Chapter 2. Cells and Structures: The Anatomy of the Nervous System
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Ian Sample Science editor High-strength cannabis may damage nerve fibres that handle the flow of messages across the two halves of the brain, scientists claim. Brain scans of people who regularly smoked strong skunk-like cannabis revealed subtle differences in the white matter that connects the left and right hemispheres and carries signals from one side of the brain to the other. The changes were not seen in those who never used cannabis or smoked only the less potent forms of the drug, the researchers found. The study is thought to be the first to look at the effects of cannabis potency on brain structure, and suggests that greater use of skunk may cause more damage to the corpus callosum, making communications across the brain’s hemispheres less efficient. Paola Dazzan, a neurobiologist at the Institute of Psychiatry at King’s College London, said the effects appeared to be linked to the level of active ingredient, tetrahydrocannabinol (THC), in cannabis. While traditional forms of cannabis contain 2 to 4 % THC, the more potent varieties (of which there are about 100), can contain 10 to 14% THC, according to the DrugScope charity. “If you look at the corpus callosum, what we’re seeing is a significant difference in the white matter between those who use high potency cannabis and those who never use the drug, or use the low-potency drug,” said Dazzan. The corpus callosum is rich in cannabinoid receptors, on which the THC chemical acts. © 2015 Guardian News and Media Limited
Sara Reardon Suicide is a puzzle. Fewer than 10% of people with depression attempt suicide, and about 10% of those who kill themselves were never diagnosed with any mental-health condition. Now, a study is trying to determine what happens in the brain when a person attempts suicide, and what sets such people apart. The results could help researchers to understand whether suicide is driven by certain brain biology — and is not just a symptom of a recognized mental disorder. The project, which launched this month, will recruit 50 people who have attempted suicide in the two weeks before enrolling in the study. Carlos Zarate, a psychiatrist at the US National Institute of Mental Health in Bethesda, Maryland, and his colleagues will compare these people's brain structure and function to that of 40 people who attempted suicide more than a year ago, 40 people with depression or anxiety who have never attempted suicide and a control group of 40 healthy people. In doing so, the researchers hope to elucidate the brain mechanisms associated with the impulse to kill oneself. Zarate's team will also give ketamine, a psychoactive ‘party drug’, to the group that has recently attempted suicide. Ketamine, which is sometimes used to treat depression, can quickly arrest suicidal thoughts and behaviour — even in cases when it does not affect other symptoms of depression1. The effect is known to last for about a week. © 2015 Nature Publishing Group,
Sara Reardon Panzee the chimpanzee was a skilled communicator that could tell untrained humans where to find hidden food by using gestures and vocalizations. Austin the chimp was particularly adept with a computer, and scientists have been scanning its genome for clues to its unusual cognitive abilities. Both apes lived at a language-research centre at Georgia State University in Atlanta, and both died several years ago — but they will live on in an online database of brain scans and behavioural data from nearly 250 chimpanzees. Researchers hope to combine this trove, now in development, with a biobank of chimpanzee brains to enable scientists anywhere in the world to study the animals’ neurobiology. This push to repurpose old data is especially timely now that the US National Institutes of Health (NIH) has decided to retire its remaining research chimpanzees. The agency decommissioned more than 300 animals in 2013, but kept 50 available for research in case of a public-health emergency. Following an 18 November decision, this remaining population will also be sent to sanctuaries in the coming years. The NIH also hopes to retire another 82 chimps that it supports but does not own, says director Francis Collins. “We were on a trajectory toward zero, and today’s the day we’re at zero,” says Jeffrey Kahn, a bioethicist at Johns Hopkins University in Baltimore, Maryland, who led a 2011 study on the NIH chimp colony for the Institute of Medicine. © 2015 Nature Publishing Group
