Chapter 2. Functional Neuroanatomy: The Nervous System and Behavior
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
By Emily Underwood Shielded by the skull and packed with fatty tissue, the living brain is perhaps the most difficult organ for scientists to probe. Functional magnetic resonance imaging (fMRI), which noninvasively measures changes in blood flow and oxygen consumption as a proxy for neuronal activation, lags far behind the actual speed of thought. Now, a new technique may provide the fastest yet method of measuring blood flow in the brain, scientists report online today in Nature Methods. The technique, which bounces laser beams off red blood cells, has a resolution of under a millisecond—slightly less time than it takes a neuron to fire—and it has a far higher spatial resolution than fMRI. Even the most powerful fMRI machines, used only on animals, can image only millimeter-wide swaths of tissues including thousands of cells. The new technique, which takes its measurements from sonic waves produced by the beams, can image structures as small as individual blood vessels and cells (see above). Although the technique is not likely to be feasible in humans due to safety concerns, it could provide an important tool to better understand how blood flow and oxygen consumption is related to brain activity. That’s a key question for those relying on cruder and safer tools, such as fMRI, to study the human brain, researchers say. It is also a powerful tool for studying how errant eddies and whorls of blood in blood vessels can sometimes lead to stroke, they say. © 2015 American Association for the Advancement of Science
Keyword: Brain imaging
Link ID: 20735 - Posted: 03.31.2015
Just like the human brain itself, the European Commission’s billion-euro Human Brain Project (HBP) defies easy explanation. Launched 18 months ago, the massive project is complex and, to most observers, confusing. Many people—both scientists and non-scientists—have thus accepted a description of the project that emerged from its leaders and its publicity machine: the aim of simulating the entire human brain in a supercomputer and so find cures for psychiatric and neurological disorders. Like many simplistic explanations of the brain, that characterization of the project provoked a backlash from neuroscientists. This climaxed in a full-scale uprising last summer, when hundreds of researchers signed a critical open letter to the commission (www.neurofuture.eu). Autocratic management, they complained, was running the project off its scientific course and exaggerating its clinical reach. An independent committee was established to investigate and mediate on the dispute. Last week it published its report. This time, the main points were easier for outsiders to decipher. The rebellious neuroscientists who made the complaints were correct. The brain project is failing and must be fixed. The committee’s criticisms endorse more or less all the concerns of the scientists. The project fails not only in its governance, the report says, but also in its scientific plan—particularly the core aim, the simulation of the entire brain that critics had long dismissed as unrealistic. © 2015 Scientific American
Keyword: Brain imaging
Link ID: 20730 - Posted: 03.30.2015
Mo Costandi Two teams of scientists have developed new ways of stimulating neurons with nanoparticles, allowing them to activate brain cells remotely using light or magnetic fields. The new methods are quicker and far less invasive than other hi-tech methods available, so could be more suitable for potential new treatments for human diseases. Researchers have various methods for manipulating brain cell activity, arguably the most powerful being optogenetics, which enables them to switch specific brain cells on or off with unprecedented precision, and simultaneously record their behaviour, using pulses of light. This is very useful for probing neural circuits and behaviour, but involves first creating genetically engineered mice with light-sensitive neurons, and then inserting the optical fibres that deliver light into the brain, so there are major technical and ethical barriers to its use in humans. Nanomedicine could get around this. Francisco Bezanilla of the University of Chicago and his colleagues knew that gold nanoparticles can absorb light and convert it into heat, and several years ago they discovered that infrared light can make neurons fire nervous impulses by heating up their cell membranes. They therefore attached gold nanorods to three different molecules that recognise and bind to proteins in the cell membranes – the scorpion toxin Ts1, which binds to a sodium channel involved in producing nervous impulses, and antibodies that bind the P2X3 and the TRPV1 channels, both found in dorsal root ganglion (DRG) neurons, which transmit touch and pain information up the spinal cord and into the brain. © 2015 Guardian News and Media Limited
Keyword: Brain imaging
Link ID: 20717 - Posted: 03.25.2015
