Links for Keyword: Glia

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By Diana Kwon Microglia, the immune cells of the brain, have long been the underdogs of the glia world, passed over for other, flashier cousins, such as astrocytes. Although microglia are best known for being the brain’s primary defenders, scientists now realize that they play a role in the developing brain and may also be implicated in developmental and neurodegenerative disorders. The change in attitude is clear, as evidenced by the buzz around this topic at this year’s Society for Neuroscience (SfN) conference, which took place from October 17 to 21 in Chicago, where scientists discussed their role in both health and disease. Activated in the diseased brain, microglia find injured neurons and strip away the synapses, the connections between them. These cells make up around 10 percent of all the cells in the brain and appear during early development. For decades scientists focused on them as immune cells and thought that they were quiet and passive in the absence of an outside invader. That all changed in 2005, when experimenters found that microglia were actually the fastest-moving structures in a healthy adult brain. Later discoveries revealed that their branches were reaching out to surrounding neurons and contacting synapses. These findings suggested that these cellular scavengers were involved in functions beyond disease. The discovery that microglia were active in the healthy brain jump-started the exploration into their underlying mechanisms: Why do these cells hang around synapses? And what are they doing? © 2015 Scientific American

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 21566 - Posted: 10.26.2015

Astrocytes help speed up brain’s messages

Laura Sanders A type of brain cell formerly known for its supporting role has landed a glamorous new job. Astrocytes, a type of glial cell known to feed, clean and guide the growth of their flashier nerve cell neighbors, also help nerve cells send electrical transmissions, scientists report in the Aug. 5 Journal of Neuroscience. The results are the latest in scientists’ efforts to uncover the mysterious and important ways in which cells other than nerve cells keep the nervous system humming. Astrocytes deliver nutrients to nerve cells, flush waste out of the brain (SN: 9/22/12) and even help control appetite (SN: 6/28/14). The latest study suggests that these star-shaped cells also help electrical messages move along certain nerve cells’ message-sending axons, a job already attributed to other glial cells called oligodendrocytes and Schwann cells. Courtney Sobieski of Washington University School of Medicine in St. Louis and colleagues grew individual rat nerve cells in a single dish that contained patches of astrocytes. Some nerve cells grew on the patches; others did not. The nerve cells deprived of astrocyte contact showed signs of sluggishness. The researchers think that astrocytes guide nerve cell growth in a way that enables the nerve cells to later fire off quick and precise messages. It’s not clear how the astrocytes do that, but the results suggest that proximity is the key: Astrocytes needed to be close to the nerve cell to help messages move. © Society for Science & the Public 2000 - 2015

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 4: Development of the Brain; Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 21264 - Posted: 08.05.2015

‘Brainbow’ illuminates cellular connections

By Ashley Yeager The image is made using Brainbow, a technique developed in 2007 that inserts genes for fluorescent proteins into animals. When activated, the proteins illuminate some cells in a range of colors. While most researchers use Brainbow to visualize connections between nerve cells in the brain, Alain Chédotal of the Institut de la Vision in Paris and colleagues customized the technique to trace networks of cells called oligodendrocytes. These cells wrap a material called myelin, the biological equivalent of electrical insulation, around long strands of nerve cells that transmit electrical signals in the brain and throughout the body. How oligodendrocytes work together to wrap nerve fibers in myelin becomes evident in Brainbow photos of the roughly 3-millimeter-long optic nerve, the team reports in the April Glia. The myelin shields the precious link between brain and eyes. Studying interactions among oligodendrocytes as well as the cells’ reactions to various drugs may lead to improved therapies for multiple sclerosis, a disease caused by the destruction of myelin. Citations L. Dumas et al. Multicolor analysis of oligodendrocyte morphology, interactions, and development with Brainbow. Glia. Vol. 63, April 2015, p. 699. doi: 10.1002/glia.22779 © Society for Science & the Public 2000 - 2015.

MIT Student Filmed His Own Brain Surgery

By Dialynn Dwyer @dia_dwyer Warning: The above video contains graphic images. Steven Keating says he fought his cancer with curiosity. The MIT doctoral student was diagnosed in the summer of 2014 with a baseball-sized brain tumor, and during his treatment he gathered his health data in order to understand the science behind what his body was going through. He even filmed his ten hour brain surgery. And though his surgery was performed and filmed last summer, it gained attention recently when Vox wrote about Keating and his surgery. Through his experience, Keating became passionate about more transparent health records. “Healthcare should be a two-way road, patients alongside doctors and researchers as a team,” he says on his website. “The future will be driven by networked healthcare, support communities, and I believe patient curiosity. I do believe learning, understanding, and access can heal.” Keating has given public talks about his experience, and he has shared all his findings, including the condensed video of his surgery, through his website for anyone to study.

