and they are all doing good science.”
Some researchers think the evidence for neurogenesis is strong enough that it’s time to focus instead on understanding what these neurons do and, ultimately, on whether this process can be used to treat diseases that involve neurodegeneration. But at the same time, questions remain about the methods used to detect neurogenesis, which today rely mostly on genetic markers associated with it and provide only indirect evidence of its existence.