Links for Keyword: Glia

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Everything we do — all of our movements, thoughts and feelings – are the result of neurons talking with one another, and recent studies have suggested that some of the conversations might not be all that private. Brain cells known as astrocytes may be listening in on, or even participating in, some of those discussions. But a new mouse study suggests that astrocytes might only be tuning in part of the time — specifically, when the neurons get really excited about something. This research, published in Neuron, was supported by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health. For a long time, researchers thought that the star-shaped astrocytes (the name comes from the Greek word for star) were simply support cells for the neurons. It turns out that these cells have a number of important jobs, including providing nutrients and signaling molecules to neurons, regulating blood flow, and removing brain chemicals called neurotransmitters from the synapse. The synapse is the point of information transfer between two neurons. At this connection point, neurotransmitters are released from one neuron to affect the electrical properties of the other. Long arms of astrocytes are located next to synapses, where they can keep tabs on the conversations going on between neurons. In recent years, it has been shown that astrocytes may also play a role in neuronal communication. When neurons release neurotransmitters, levels of calcium change within astrocytes. Calcium is critical for many processes, including release of molecules from the cell, and activation of a host of proteins within the cell. The role of this astrocytic calcium signaling for brain function remains a mystery.

Related chapters from BP7e: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 19505 - Posted: 04.17.2014

R. Douglas Fields The Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative announced by US President Barack Obama in April seeks to map and monitor the function of neural connections in the entire brains of experimental animals, and eventually in the human cerebral cortex. Several researchers have raised doubts about the project, cautioning that mapping the brain is a much more complex endeavour than mapping the human genome, and its usefulness more uncertain. I believe that exploring neural networks and developing techniques with which to do so are important goals that should be vigorously supported. But simply scaling up current efforts to chart neural connections is unlikely to deliver the promised benefits — which include understanding perception, consciousness, how the brain produces memories, and the development of treatments for diseases such as epilepsy, depression and schizophrenia1. A major stumbling block is the project's failure to consider that although the human brain contains roughly 100 billion neurons, it contains billions more non-electrical brain cells called glia2. These reside outside the neuronal 'connectome' and operate beyond the reach of tools designed to probe electrical signalling in neurons. Dismissed as connective tissue when they were first described in the mid-1800s, glia have long been neglected in the quest to understand neuronal signalling. Research is revealing that glia can sense neuronal activity and control it3. Various studies also indicate that glia operate in diverse mental processes, for instance, in the formation of memories. They have a central role in brain injury and disease, and they are even at the root of various disorders — such as schizophrenia and Alzheimer's — previously presumed to be exclusively neuronal. That the word 'glia' was not uttered in any of the announcements of the BRAIN Initiative, nor written anywhere in the 'white papers' published in 2012 and 2013 in prominent journals outlining the ambitious plan1, 4, speaks volumes about the need for the community of neuroscientists behind the initiative to expand its thinking. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 18610 - Posted: 09.05.2013

By Andrea Anderson In spring a band of brainy rodents made headlines for zipping through mazes and mastering memory tricks. Scientists credited the impressive intellectual feats to human cells transplanted into their brains shortly after birth. But the increased mental muster did not come from neurons, the lanky nerve cells that swap electrical signals and stimulate muscles. The mice benefited from human stem cells called glial progenitors, immature cells poised to become astrocytes and other glia cells, the supposed support cells of the brain. Astrocytes are known for mopping up excess neuro-transmitters and maintaining balance in brain systems. During the past couple of decades, however, researchers started suspecting astrocytes of making more complex cognitive contributions. In the 1990s the cells got caught using calcium to accomplish a form of nonelectrical signaling. Studies since then have revealed how extensively astrocytes interact with neurons, even coordinating their activity in some cases. Perhaps even more intriguing, our astrocytes are enormous compared with the astrocytes of other animals—20 times larger than rodent astrocytes—and they make contact with millions of neurons apiece. Neurons, on the other hand, are nearly identical in all mammals, from rodents to great apes like us. Such clues suggest astrocytes could be evolutionary contributors to our outsized intellect. The new study, published in March in Cell Stem Cell, tested this hypothesis. A subset of the implanted human stem cells matured into rotund, humanlike astrocytes in the animals' brains, taking over operations from the native mouse astrocytes. When tested under a microscope, these human astrocytes accomplished calcium signaling at least three times faster than the mouse astrocytes did. The enhanced mice masterfully memorized new objects, swiftly learned to link certain sounds or situations to an unpleasant foot shock, and displayed unusually savvy maze navigation—signs of mental acuity that surpassed skills exhibited by either typical mice or mice transplanted with glial progenitor cells from their own species. © 2013 Scientific American

