Links for Keyword: Neurogenesis

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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 BP7e: 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 BP7e: 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 BP7e: 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 BP7e: 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: Biological Basis of Behavioral Disorders
Link ID: 18344 - Posted: 07.03.2013

by Emily Underwood The mushroom clouds produced by more than 500 nuclear bomb tests during the Cold War may have had a silver lining, after all. More than 50 years later, scientists have found a way to use radioactive carbon isotopes released into the atmosphere by nuclear testing to settle a long-standing debate in neuroscience: Does the adult human brain produce new neurons? After working to hone their technique for more than a decade, the researchers report that a small region of the human brain involved in memory makes new neurons throughout our lives—a continuous process of self-renewal that may aid learning. For a long time, scientific dogma held that our brains did not produce new neurons during adulthood, says Pasko Rakic, a neuroscientist at Yale University who was not involved in the study. In 1998, however, a group of Swedish researchers reported the first evidence that neurons are continually born throughout the human lifespan. The researchers injected a compound normally used to label tumor cell division into patients who had agreed to have their brains examined after death. When the scientists examined the postmortem brain tissue, they found that new neurons had indeed sprung forth during adulthood. The cells were located in a part of the hippocampus—a pair of seahorse-shaped structures located deep within the brain and involved in memory and learning. The compound was later found to be toxic, however, and the experiment was never repeated. Since 1998, a number of studies have demonstrated that new neurons are generated in the same small region of the hippocampus in mice and appear to play an important role in memory and learning, says Kirsty Spalding, a molecular biologist at the Karolinska Institute in Stockholm and lead author of the new study. Because the 1998 work was never confirmed by independent research, however, scientists have fiercely argued over whether the neuron birth seen in mice also occurs in people. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: 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: 18249 - Posted: 06.08.2013

By Ferris Jabr The human body is a tireless gardener, growing new cells throughout life in many organs—in the skin, blood, bones and intestines. Until the 1980s most scientists thought that brain cells were the exception: the neurons you are born with are the neurons you have for life. In the past three decades, however, researchers have discovered hints that the human brain produces new neurons after birth in two places: the hippocampus—a region important for memory—and the walls of fluid-filled cavities called ventricles, from which stem cells migrate to the olfactory bulb, a knob of brain tissue behind the eyes that processes smell. Studies have clearly demonstrated that such migration happens in mice long after birth and that human infants generate new neurons. But the evidence that similar neurogenesis persists in the adult human brain is mixed and highly contested. A new study relying on a unique form of carbon dating suggests that neurons born during adulthood rarely if ever weave themselves into the olfactory bulb's circuitry. In other words, people—unlike other mammals—do not replenish their olfactory bulb neurons, which might be explained by how little most of us rely on our sense of smell. Although the new research casts doubt on the renewal of olfactory bulb neurons in the adult human brain, many neuroscientists are far from ready to end the debate. In preparation for the new study, Olaf Bergmann and Jonas Frisén of the Karolinska Institute in Stockholm and their colleagues acquired 14 frozen olfactory bulbs from autopsies performed between 2005 and 2011 at the institute's Department of Forensic Medicine. To determine whether the neurons were younger than the people they came from—which would mean the cells were generated after birth—the researchers needed to isolate the cells' DNA. © 2012 Scientific American,

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 16897 - Posted: 06.11.2012

By Tina Hesman Saey Newborn nerve cells may help heal the brain after a traumatic injury. In a study in mice, blocking the birth of new neurons hindered the mice’s ability to learn and remember a water maze after a brain injury, researchers from the University of Texas Southwestern Medical Center at Dallas report in the March 30 Journal of Neuroscience. The finding could help settle a debate about what new nerve cells do for the brain and may eventually change the way brain-injured patients are treated. Although scientists have known for a decade that adult brains can make new neurons in two parts of the brain, the role of the newborn cells has not been clear. Some scientists thought that, in adults, neurogenesis, as researchers call the process of generating new nerve cells, may be a leftover from building a new brain during development and has no affect on the adult brain at all. Others have evidence that the new wiring that hooks up new brain cells sometimes gets tangled and may lead to seizures after a brain injury or in epilepsy. Many researchers have suspected that making new cells is good for the brain, but data to definitely settle the claim has been lacking. The new study suggests that newborn neurons made in the hippocampus — an important learning and memory center in the brain — are beneficial, at least in aiding recovery after traumatic brain injuries. “It’s clear they are doing something, and that that something aids recovery,” says Jack Parent, a neurologist and neuroscientist at the University of Michigan Medical Center. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 15: Language and Our Divided Brain
Link ID: 15155 - Posted: 03.31.2011

