Links for Keyword: Neurogenesis

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Ashley Yeager In March 2018, researchers reported evidence suggesting that adult humans do not generate new neurons in the hippocampus—the brain’s epicenter of learning and memory. The result contradicted two decades of work that said human adults actually do grow new neurons there, and revealed a need for new and better tools to study neurogenesis, Salk Institute President Fred Gage, who generated foundational evidence for adult human neurogenesis, told The Scientist at the time. Since that study was published, several other teams have used similar techniques—but have come to different conclusions, publishing evidence that adult humans do indeed grow new hippocampal neurons, even at the age of 99. Despite the equivocal results, Maura Boldrini, a neuroscientist at Columbia University, and a number of other neuroscientists tell The Scientist they think neurogenesis does occur in the adult human brain, bolstering learning and memory and possibly also our stress and emotional responses. Neurogenesis is “fundamentally important for the brain to react to all sorts of different insults and prevent neurological and psychiatric problems,” Boldrini says. Because of its role in brain function, researchers want to learn how neurogenesis works to potentially use it to treat brain trauma, neurodegeneration, psychiatric disorders, such as depression, and possibly even the ill effects of aging. The growth of new neurons is well studied in newborn and adult animals, especially rodents. There’s prolific neurogenesis as the brain develops, which then drops off and plateaus in adulthood, only occurring in particular areas of the brain. Examinations of human postmortem tissue suggest that the process is similar in people, based on antibody markers that label neural progenitors and young neurons. But those signals can be hard to detect in preserved cells, and the gap in time between the death of a donor and when her tissue is fixed and analyzed can affect the reliability of the markers, scientists say, which might explain the disparities in findings between different studies. © 1986–2019 The Scientist

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 26685 - Posted: 10.09.2019

By Karen Weintraub If the memory center of the human brain can grow new cells, it might help people recover from depression and post-traumatic stress disorder (PTSD), delay the onset of Alzheimer’s, deepen our understanding of epilepsy and offer new insights into memory and learning. If not, well then, it’s just one other way people are different from rodents and birds. For decades, scientists have debated whether the birth of new neurons—called neurogenesis—was possible in an area of the brain that is responsible for learning, memory and mood regulation. A growing body of research suggested they could, but then a Nature paper last year raised doubts. Now, a new study published today in another of the Nature family of journals—Nature Medicine—tips the balance back toward “yes.” In light of the new study, “I would say that there is an overwhelming case for the neurogenesis throughout life in humans,” Jonas Frisén, a professor at the Karolinska Institute in Sweden, said in an e-mail. Frisén, who was not involved in the new research, wrote a News and Views about the study in the current issue of Nature Medicine. Not everyone was convinced. Arturo Alvarez-Buylla was the senior author on last year’s Nature paper, which questioned the existence of neurogenesis. Alvarez-Buylla, a professor of neurological surgery at the University of California, San Francisco, says he still doubts that new neurons develop in the brain’s hippocampus after toddlerhood. © 2019 Scientific American

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 26082 - Posted: 03.26.2019

By Emily Underwood One of the thorniest debates in neuroscience is whether people can make new neurons after their brains stop developing in adolescence—a process known as neurogenesis. Now, a new study finds that even people long past middle age can make fresh brain cells, and that past studies that failed to spot these newcomers may have used flawed methods. The work “provides clear, definitive evidence that neurogenesis persists throughout life,” says Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto, Canada. “For me, this puts the issue to bed.” Researchers have long hoped that neurogenesis could help treat brain disorders like depression and Alzheimer’s disease. But last year, a study in Nature reported that the process peters out by adolescence, contradicting previous work that had found newborn neurons in older people using a variety of methods. The finding was deflating for neuroscientists like Frankland, who studies adult neurogenesis in the rodent hippocampus, a brain region involved in learning and memory. It “raised questions about the relevance of our work,” he says. But there may have been problems with some of this earlier research. Last year’s Nature study, for example, looked for new neurons in 59 samples of human brain tissue, some of which came from brain banks where samples are often immersed in the fixative paraformaldehyde for months or even years. Over time, paraformaldehyde forms bonds between the components that make up neurons, turning the cells into a gel, says neuroscientist María Llorens-Martín of the Severo Ochoa Molecular Biology Center in Madrid. This makes it difficult for fluorescent antibodies to bind to the doublecortin (DCX) protein, which many scientists consider the “gold standard” marker of immature neurons, she says. © 2019 American Association for the Advancement of Science