By JENEEN INTERLANDI Nyiregyhaza (pronounced NEAR-re-cha-za) is a medium-size city tucked into the northeastern corner of Hungary, about 60 miles from the Ukrainian border. It has a world-class zoo, several museums and universities and a new Lego Factory. It also has two Roma settlements, or “Gypsy ghettos.” The larger of these settlements is Gusev, a crumbling 19th-century military barracks separated from the city proper by a railway station and a partly defunct industrial zone. Gusev is home to more than 1,000 Roma. Its chief amenities include a small grocery store and a playground equipped with a lone seesaw and a swingless swing set. There’s also a freshly painted elementary school, where approximately 60 students are currently enrolled. Almost all those students are Roma and almost all of them live in Gusev. Officially, most of the schools in Nyiregyhaza are integrated. Roma students have access to the same facilities as non-Roma students, and the ethnic balance of any given facility largely reflects the ethnic balance of the neighborhoods it serves. In practice, things are muddier. While many families in Gusev have been assigned to perfectly reputable schools, there is no busing program, and most schools are not within walking distance. For families living on just 60,000 forints ($205) a month, the schools are also too expensive to reach by public transit. “Everything is fine on paper,” Adel Kegye, an attorney with the Chance for Children Foundation (C.F.C.F.), told me when I visited Hungary this past fall. “But in reality, they make it very hard for the Roma to go anywhere but the settlement school.” ..... In the past two decades, with the advent of f.M.R.I. technology, neuroscientists also began to tackle such questions. Emile Bruneau, a cognitive neuroscientist at the Massachusetts Institute of Technology, has spent the past seven years studying intractable conflicts around the world. © 2015 The New York Times Company
By Martin Enserink The Human Brain Project (HBP) has listened to the critics, the reviewers, and the mediators. At a meeting in Paris, the board of directors of the €1 billion project yesterday approved a series of recommendations for reform, proposed by a mediation committee, which will change both HBP’s governance and its research program. Critics of the troubled project welcome the move. “We are absolutely delighted that the board has adopted these recommendations,” says computational neuroscientist Peter Dayan of University College London, one of the hundreds of researchers who signed an open letter last year calling for a major reorganization of HBP. Dayan was a member of the mediation committee charged with finding a way out of the crisis after the publication of the letter. That panel’s report—a summary of which was released on 10 March—roundly acknowledges that the critics were right. The committee “largely supports and emphasizes the critique voiced by parts of the scientific community regarding objectives, scientific approach, governance and management practices,” the report says. The mediation committee said that HBP, now administered by the Swiss Federal Institute of Technology in Lausanne (EPFL), should be run by a new, international entity. “In a first concrete step towards implementing that vision, the board [of directors] has created a governance working group composed of former or current heads of international scientific organisations,” an HBP press release issued today said. (They include CERN, the European Space Agency, and the European Molecular Biology Laboratory.) © 2015 American Association for the Advancement of Science
Keyword: Brain imaging
Link ID: 20704 - Posted: 03.21.2015
Alison Abbott Mediators appointed to analyse the rifts within Europe’s ambitious €1-billion (US$1.1-billion) Human Brain Project (HBP) have called for far-reaching changes both in its governance and its scientific programmes. Most significantly, the report recommends that systems neuroscience and cognitive neuroscience should be reinstated into the HBP. The mediation committee, led by engineer Wolfgang Marquardt, director of Germany’s national Jülich Research Centre, sent its final report to the HBP board of directors on 9 March, and issued a press release summarizing its findings. (The full report will not be published until after the board, a 22-strong team of scientists, discusses its contents at a meeting on 17–18 March). The European Commission flagship project, which launched in October 2013, is intended to boost supercomputing through neuroscience, with the aim of simulating the brain in a computer. But the project has been racked by dissent from the outset. In early 2014, a three-person committee of scientists who ran the HBP’s scientific direction revealed that they planned to eliminate cognitive neuroscience from the initiative, which precipitated a mass protest. More than 150 of Europe’s leading neuroscientists signed a letter to the European Commission, complaining about the project’s management and charging that the HBP plan to simulate the brain using only ‘bottom-up’ data on the behaviour of neurons was doomed to failure if it did not include the top-down constraints provided by systems and cognitive neuroscience. © 2015 Nature Publishing Group
