The long-standing notion that 'no new brain cells are created after becoming an adult' has been debated in the scientific community for decades. Finally, decisive research results have emerged to put an end to this controversy.
Jonas Frisén, a professor at the Karolinska Institute in Sweden, confirmed on the 4th that evidence shows new neurons continue to be produced in the hippocampus of adults, as reported in the international journal Science. The hippocampus is a key brain area for storing memories and regulating emotions.
For a long time, scientists have thought that 'humans are born with the majority of their neurons, and the number of neurons remains constant once growth is complete.' Even if some damaged brain cells regenerate locally, they believed that no new neurons are created. However, the claim that neurons are naturally generated even in adulthood has been raised by some researchers, leading to ongoing debate.
In fact, in 2013, Professor Frisén's research team discovered evidence that new neurons are produced in the hippocampus of adults and published the findings in the international journal Cell. By analyzing the carbon components in brain tissue, they showed that over one-third of the neurons in the hippocampus are regularly regenerated throughout a person's life. However, there remained controversy due to the lack of clear evidence that 'neural progenitor cells,' the precursor cells necessary for creating new neurons, actually exist and divide in adults.
The research team secured and analyzed brain tissue samples from various age groups, ranging from 0 to 78 years old. They analyzed each cell's gene activity and distinguished cell characteristics while utilizing artificial intelligence (AI) to trace the various stages of cell growth.
As a result, they revealed that neurons progenitor cells are present in the normal adult brain and are actively dividing. This proves that adults can also create new neurons. Interestingly, the number of neural progenitor cells varied greatly among individuals. The research team noted, 'This difference may lead to variations in memory capacity or brain health, and further research is needed.'
The research team also confirmed that the newly generated neurons are concentrated in the dentate gyrus area of the hippocampus. The dentate gyrus is the brain region that helps remember new information and allows for flexible thinking depending on the situation.
Professor Frisén stated, 'This research provides key insights into how the human brain changes and adapts throughout a lifetime,' and expressed hope that it would help develop new treatments to promote brain cell generation for degenerative brain diseases such as Alzheimer's disease and depression.
References
Science (2025), DOI: https://doi.org/10.1126/science.adu9575