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 26081 - Posted: 03.26.2019

Katarina Zimmer It’s well established that exercise is good for the mammalian brain. As early as 1999, researchers discovered considerably more newborn neurons in the hippocampi of mice that had access to a running wheel than in animals that didn’t. But 20 years later, scientists are still trying to understand why. A team of Australian and German researchers has uncovered one mechanism that explains how exercise boosts neurogenesis in mice: the activity causes platelets circulating in the blood to release factors that boost the growth of neural precursor cells in the hippocampus, the researchers report today (March 21) in Stem Cell Reports. “We all know about the positive effect of exercise on the brain and other organ systems, but what the actual mechanism is to promote new neuron production is still a bit of a mystery,” remarks Vince Tropepe, who studies neurogenesis at the University of Toronto and who was not involved in the study. “This paper is quite interesting in that they’ve identified a player—these platelets and platelet-derived factors that are circulating in the blood after exercise—that might be a mediator of this effect.” The researchers came to this conclusion through a series of experiments comparing mice that had access to a running wheel for four days with control mice that didn’t. Lab mice voluntarily run up to 10 kilometers per night, “equivalent to us running more than a marathon a day,” explains coauthor Tara Walker, a senior research associate at the Queensland Brain Institute. © 1986 - 2019 The Scientist

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 5: The Sensorimotor System
Link ID: 26066 - Posted: 03.23.2019

Laura Sanders Just a generation ago, common wisdom held that once a person reaches adulthood, the brain stops producing new nerve cells. Scientists countered that depressing prospect 20 years ago with signs that a grown-up brain can in fact replenish itself. The implications were huge: Maybe that process would offer a way to fight disorders such as depression and Alzheimer’s disease. This year, though, several pieces of contradictory evidence surfaced and a heated debate once again flared up. Today, we still don’t know whether the fully grown brain churns out new nerve cells. This year’s opening shot came March 7 in a controversial report in Nature. Contradicting several landmark findings that had convinced the scientific community that adults can make new nerve cells, researchers described an utter lack of dividing nerve cells, or neurons, in adult postmortem brain tissue (SN Online: 3/8/18). A return volley came a month later, when a different research group described loads of newborn neurons in postmortem brains, in an April 5 paper in Cell Stem Cell (SN: 5/12/18, p. 10). Scientific whiplash ensued when a third group found no new neurons in postmortem brains, describing the results in the July Cerebral Cortex. Still more neuroscientists jumped into the fray with commentaries and perspective articles. This ping-ponging over the rejuvenating powers of the brain is the most recent iteration of a question that still hasn’t been answered. The first encouraging news about brain cells came in 1998 when scientists looked at the brains of people who had been treated with a compound that marks DNA in newly born neurons. The compound turned up in cells in the adult hippocampus, a brain structure important for learning and memory. Those results, along with a 2013 study that used a different tagging method, suggested that the brain can pump out neurons throughout life. |© Society for Science & the Public 2000 - 2018

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25808 - Posted: 12.21.2018

Ruth Williams If youngsters told their elders to be quiet, stress levels would surely rise. But, when it comes to brain cells, it seems the opposite is true—silencing of old neurons by young ones appears to make an animal more stress resilient. A report today (June 27) in Nature shows that mice whose production of new hippocampal neurons was ramped up suffered less anxiety in a stressful social situation than their control counterparts, and this was thanks to an increased inhibition of mature hippocampal cells. “It’s a very elegant paper showing how adult neurogenesis protects against chronic stress,” says neuroscientist Sandrine Thuret of King’s College London in the U.K. who was not involved in the research. It was known that the birth of new neurons in the hippocampus could prevent stress, “but we didn’t really know how,” she explains. “[The authors] show that the new neurons modulate the activity of mature neurons and that this has a behavioral effect.” In the adult brains of most mammals, neurogenesis occurs in two regions: the dentate gyrus of the hippocampus—an area implicated in memory formation, exploration, stress, and depression—and the striatum—implicated in, among other things, reward and reinforcement. While humans appear to have little if any striatal neurogenesis, evidence suggests they continue to produce new neurons in the dentate gyrus throughout life, though there has been some recent debate regarding this. © 1986 - 2018 The Scientist. All rights reserved.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 11: Emotions, Aggression, and Stress
Link ID: 25157 - Posted: 06.29.2018