Keyword: Brain imaging
Link ID: 20670 - Posted: 03.10.2015
In Archaeology it is very rare to find any soft tissue remains: no skin, no flesh, no hair and definitely no brains. However, in 2009, archaeologists from York Archaeological Trust found something very surprising at a site in Heslington, York. During the excavation of an Iron-age landscape at the University of York, a skull, with the jaw and two vertebrae still attached, was discovered face down in a pit, without any evidence of what had happened to the rest of its body. At first it looked like a normal skull but it was not until it was being cleaned, that Collection Projects Officer, Rachel Cubitt, discovered something loose inside. “I peered though the hole at the base of the skull to investigate and to my surprise saw a quantity of bright yellow spongy material. It was unlike anything I had seen before.” says Rachel. Sonia O’Connor, from Archaeological Sciences, University of Bradford, was able to confirm that this was brain. With the help of York Hospital’s Mortuary they were able to remove the top of the skull in order to get their first look at this astonishingly well-preserved human brain. Since the discovery, a team of 34 specialists have been working on this brain to study and conserve it as much as possible. By radiocarbon dating a sample of jaw bone, it was determined that this person probably lived in the 6th Century BC, which makes this brain about 2,600 years old. By looking at the teeth and the shape of the skull it is likely this person was a man between 26 and 45 years old. An examination of the vertebrae in the neck tells us that he was first hit hard on the neck, and then the neck was severed with a small sharp knife, for reasons we can only guess. © Copyright York Archaeological Trust 2013-2015.
Keyword: Brain imaging
Link ID: 20657 - Posted: 03.07.2015
Alison Abbott Europe’s ambitious but contentious €1-billion Human Brain Project (HBP) has announced changes to its organization in a response to criticisms of its management and scientific trajectory by many high-ranking neuroscientists. On 26 February, the HBP's Board of Directors voted narrowly to disband the three-person executive committee that had run the project, which launched in October 2013 and is intended to boost digital technologies such as supercomputing through collaboration with neuroscience. That decision is expected to be endorsed by HBP’s 85 or so partner universities and research institutes by the end of this week. The revamp comes seven months after 150 top neuroscientists signed a protest letter to the European Commission, charging, among other things, that the committee was acting autocratically and running the project's scientific plans off course. Led by the charismatic but divisive figure of Henry Markram, a neuroscientist at the Swiss Federal Institute of Technology in Lausanne (EPFL) which coordinates the HBP, the committee had stirred up anger last spring when it revealed plans to cut cognitive neuroscience from the initiative. The neuroscientists vowed to boycott the HBP's future phases if their concerns were ignored. An independent mediation committee was established to look into the charges and make recommendations. Its report, which is expected to further shake up the HBP's management, will be published in the next few weeks. In the meantime, the three-person committee's responsibilities will be taken on by the HBP's Board of Directors (currently a 22-strong team of scientists that includes the disbanded executive committee, although they do not have voting rights). © 2015 Nature Publishing Group
Keyword: Brain imaging
Link ID: 20651 - Posted: 03.05.2015
By Roni Caryn Rabin When my mother, Pauline, was 70, she lost her sense of balance. She started walking with an odd shuffling gait, taking short steps and barely lifting her feet off the ground. She often took my hand, holding it and squeezing my fingers. Her decline was precipitous. She fell repeatedly. She stopped driving, and she could no longer ride her bike in a straight line along the C&O Canal. The woman who taught me the sidestroke couldn’t even stand in the shallow end of the pool. “I feel like I’m drowning,” she’d say. A retired psychiatrist, my mother had numerous advantages — education, resources and insurance — but, still, getting the right diagnosis took nearly 10 years. Each expert saw the problem through the narrow prism of a single specialty. Surgeons recommended surgery. Neurologists screened for common incurable conditions. The answer was under their noses, in my mother’s hunches and her family history. But it took a long time before someone connected the dots. My mother was using a walker by the time she was told she had a rare condition that causes gait problems and cognitive loss, and is one of the few treatable forms of dementia. The bad news was that it had taken so long to get the diagnosis that some of the damage might not be reversible. “This should be one of the first things physicians look for in an older person,” my mother said recently. “You can actually do something about it.”
