In 1928, Santiago Ramón y Cajal, the father of modern neuroscience, proclaimed that the brains of adult humans never make new neurons. “Once development was ended,” he wrote, “the founts of growth and regeneration ... dried up irrevocably. In the adult centers the nerve paths are something fixed, ended and immutable. Everything must die, nothing may be regenerated.”
Ninety years later, it’s still unclear if his statement is true.
For decades, scientists believed that neurogenesis—the creation of new neurons—whirrs along nicely in the brains of embryos and infants, but grinds to a halt by adulthood. But from the 1980s onward, this dogma started to falter. Researchers showed that neurogenesis does occur in the brains of various adult animals, and eventually found signs of newly formed neurons in the adult human brain. Hundreds of these cells are supposedly added every day to the hippocampus—a comma-shaped structure involved in learning and memory. The concept of adult neurogenesis is now so widely accepted that you can find diets and exercise regimens that purportedly boost it. Predictably, there’s even a TED talk about it.
[For more on this story by ED YONG, https://www.theatlantic.com/sc...tudy-says-no/555026/]
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