By Tina Hesman Saey Rubbernecking neurons don’t do an injured brain any good. Newborn neurons rush to the scene of the damage but don’t pitch in to help heal the wound, a new study shows. Scientists have had great hopes that new neurons produced in the brain after a stroke or other insult could migrate to the wounded area and replace damaged cells. Previous research has shown that the newborns are attracted to injury sites, but a new study that appears in the April 22 Journal of Neuroscience shows that those neurons don’t form replacements for the majority of cells. The results indicate that simply boosting neuron production may not help heal the brain. Zhengang Yang of Fudan University in Shanghai and colleagues induced strokes in a part of rats’ brains called the striatum, which controls movement, and marked new neurons so the cells could be traced as they migrated through the brain. The researchers examined the cells for certain proteins that are hallmarks of different neuron types, to see which kind of neuron the cells differentiated into. Previous research has shown that new neurons are born in the adult brain in two places — the hippocampus and the subventricular zone, or SVZ. Neurons born in the SVZ usually migrate to the olfactory bulb. But after a stroke, some of the new SVZ neurons flock to the wound site. Yang and his colleagues show in the new study that the new SVZ neurons don’t form medium-sized spiny neurons, the type of cell most common in the striatum. Only neurons producing calretinin and Sp8, two markers of olfactory bulb neurons, migrate into the wounded striatum. There, the neurons form the same type that they would in the olfactory bulb, if they survive at all. © Society for Science & the Public 2000 - 2009

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 15: Language and Our Divided Brain
Link ID: 12787 - Posted: 06.24.2010

Electrodes inserted into certain parts of the brain — in a technique known as deep brain stimulation — can stimulate the growth of new neurons that are used in memory formation, according to research in mice. The findings show that artificially created neurons can be fully functional — a topic of hot debate in the neuroscience community. Knowing that the cells are functional, rather than just useless growths, is a boost for those seeking to use the treatment against Alzheimer's disease and other memory-degeneration disorders. "I'm hoping to help people who have difficulty remembering things," says Scellig Stone, a neurosurgery resident and PhD candidate at the University of Toronto. One of Stone's supervisors, Paul Frankland of the Hospital for Sick Children in Toronto, presented the results at the annual meeting of the Canadian Association for Neuroscience in Vancouver, Canada, on 25 May. In his study, Stone electrically stimulated part of the limbic system in the brains of mice for an hour. Rodent brains normally produce thousands of new neurons a day; by 3–5 days after the procedure, the electrical stimulation had doubled that. During this time of high neuron growth, the team injected the mice with iododeoxyuridine to label the newly formed cells. Six weeks after the stimulation, the mice were trained to find a platform hidden underwater in a swimming tank. Once the researchers were convinced the mice had learned the task, they examined their brains, looking for a protein called Fos. Fos is produced only by active cells, and takes around 90 minutes to form, so the team could time their examination to pinpoint neurons that had been used explicitly in the memory task. They found that the new neurons had the same level of Fos and were therefore just as active as other, older neurons. "These new neurons aren't just sitting around doing nothing," says Stone. © 2009 Nature Publishing Group,

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 14: Attention and Consciousness
Link ID: 12898 - Posted: 06.24.2010

Helen Thomson Adult human brain cells can generate new tissue when implanted into in the brains of mice, new research reveals. The findings could pave the way to new therapies for a host of neurodegenerative diseases, including Alzheimer’s, the researchers say. Furthermore, lab tests show that the mature brain cells have the versatility to divide many times in culture and develop into a wide range of specialised cell types. Researchers at the University of Florida, US, showed for the first time that common human brain cells are adaptable and self-renewing – qualities normally associated with stem cells. Dennis Steindler and his colleagues transplanted adult human brain cells into mice and found that they could successfully generate new neurons and incorporate themselves in a variety of brain regions. The researchers also coaxed a single adult brain cell to divide into millions of new cells in culture. “We can, theoretically, take a single brain cell out of a human being and generate enough brain cells to replace every cell of the donor’s brain,” says Steindler. The new source of human brain cells could be used to repair or replace damaged tissue in degenerative disorders such as Alzheimer’s and Parkinson’s disease, the researchers suggest. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 9240 - Posted: 06.24.2010