Link ID: 20643 - Posted: 03.03.2015
By Christian Jarrett Imagine a politician from your party is in trouble for alleged misdemeanors. He’s been assessed by an expert who says he likely has early-stage Alzheimer’s. If this diagnosis is correct, your politician will have to resign, and he’ll be replaced by a candidate from an opposing party. This was the scenario presented to participants in a new study by Geoffrey Munro and Cynthia Munro. A vital twist was that half of the 106 student participants read a version of the story in which the dementia expert based his diagnosis on detailed cognitive tests; the other half read a version in which he used a structural MRI brain scan. All other story details were matched, such as the expert’s years of experience in the field, and the detail provided for the different techniques he used. Overall, the students found the MRI evidence more convincing than the cognitive tests. For example, 69.8 percent of those given the MRI scenario said the evidence the politician had Alzheimer’s was strong and convincing, whereas only 39.6 percent of students given the cognitive tests scenario said the same. MRI data was also seen to be more objective, valid and reliable. Focusing on just those students in both conditions who showed skepticism, over 15 percent who read the cognitive tests scenario mentioned the unreliability of the evidence; none of the students given the MRI scenario cited this reason. In reality, a diagnosis of probable Alzheimer’s will always be made with cognitive tests, with brain scans used to rule out other explanations for any observed test impairments. The researchers said their results are indicative of naive faith in the trustworthiness of brain imaging data. “When one contrasts the very detailed manuals accompanying cognitive tests to the absences of formalized operational criteria to guide the clinical interpretation of structural brain MRI in diagnosing disease, the perception that brain MRI is somehow immune to problems of reliability becomes even more perplexing,” they said. WIRED.com © 2015 Condé Nast.
By Francis Shen and Dena Gromet Neuroscience is appearing everywhere. And the legal system is taking notice. The past few years have seen the emergence of “neurolaw.” A spread in the NYT Magazine, a best-selling NYT book, a primetime PBS documentary, the first Law and Neuroscience casebook, and a multimillion-dollar investment from the MacArthur Foundation to fund a Research Network on Law and Neuroscience have all fueled interest in how neuroscience might revolutionize the law. The potential implications of neurolaw are broad. For example, future developments in brain science might allow: criminal law to better identify recidivists; tort law to better differentiate between those in real pain and those who are faking; insurance law to more accurately and adequately compensate those with mental illness; and end-of-life law to more ethically treat patients who might be able to communicate only through their thoughts. Increasingly courts, including the U.S. Supreme Court, and legislatures are citing brain evidence. But despite the media coverage, and much enthusiasm from science and legal elites, our new research shows that Americans know very little about neurolaw, and that Republicans and independents may diverge from Democrats in their support for neuroscience based legal reforms. In our study, we conducted an experiment within a national survey of Americans (more details about the survey are in our article). Everyone in the survey was told that, “Recently developed neuroscientific techniques allow researchers to see inside the human brain as never before.”
