Why in the News?

A recent study (2025, Science) found young neurons in the adult brain, challenging the old belief that Neurogenesis (neurons formation) occur only in childhood.

What is Neurogenesis?

• Overview: Formation of new neurons from stem or progenitor cells.
• Established in Animals: Well-known in mice, rats, and monkeys; also active during human childhood development.
• Debate in Humans: Longstanding question if it continues in adulthood, especially in the hippocampus (brain’s memory and learning hub).
• Hippocampal Role: The dentate gyrus is believed to sustain lifelong neurogenesis, helping in memory formation, flexibility, and stress control.

Key findings of the Study:

• Conducted by: Karolinska Institutet, Stockholm, published in Science (2025).
• Study: Analysed 400,000 neurons from post-mortem hippocampus samples of people aged from infants (<1 year) to 78 years.
• Methodology: Used single nuclei RNA sequencing with machine learning to detect signs of new cells.
• Outcome: Validated with RNAscope and Xenium imaging, which confirmed the presence of neural stem cells, progenitors, and young neurons (neuroblasts) even in adolescent and adult brains.

Why are the findings important?

• Evidence in Adults: Strong proof that new neurons form in adult brains, not just in early years.
• Evolutionary Insight: Suggests neurogenesis is a conserved feature across mammals, not unique to certain species.
• Brain Functions: Explains memory flexibility, ability to overwrite memories, and resilience to stress.
• Therapeutic Potential: Opens up scope for regenerative treatments in brain disorders like Alzheimer’s, Parkinson’s, and dementia by stimulating local progenitor cells.
• Lifestyle Link: Implies that exercise, social connections, and stress levels could influence how much neurogenesis happens in individuals.

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