by Dan Ferber For a father to truly bond with his children, he needs to grow some new gray matter. At least that seems to be the case in mice. A new study shows that when a mouse father nuzzles his pups, he develops new neurons that help him remember—and protect—those offspring later in life. The results suggest that in mice, and perhaps in humans, young babies and dads bond biologically in ways that can last a lifetime. A few years ago, neuroscientist Samuel Weiss of the University of Calgary in Canada discovered that female mice grow new neurons when they smell pheromones from dominant male mice. The neurons appear in two key structures of the brain: the olfactory bulb and the hippocampus, which together coordinate the memory of odors. That helps the females identify and mate with the dominant males, thereby giving their offspring better odds at survival. Weiss wondered if bonding with their pups would cause similar changes in the brains of new mouse fathers, altering their behavior toward their offspring in ways that might give the pups better odds of success in life. To find out, Weiss and one of his graduate students, Gloria Mak, let mouse couples cohabit in a cage, mate, and produce pups. They removed some of the fathers to another cage as soon as the pups were born, let others hang around for a couple of days and nuzzle with mom and baby, and let a third group hang around, watching and sniffing—but not nuzzling—from outside of a mesh tent. Then the researchers removed all of the dads and reunited them with their sons 6 weeks later when they were fully grown. (They avoided testing daughters because father mice tend to mate with them, making the study hard to interpret.) Dads who did not attack their sons and who spent a significant amount of time nuzzling them were seen as recognizing their offspring. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 14058 - Posted: 06.24.2010

By Nikhil Swaminathan For the first time, researchers have developed a way to view stem cells in the brains of living animals, including humans—a finding that allows scientists to follow the process neurogenesis (the birth of neurons). The discovery comes just months after scientists confirmed that such cells are generated in adult as well as developing brains. "I was looking for a method that would enable us to study these cells through[out a] life span," says Mirjana Maletic-Savatic, an assistant professor of neurology at Stony Brook University in New York State, who specializes in neurological disorders such as cerebral palsy that premature and low-weight babies are at greater risk of developing. She says the new technique will enable her to track children at risk by monitoring the quantity and behavior of these so-called progenitor cells in their brains. The key ingredient in this process is a substance unique to immature cells that is neither found in mature neurons nor in glia, the brain's nonneuronal support cells. Maletic-Savatic and her colleagues collected samples of each of the three cell types from rat brains (stem cells from embryonic animals, the others from adults) and cultured the varieties separately in the lab. They were able to determine the chemical makeup of each variety—and isolate the compound unique to stem cells—with nuclear magnetic resonance (NMR) spectroscopy. (NMR helps to determine a molecule's structure by measuring the magnetic properties of its subatomic particles.) © 1996-2007 Scientific American, Inc.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 10957 - Posted: 06.24.2010

By GRETCHEN REYNOLDS The Morris water maze is the rodent equivalent of an I.Q. test: mice are placed in a tank filled with water dyed an opaque color. Beneath a small area of the surface is a platform, which the mice can’t see. Despite what you’ve heard about rodents and sinking ships, mice hate water; those that blunder upon the platform climb onto it immediately. Scientists have long agreed that a mouse’s spatial memory can be inferred by how quickly the animal finds its way in subsequent dunkings. A “smart” mouse remembers the platform and swims right to it. In the late 1990s, one group of mice at the Salk Institute for Biological Studies, near San Diego, blew away the others in the Morris maze. The difference between the smart mice and those that floundered? Exercise. The brainy mice had running wheels in their cages, and the others didn’t. Scientists have suspected for decades that exercise, particularly regular aerobic exercise, can affect the brain. But they could only speculate as to how. Now an expanding body of research shows that exercise can improve the performance of the brain by boosting memory and cognitive processing speed. Exercise can, in fact, create a stronger, faster brain. This theory emerged from those mouse studies at the Salk Institute. After conducting maze tests, the neuroscientist Fred H. Gage and his colleagues examined brain samples from the mice. Conventional wisdom had long held that animal (and human) brains weren’t malleable: after a brief window early in life, the brain could no longer grow or renew itself. The supply of neurons — the brain cells that enable us to think — was believed to be fixed almost from birth. As the cells died through aging, mental function declined. The damage couldn’t be staved off or repaired. Copyright 2007 The New York Times Company