Sara Reardon Annie is lying down when she answers the phone; she is trying to recover from a rare trip out of the house. Moving around for an extended period leaves the 56-year-old exhausted and with excruciating pain shooting up her back to her shoulders. “It's really awful,” she says. “You never get comfortable.” In 2011, Annie, whose name has been changed at the request of her lawyer, slipped and fell on a wet floor in a restaurant, injuring her back and head. The pain has never eased, and forced her to leave her job in retail. Annie sued the restaurant, which has denied liability, for several hundred thousand dollars to cover medical bills and lost income. To bolster her case that she is in pain and not just malingering, Annie's lawyer suggested that she enlist the services of Millennium Magnetic Technologies (MMT), a Connecticut-based neuroimaging company that has a centre in Birmingham, Alabama, where Annie lives. MMT says that it can detect pain's signature using functional magnetic resonance imaging (fMRI), which measures and maps blood flow in the brain as a proxy for neural activity. The scan is not cheap — about US$4,500 — but Steven Levy, MMT's chief executive, says that it is a worthwhile investment: the company has had ten or so customers since it began offering the service in 2013, and all have settled out of court, he says. If the scans are admitted to Annie's trial, which is expected to take place early this year, it could establish a legal precedent in Alabama. Most personal-injury cases settle out of court, so it is impossible to document how often brain scans for pain are being used in civil law. But the practice seems to be getting more common, at least in the United States, where health care is not covered by the government and personal-injury cases are frequent. Several companies have cropped up, and at least one university has offered the service. © 2015 Nature Publishing Group
By Kate Baggaley Stem cells can help heal long-term brain damage suffered by rats blasted with radiation, researchers report in the Feb. 5 Cell Stem Cell. The treatment allows the brain to rebuild the insulation on its nerve cells so they can start carrying messages again. The researchers directed human stem cells to become a type of brain cell that is destroyed by radiation, a common cancer treatment, then grafted the cells into the brains of irradiated rats. Within a few months, the rats’ performance on learning and memory tests improved. “This technique, translated to humans, could be a major step forward for the treatment of radiation-induced brain … injury,” says Jonathan Glass, a neurologist at Emory University in Atlanta. Steve Goldman, a neurologist at the University of Rochester in New York, agrees that the treatment could repair a lot of the damage caused by radiation. “Radiation therapy … is very effective, but the problem is patients end up with severe disability,” he says. “Fuzzy thinking, a loss in higher intellectual functions, decreases in memory — all those are part and parcel of radiation therapy to the brain.” For children, the damage can be profound. “Those kids have really significant detriments in their adult IQs,” Goldman says. Radiation obliterates cells that mature into oligodendrocytes, a type of cell that coats the message-carrying part of nerve cells with insulation. Without that cover, known as the myelin sheath, nerve cells can’t transmit information, leading to memory and other brain problems. © Society for Science & the Public 2000 - 2015
by Clare Wilson Once only possible in an MRI scanner, vibrating pads and electrode caps could soon help locked-in people communicate on a day-to-day basis YOU wake up in hospital unable to move, to speak, to twitch so much as an eyelid. You hear doctors telling your relatives you are in a vegetative state – unaware of everything around you – and you have no way of letting anyone know this is not the case. Years go by, until one day, you're connected to a machine that allows you to communicate through your brain waves. It only allows yes or no answers, but it makes all the difference – now you can tell your carers if you are thirsty, if you'd like to sit up, even which TV programmes you want to watch. In recent years, breakthroughs in mind-reading technology have brought this story close to reality for a handful of people who may have a severe type of locked-in syndrome, previously diagnosed as being in a vegetative state. So far, most work has required a lab and a giant fMRI scanner. Now two teams are developing devices that are portable enough to be taken out to homes, to help people communicate on a day-to-day basis. The technology might also be able to identify people who have been misdiagnosed. People with "classic" locked-in syndrome are fully conscious but completely paralysed apart from eye movements. Adrian Owen of Western University in London, Canada, fears that there is another form of the condition where the paralysis is total. He thinks that a proportion of people diagnosed as being in a vegetative state – in which people are thought to have no mental awareness at all – are actually aware but unable to let anyone know. "The possibility is that we are missing people with some sort of complete locked-in syndrome," he says. © Copyright Reed Business Information Ltd.