Related chapters from BP7e: Chapter 17: Learning and Memory; 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: 18455 - Posted: 08.05.2013

By Ben Thomas Your neurons are outnumbered. Many of the cells in your brain – in your whole nervous system, in fact – are not neurons, but glia. These busy little cells shape and insulate neural connections, provide vital nutrients for your neurons, regulate many of the automatic processes that keep you alive, and even enable your brain to learn and form memories. The latest research is revealing that glia are far more active and mysterious than we’d ever suspected. But their journey into the spotlight hasn’t been an easy one. Unlike neurons, which earned their starring roles in neuroscience as soon as researchers demonstrated what they did, neuroglia didn’t get much respect until more than a century after their discovery. The man who first noted the existence of glia – a French physician named Rene Dutrochet – didn’t even bother to give them a name when he noticed them in 1824; he just described them as “globules” that adhered between nerve fibers. In 1856, when the German anatomist Rudolf Virchow examined these “globules” in more detail, he figured they must be some sort of neural adhesive, which he named neuroglia – “nerve glue” in Greek. As publicity campaigns go, it wasn’t the most promising start. Even worse, as other biologists investigated neuroglia over the next few decades, they started jumping to a variety of conclusions – not all of them accurate. For example, since glia appeared not to have axons – the long connective fibers that carry signals from one neuron to the next – most researchers assumed these cells must act as structural support; essentially serving as a stage on which neurons, the real stars of the show, could play their roles. Some even wondered if glia might not be nerve cells at all, but specially adapted skin cells instead. Though a few scientists did argue that glia also seemed to be crucial for neuron nutrition and healing, it was rare for anyone even to speculate that these cells might actually be involved in neural communication. © 2013 Scientific American

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 18305 - Posted: 06.25.2013

By Tina Hesman Saey Cells that sheathe the brain’s electrical wires in a protective coating called myelin have a brief career, a new study of zebrafish finds. Specialized brain cells known as oligodendrocytes wrap myelin around axons, long fibers that carry electrical messages between nerve cells. After only five hours, the cells bow out of the myelin production business, researchers from the University of Edinburgh report in the June 24 Developmental Cell. Myelination is crucial for brain function, and when it breaks down, so does communication among brain cells. The new results could influence treatment strategies for diseases such as multiple sclerosis, which damages myelin. Instead of coaxing existing cells to replenish myelin, doctors may need to stimulate new oligodendrocyte growth in patients’ nervous systems. In the new study, researchers made time-lapse movies of neural development in zebrafish by tagging electricity-generating neurons and myelin-making oligodendrocytes in the fishes’ spinal cords with different colors. A protein called Fyn kinase stimulates oligodendrocytes to produce more myelin sheaths for the first five hours of the cells’ existence, but the protein can’t persuade the cells to postpone retirement, the researchers discovered. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 13: Memory, Learning, and Development
Link ID: 18304 - Posted: 06.25.2013

By John McCarthy Into brains of newborn mice, researchers implanted human “progenitor cells.” These mature into a type of brain cell called astrocytes (see below). They grew into human astrocytes, crowding out mouse astrocytes. The mouse brains became chimeras of human and mouse, with the workhorse mouse brain cells – neurons – nurtured by billions of human astrocytes. Neuroscience is only beginning to discover what astrocytes do in brains. One job that is known is that they help neurons build connections (synapses) with other neurons. (Firing neurotransmitter molecules across synapses is how neurons communicate.) Human astrocytes are larger and more complex than those of other mammals. Humans’ unique brain capabilities may depend on this complexity. Human astrocytes certainly inspired the mice. Their neurons did indeed build stronger synapses. (Perhaps this was because human astrocytes signal three times faster than mouse astrocytes do.) Mouse learning sharpened, too. On the first try, for instance, altered mice perceived the connection between a noise and an electric shock (a standard learning test in mouse research). Normal mice need a few repetitions to get the idea. Memories of the doctored mice were better too: they remembered mazes, object locations, and the shock lessons longer. The reciprocal pulsing of billions of human and mouse brain cells inside a mouse skull is a little creepy. Imagine one of these hybrid mice exploring your living room. Would you feel like a Stone Age tribesman observing a toy robot? Does the thing think? © 2013 Scientific American