Jon Hamilton A look at the brain's wiring can often reveal whether a person has trouble staying focused, and even whether they have attention deficit hyperactivity disorder, known as ADHD. A team led by researchers at Yale University reports that they were able to identify many children and adolescents with ADHD by studying data on the strength of certain connections in their brains. "There's an intrinsic signature," says Monica Rosenberg, a graduate student and lead author of the study in Nature Neuroscience. But the approach isn't ready for use as a diagnostic tool yet, she says. The finding adds to the evidence that people with ADHD have a true brain disorder, not just a behavioral problem, says Mark Mahone, director of neuropsychology at the Kennedy Krieger institute in Baltimore. "There are measurable ways that their brains are different," he says. The latest finding came from an effort to learn more about brain connections associated with attention. Initially, the Yale team used functional MRI, a form of magnetic resonance imaging, to monitor the brains of 25 typical people while they did something really boring. Their task was to watch a screen that showed black-and-white images of cities or mountains and press a button only when they saw a city. © 2015 npr
Jon Hamilton Patterns of gene expression in human and mouse brains suggest that cells known as glial cells may have helped us evolve brains that can acquire language and solve complex problems. Scientists have been dissecting human brains for centuries. But nobody can explain precisely what allows people to use language, solve problems or tell jokes, says Ed Lein, an investigator at the Allen Institute for Brain Science in Seattle. "Clearly we have a much bigger behavioral repertoire and cognitive abilities that are not seen in other animals," he says. "But it's really not clear what elements of the brain are responsible for these differences." Research by Lein and others provides a hint though. The difference may involve brain cells known as glial cells, once dismissed as mere support cells for neurons, which send and receive electrical signals in the brain. Lein and a team of researchers made that finding after studying which genes are expressed, or switched on, in different areas of the brain. The effort analyzed the expression of 20,000 genes in 132 structures in brains from six typical people. Usually this sort of study is asking whether there are genetic differences among brains, Lein says. "And we sort of flipped this question on its head and we asked instead, 'What's really common across all individuals and what elements of this seem to be unique to the human brain?' " he says. It turned out the six brains had a lot in common. © 2015
Sarah Schwartz With outposts in nearly every organ and a direct line into the brain stem, the vagus nerve is the nervous system’s superhighway. About 80 percent of its nerve fibers — or four of its five “lanes” — drive information from the body to the brain. Its fifth lane runs in the opposite direction, shuttling signals from the brain throughout the body. Doctors have long exploited the nerve’s influence on the brain to combat epilepsy and depression. Electrical stimulation of the vagus through a surgically implanted device has already been approved by the U.S. Food and Drug Administration as a therapy for patients who don’t get relief from existing treatments. Now, researchers are taking a closer look at the nerve to see if stimulating its fibers can improve treatments for rheumatoid arthritis,heart failure, diabetes and even intractable hiccups. In one recent study, vagus stimulation made damaged hearts beat more regularly and pump blood more efficiently. Researchers are now testing new tools to replace implants with external zappers that stimulate the nerve through the skin. But there’s a lot left to learn. While studies continue to explore its broad potential, much about the vagus remains a mystery. In some cases, it’s not yet clear exactly how the nerve exerts its influence. And researchers are still figuring out where and how to best apply electricity. © Society for Science & the Public 2000 - 2015.
Link ID: 21633 - Posted: 11.14.2015
For the first time, the barrier that protects the brain has been opened without damaging it, to deliver chemotherapy drugs to a tumour. The breakthrough could be used to treat pernicious brain diseases such as cancer, Parkinson’s and Alzheimer’s, by allowing drugs to pass into the brain. The blood-brain barrier 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 the passage of viruses, bacteria and other toxins, while ushering in vital molecules such as glucose via specialised transport mechanisms. The downside of this is that the blood-brain barrier also blocks the vast majority of drugs. There are a few exceptions, but those drugs that are able to sneak through can also penetrate every cell in the body, which makes for major side effects. Now researchers at Sunnybrook Health Sciences Centre in Toronto, Canada, say they have successfully used ultrasound to temporarily open the blood-brain barrier, with the ultimate aim of treating a brain tumour. The procedure took place on 4 November. Ultrasound prises open brain's protective barrier for first time The team, led by neurosurgeon Todd Mainprize and physicist Kullervo Hynynen, injected the chemotherapy drug doxorubicin along with tiny gas-filled microbubbles, into the blood of a patient with a brain tumour. The microbubbles and the drug spread throughout their body, including into the blood vessels that serve the brain. © Copyright Reed Business Information Ltd.