By Ben Thomas The past several years have brought two parallel revolutions in neuroscience. Researchers have begun using genetically encoded sensors to monitor the behavior of individual neurons, and they’ve been using brief pulses of light to trigger certain types of neurons to activate. These two techniques are known collectively as optogenetics—the science of using light to read and activate genetically specified neurons—but until recently, most researchers have used them separately. Though many had tried, no one had succeeded in combining optogenetic readout and stimulation into one unified system that worked in the brains of living animals. But now, a team led by Michael Hausser, a neuroscientist at University College London’s Wolfson Institute for Biomedical Research, has succeeded in creating just such a unified optogenetic input/output system. In a paper published this January in the journal Nature Methods [Scientific American is part of the Nature Publishing Group], the team explain how they’ve used the system to record complex signaling codes used by specific sets of neurons and to “play” those codes back by reactivating the same neural firing patterns they recorded, paving the way to get neural networks in the brains of living animals to recognize and respond to the codes they send. “This is going to be a game-changer,” Hausser says. Conventional optogenetics starts with genes. Certain genes encode instructions for producing light-sensitive proteins. By introducing these genes into brain cells, researchers are able to trick specific populations of those cells—all the neurons in a given brain region that respond to dopamine, for example—to fire their signals in response to tiny pulses of light. © 2015 Scientific American
Keyword: Brain imaging
Link ID: 20514 - Posted: 01.23.2015
By JOHN MARKOFF A new laboratory technique enables researchers to see minuscule biological features, such as individual neurons and synapses, at a nearly molecular scale through conventional optical microscopes. In a paper published last week in the journal Science, researchers at M.I.T. said they were able to increase the physical size of cultured cells and tissue by as much as five times while still preserving their structure. The scientists call the new technique expansion microscopy. The idea of making objects larger to make them more visible is a radical solution to a vexing challenge. By extending the resolving power of conventional microscopes, scientists are able to glimpse such biological mysteries as the protein structures that form ion channels and the outline of the membrane that holds the genome within a cell. The researchers have examined minute neural circuits, gaining new insights into local connections in the brain and a better understanding of larger networks. The maximum resolving power of conventional optical microscopes is about 200 nanometers, about half the wavelength of visible light. (By contrast, a human hair is about 500 times wider.) In recent decades, scientists have struggled to push past these limits. Last year, three scientists received a Nobel Prize for a technique in which fluorescent molecules are used to extend the resolving power of optical microscopes. But the technique requires specialized equipment and is costly. With expansion microscopy, Edward S. Boyden, a co-director of the M.I.T. Center for Neurobiological Engineering, and his colleagues were able to observe objects originally measuring just 70 nanometers in cultured cells and brain tissue through an optical microscope. © 2015 The New York Times Company
Keyword: Brain imaging
Link ID: 20499 - Posted: 01.20.2015
Vernon Mountcastle, one of Johns Hopkins Medicine's giants of the 20th century, died peacefully at his North Baltimore home on Sunday, with Nancy, his wife of seven decades, and family at his bedside. He was 96. Mountcastle was universally acknowledged as the "father of neuroscience" and served Johns Hopkins with extraordinary dedication for nearly 65 years. A 1942 graduate of the School of Medicine and a member of the faculty since 1948, Mountcastle served as director of the Department of Physiology and head of the Philip Bard Laboratories of Neurophysiology at Johns Hopkins from 1964 to 1980. He later became one of the founding members of Johns Hopkins' Zanvyl Krieger Mind/Brain Institute, where he continued to work until his retirement at 87. Colleagues remember his dedication to the professional development of neuroscientists, fiercely focused work ethic, and devotion to collaborative research. Also see: Mind/Brain's Mountcastle wins NAS award for lifetime of groundbreaking work (Gazette, April 1998) Mountcastle once was dubbed the "Jacques Cousteau of the cortex" for his revolutionary research delving into the unknown depths of the brain and establishing the basis for modern neuroscience. In 1957, he made the breakthrough discovery that revolutionized the concept of how the brain is built. He found that the cells of the cerebral cortex are organized in vertical columns, extending from the surface of the brain down through six layers of the cortex, each column processing a specific kind of information.