Related chapters from BN: Chapter 1: Introduction: Scope and Outlook
Related chapters from MM:Chapter 20:
Link ID: 20884 - Posted: 05.05.2015

Thoughts Can Fuel Some Deadly Brain Cancers

Jon Hamilton The simple act of thinking can accelerate the growth of many brain tumors. That's the conclusion of a paper in Cell published Thursday that showed how activity in the cerebral cortex affected high-grade gliomas, which represent about 80 percent of all malignant brain tumors in people. "This tumor is utilizing the core function of the brain, thinking, to promote its own growth," says Michelle Monje, a researcher and neurologist at Stanford who is the paper's senior author. In theory, doctors could slow the growth of these tumors by using sedatives or other drugs to reduce mental activity, Monje says. But that's not a viable option because it wouldn't eliminate the tumor and "we don't want to stop people with brain tumors from thinking or learning or being active." Even so, the discovery suggests other ways to slow down some of the most difficult brain tumors, says Tracy Batchelor, who directs the neuro-oncology program at Massachusetts General Hospital and was not involved in the research. "We really don't have any curative treatments for high-grade gliomas," Batchelor says. The discovery of a link between tumor growth and brain activity "has opened up a window into potential therapeutic interventions," he says. The discovery came from a team of scientists who studied human glioma tumors implanted in mouse brains. The scientists used a technique called optogenetics, which uses light to control brain cells, to increase the activity of cells near the tumors. © 2015 NPR

Human brain's ultimate barrier to open for first time

by Helen Thomson KULLERVO HYNYNEN is preparing to cross neuroscience's final frontier. In July he will work with a team of doctors in the first attempt to open the blood-brain barrier in humans – the protective layer around blood vessels that shields our most precious organ against threats from the outside world. If successful, the method would be a huge step in the treatment of pernicious brain diseases such as cancer, Parkinson's and Alzheimer's, by allowing drugs to pass into the brain. The blood-brain barrier (BBB) keeps toxins in the bloodstream away from the brain. It consists of a tightly packed layer of endothelial cells that wrap around every blood vessel throughout the brain. It prevents viruses, bacteria and any other toxins passing into the brain, while simultaneously ushering in vital molecules such as glucose via specialised transport mechanisms. The downside of this is that the BBB also completely blocks the vast majority of drugs. Exceptions include some classes of fat and lipid-soluble chemicals, but these aren't much help as such drugs penetrate every cell in the body – resulting in major side effects. "Opening the barrier is really of huge importance. It is probably the major limitation for innovative drug development for neurosciences," says Bart De Strooper, co-director of the Leuven Institute for Neuroscience and Disease in Belgium. © Copyright Reed Business Information Ltd.

Insulating sheath on nerve cells isn't an even coat

by Ashley Yeager A nerve cell's long, slender tentacle isn’t evenly coated with an insulating sheath as scientists had thought. Instead, many nerve cells in the brains of mice have stretches of these tentacles, called axons, that are naked, researchers report April 18 in Science. The unsheathed feeler can be as long as 80 micrometers. Nerve cells can also have specific patterns in the gaps of the insulating layer, called myelin. The differences in the thickness of that coating may control how fast signals travel between nerve cells, the scientists suggest. The finding could have implications for understanding nerve-based diseases, such as multiple sclerosis, and improve scientists’ understanding of how signals are transmitted in the brain. © Society for Science & the Public 2000 - 2013.

Eavesdropping on brain cell chatter

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 BN: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 19505 - Posted: 04.17.2014

Neuroscience: Map the other brain

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 BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 18610 - Posted: 09.05.2013

Human Cells Make Mice Smarter

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 BN: Chapter 17: Learning and Memory; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 18455 - Posted: 08.05.2013

A Secret Society of Cells Runs Your Brain

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

Brain cell insulators are short-timers

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 BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System; Chapter 4: Development of the Brain
Link ID: 18304 - Posted: 06.25.2013

Human Brain Cells Alive in Mouse Brains

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

Human Brain Cells Boost Mouse Memory

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.

Immune cells chow down on living brain

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

Structured Unlearning: Marijuana May Impair Memory via the Brain's Non-Firing Cells

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 BN: Chapter 17: Learning and Memory; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 16467 - Posted: 03.03.2012

Brain electrical activity spurs insulation of brain’s wiring

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.

How exercise benefits nerve cells

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

New videos show NIH studies of communication between brain cells

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."

Brain Tumors Grow Their Own Blood Supply

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.

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