New Research Reveals Continued Neuron Formation in Adult Hippocampus

A groundbreaking study published in the journal Science on July 4, 2025, by researchers from Karolinska Institutet in Sweden, has provided compelling evidence that new neurons continue to form in the hippocampus, a critical area of the brain associated with memory and learning, well into late adulthood. This research adds significant insight into the adaptability of the human brain and challenges long-held beliefs about neurogenesis in adults.

The hippocampus plays a vital role in emotional regulation, learning, and memory. Previous studies, including notable research conducted in 2013 by Dr. Jonas Frisén's group at Karolinska Institutet, had already established that new neurons could indeed form in the adult human hippocampus. However, the latest findings delve deeper, identifying the cellular origins of these neurons, known as neural progenitor cells, and confirming their existence and division in adult human brains.

According to Dr. Frisén, a Professor of Stem Cell Research at the Department of Cell and Molecular Biology at Karolinska Institutet, “We have now been able to identify these cells of origin, which confirms that there is an ongoing formation of neurons in the hippocampus of the adult brain.” This study examined brain tissue from individuals aged 0 to 78, utilizing advanced techniques such as single-nucleus RNA sequencing and flow cytometry to analyze gene activity in individual cell nuclei.

The researchers’ innovative approach allowed them to trace the development stages of neurons, from stem cells to immature neurons, many of which were found to be in the process of division. Notably, the study localized these newly formed cells in the dentate gyrus, a specific area of the hippocampus crucial for memory formation and cognitive flexibility.

This research was conducted in collaboration with various international biobanks and involved contributions from researchers at Chalmers University of Technology in Sweden. The findings suggest that while the progenitors of adult neurons show similarities to those found in other species such as mice and monkeys, there are distinct differences in gene activity, indicating that human neurogenesis is a complex and variable process. Some individuals exhibited a higher number of neural progenitor cells, while others showed very few, highlighting the variability in neurogenesis among adults.

The implications of this research extend far beyond academic curiosity. By further understanding how the human brain adapts and changes throughout life, the findings may pave the way for developing regenerative treatments aimed at stimulating neurogenesis. This could have significant applications in treating neurodegenerative diseases and psychiatric disorders, potentially revolutionizing therapeutic approaches in neurology.

Funding for the study was provided by various prestigious organizations, including the Swedish Research Council, the European Research Council, and the Swedish Cancer Society, emphasizing the importance of this research in the broader scientific context. The study, titled 'Identification of proliferating neural progenitors in the adult human hippocampus,' serves as a pivotal contribution to the ongoing exploration of human brain plasticity, and its findings may influence future research directions and therapeutic strategies.

In conclusion, this significant advancement in our understanding of neurogenesis in adults highlights the brain's remarkable capacity for adaptation and growth, even in late adulthood. As research continues to uncover the complexities of brain function and development, the potential for new interventions and treatments that harness the power of neurogenesis may soon become a reality, offering hope for those affected by cognitive decline and related disorders.