Latest news with #JonasFrisén
Yahoo
07-07-2025
- Health
- Yahoo
Brain's Memory Center Never Stops Making Neurons, Study Confirms
Though it's now clear humans continue to grow new brain cells throughout their entire lives, debate persists over whether this applies to specific areas involved with memory. Previous studies have made the case for and against the existence of neurogenesis in hippocampus beyond childhood. A new study now offers some of the clearest evidence yet that this crucial memory-forming region does form fresh neurons well into adulthood. The study is the work of researchers from the Karolinska Institute and the Chalmers University of Technology in Sweden, and looks specifically at the dentate gyrus section of the hippocampus, the part of the brain that acts as a key control center for emotions, learning, and storing episodic memories. Related: "This gives us an important piece of the puzzle in understanding how the human brain works and changes during life," says molecular biologist Jonas Frisén. Confirmation that humans can form new neurons in the hippocampus through life (as several other animals can) would inform a whole host of other scientific investigations, from how adults learn new skills to what happens to the brain as it deteriorates in old age. The team used RNA analysis to identify functions of brain cells in samples collected from people up to age 78, finding that some neurons were geared to function as neural progenitor cells (NPCs), which generate new nerve cells. The researchers also found similarities between human NPCs and those in mice, pigs, and monkeys. Through a process of machine learning, the researchers could also group cells according to their development, from their initial 'blank slate' stem cell characterization to being an immature neuron in the process of dividing. The results address questions raised by earlier studies (including one from some of the same researchers), which determined that new neurons were present in the human brain without being able to confirm exactly how they'd got there. "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," says Frisén. By studying such a wide range of ages, the researchers confirmed neurogenesis keeps happening in the hippocampus throughout our adult lives – albeit at a slower rate, generally speaking, as we get older. It's also important to note that the analysis revealed different rates of neurogenesis in different people. That might point to differences in brain plasticity that affect learning, personality, and disease risk, but that's something that future studies will need to look at. One hypothesis is that certain brain conditions might be affected by how quickly fresh new neurons can be produced – some of the subjects in this study had a history of psychiatric or neurological diseases – but again this wasn't something that the researchers looked at directly, so follow-up studies will be needed. "Our research may also have implications for the development of regenerative treatments that stimulate neurogenesis in neurodegenerative and psychiatric disorders," says Frisén. The research has been published in Science. Pomegranates Could Limit Risks From Controversial Sports Supplement OCD's Origins Might Not Lie in The Brain Like We Thought The News Cycle Is a Stress Monster. But There's a Healthy Way to Stay Informed.
Yahoo
04-07-2025
- Health
- Yahoo
Human brains keep growing neurons even in old age, study finds for first time
For decades, scientists believed the human brain stopped producing new neurons after childhood. This long-held view painted the adult brain as a fixed organ, incapable of generating fresh cells in the very region responsible for memory and learning. But a landmark new study turns that dogma on its head, offering the clearest evidence yet that adult humans continue to form new neurons well into the old age. A team of researchers from Karolinska Institutet in Sweden has identified and tracked the formation of new neurons in the hippocampus, a region critical for memory, learning, and emotional regulation. In 2013, a team of researchers led by Professor Jonas Frisén made headlines with a study showing that new neurons can form in the hippocampus of adult humans. They used carbon-14 dating in DNA extracted from brain tissue to pinpoint when individual cells were created, providing rare evidence of adult neurogenesis. But while the study proved that new neurons could exist, it did not answer where these neurons come from. Until now, scientists lacked direct proof that the neural progenitor cells were present and actively dividing in the adult human brain. '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,' said Frisén. In the new study, the team analyzed post-mortem brain tissue from individuals ranging in age from infancy to 78 years to discover that neural progenitor cells—precursors to fully developed neurons—not only exist in the adult brain but are also actively dividing. The study used advanced techniques like single-nucleus RNA sequencing to map gene activity in individual brain cell nuclei. Combined with flow cytometry and machine learning, the approach allowed researchers to identify various stages of neuronal development, ranging from stem-like cells to immature, still-dividing neurons. To visualize where these new neurons were forming, the scientists employed RNAscope and Xenium, two powerful spatial transcriptomics tools. These confirmed that the cell formation was happening in the dentate gyrus, a part of the hippocampus linked to learning, cognitive flexibility, and the encoding of new memories. The findings reveal that adult human neural progenitor cells closely resemble those seen in mice, pigs, and monkeys, though some gene activity patterns differ between species. What's especially intriguing is the variability between individuals. While some adults had abundant neural progenitor cells, others had very few, raising new questions about what factors might influence adult neurogenesis. 'This gives us an important piece of the puzzle in understanding how the human brain works and changes during life,' Frisén explained. 'Our research may also have implications for the development of regenerative treatments that stimulate neurogenesis in neurodegenerative and psychiatric disorders.' The findings could also pave the way for new regenerative therapies for neurodegenerative and psychiatric conditions, potentially helping to restore or enhance brain function by stimulating neuron formation in targeted ways. The groundbreaking study has been published in the journal Science.