Laurel Hamers Your brain might make new nerve cells well into old age. Healthy people in their 70s have just as many young nerve cells, or neurons, in a memory-related part of the brain as do teenagers and young adults, researchers report in the April 5 Cell Stem Cell. The discovery suggests that the hippocampus keeps generating new neurons throughout a person’s life. The finding contradicts a study published in March, which suggested that neurogenesis in the hippocampus stops in childhood (SN Online: 3/8/18). But the new research fits with a larger pile of evidence showing that adult human brains can, to some extent, make new neurons. While those studies indicate that the process tapers off over time, the new study proposes almost no decline at all. Understanding how healthy brains change over time is important for researchers untangling the ways that conditions like depression, stress and memory loss affect older brains. When it comes to studying neurogenesis in humans, “the devil is in the details,” says Jonas Frisén, a neuroscientist at the Karolinska Institute in Stockholm who was not involved in the new research. Small differences in methodology — such as the way brains are preserved or how neurons are counted — can have a big impact on the results, which could explain the conflicting findings. The new paper “is the most rigorous study yet,” he says. Researchers studied hippocampi from the autopsied brains of 17 men and 11 women ranging in age from 14 to 79. In contrast to past studies that have often relied on donations from patients without a detailed medical history, the researchers knew that none of the donors had a history of psychiatric illness or chronic illness. |© Society for Science & the Public 2000 - 2018.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 24830 - Posted: 04.06.2018

Giorgia Guglielmi Every day, the human hippocampus, a brain region involved in learning and memory, creates hundreds of new nerve cells — or so scientists thought. Now, results from a study could upend this long-standing idea. A team of researchers has found that the birth of neurons in this region seems to stop once we become adults. A few years ago, the group looked at a well-preserved adult brain sample and spotted a few young neurons in several regions, but none in the hippocampus. So they decided to analyse hippocampus samples from dozens of donors, ranging from fetuses to people in their 60s and 70s. They concluded that the number of new hippocampal neurons starts to dwindle after birth and drops to near zero in adulthood. The results1, published in Nature on 7 March, are already raising controversy. If confirmed, the findings would be a “huge blow” not only to scientists in the field, but also to people with certain brain disorders, says Ludwig Aigner, a neuroscientist at Paracelsus Medical University in Salzburg, Austria. This is because researchers had hoped to harness the brain’s ability to generate new neurons to treat neurodegenerative diseases such as Alzheimer’s and Parkinson’s, he says. But Aigner and other neuroscientists are not fully persuaded by the findings, which contradict multiple lines of evidence that the hippocampus keeps producing neurons throughout a person’s life. “I wouldn’t close the books on [that],” says neuroscientist Heather Cameron of the US National Institute of Mental Health in Bethesda, Maryland. © 2018 Macmillan Publishers Limited

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 13: Memory, Learning, and Development
Link ID: 24733 - Posted: 03.08.2018

Laura Sanders Brain scientists have filmed a first-of-a-kind birth video. It reveals specialized cells in the brains of mice dividing to create newborn nerve cells. The images, published in the Feb. 9 Science, show intricacies of how certain parts of the adult mouse brain can churn out new nerve cells. These details may help lead to a deeper understanding of the role of this nerve cell renewal in such processes as memory. Deep in the brains of mice, a memory-related structure called the hippocampus is known to be flush with new nerve cells. But because this buried neural real estate is hard to study, the circumstances of these births weren’t clear. Using living mice, Sebastian Jessberger, a neuroscientist at the University of Zurich, and colleagues removed the outer layers of brain tissue that obscure the hippocampus. The scientists marked 63 cells called radial stem cells, which can divide to create new nerve cells. Researchers then watched these stem cells for up to two months, taking pictures every 12 or 24 hours. During that time, 42 of these stem cells underwent a spurt of division, churning out two kinds of cells: intermediate cells that would go on to produce nerve cells as well as mature nerve cells themselves. Once this burst of activity ended, the radial stem cells disappeared by dividing themselves into mature nerve cells that could no longer split. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 13: Memory, Learning, and Development
Link ID: 24635 - Posted: 02.09.2018

