Links for Keyword: Neurogenesis

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Neurogenesis in the central nervous system can be the start of something huge By Ricki Lewis The brain and spinal cord were once considered mitotic dead ends, a division of neurons dwindling with toddlerhood, with memory and learning the consequence of synaptic plasticity, not new neurons. But the discovery of neural stem cells (NSCs) in the human adult central nervous system (CNS) has raised the possibility of reawakening neurogenesis in the adult to treat neurodegenerative diseases, such as Parkinson, Alzheimer, and Huntington diseases, and spinal cord injuries. "Does the human CNS self-repair? Of course it does! We live 90 years. It is unreasonable to think that there is no turnover, like in every other organ," says Fred Gage, of Salk Institute for Biological Studies, La Jolla, Calif., who led the team that discovered neural stem cells in the human brain in 1998. "Can we turn endogenous cells into neurons in a disease setting? Can we activate our own systems? We are beginning to unravel cell fates and choices, to distinguish intrinsic properties of cells versus local environment cues. For cells, it is not who you are, but where you are, that counts." ©2003, The Scientist 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: 3963 - Posted: 06.24.2010

By Mark K. Anderson Until recently, prevailing scientific wisdom held that the human brain is closer to a game of hearts than one of gin rummy. As a young adult, your skull contains all the brain cells you'll ever have. No new cards are dealt, and from there on in, all that can be done is discard. Yet, since the late 1990s, a spate of scientific research has begun to establish that adults do generate new brain cells in some regions of the brain, well into old age. And now, for the first time, scientists have seen that new neurons become functional members of the brain, forging new connections and firing "action potentials" like any other neuron. © Copyright 2002, Lycos, Inc. All Rights Reserved.

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: 1610 - Posted: 06.24.2010

Debate fires stoked again with recent findings By Hal Cohen In his most recent paper,1 Pasko Rakic , chairman of the neurobiology department at Yale University, has rekindled a debate over whether neurogenesis occurs in the neocortex of the normal adult primate. This 'he-said, she-said' battle began in 1985, when Rakic published a study of rhesus monkeys2 and stated unambiguously that neurons were not born in any animal's brain after infancy. Contradicting Rakic's findings in 1998 was neuroscientist Elizabeth Gould, Princeton University, who used a new labeling technique to show that the adult marmoset brain generated neurons.3 The following year she published findings that some neurons were made in the neocortex, which is home to higher cognitive functions such as language and complex thought in primates.4 Rakic looked for new neurons in adult macaque monkeys by labeling neuronal and glial cells with bromodeoxyuridine (BrdU). He found newly generated neurons, which were limited to the hippocampus and olfactory bulb; some BrdU cells were found in the neocortex but were identified to be non-neuronal. The Scientist 16[1]:28, Jan. 7, 2002 © Copyright 2002, The Scientist, Inc. All rights reserved.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 1: An Introduction to Brain and Behavior
Link ID: 1266 - Posted: 06.24.2010

For the first time, investigators have identified a way to detect neural progenitor cells (NPCs), which can develop into neurons and other nervous system cells, in the living human brain using a type of imaging called magnetic resonance spectroscopy (MRS). The finding, supported by the National Institutes of Health (NIH), may lead to improved diagnosis and treatment for depression, Parkinson's disease, brain tumors, and a host of other disorders. Research has shown that, in select brain regions, NPCs persist into adulthood and may give rise to new neurons. Studies have suggested that the development of new neurons from NPCs, called neurogenesis, is disrupted in disorders ranging from depression and schizophrenia to Parkinson's disease, epilepsy, and cancer. Until now, however, there has been no way to monitor neurogenesis in the living human brain. "The recent finding that neural progenitor cells exist in adult human brain has opened a whole new field in neuroscience. The ability to track these cells in living people would be a major breakthrough in understanding brain development in children and continued maturation of the adult brain. It could also be a very useful tool for research aimed at influencing NPCs to restore or maintain brain health," says Walter J. Koroshetz, M.D., deputy director of the NIH's National Institute of Neurological Disorders and Stroke (NINDS), which helped fund the work. The study was also funded by the NIH's National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

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: 10950 - Posted: 11.09.2007

Experience in the early development of new neurons in specific brain regions affects their survival and activity in the adult brain, new research shows. How these new neurons store information about these experiences may explain how they can affect learning and memory in adults. A team of researchers headed by Fred Gage, PhD, of the Salk Institute, found that experience enhances the survival of new neurons in a brain area called the dentate gyrus, and that more of these new neurons were activated when exposed to the same experience later. This change in function may be a mechanism for long-term memory. The findings are published in the March 21 issue of The Journal of Neuroscience. "The results identify a critical period for experience-induced enhancement of new neuron survival in the hippocampus," says Elizabeth Gould, PhD, of Princeton University, who was not affiliated with the study. The hippocampus contains the dentate gyrus. After injecting mice with a chemical used to mark proliferating cells, the researchers exposed the animals to an "enriched cage" environment, containing tunnels, shelters, and a running wheel. After several weeks, the researchers again exposed the mice in the same enriched experience. They discovered that the enriched experience increased new neuron survival and that more new neurons were activated by re-exposure to the same environment. To determine if the increase in neuronal activity was due to having the same experience or if any new experience was sufficient to achieve this effect, the researchers exposed mice to the enriched cage first and then a water maze task. While both cases promoted new neuron survival, more new neurons were activated in mice that had repeated the same experience but not in those that were exposed to the different experience (the water maze).