Related chapters from BP7e: Chapter 17: Learning and Memory; 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: 18139 - Posted: 05.11.2013

by Moheb Costandi Mice transplanted with a once-discounted class of human brain cells have better memories and learning abilities than normal counterparts, according to a new study. Far from a way to engineer smarter rodents, the work suggests that human brain evolution involved a major upgrade to cells called astrocytes. Astrocytes are one of several types of glia, the other cells found alongside neurons in the nervous system. Although long thought to merely provide support and nourishment for neurons, it's now clear that astrocytes are vital for proper brain function. They are produced during development from stem cells called glial progenitors. In 2009, Steven Goldman of the University of Rochester Medical Center in New York and his colleagues reported that human astrocytes are bigger, and have about 10 times as many fingerlike projections that contact other brain cells and blood vessels, than those of mice. To further investigate these differences, they have more recently grafted fluorescently labeled human glial progenitors into the brains of newborn mice and examined the animals when they reached adulthood. Most of the grafted cells remained as progenitors, but some matured into typical human-looking astrocytes. They connected to their mouse counterparts to form astrocyte networks that transmitted electrical signals. Furthermore, they propagated internal signals about three times faster than the mouse astrocytes and improved the strengthening of connections between neurons in the hippocampus, a process thought to be critical for learning and memory. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 17: Learning and Memory; 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: 17883 - Posted: 03.09.2013

By Meghan Rosen Zombies aren’t the only things that feast on brains. Immune cells called microglia gorge on neural stem cells in developing rat and monkey brains, researchers report in the March 6 Journal of Neuroscience. Chewing up neuron-spawning stem cells could help control brain size by pruning away excess growth. Scientists have previously linked abnormal human brain size to autism and schizophrenia. “It shows microglia are very important in the developing brain,” says neuroscientist Joseph Mathew Antony of the University of Toronto, who was not involved in the research. Scientists have long known that in adult brains, microglia hunt for injured cells as well as pathogens. “They mop up all the dead and dying cells,” Antony says. And when the scavengers find a dangerous intruder, they pounce. “These guys are relentless,” says study coauthor Stephen Noctor, of the University of California, Davis MIND Institute in Sacramento. “They seek and destroy bacteria — it’s really quite amazing.” Microglia also lurk in embryonic brains, but the immune cells’ role there is less well understood. Previous studies had found microglia near neural stem cells — tiny factories that pump out new neurons. When Noctor’s team examined slices of embryonic human, monkey and rodent brains, he was struck by just how many microglia crowded around the stem cells and how closely the two cell types touched. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 17872 - Posted: 03.07.2013

By Ferris Jabr In a 2006, season 2 episode of The Office entitled "Drug Testing," Dwight Schrute interrogates his fellow employees about the partially smoked joint he found in the parking lot. Dwight is determined to identify the culprit, but Jim Halpert turns the tables: Jim: I'm just saying that you can't be sure that it wasn't you. Dwight: That's ridiculous. Of course it wasn't me. Jim: Marijuana is a memory-loss drug, so maybe you just don't remember. Half a joint is unlikely to obliterate entire memories, but studies have shown that regularly smoking marijuana for many years does impair working memorythe ability to temporarily hold information in your head, such as a telephone number or the name of someone you just met. Exactly what marijuana does to the brain to muddle up memory formation has remained unclear. Now, a team of researchers has proposed that marijuana hinders the process not by acting on neurons, but rather by acting on non-neuronal brain cells called astrocytes. The finding adds to a growing heap of evidence that such non-electrical structural cells, collectively known as glia, play a far more active role in neural activity than researchers once realized. Memory depends on a balance of two opposing cellular processes: long-term potentiation, in which connected neurons learn to fire in sync, and long-term depression, the weakening of unnecessary connections among neurons. Xia Zhang of the University of Ottawa Institute of Mental Health Research and his colleagues think that marijuana impairs working memory by throwing off this balance, bolstering long-term depression (LTD) at the expense of long-term potentiation (LTP). Their new study suggests that marijuana increases LTD by triggering a chemical cascade that starts in astrocytes. © 2012 Scientific American,