Laura Sanders In stark contrast to earlier findings, adults do not produce new nerve cells in a brain area important to memory and navigation, scientists conclude after scrutinizing 54 human brains spanning the age spectrum. The finding is preliminary. But if confirmed, it would overturn the widely accepted and potentially powerful idea that in people, the memory-related hippocampus constantly churns out new neurons in adulthood. Adult brains showed no signs of such turnover in that region, researchers reported November 13 at a meeting of the Society for Neuroscience in Washington, D.C. Previous studies in animals have hinted that boosting the birthrate of new neurons, a process called neurogenesis, in the hippocampus might enhance memory or learning abilities, combat depression and even stave off the mental decline that comes with dementia and old age (SN: 9/27/08, p. 5). In rodents, exercise, enriched environments and other tweaks can boost hippocampal neurogenesis — and more excitingly, memory performance. But the new study may temper those ambitions, at least for people. Researchers studied 54 human brain samples that ranged from fetal stages to age 77, acquired either postmortem or during brain surgery. These samples were cut into thin slices and probed with molecular tools that can signal dividing or young cells, both of which are signs that nerve cells are being born. As expected, fetal and infant samples showed evidence of both dividing cells that give rise to new neurons and young neurons themselves in the hippocampus. But with age, these numbers declined. In brain tissue from a 13-year-old, the researchers spotted only a handful of young neurons. And in adults, there were none. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 13: Memory, Learning, and Development
Link ID: 24334 - Posted: 11.16.2017

By GRETCHEN REYNOLDS Because we can never have enough reasons to keep exercising, a new study with mice finds that physical activity not only increases the number of new neurons in the brain, it also subtly changes the shape and workings of these cells in ways that might have implications for memory and even delaying the onset of dementia. As most of us have heard, our brains are not composed of static, unchanging tissue. Instead, in most animals, including people, the brain is a dynamic, active organ in which new neurons and neural connections are created throughout life, especially in areas of the brain related to memory and thinking. This process of creating new neurons, called neurogenesis, can be altered by lifestyle, including physical activity. Many past studies have shown that in laboratory rodents, exercise doubles or even triples the number of new cells produced in adult animals’ brains compared to the brains of animals that are sedentary. But it has not been clear whether the new brain cells in active animals are somehow different from comparable new neurons in inactive animals or if they are just more numerous. That question has long interested scientists at the Laboratory of Neurosciences at the National Institute on Aging, who have been examining how running alters the brains and behavior of lab animals. Last year, in an important study published in NeuroImage, the researchers found for the first time that young brain cells in adult mice that spent a month with running wheels in their cages did seem to be different from those in animals that did not run. For the experiment, the scientists injected a modified rabies vaccine into the animals, where it entered the nervous system and brain. They then tracked and labeled connections between brain cells and learned that compared to the sedentary animals’ brain cells, the runners’ newborn neurons had more and longer dendrites, the snaky tendrils that help to connect the cells into the neural communications network. They also found that more of these connections led to portions of the brain that are important for spatial memory, which is our internal map of where we have been and how we got there. © 2017 The New York Times Company

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 5: The Sensorimotor System
Link ID: 24145 - Posted: 10.04.2017