By Simon Makin Optogenetics is probably the biggest buzzword in neuroscience today. It refers to techniques that use genetic modification of cells so they can be manipulated with light. The net result is a switch that can turn brain cells off and on like a bedside lamp. The technique has enabled neuroscientists to achieve previously unimagined feats and two of its inventors—Karl Deisseroth of Stanford University and the Howard Hughes Medical Institute and Ed Boyden of Massachusetts Institute of Technology—received a Breakthrough Prize in the life sciences on November 8 in recognition of their efforts. The technology is able to remotely control motor circuits—one example is having an animal run in circles at the flick of a switch. It can even label and alter memories that form as a mouse explores different environments. These types of studies allow researchers to firmly establish a cause-and-effect relationship between electrical activity in specific neural circuits and various aspects of behavior and cognition, making optogenetics one of the most widely used methods in neuroscience today. As its popularity soars, new tricks are continually added to the optogenetic arsenal. The latest breakthroughs, promise to deliver the biggest step forward for the technology since its inception. Researchers have devised ways of broadening optogenetics to enter into a dynamic dialogue with the signals moving about inside functioning brains. © 2015 Scientific American
Keyword: Brain imaging
Link ID: 21621 - Posted: 11.10.2015
Laura Sanders Blood tells a story about the body it inhabits. As it pumps through vessels, delivering nutrients and oxygen, the ruby red liquid picks up information. Hormones carried by blood can hint at how hungry a person is, or how scared, or how sleepy. Other messages in the blood can warn of heart disease or announce a pregnancy. When it comes to the brain, blood also seems to be more than a traveling storyteller. In some cases, the blood may be writing the script. A well-fed brain is crucial to survival. Blood ebbs and flows within the brain, moving into active areas in response to the brain’s demands for fuel. Now scientists have found clues that blood may have an even more direct and powerful influence. Early experiments suggest that, instead of being at the beck and call of nerve cells, blood can actually control them. This role reversal hints at an underappreciated layer of complexity — a layer that may turn out to be vital to how the brain works. The give-and-take between brain and blood appears to change with age and with illness, researchers are finding. Just as babies aren’t born walking, their developing brain cells have to learn how to call for blood. And a range of age-related disorders, including Alzheimer’s disease, have been linked to dropped calls between blood and brain, a silence that may leave patches of brain unable to do their jobs. © Society for Science & the Public 2000 - 2015
Keyword: Brain imaging
Link ID: 21604 - Posted: 11.05.2015
Alison Abbott Europe’s troubled Human Brain Project (HBP) has secured guarantees of European Commission financing until at least 2019 — but some scientists are still not sure that they want to take part in the mega-project, which has been fraught with controversy since its launch two years ago. On 30 October, the commission signed an agreement formally committing to fund the HBP past April 2016, when its preliminary 30-month ‘ramp-up’ phase ends. The deal also starts a process to change the project’s legal status so as to spread responsibility across many participating institutions. The commission hopes that this agreement will restore lost confidence in the HBP, which aims to better understand the brain using information and computing technologies, primarily through simulation. Last year, hundreds of scientists signed a petition claiming that the project was being mismanaged and was running off its scientific course; they pledged to boycott it if their concerns were ignored. Since then, the HBP has been substantially reformed along lines recommended by a mediation committee. It has dissolved its three-person executive board, which had assumed most of the management power. And it has committed to including studies on cognitive neuroscience (which the triumvirate had wanted to eliminate). It also opened up for general competition some €8.9 million ($US10 million) of cash previously allocated only to project insiders, and in September selected four major projects in systems and cognitive neuroscience proposed by different groups around Europe. © 2015 Nature Publishing Group
Keyword: Brain imaging
Link ID: 21596 - Posted: 11.03.2015
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