Related chapters from BP7e: Chapter 17: Learning and Memory; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 16467 - Posted: 03.03.2012

Researchers at the National Institutes of Health have discovered in mice a molecular trigger that initiates myelination, the process by which brain cell networks are reinforced with an insulating material called myelin that speeds their ability to transmit messages. The myelination process is an essential part of brain development. Myelin formation is necessary for brain cells to communicate and it may contribute to development of skills and learning. The researchers showed that an electrical signal passing through a brain cell (neuron) results in the brain cell releasing the molecule glutamate. Glutamate, in turn, triggers another type of brain cell, called an oligodendrocyte, to form a point of contact with the neuron. Signals transmitted through this contact point stimulate the oligodendrocyte to make myelin protein and begin the process of myelination. In this process, the oligodendrocyte wraps myelin around axons— the long, cable-like projections that extend from each neuron. The myelination process is analogous to wrapping electrical tape around bare wires. Myelin formation Electrical signals transmitted from one neuron to the next are a basic form of communication in the brain. The myelin layers that oligodendrocytes wrap around neurons boost these signals so that they travel 50 times faster than before. The study was conducted by Hiroaki Wake, Philip R. Lee, and R. Douglas Fields.

Related chapters from BP7e: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 15667 - Posted: 08.11.2011

By Laura Sanders Nerve cell communication gets better with use. A neuron’s electrical activity triggers other cells to come and slather on a protective coating that makes messages travel faster, a study published online August 4 in Science shows. Like rubber insulation around electrical wires, myelin wraps around message-sending axons, protecting and speeding electrical impulses. Specialized brain cells called oligodendrocytes wrap up to 150 layers of this insulation around a single axon. In this image, a single oligodendrocyte (green) wraps several axons (purple). The process begins when neurons fire off an electrical signal and the chemical messenger glutamate is released. Mouse neurons treated so they were unable to release glutamate had lower levels of myelin, Hiroaki Wake of the National Institute of Child Health and Human Development in Bethesda, Md., and colleagues found. When the team activated normal axons, boosting their glutamate production, oligodendrocytes produced more of the fatty proteins that make up the myelin coating. The results suggest one way that the brain quickly adapts and improves when a person practices new tasks such as playing the violin or juggling. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 13: Memory, Learning, and Development
Link ID: 15651 - Posted: 08.08.2011

An NIH researcher has captured video images of a previously unknown form of communication between brain cells that might hold clues to the way learning shapes the brain. The videos, offered as a resource for educators teaching high school, undergraduate and graduate students, are available on the Web from Science Signaling. These newly recorded signals are emitted along the length of nerve fibers. Earlier research has documented the transmission of signals across the synapse — a gap between individual nerve cells, known as neurons. The new videos show that when neurons communicate, electrical signals emitted along the length of neurons stimulates nearby brain cells known as glia, or glial cells. As a result, the glial cells begin making a substance called myelin, which coats the nerve fibers and allows electrical charges to travel with greater speed through the brain's networks. Other studies have shown that the process of myelination underlies learning and is crucial for the development of new skills. The teaching resource on the Science Signaling website features short video clips that document these previously unknown non-synaptic signals. "For the last 100 years researchers have studied how information traverses the brain, crossing synapses and traveling from one nerve cell to the next," said Dr. Fields. "We can now see another type of communication, in which cells along a neuron’s length can sense the chemical signals the neuron releases."

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 14924 - Posted: 01.29.2011

by Jocelyn Kaiser Tumors are notoriously hard to kill. Attack them with chemotherapy, and they develop drug resistance; surgically remove them, and they may have already metastasized to other parts of the body. Now scientists have found that tumors have yet another trick up their sleeve: They can create their own blood supply by morphing into blood vessels. The observations, reported by two separate teams online today in Nature, could explain why drugs designed to choke off blood to brain tumors often fail. The researchers drew the link between tumor cells and blood vessel cells with a series of experiments on glioblastomas—fast-growing brain tumors that contain tufts of thin, abnormal blood vessels. Neurosurgeon and stem cell scientist Viviane Tabar and colleagues at Memorial Sloan-Kettering Cancer Center in New York City first took glioma samples from the operating room and looked for chromosomal abnormalities in the endothelial cells lining the tumor's blood vessels. They found patterns exactly like those in cells from the tumor itself, suggesting that at least some of the blood vessel cells came from the tumor. The researchers then sorted glioma cells into different types using antibodies that stick to specific proteins on a cell's surface. They showed that the cells that give rise to blood vessels are an immature cancer cell, known as a stemlike cancer cell. Finally, the researchers injected these cancer stem cells into the brains of mice with weakened immune systems and then examined the blood vessels within the resulting tumors. The vessels stained positive for antibodies to human endothelial cells, again showing that some of the cells had to come from the tumor. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 14696 - Posted: 11.22.2010