By Ruth Williams .Newly made cells in the brains of mice adopt a more complex morphology and connectivity when the animals encounter an unusual environment than if their experiences are run-of-the-mill. Researchers have now figured out just how that happens. According to a study published today (October 27) in Science, a particular type of cell—called an interneuron—in the hippocampus processes the animals’ experiences and subsequently shapes the newly formed neurons. “We knew that experience shapes the maturation of these new neurons, but what this paper does is it lays out the entire circuit through which that happens,” said Heather Cameron, a neuroscientist at the National Institute of Mental Health in Bethesda who was not involved with the work. “It’s a really nicely done piece of work because they go step-by-step and show all of the cells that are involved and how they’re connected.” Most of the cells in the adult mammalian brain are mature and don’t divide, but in a few regions, including an area of the hippocampus called the dentate gyrus, neurogenesis occurs. The dentate gyrus is thought to be involved in the formation of new memories. In mice, for instance, exploring novel surroundings electrically activates the dentate gyrus and can affect the production, maturation, and survival of the newly born cells. Now, Alejandro Schinder and his team at the Leloir Institute in Buenos Aires, Argentina, have investigated the process in detail. © 1986-2016 The Scientist

Related chapters from BN8e: Chapter 17: Learning and Memory; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 13: Memory, Learning, and Development
Link ID: 22804 - Posted: 10.29.2016

David R. Jacobs, We all know that exercise improves our physical fitness, but staying in shape can also boost our brainpower. We are not entirely sure how, but evidence points to several explanations. First, to maintain normal cognitive function, the brain requires a constant supply of oxygen and other chemicals, delivered via its abundant blood vessels. Physical exercise—and even just simple activities such as washing dishes or vacuuming—helps to circulate nutrient-rich blood efficiently throughout the body and keeps the blood vessels healthy. Exercise increases the creation of mitochondria—the cellular structures that generate and maintain our energy—both in our muscles and in our brain, which may explain the mental edge we often experience after a workout. Studies also show that getting the heart rate up enhances neurogenesis—the ability to grow new brain cells—in adults. Regardless of the mechanism, mounting evidence is revealing a robust relation between physical fitness and cognitive function. In our 2014 study, published in Neurology, we found that physical activity has an extensive, long-lasting influence on cognitive performance. We followed 2,747 healthy people between the ages of 18 and 30 for 25 years. In 1985 we evaluated their physical fitness using a treadmill test: the participants walked up an incline that became increasingly steep every two minutes. On average, they walked for about 10 minutes, reaching 3.4 miles per hour at an 18 percent incline (a fairly steep hill). Low performers lasted for only seven minutes and high performers for about 13 minutes. A second treadmill test in 2005 revealed that our participants' fitness levels had declined with age, as would be expected, but those who were in better shape in 1985 were also more likely to be fit 20 years later. © 2016 Scientific American

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 5: The Sensorimotor System
Link ID: 22555 - Posted: 08.13.2016

THERE they are! Newborn neurons vital for memory have been viewed in a live brain for the first time. The work could aid treatments for anxiety and stress disorders. Attila Losonczy at Columbia University Medical Center in New York and his team implanted a tiny microscope into the brains of live mice, the brain cells of which had been modified to make newly made neurons glow. The mice then ran on a treadmill as the team tweaked the surrounding sights, smells and sounds. The researchers paired a small electric shock with some cues, so the mice learned to associate these with an unpleasant experience. They then deactivated the newborn neurons – present in areas of the brain responsible for learning and memory – using optogenetics, which switches off specific cells with light. After this, the mice were unable to tell the difference between the scary and safe cues, becoming fearful of them all (Neuron, doi.org/bc7v). “It suggests that newborn cells do something special that allows animals to tell apart and separate memories,” says Losonczy. An inability to discriminate between similar sensory information triggered by different events – such as the sound of a gunshot and a car backfiring – is often seen in panic and anxiety disorders, such as PTSD. This suggests that new neurons, or a lack of them, plays a part in such conditions and could guide novel treatments. © Copyright Reed Business Information Ltd.