Related chapters from BP7e: 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: 10621 - Posted: 06.24.2010

by Jonah Lehrer Posted February 23, 2006 12:37 AM Elizabeth Gould overturned one of the central tenets of neuroscience. Now she’s building on her discovery to show that poverty and stress may not just be symptoms of society, but bound to our anatomy. Professor Elizabeth Gould has a picture of a marmoset on her computer screen. Marmosets are a new world monkey, and Gould has a large colony living just down the hall. Although her primate population is barely three years old, Gould is clearly smitten, showing off these photographs like a proud parent. Marmosets are the ideal experimental animal: a primate brain trapped inside the body of a rat. They recognize themselves in the mirror, form elaborate dominance hierarchies and raise their young cooperatively. If you can look past their rodent-like stature and punkish pompadour, marmosets can seem disconcertingly human. In her laboratory at Princeton University’s Department of Psychology, Gould is determined to create a marmoset environment that takes full advantage of their innate intelligence. She doesn’t believe in metal cages. “We are housing our marmosets in large, enriched enclosures,” she says, “and with a variety of objects to support foraging. These are social animals, and it’s important to let them be social. Basically, we want to bring our experimental conditions closer to the wild.” © Copyright 2006 Seed Media Group, LLC.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 8590 - Posted: 06.24.2010

by Steven Schultz Recent studies from the lab of neuroscientist Elizabeth Gould are helping to show how major experiences -- such as early-life traumas -- can have a long-term effect on the structure of the brain. In one study published last year, researchers in Gould’s lab found that baby rats that were separated from a care-giving adult for several hours a day formed fewer new neurons in their brains later in life. Another study showed that adult rats that grew up normally produced elevated numbers of new neurons if they achieved social dominance in a small community of rats. “These are different examples of how life experience changes the brain,” said Gould, a professor of psychology at Princeton. Until the last decade, scientists did not believe that the brain changes that Gould and colleagues study were even possible. The conventional view in neuroscience was that once animals, including humans, reach adulthood, they acquire no new neurons, or nerve cells. Gould is a pioneer in showing that several important areas of the brain continue to create neurons throughout life, a process called adult neurogenesis. In recent years, Gould has investigated factors that influence the rate of adult neurogenesis and the roles played by the new brain cells. © 2005 The Trustees of Princeton University

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 14: Attention and Consciousness
Link ID: 7014 - Posted: 06.24.2010

Like a double-edged sword, radiation therapy for brain cancer wipes out tumors but sometimes causes cognitive decline as well. Now researchers have found that, in rat brains, the treatment prevents new neurons from growing. Further findings suggest that dampening the brain's inflammatory response to radiation therapy may help avert such damage. To destroy brain tumors, neurosurgeons give patients a strong dose of radiation that’s supposed to kill the fastest growing cells--those in the tumor--while leaving slow-growing neurons alone. Years later, however, patients cured of brain cancer often lose their ability to make new memories. Researchers suspected that radiation therapy damages the stem cells that give rise to new neurons, which are concentrated in the hippocampus, a brain region necessary for storing memories. Copyright © 2002 by the American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 2417 - Posted: 06.24.2010