Keyword: Brain imaging
Link ID: 20478 - Posted: 01.14.2015
By GARETH COOK In 2005, Sebastian Seung suffered the academic equivalent of an existential crisis. More than a decade earlier, with a Ph.D. in theoretical physics from Harvard, Seung made a dramatic career switch into neuroscience, a gamble that seemed to be paying off. He had earned tenure from the Massachusetts Institute of Technology a year faster than the norm and was immediately named a full professor, an unusual move that reflected the sense that Seung was something of a superstar. His lab was underwritten with generous funding by the elite Howard Hughes Medical Institute. He was a popular teacher who traveled the world — Zurich; Seoul, South Korea; Palo Alto, Calif. — delivering lectures on his mathematical theories of how neurons might be wired together to form the engines of thought. And yet Seung, a man so naturally exuberant that he was known for staging ad hoc dance performances with Harvard Square’s street musicians, was growing increasingly depressed. He and his colleagues spent their days arguing over how the brain might function, but science offered no way to scan it for the answers. “It seemed like decades could go by,” Seung told me recently, “and you would never know one way or another whether any of the theories were correct.” That November, Seung sought the advice of David Tank, a mentor he met at Bell Laboratories who was attending the annual meeting of the Society for Neuroscience, in Washington. Over lunch in the dowdy dining room of a nearby hotel, Tank advised a radical cure. A former colleague in Heidelberg, Germany, had just built a device that imaged brain tissue with enough resolution to make out the connections between individual neurons. But drawing even a tiny wiring diagram required herculean efforts, as people traced the course of neurons through thousands of blurry black-and-white images. What the field needed, Tank said, was a computer program that could trace them automatically — a way to map the brain’s connections by the millions, opening a new area of scientific discovery. For Seung to tackle the problem, though, it would mean abandoning the work that had propelled him to the top of his discipline in favor of a highly speculative engineering project. © 2015 The New York Times Company
Keyword: Brain imaging
Link ID: 20470 - Posted: 01.10.2015
Ewen Callaway Microscopes make living cells and tissues appear bigger. But what if we could actually make the things bigger? It might sound like the fantasy of a scientist who has read Alice’s Adventures in Wonderland too many times, but the concept is the basis for a new method that could enable biologists to image an entire brain in exquisite molecular detail using an ordinary microscope, and to resolve features that would normally be beyond the limits of optics. The technique, called expansion microscopy, involves physically inflating biological tissues using a material more commonly found in baby nappies (diapers). Edward Boyden, a neuroengineer at the Massachusetts Institute of Technology (MIT) in Cambridge, discussed the technique, which he developed with his MIT colleagues Fei Chen and Paul Tillberg, at a conference last month. Prizewinning roots Expansion microscopy is a twist on super-resolution microscopy, which earned three scientists the 2014 Nobel Prize in Chemistry. Both techniques attempt to circumvent a limitation posed by the laws of physics. In 1873, German physicist Ernst Abbe deduced that conventional optical microscopes cannot distinguish objects that are closer together than about 200 nanometres — roughly half the shortest wavelength of visible light. Anything closer than this 'diffraction limit' appears as a blur. © 2015 Nature Publishing Group
Keyword: Brain imaging
Link ID: 20464 - Posted: 01.10.2015
Mo Costandi A team of neuroscientists at University College London has developed a new way of simultaneously recording and manipulating the activity of multiple cells in the brains of live animals using pulses of light. The technique, described today in the journal Nature Methods, combines two existing state-of-the-art neurotechnologies. It may eventually allow researchers to do away with the cumbersome microelectrodes they traditionally used to probe neuronal activity, and to interrogate the brain’s workings at the cellular level in real time and with unprecedented detail. One of them is optogenetics. This involves creating genetically engineered mice expressing algal proteins called Channelrhodopsins in specified groups of neurons. This renders the cells sensitive to light, allowing researchers to switch the cells on or off, depending on which Channelrhodopsin protein they express, and which wavelength of light is used. This can be done on a millisecond-by-millisecond timescale, using pulses of laser light delivered into the animals’ brains via an optical fibre. The other is calcium imaging. Calcium signals are crucial for just about every aspect of neuronal function, and nerve cells exhibit a sudden increase in calcium ion concentration when they begin to fire off nervous impulses. Using dyes that give off green fluorescence in response to increases in calcium concentration, combined with two-photon microscopy, researchers can detect this signature to see which cells are activated. In this way, they can effectively ‘read’ the activity of entire cell populations in brain tissue slices or live brains. Calcium-sensitive dyes are injectable, so targeting them with precision is difficult, and more recently, researchers have developed genetically-encoded calcium sensors to overcome this limitation. Mice can be genetically engineered to express these calcium-sensitive proteins in specific groups of cells; like the dyes before them, they, too, fluoresce in response to increases in calcium ion concentrations in the cells expressing them.
Keyword: Brain imaging
Link ID: 20441 - Posted: 12.23.2014