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: 10124 - Posted: 03.23.2007

Researchers have discovered a type of brain cell that continuously regenerates in humans. A pool of "resting cells" migrate to create new nerve cells in the part of the brain which deals with smell. The system has been shown in mice and rats but it was believed it did not exist in the human brain. Experts said the findings, published in Science, opened up the potential for research into repairing brains in conditions such as Alzheimer's disease. The researchers from the University of Auckland, New Zealand and the Sahlgrenska Academy in Sweden showed stem cells rest in certain areas of the brain, just beneath large fluid-filled chambers called ventricles. But then they needed to work out how they got to the right part of the brain. In many species, it was known that a tube filled with brain fluid enabled these cells to travel to the olfactory bulb - the region of the brain that registers smells - turning into nerve cells as they went. But until now, this system had not been shown in humans. Using several techniques, including a powerful electron microscope, the team identified the tube, and showed it contained stem cells as well as cells which were gradually turning into nerve cells as they travelled along. The researchers said the addition of new nerve cells in the olfactory bulb in humans helped the system respond to different stimuli throughout a person's life. Experts said the findings could be important for future research into brain cell repair in patients with neurodegenerative diseases such as Alzheimer's disease and, importantly, that studies in mice would be applicable to humans. (C)BBC

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: 9986 - Posted: 02.18.2007

In mammals, the production of new brain cells occurs primarily at the time the nervous system is developing, although certain brain areas generate neurons throughout adulthood. One such area is the hippocampus, a part of the brain involved in the critical function of memory and spatial perception. Hippocampal cells, specifically dentate granule cells, are continuously produced in adults as well as in young animals. How these "adult-born" cells build their connections with the rest of the brain, and the extent to which they resemble "pup-born" cells, is of great interest to those who would like to coax other parts of adult brains to make new cells as a strategy for reversing the loss of function from trauma or degenerative disorders. To find out whether adult-born hippocampal neurons have different properties than mature neurons that arose when the brain was developing, Diego Laplagne, Alejandro Schinder, and colleagues compared how each type of neuron incorporated functionally into brain circuits. The researchers' first task was to figure out a way to distinguish between pup-born and adult-born neurons in brain tissue that contained both. To accomplish that task, they used retroviruses to introduce one kind of fluorescent protein into the developing neurons and a second protein into the adult mouse brain. As a result of this treatment, the pup-born cells fluoresced green and the adult-born cells fluoresced red, making them readily distinguishable in brain slices. Once they could tell the two types of cells apart, the researchers gained insight into the connections formed. They looked at glutamatergic (excitatory) nerves connecting the hippocampus with the entorhinal cortex, another brain area associated with memory. When they stimulated the excitatory inputs carrying information from the neocortex to the hippocampus, the researchers evoked similar responses in both pup-born and adult-born neurons.

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: 9648 - Posted: 11.21.2006

Recent evidence suggesting that antidepressants may act by triggering the birth of new neurons in the adult hippocampus, the brain's memory hub, has heightened interest in such adult neurogenesis and raised the question: Could new neurons also be sprouting up in the parts of the adult brain involved in the thinking and mood disturbances of depression and anxiety? Now, scientists at the National Institute of Health's (NIH) National Institute of Mental Health (NIMH) have found newly born neurons that communicate via the chemical messenger GABA (gamma-aminobutyric acid) in adult rat cortex, seat of higher order "executive" functions, and in the striatum, site of habits, reward and motor skill learning. In the cortex, the new neurons appear to arise from previously unknown precursor cells native to the area, rather than from cells migrating in from another area. NIMH's Drs. Heather Cameron, Alexandre Dayer, and colleagues, report on their findings in the January 31, 2005 Journal of Cell Biology. Their discovery adds to the scientific debate over adult neurogenesis, which has potential implications for understanding a variety of brain disorders, possibly including Alzheimer's and schizophrenia. While most researchers agree that new neurons are generated in the adult hippocampus and olfactory bulb, the existence of adult neurogenesis in other brain regions remains controversial.

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: 6809 - Posted: 02.04.2005

Scientists have known for some time that some social insects undergo dramatic behavioral changes as they mature, and now a research team has found that the brains of a wasp species correspondingly enlarge as the creatures engage in more complex tasks. "The amount of change is striking," said Sean O'Donnell, a University of Washington associate professor of psychology and lead author of a new study published in the February issue of Neuroscience Letters. "It is easily apparent with magnification." O'Donnell said the changes take place in sections of the brain called the mushroom bodies. There is one mushroom body on top of each hemisphere of the wasp brain and the structures have a superficial resemblance to the cerebrum in humans and other vertebrates, he said. The enlargement was centered in a part of the mushroom body called the calyx where neural connections are made. O'Donnell and other researchers study social insects such as wasps, honeybees and ants as models to understand the role of neuroplasticity in driving complex social behaviors such as the division of labor.