A new study finds that neural stem cells may be able to save dying brain cells without transforming into new brain tissue, at least in rodents. Researchers from the University of California, Irvine, report that stem cells rejuvenated the learning and memory abilities of mice engineered to lose neurons in a way that simulated the aftermath of Alzheimer's disease, stroke and other brain injuries. Researchers expect stem cells to transform into replacement tissue capable of replacing damaged cells. But in this case, the undifferentiated stem cells, harvested from 14-day-old mouse brains, did not simply replace neurons that had died off. Rather, the group speculates that the transplanted cells secreted protective neurotrophins, proteins that promote cell survival by keeping neurons from inducing apoptosis (programmed cell death). Instead, the once ill-fated neurons strengthened their interconnections and kept functioning. "The primary implication here is that stem cells can help rescue memory deficits that are due to cell loss," says Frank LaFerla, a professor of neurobiology and behavior at U.C. Irvine and the senior author on a new study published in The Journal of Neuroscience. If the therapeutic benefit was indeed solely due to a neurotrophic factor, the door could be opened to using that protein alone as a drug to restore learning ability. LaFerla's team genetically engineered mice to lose cells in their hippocampus, a region in the forebrain important for short-term memory formation. These mice were about twice as likely than unaltered rodents to fail a test of their ability to discern whether an object in a cage had been moved since their previous visit. © 1996-2007 Scientific American, Inc.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 15: Language and Our Divided Brain
Link ID: 10920 - Posted: 06.24.2010

Recent research has revealed that brains continue to produce new neurons throughout life, helping create new neural networks. This neurogenesis only takes place in a few specific areas, such as the area in which the brain and spinal column meet. The new cells, however, can migrate throughout the brain and turn up as far away as the olfactory bulb--a cluster of nerve cells at the front surface of the brain responsible for the sense of smell. A recent study in mice has revealed that these neurons make the long and complicated journey by going with the flow of spinal fluid circulating in the brain. Neurologist Kazunobu Sawamoto at Keio University in Japan and an international team of his colleagues used fluorescent dye and India ink to trace the flow of spinal fluid in mice and found that it followed the whiplike waving of hairlike projections known as cilia from cells lining the route. They then tracked neurons as they migrated from region to region of the brain and found that new neurons oriented in the direction of fluid flow rather than the direction of their ultimate destination in the olfactory bulb. © 1996-2006 Scientific American, Inc.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 8389 - Posted: 06.24.2010

Scientists have found a link between neurons generated during adulthood and those that fall victim to diseases such as Alzheimer's. According to a new report, both types of brain cells have strangely low levels of a protein known as UCHL1. The discovery that new neurons can arise in adult brains--a feat first observed in songbirds--overturned the long-held belief that a vertebrate's complete supply of neurons is created at birth or soon thereafter. In the new work, Fernando Nottebohm of Rockefeller University and his colleagues investigated how latecomer neurons differ from lifelong ones. The researchers injected two types of dye into the brains of 19 songbirds and collected samples from both types of neurons, which are used in two different pathways in the brain. After analyzing genetic information from more than 3,000 cells from each animal, the team determined that one gene (UCHL1) showed remarkably low activity in the newer, or "replaceable neurons": the longstanding ones exhibited 2.5 times the amount of the UCHL1 protein. "Low levels of UCHL1 appear to be a feature of replaceable neurons wherever they occur," says study co-author Anthony Lombardino of Rockefeller University. Work with mice confirmed the correlation between low levels of UCHL1 and replaceable neurons. Finally, the scientists investigated whether levels of UCHL1 change when the animals sing--an activity that had previously been shown to increase the odds of survival for newly generated neurons. After the male birds sang to a female, the levels of UCHL1 in their replaceable neurons had increased. "These findings suggest that rising levels of UCHL1 may be associated with a reduced risk of neuronal death," Nottebohm explains. The results, published online this week by the Proceedings of the National Academy of Sciences, complement other studies that had linked deficiencies in UCHL1 to degenerative diseases such as Alzheimer's and Parkinson's disease. --Sarah Graham © 1996-2005 Scientific American, Inc

Related chapters from BP7e: 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: 7394 - Posted: 06.24.2010

Helen Pilcher Assertiveness really is all in the mind. Dominant rats have more new nerve cells in a key brain region than their subordinates, a study reveals. The finding hints that social hierarchies can influence brain structure, and raises questions over the use of standard animal behaviour tests in laboratory research. Yevgenia Kozorovitskiy and Elizabeth Gould from Princeton University, New Jersey, studied the brains of around 40 rats that had been left to form social hierarchies in a semi-natural setting. Their results are published in The Journal of Neuroscience1. In each experiment, four males and two females were placed inside a large box comprising an underground tangle of burrows and chambers and a feeding area above. Within three days, the males had established their preferred pecking order: an aggressive leader who attracted the females and three defensive subordinates. © 2004 Nature Publishing Group

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 5953 - Posted: 06.24.2010