Gizmodo
03-07-2025
- Health
- Gizmodo
New Research Debunks Myth That Brain Cells Stop Growing After Childhood
You've probably heard the old canard that new brain cells simply stop forming as we become adults. But research out today is the latest to show that this isn't really true. Scientists in Sweden led the study, published Thursday in Science. They found abundant signs of neural stem cells growing in the hippocampus of adult brains. The findings reveal more about the human brain as we get older, the researchers say, and also hint at potential new ways to treat neurological disorders. 'We've found clear evidence that the human brain keeps making new nerve cells well into adulthood,' study co-author Marta Paterlini, a neuroscientist at the Karolinska Institute in Stockholm, told Gizmodo. This Is What Your Brain Looks Like When You Solve a Problem This isn't the first paper to chip away at the idea of new neurons ceasing to form in adulthood (a concept not to be confused with general brain development, which does seem to reach maturity around age 30). In 2013, study researcher Jonas Frisén and his team at the Karolinska Institute concluded that substantial neuron growth—also known as neurogenesis—occurs throughout our lives, albeit with a slight decline as we become elderly. But there's still some debate ongoing among scientists. In spring 2018, for instance, two different studies of neurogenesis published a month apart came to the exact opposite conclusion. The researchers were hoping to settle one particular aspect of human neurogenesis in adults. If we do keep growing new neurons as we age, then we should be able to spot the cells that eventually mature into neurons, neural progenitor cells, growing and dividing inside the adult brain. To look for these cells, the team analyzed brain tissue samples from people between the ages of 0 and 78 using relatively new advanced methods. These methods allowed them to figure out the characteristics of brain cells on an individual level and to track the genes being expressed by a single cell's nucleus. All told, the researchers examined more than 400,000 individual cell nuclei from these samples. And as hoped, they found these progenitor cells along various stages of development in adult brains, including cells just about to divide. They also pinpointed the location within the hippocampus where the new cells appeared to originate: the dentate gyrus, a brain region critical to helping us form certain types of memory. 'We saw groups of dividing precursors sitting right next to the fully formed nerve cells, in the same spots where animal studies have shown adult stem cells live,' said Paterlini, a senior scientist at the Frisén lab. 'In short, our work puts to rest the long-standing debate about whether adult human brains can grow new neurons.' Something Strange Happens to Brains During a Marathon The findings, as is often true in science, foster more questions in need of an answer. Our adult precursor cells seem to have different patterns of gene activity compared to the cells found in pigs, mice, and other mammals with clear evidence of adult neurogenesis, for instance. The researchers also found that some adults' brains were filled with these growing precursors, while others had relatively few. These differences—combined with the team's earlier research showing that adult neurogenesis slows down over time—may help explain people's varying risk of neurological or psychological conditions, the authors say. And likewise, finding a safe way to improve the adult brain's existing ability to grow new cells could help treat these conditions or improve people's recovery from serious head injuries. 'Although precise therapeutic strategies for humans are still being researched, the simple fact that our adult brains can generate new neurons radically changes the way we view lifelong learning, recovery from injury, and the untapped potential of neuronal plasticity,' said Paterlini. There's plenty more to be learned about how our brains change over time. The team is planning to investigate other likely hotspots of neurogenesis in the adult brain, such as the wall of the lateral ventricles (c-shaped cavities found in each of the brain's cerebral hemispheres) and nearby regions. But we can be fairly certain that our neurons keep on growing and replacing themselves into adulthood—at least for some of us.