Related chapters from BN8e: Chapter 17: Learning and Memory; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 13: Memory, Learning, and Development
Link ID: 22001 - Posted: 03.17.2016

By Emily Underwood Nestled deep within a brain region that processes memory is a sliver of tissue that continually sprouts brand-new neurons, at least into late adulthood. A study in mice now provides the first glimpse at how these newborn neurons behave in animals as they learn, and hints at the purpose of the new arrivals: to keep closely-related but separate memories distinct. A number of previous studies have suggested that the birth of new neurons is key to memory formation. In particular, scientists believe the new cell production—known as neurogenesis—plays a role in pattern separation, the ability to discriminate between similar experiences, events, or contexts based on sensory cues such as a certain smell or visual landmark. Pattern separation helps us use cues such as the presence of a particular tree or cars nearby, for example, to distinguish which parking space we chose today, as opposed to yesterday or the day before. This ability appears to be particularly diminished in people with anxiety and mood disorders. Scientists can produce deficits in pattern separation in animals by blocking neurogenesis, using x-ray radiation to kill targeted populations of cells in the dentate gyrus. Because such studies have not established the precise identity of which cells are being recorded from, however, no one has been able to address the “burning question” in the field: "how young, adult-born neurons and mature dentate granule neurons differ in their activity," says Amar Sahay, a neuroscientist at the Massachusetts General Hospital and Harvard Medical School. © 2016 American Association for the Advancement of Scienc

Related chapters from BN8e: Chapter 17: Learning and Memory; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 13: Memory, Learning, and Development
Link ID: 21980 - Posted: 03.12.2016

By Gretchen Reynolds Some forms of exercise may be much more effective than others at bulking up the brain, according to a remarkable new study in rats. For the first time, scientists compared head-to-head the neurological impacts of different types of exercise: running, weight training and high-intensity interval training. The surprising results suggest that going hard may not be the best option for long-term brain health. As I have often written, exercise changes the structure and function of the brain. Studies in animals and people have shown that physical activity generally increases brain volume and can reduce the number and size of age-related holes in the brain’s white and gray matter. Exercise also, and perhaps most resonantly, augments adult neurogenesis, which is the creation of new brain cells in an already mature brain. In studies with animals, exercise, in the form of running wheels or treadmills, has been found to double or even triple the number of new neurons that appear afterward in the animals’ hippocampus, a key area of the brain for learning and memory, compared to the brains of animals that remain sedentary. Scientists believe that exercise has similar impacts on the human hippocampus. These past studies of exercise and neurogenesis understandably have focused on distance running. Lab rodents know how to run. But whether other forms of exercise likewise prompt increases in neurogenesis has been unknown and is an issue of increasing interest, given the growing popularity of workouts such as weight training and high-intensity intervals. So for the new study, which was published this month in the Journal of Physiology, researchers at the University of Jyvaskyla in Finland and other institutions gathered a large group of adult male rats. The researchers injected the rats with a substance that marks new brain cells and then set groups of them to an array of different workouts, with one group remaining sedentary to serve as controls. © 2016 The New York Times Company

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 5: The Sensorimotor System
Link ID: 21902 - Posted: 02.17.2016

by Catherine Brahic Think crayfish and you probably think supper, perhaps with mayo on the side. You probably don't think of their brains. Admittedly, crayfish aren't known for their grey matter, but that might be about to change: they can grow new brain cells from blood. Humans can make new neurons, but only from specialised stem cells. Crayfish, meanwhile, can convert blood to neurons that resupply their eyestalks and smell circuits. Although it's a long way from crayfish to humans, the discovery may one day help us to regenerate our own brain cells. Olfactory nerves are continuously exposed to damage and so naturally regenerate in many animals, from flies to humans, and crustaceans too. It makes sense that crayfish have a way to replenish these nerves. To do so, they utilise what amounts to a "nursery" for baby neurons, a little clump at the base of the brain called the niche. In crayfish, blood cells are attracted to the niche. On any given day, there are a hundred or so cells in this area. Each cell will split into two daughter cells, precursors to full neurons, both of which migrate out of the niche. Those that are destined to be part of the olfactory system head to two clumps of nerves in the brain called clusters 9 and 10. It's there that the final stage of producing new smell neurons is completed. © Copyright Reed Business Information Ltd.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 5: The Sensorimotor System
Link ID: 19954 - Posted: 08.13.2014