Kerri Smith Halfway through a satellite meeting at the Federation of European Neurosciences conference in Amsterdam in July, researcher Ken McCarthy takes the stage to give his presentation. He sports a black shirt and jeans, and his strong cheekbones, shock of white hair and tanned skin give him the look of a film star. But he doesn't have the confidence to match. I find this a little bit daunting, he says, as he organizes his slides. McCarthy, a geneticist at the University of North Carolina School of Medicine in Chapel Hill, is about to fan the flames of a debate about whether glia, the largest contingent of non-neuronal cells in the brain, are important in transmitting electrical messages. For many years, neurons were thought to be alone in executing this task, and glia were consigned to a supporting role regulating a neuron's environment, helping it to grow, and even providing physical scaffolding (glia is Greek for 'glue'). In the past couple of decades, however, this picture has been changing. Some glia, known as astrocytes, have thousands of bushy tendrils that nestle close to the active junctions between neurons the synapses (see 'Neural threesome'). Here they seem to listen in on neuronal activity and, in turn, to influence it. Studies show that chemical transmitters released by neurons cause an increase in the levels of calcium inside astrocytes, spurring them to release transmitters of their own. These can enhance or mute the signalling between neurons, or influence the strength of their connections over time. Moreover, astrocytes activated at one synapse might communicate with other synapses and astrocytes with which they make contact. © 2010 Nature Publishing Group,

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 14649 - Posted: 11.11.2010

Miriam Frankel A type of brain cell thought to be responsible for supporting other cells may have a previously unsuspected role in controlling breathing. Star-shaped cells called astrocytes, found in the brain and spinal cord, can 'sense' changes in the concentration of carbon dioxide in the blood and stimulate neurons to regulate respiration, according to a study published online in Science today1. The research may shed some light on the role of astrocytes in certain respiratory illnesses, such as cot death, which are not well understood. Astrocytes are a type of glial cell — the most common type of brain cell, and far more abundant than neurons. "Historically, glial cells were only thought to 'glue' the brain together, providing neuronal structure and nutritional support but not more," explains physiologist Alexander Gourine of University College London, one of the authors of the study. "This old dogma is now changing dramatically; a few recent studies have shown that astrocytes can actually help neurons to process information." "The most important aspect of this study is that it will significantly change ideas about how breathing is controlled," says David Attwell, a neuroscientist at University College London, who was not involved in the study. During exercise, the amount of CO2 in the blood increases, making the blood more acidic. Until now, it was thought that this pH change was 'sensed' by specialized neurons that signal to the lungs to expel more CO2. But the study found that astrocytes can sense such a decrease in pH too — a change that causes an increase in the concentration of calcium ions (Ca2+) in the cells and the release of the chemical messenger adenosine-5'-triphosphate (ATP). © 2010 Nature Publishing Group,

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 14264 - Posted: 07.17.2010

by Roberta Friedman Research presented here is beginning to reveal the molecular signals that guide the assembly of the brain, and that perhaps can be tapped into for making repairs. The glial cells that most neuroscientists have regarded as merely support cells in fact take an active role in building a brain. A primitive type of glial cell serves as the stem cells that actually generate the brain's neurons. Even in adults, these glial cells can form new neurons, scientists are finding. Evidence presented in a symposium supports the idea that the radial glial cells are actually the stem cells that give rise to neurons, and are not just directing their migration passively. Magdalena Götz and colleagues at the Max-Plank Institute of Neurobiology find that a transcription factor, Pax6, is used in the radial glial cells that are forming neurons. © Elsevier Science Limited 2000