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: 5142 - Posted: 03.16.2004

New nerve cells put fall foraging on fast track The "senior moments" that herald old age, and the ability to forget where we put something we held in our hands just moments ago, give us humans much cause to envy a species like the black-capped chickadee. Especially when fall is right around the corner. Every autumn, the chickadee roams a territory covering tens of square miles, gathering seeds and storing them in hundreds of hiding places in trees and on the ground. Over the harsh winter that follows, the tireless songbird, which weighs about 12 grams and fits inside the typical human hand, faithfully re-visits its caches to feed.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 10: Biological Rhythms and Sleep
Link ID: 4251 - Posted: 09.12.2003

By NICHOLAS WADE Yale and Princeton are scrapping over an issue less simple than football but probably of greater consequence, how the human brain works. A quarter-century ago, work by Pasko Rakic, a leading neuroanatomist at Yale, indicated that no new neurons were formed in the adult brain. That doctrine is still regarded as generally true, with two exceptions. New neurons have been detected in two specialized organs of the mammalian brain: the olfactory bulb, which handles the sense of smell, and the hippocampus, where new memories of faces and places are formed. Two years ago, Dr. Elizabeth Gould of Princeton published a challenge to Dr. Rakic's doctrine, reporting that she had found newborn neurons in the adult cortex, the region for most higher mental functions. The finding is of great interest, if true, for clinical reasons ? if the brain can make new neurons, it can perhaps also repair itself better than supposed ? and because the generation of new neurons could be central to the operation of memory. Copyright 2001 The New York Times Company

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: 1142 - Posted: 12.09.2001

Hippocampus plasticity surprises researchers By Leslie Pray For decades, biologists believed that brain cells didn't regenerate. But over the past several years, researchers from a handful of laboratories across the country, including Elizabeth Gould's lab at Princeton University, proved this opinion to be wrong. Indeed, up to 5,000 new cells are generated in the hippocampus every day, says Tracey Shors, behavioral neuroscientist and associate professor at Rutgers University, and a coauthor on this Hot Paper. The hippocampus, or hippocampal formation, is a region of the mammalian forebrain involved with memory and learning. For Shors and Gould, it was a logical next step to ask whether this new cell growth in the hippocampus was connected with hippocampus-dependent learning. What they discovered was both expected and surprising: Since the hippocampus is the neurological seat of learning, it made sense that the new cell growth was affected, but researchers didn't expect the evidence to be so strong. The Scientist 15[24]:28, Dec. 10, 2001 © Copyright 2001, The Scientist, Inc. All rights reserved.

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: 1135 - Posted: 12.08.2001

Nerve cells can break memories, as well as make them. HELEN PEARSON Might the brains of Alzheimer's patients be unable to erase old memories? New brain cells may be needed to erase old memories, suggest US neuroscientists. Implanting stem cells to treat brain disorders might disrupt the brain's memory circuits. Mice engineered to lack a protein called presenilin-1 hang on to memories that others forget, Joe Tsien of Princeton University, New Jersey, and his colleagues have found1. Presenilin-1 is mutated in the majority of early-onset Alzheimer's disease patients. The mutant mice make fewer nerve cells in the hippocampus, an area of the brain associated with learning and memory. New cells might disrupt the connections between memory circuits, ousting outdated memories to make room for new ones, suggests Tsien. * Feng, R. et al. Deficient neuroegenesis in forebrain-specific presinilin-1 knockout mice is associated with reduced clearance of hippocampal memory traces. Neuron, 32, 911 - 926, (2001). * Shors, T.J. Neurogenesis in the adult is involved in the formation of trace memories. Nature, 410, 372 - 376, (2001). © Nature News Service / Macmillan Magazines Ltd 2001

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: 1125 - Posted: 12.07.2001

Neuroscientists have not found any evidence that adult primates are able to create new neurons in the most sophisticated part of the brain, the neocortex, according to the results of a study published in the Dec. 7 issue of the journal Science. The results from scientists at Yale University and the University of Rochester run counter to a widely publicized report two years ago when other researchers reported the first discovery of neurogenesis ? formation of new neurons ? in the neocortex of adult monkeys. The new findings, in a study funded by the National Institutes of Health, come from David Kornack, assistant professor of neurobiology and anatomy at the University of Rochester, and his former adviser, neuroscience pioneer Pasko Rakic of Yale. ?As a neuroscientist, oftentimes the first question I?m asked when I meet someone is, ?How can I get more brain cells?? I?m as interested in the question as everyone else,? says Kornack. ?It?s now apparent that although some parts of the primate brain do acquire new neurons in adulthood, the neocortex is not among these regions.?

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: 1115 - Posted: 12.06.2001