By Charles Q. Choi Scientists have found a kind of brain cell in mice that can instruct stem cells to start making more neurons, according to a new study. In addition, they found that electrical signals could trigger this growth in rodents, raising the intriguing possibility that devices could one day help the human brain repair itself. The study appears in the journal Nature Neuroscience. We knew the brain can generate new neurons, a process known as neurogenesis, via neural stem cells. And neuroscientists knew these stem cells got their instructions from a variety of sources from chemicals in the bloodstream, for instance, and from cells in the structures that hold the cerebrospinal fluid that cushion the brain. Earlier research had suggested brain cells might also be able to command these stem cells to create neurons. Neuroscientist Chay Kuo at the Duke University School of Medicine in Durham, N.C., and his colleagues have now discovered such cells in mice. "It's really cool that the brain can tell stem cells to make more neurons," Kuo says. To begin their experiments, the researchers tested how well a variety of neurotransmitters performed at spurring mouse neural stem cells to produce new neurons; they found that a compound known as acetylcholine performed best. The team then discovered a previously unknown type of neuron that produces an enzyme needed to make acetylcholine. These neurons are found in a part of the adult mouse brain known as the subventricular zone, where neurogenesis occurs. ©2014 Hearst Communication, Inc

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 19694 - Posted: 06.05.2014

Brain cell regeneration has been discovered in a new location in human brains. The finding raises hopes that these cells could be used to help people recover after a stroke, or to treat other brain diseases. For years it was unclear whether or not we could generate new brain cells during our lifetime, as the process – neurogenesis – had only been seen in animals. Instead, it was thought that humans, with our large and complex brains, are born with all the required neurons. Then last year Jonas Frisén of the Karolinska Institute in Stockholm, Sweden, and his colleagues found that neurogenesis occurs in the hippocampi of the human brain. These structures are crucial for memory formation (Cell, DOI: 10.1016/j.cell.2013.05.002) Now they have found more new brain cells in a second location – golf-ball-sized structures called the striata. These seem to be involved in many different functions, including in learning and memory. These particular aspects, related as they are to the hippocampi, lead Frisén to speculate that these new brain cells may also be involved with learning. "New neurons may convey some sort of plasticity," he says, which might help people learn and adapt to new situations. To reveal the new brain cells, the team exploited the fact that there have been varying levels of a radioactive isotope of carbon – carbon-14 – in the atmosphere since nuclear bomb tests during the cold war. This means that the year of creation of many cells in the body can be found by measuring the ratio of carbon-14 to carbon-12 in its DNA. Analysis of 30 donated brains revealed which brain cells had been born during the lifetimes of the donors. © Copyright Reed Business Information Ltd.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 19282 - Posted: 02.22.2014

By GRETCHEN REYNOLDS In an eye-opening demonstration of nature’s ingenuity, researchers at Princeton University recently discovered that exercise creates vibrant new brain cells — and then shuts them down when they shouldn’t be in action. For some time, scientists studying exercise have been puzzled by physical activity’s two seemingly incompatible effects on the brain. On the one hand, exercise is known to prompt the creation of new and very excitable brain cells. At the same time, exercise can induce an overall pattern of calm in certain parts of the brain. Most of us probably don’t realize that neurons are born with certain predispositions. Some, often the younger ones, are by nature easily excited. They fire with almost any provocation, which is laudable if you wish to speed thinking and memory formation. But that feature is less desirable during times of everyday stress. If a stressor does not involve a life-or-death decision and require immediate physical action, then having lots of excitable neurons firing all at once can be counterproductive, inducing anxiety. Studies in animals have shown that physical exercise creates excitable neurons in abundance, especially in the hippocampus, a portion of the brain known to be involved in thinking and emotional responses. But exercise also has been found to reduce anxiety in both people and animals. How can an activity simultaneously create ideal neurological conditions for anxiety and leave practitioners with a deep-rooted calm, the Princeton researchers wondered? So they gathered adult mice, injected them with a substance that marks newborn cells in the brain, and for six weeks, allowed half of them to run at will on little wheels, while the others sat quietly in their cages. Copyright 2013 The New York Times Company

Related chapters from BN8e: Chapter 15: Emotions, Aggression, and Stress; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 18344 - Posted: 07.03.2013