By Emily Underwood CHICAGO—In 1898, Italian biologist Camillo Golgi found something odd as he examined slices of brain tissue under his microscope. Weblike lattices, now known as "perineuronal nets," surrounded many neurons, but he could not discern their purpose. Many dismissed the nets as an artifact of Golgi's staining technique; for the next century, they remained largely obscure. Today, here at the annual meeting of the Society for Neuroscience, researchers offered tantalizing new evidence that holes in these nets could be where long-term memories are stored. Scientists now know that perineuronal nets (PNNS) are scaffolds of linked proteins and sugars that resemble cartilage, says neuroscientist Sakina Palida, a graduate student in Roger Tsien's lab at the University of California,San Diego, and co-investigator on the study. Although it's still unclear precisely what the nets do, a growing body of research suggests that PNNs may control the formation and function of synapses, the microscopic junctions between neurons that allow cells to communicate, and that may play a role in learning and memory, Palida says. One of the most pressing questions in neuroscience is how memories—particularly long-term ones—are stored in the brain, given that most of the proteins inside neurons are constantly being replaced, refreshing themselves anywhere from every few days to every few hours. To last a lifetime, Palida says, some scientists believe that memories must somehow be encoded in a persistent, stable molecular structure. Inspired in part by evidence that destroying the nets in some brain regions can reverse deeply ingrained behaviors, Palida’s adviser Tsien, a Nobel-prize-winning chemist, recently began to explore whether PNNs could be that structure. Adding to the evidence were a number of recent studies linking abnormal PNNs to brain disorders including schizophrenia and Costello syndrome, a form of intellectual disability. © 2015 American Association for the Advancement of Science.
Jon Hamilton Babies born prematurely are much more likely than other children to develop autism, ADHD and emotional disorders. Now researchers think they may have an idea about how that could happen. There's evidence that preemies are born with weak connections in some critical brain networks, including those involved in focus, social interactions, and emotional processing, researchers reported at the Society for Neuroscience meeting in Chicago. A study comparing MRI scans of the brains of 58 full-term babies with those of 76 babies born at least 10 weeks early found that "preterm infants indeed have abnormal structural brain connections," says Cynthia Rogers, an assistant professor of psychiatry at Washington University School of Medicine in St. Louis. "We were really interested that the tracts that we know connect areas that are involved in attention and emotional networks were heavily affected," Rogers says. That would make it harder for these brain areas to work together to focus on a goal or read social cues or regulate emotions, she says. The team used two different types of MRI to study the nerve fibers that carry signals from one part of the brain to another and measure how well different areas of the brain are communicating. Full-term infants were scanned shortly after they were born, while premature infants were scanned near their expected due date. The researchers are continuing to monitor the brains of the children in their study to see which ones actually develop disorders. © 2015 NPR
Rachel Ehrenberg Patterns of neural circuitry in the brain's frontal and parietal lobes can be used to distinguish individuals on the basis of their brain scans. Our brains are wired in such distinctive ways that an individual can be identified on the basis of brain-scan images alone, neuroscientists report. In a study published in Nature Neuroscience1 on 12 October, researchers studied scans of brain activity in 126 adults who had been asked to perform various cognitive tasks, such as memory and language tests. The data were gathered by the Human Connectome Project, a US$40-million international effort that aims to map out the highways of neural brain activity in 1200 people. To study connectivity patterns, researchers divided the brain scans into 268 regions or nodes (each about two centimetres cubed and comprising hundreds of millions of neurons). They looked at areas that showed synchronized activity, rather like discerning which instruments are playing together in a 268-piece orchestra, says Emily Finn, a co-author of the study and a neuroscience PhD student at Yale University in New Haven, Connecticut. In some regions of the brain — such as those that involve networks controlling basic vision and motor skills — most people’s neural circuitry connects up in similar ways, the team found. But patterns of connectivity in other brain regions, such as the frontal lobes, seem to differ between individuals. The researchers were able to match the scan of a given individual's brain activity during one imaging session to the same person’s brain scan taken at another time — even when that person was engaged in a different task in each session. © 2015 Nature Publishing Group
Keyword: Brain imaging
Link ID: 21506 - Posted: 10.13.2015