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 1050 - Posted: 06.24.2010

By Victoria Stern The deadliest and most common type of brain cancer has a strange bedfellow: cytomegalovirus, a kind of herpes present in about 80 percent of the U.S. population. Now scientists are exploiting this coincidence to treat the cancer with a vaccine that targets the virus and slows tumor regrowth. In 2002 scientists showed that cytomegalovirus, or CMV, was active in the brain tumors but not the surrounding healthy tissue of all 27 patients they tested who had glioblastoma multiforme. CMV is dormant and undetectable in most people. Neuroscientist Duane Mitchell of Duke University Medical Center and his colleagues confirmed in 2007 that CMV is active in at least 90 percent of glioblastoma tumors. Now Mitchell’s team has developed an experimental vaccine that triggers the immune system to attack CMV, thereby attacking its tumor tissue home. As reported at the American Society of Clinical Oncology meeting in June, the vaccine, together with radiation and chemotherapy, prevented the brain tumor from reemerging after surgery for 12 months as compared with the typical six to seven months with no vaccine. Patients’ average life span increased from 14 months to more than 20. So does this herpes virus cause cancer? The answer is unclear: tumor cells may simply be a fertile ground for growing the virus, as cells such as these often lack the normal immune functions that suppress CMV reproduction. But University of Wisconsin–Madison researchers reported in May that the virus has the ability to take over a cell’s braking mechanism and cause uncontrolled reproduction. Even so, the numbers do not seem to add up: four of five Americans has CMV, but only about one in 30,000 ends up with glioblastoma. And a small number of glioblastoma patients do not have CMV in their tumors. © 1996-2008 Scientific American Inc.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 11777 - Posted: 06.24.2010

Roxanne Khamsi The brains and spinal cords of male mice contain more of the protective, fatty substance called myelin, which insulates nerve cells, than their female counterparts, new research reveals. The finding could help to explain why some neurological diseases, including multiple sclerosis, strike one sex more than another. Robert Skoff of the Wayne State University School of Medicine in Detroit, US, and colleagues found an unexpected difference when they compared the composition of white matter in the brains of male and female mice. White matter consists of nerve cells coated with insulating myelin, which helps the cells to relay signals efficiently. Skoff’s team determined the density of oligodendrocytes – cells which produce myelin – in the male and female mouse central nervous system by testing for their molecular signature. They found that these specialised cells are roughly one-third more dense within the brains and spinal cords of male rodents. They add that the differences are present in young and old mice, and independent of strain and species. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 8471 - Posted: 06.24.2010

WEST LAFAYETTE, Ind. – Purdue University researchers have shown that extremely thin carbon fibers called "nanotubes" might be used to create brain probes and implants to study and treat neurological damage and disorders. Probes made of silicon currently are used to study brain function and disease but may one day be used to apply electrical signals that restore damaged areas of the brain. A major drawback to these probes, however, is that they cause the body to produce scar tissue that eventually accumulates and prevents the devices from making good electrical contact with brain cells called neurons, said Thomas Webster, an assistant professor of biomedical engineering. New findings showed that the nanotubes not only caused less scar tissue but also stimulated neurons to grow 60 percent more fingerlike extensions, called neurites, which are needed to regenerate brain activity in damaged regions, Webster said.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 4771 - Posted: 06.24.2010

By Carolyn Y. Johnson They have long been dismissed as the brain’s Bubble Wrap, packing material to protect precious cells that do the real work of the mind. But glial cells — the name literally means “glue’’ — are now being radically recast as neuroscientists explore the role they play in disease and challenge longstanding notions about how the brain works. More than a century ago, scientists proposed the “neuron doctrine,’’ a theory that individual brain cells called neurons are the main players in the nervous system. It became an underpinning of modern neuroscience and led to major advances in understanding the brain, but it has become increasingly apparent that the other 85 percent of brain cells, glia, do more than just housekeeping. “In a play in a theater, it’s not just the actors on the stage, but the whole ensemble that is critical for that production to be perfect,’’ said Philip Haydon, chairman of the neuroscience department at Tufts University School of Medicine. “The players on the stage are neurons, but if you don’t have every person backstage, you don’t have a production, and what we’re now realizing is this whole support cast [of glia] is essential for normal brain function.’’ Haydon became curious about glia nearly two decades ago as an unintentional consequence of an experiment. He killed neurons in a dish of brain cells and left the glia, expecting to see the chemical signals that neurons use to communicate with one another disappear. To his surprise, the signals did not stop — suggesting the glia were not passive. © 2010 NY Times Co

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 13: Memory, Learning, and Development
Link ID: 14124 - Posted: 06.24.2010