Neuroscientists long believed you are born with all the neurons you will ever have — in 2025, researchers found newly formed neurons in the brains of adults as old as 78, overturning decades of settled thinking

For most of the twentieth century, the rule seemed simple. You are born with all the neurons you will ever have, and the adult brain makes no new ones. In July 2025, a team at the Karolinska Institutet in Sweden reported finding the cells that give rise to new neurons in the adult human hippocampus, [...] The post Neuroscientists long believed you are born with all the neurons you will ever have — in 2025, researchers found newly formed neurons in the brains of adults as old as 78, overturning d