By KENNETH D. MILLER SOME hominid along the evolutionary path to humans was probably the first animal with the cognitive ability to understand that it would someday die. To be human is to cope with this knowledge. Many have been consoled by the religious promise of life beyond this world, but some have been seduced by the hope that they can escape death in this world. Such hopes, from Ponce de León’s quest to find a fountain of youth to the present vogue for cryogenic preservation, inevitably prove false. In recent times it has become appealing to believe that your dead brain might be preserved sufficiently by freezing so that some future civilization could bring your mind back to life. Assuming that no future scientists will reverse death, the hope is that they could analyze your brain’s structure and use this to recreate a functioning mind, whether in engineered living tissue or in a computer with a robotic body. By functioning, I mean thinking, feeling, talking, seeing, hearing, learning, remembering, acting. Your mind would wake up, much as it wakes up after a night’s sleep, with your own memories, feelings and patterns of thought, and continue on into the world. I am a theoretical neuroscientist. I study models of brain circuits, precisely the sort of models that would be needed to try to reconstruct or emulate a functioning brain from a detailed knowledge of its structure. I don’t in principle see any reason that what I’ve described could not someday, in the very far future, be achieved (though it’s an active field of philosophical debate). But to accomplish this, these future scientists would need to know details of staggering complexity about the brain’s structure, details quite likely far beyond what any method today could preserve in a dead brain. © 2015 The New York Times Company
Fragment of rat brain simulated in supercomputer Moheb Costandi A controversial European neuroscience project that aims to simulate the human brain in a supercomputer has published its first major result: a digital imitation of circuitry in a sandgrain-sized chunk of rat brain. The work models some 31,000 virtual brain cells connected by roughly 37 million synapses. The goal of the Blue Brain Project, which launched in 2005 and is led by neurobiologist Henry Markram of the Swiss Federal Institute of Technology in Lausanne (EPFL), is to build a biologically-detailed computer simulation of the brain based on experimental data about neurons' 3D shapes, their electrical properties, and the ion channels and other proteins that different cell types typically produce (see ‘Brain in a box’). Such a simulation would provide deep insights into the way the brain works, says Markram. But other neuroscientists have argued that it will reveal no more about the brain’s workings than do simpler, more abstract simulations of neural circuitry — while sucking up a great deal of computing power and resources. The initiative has links with the Human Brain Project, a €1-billion (US$1.1-billion), decade-long initiative which Markram helped persuade the European Commission to fund, and which also aims to advance supercomputer brain simulation. It launched in 2013, with Markram as co-leader, although this March its leadership was switched and its scientific programme altered, after criticism of the way it was being managed. © 2015 Nature Publishing Group
Keyword: Brain imaging
Link ID: 21494 - Posted: 10.09.2015
By Emily Underwood WASHINGTON, D.C.—As part of President Barack Obama’s high-profile initiative to study the brain, the Kavli Foundation and several university partners today announced $100 million in new funding for neuroscience research, including three new institutes at universities in Maryland, New York, and California. Each of the institutes will receive a $20 million endowment, provided equally by their universities and the foundation, along with start-up funding to pursue projects in areas such as brain plasticity and tool development. The new funding, geared at providing stable support for high-risk, interdisciplinary research, exceeds the original commitment of $40 million that the Kavli Foundation made to the national Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, when it was first launched by President Obama in 2013. The funds are also unrestricted, allowing each institute to determine which projects to pursue. “That’s the most precious money any scientist can have,” Robert Conn, president and CEO of The Kavli Foundation, noted at a meeting today on Capitol Hill. Neuroscientist Loren Frank, who will serve as co-director at the new institute at the University of California, San Francisco, says the funds will allow his lab to explore fundamental questions such as how the brain can maintain its function despite constant change, and to form interdisciplinary partnerships with labs such as the Lawrence Livermore National Laboratory. The other two sites creating new institutes are Johns Hopkins University in Baltimore, Maryland, and Rockefeller University in New York City. In addition, Kavli announced a $40 million boost for four of its existing neuroscience institutes, located at Yale University, UC San Diego, Columbia University, and the Norwegian University of Science and Technology. © 2015 American Association for the Advancement of Science.
Keyword: Brain imaging
Link ID: 21471 - Posted: 10.03.2015
Sara Reardon The brain’s wiring patterns can shed light on a person’s positive and negative traits, researchers report in Nature Neuroscience1. The finding, published on 28 September, is the first from the Human Connectome Project (HCP), an international effort to map active connections between neurons in different parts of the brain. The HCP, which launched in 2010 at a cost of US$40 million, seeks to scan the brain networks, or connectomes, of 1,200 adults. Among its goals is to chart the networks that are active when the brain is idle; these are thought to keep the different parts of the brain connected in case they need to perform a task. In April, a branch of the project led by one of the HCP's co-chairs, biomedical engineer Stephen Smith at the University of Oxford, UK, released a database of resting-state connectomes from about 460 people between 22 and 35 years old. Each brain scan is supplemented by information on approximately 280 traits, such as the person's age, whether they have a history of drug use, their socioeconomic status and personality traits, and their performance on various intelligence tests. Smith and his colleagues ran a massive computer analysis to look at how these traits varied among the volunteers, and how the traits correlated with different brain connectivity patterns. The team was surprised to find a single, stark difference in the way brains were connected. People with more 'positive' variables, such as more education, better physical endurance and above-average performance on memory tests, shared the same patterns. Their brains seemed to be more strongly connected than those of people with 'negative' traits such as smoking, aggressive behaviour or a family history of alcohol abuse. © 2015 Nature Publishing Group,
James Gorman Turning certain brain cells on and off with light — a technique called optogenetics — is one of the most important tools in neuroscience. It allows scientists to test basic ideas about how brains work. But because waves of visible light don’t penetrate living tissue well, the technique requires the insertion of a conduit for the light into the brain— a very thin fiber optic cable. For the first time, researchers say, they have done the same with ultrasound, opening the way to a noninvasive way to probe the functions of neurons. They call the technique sonogenetics. They achieved this in a microscopic worm, a creature so simple that it doesn’t have a brain. But it does have neurons, which have a great deal in common with the neurons in more complex animals that make up the brain and nervous system. If the technique works in more complex animals, it would mean a noninvasive way to do basic research, and perhaps even treat brain circuits. “Previous studies have shown if you use ultrasound, you can manipulate the nervous system,” said Sreekanth H. Chalasani of the Salk Institute in San Diego and senior author of a recent report in Nature Communications that describes the research. But, he said, nobody had shown that, with genetic modifications, specific neurons could be targeted. “It’s going to be a viable technique,” said William Tyler, a neuroscientist at Arizona State University, who said the ability to zero in on one neuron or a group of neurons without having to insert anything into the body was “unparalleled.” © 2015 The New York Times Company
Keyword: Brain imaging
Link ID: 21453 - Posted: 09.28.2015
Ellen Brait in New York Mind reading might not be as far-fetched as many people believe, says a study published by researchers at the University of Washington. Their research, published in PLOS One on Wednesday, demonstrated “that a non-invasive brain-to-brain interface (BBI) can be used to allow one human to guess what is on the mind of another human”. With only the use of brainwaves and a specifically designed computer, they examined the potential for exchanging basic information without saying a word. “We are actually still at the beginning of the field of interface technology and we are just mapping out the landscape so every single step is a step that opens up some new possibilities,” said lead author Andrea Stocco, an assistant professor of psychology and a researcher at UW’s Institute for Learning and Brain Sciences. The experiment had five pairs of men and women between the ages of 19 and 39 play a game similar to 20 questions. Each group had a “respondent”, who picked an object from lists provided, and an “inquirer”, who tried to guess the object by asking yes or no questions. They were placed in different rooms, approximately one mile apart. After a question was picked, it appeared on the respondent’s computer screen. They had two seconds to look at the question and one second to choose an answer. To do so, they looked at one of two flashing lights that were labeled yes or no. Each answer generated slightly different types of neural activity. © 2015 Guardian News and Media Limited