Links for Keyword: Brain imaging

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By Scicurious This past weekend, I read an interesting piece in the New Yorker. It’s another one of the current rash of pieces that are warning us (rightly!) to beware of neuro-hype. It references another recent piece in the New York Times, which referenced those fighting back against things like “How Creativity Works” (correct answer: it’s very complicated and we don’t know), and the ever-present fMRI studies hyped in the news (I’ve been guilty of a few of those, though I try very hard to be skeptical). Both pieces referenced the excellent Neuroskeptic and Neurocritic (though sadly, the NYT didn’t give them the links they definitely deserve). And both pieces warned that neuroscience is more, and better than, the gee-whiz of “This is your brain on poker“. I particularly liked the New Yorker piece, for making clear the incredible complexity of the human brain. The brain, though, rarely works that way. Most of the interesting things that the brain does involve many different pieces of tissue working together. Saying that emotion is in the amygdala, or that decision-making is the prefrontal cortex, is at best a shorthand, and a misleading one at that. Different emotions, for example, rely on different combinations of neural substrates. The act of comprehending a sentence likely involves Broca’s area (the language-related spot on the left side of the brain that they may have told you about in college), but it also draws on the parts of the brain in the temporal lobe that analyze acoustic signals, and part of sensorimotor cortex and the basal ganglia become active as well. (In congenitally blind people, some of the visual cortex also plays a role.) It’s not one spot, it’s many, some of which may be less active but still vital, and what really matters is how vast networks of neural tissue work together. © 2012 Scientific American

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17568 - Posted: 12.04.2012

Posted by Gary Marcus In the early nineteen-nineties, David Poeppel, then a graduate student at M.I.T. (and a classmate of mine)—discovered an astonishing thing. He was studying the neurophysiological basis of speech perception, and a new technique had just come into vogue, called positron emission tomography (PET). About half a dozen PET studies of speech perception had been published, all in top journals, and David tried to synthesize them, essentially by comparing which parts of the brain were said to be active during the processing of speech in each of the studies. What he found, shockingly, was that there was virtually no agreement. Every new study had published with great fanfare, but collectively they were so inconsistent they seemed to add up to nothing. It was like six different witnesses describing a crime in six different ways. This was terrible news for neuroscience—if six studies led to six different answers, why should anybody believe anything that neuroscientists had to say? Much hand-wringing followed. Was it because PET, which involves injecting a radioactive tracer into the brain, was unreliable? Were the studies themselves somehow sloppy? Nobody seemed to know. And then, surprisingly, the field prospered. Brain imaging became more, not less, popular. The technique of PET was replaced with the more flexible technique of functional magnetic resonance imaging (fMRI), which allowed scientists to study people’s brains without the use of the risky radioactive tracers, and to conduct longer studies that collected more data and yielded more reliable results. Experimental methods gradually become more careful. As fMRI machines become more widely available, and methods became more standardized and refined, researchers finally started to find a degree of consensus between labs. © 2012 Condé Nast.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17567 - Posted: 12.04.2012

By ALISSA QUART THIS fall, science writers have made sport of yet another instance of bad neuroscience. The culprit this time is Naomi Wolf; her new book, “Vagina,” has been roundly drubbed for misrepresenting the brain and neurochemicals like dopamine and oxytocin. Earlier in the year, Chris Mooney raised similar ire with the book “The Republican Brain,” which claims that Republicans are genetically different from — and, many readers deduced, lesser to — Democrats. “If Mooney’s argument sounds familiar to you, it should,” scoffed two science writers. “It’s called ‘eugenics,’ and it was based on the belief that some humans are genetically inferior.” Sharp words from disapproving science writers are but the tip of the hippocampus: today’s pop neuroscience, coarsened for mass audiences, is under a much larger attack. Meet the “neuro doubters.” The neuro doubter may like neuroscience but does not like what he or she considers its bastardization by glib, sometimes ill-informed, popularizers. A gaggle of energetic and amusing, mostly anonymous, neuroscience bloggers — including Neurocritic, Neuroskeptic, Neurobonkers and Mind Hacks — now regularly point out the lapses and folly contained in mainstream neuroscientific discourse. This group, for example, slammed a recent Newsweek article in which a neurosurgeon claimed to have discovered that “heaven is real” after his cortex “shut down.” Such journalism, these critics contend, is “shoddy,” nothing more than “simplified pop.” Additionally, publications from The Guardian to the New Statesman have published pieces blasting popular neuroscience-dependent writers like Jonah Lehrer and Malcolm Gladwell. The Oxford neuropsychologist Dorothy Bishop’s scolding lecture on the science of bad neuroscience was an online sensation last summer. © 2012 The New York Times Company

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17524 - Posted: 11.24.2012

Daniel Cressey Rappers making up rhymes on the fly while in a brain scanner have provided an insight into the creative process. Freestyle rapping — in which a performer improvises a song by stringing together unrehearsed lyrics — is a highly prized skill in hip hop. But instead of watching a performance in a club, Siyuan Liu and Allen Braun, neuroscientists at the US National Institute on Deafness and Other Communication Disorders in Bethesda, Maryland, and their colleagues had 12 rappers freestyle in a functional magnetic resonance imaging (fMRI) machine. The artists also recited a set of memorized lyrics chosen by the researchers. By comparing the brain scans from rappers taken during freestyling to those taken during the rote recitation, they were able to see which areas of the brain are used during improvisation. The study is published today in Scientific Reports1. The results parallel previous imaging studies in which Braun and Charles Limb, a doctor and musician at Johns Hopkins University in Baltimore, Maryland, looked at fMRI scans from jazz musicians2. Both sets of artists showed lower activity in part of their frontal lobes called the dorsolateral prefrontal cortex during improvisation, and increased activity in another area, called the medial prefrontal cortex. The areas that were found to be ‘deactivated’ are associated with regulating other brain functions. © 2012 Nature Publishing Group

Related chapters from BP7e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 15: Language and Our Divided Brain; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17498 - Posted: 11.17.2012

Mo Costandi Albert Einstein is considered to be one of the most intelligent people that ever lived, so researchers are naturally curious about what made his brain tick. Photographs taken shortly after his death, but never before analysed in detail, have now revealed that Einstein’s brain had several unusual features, providing tantalizing clues about the neural basis of his extraordinary mental abilities1. While doing Einstein's autopsy, the pathologist Thomas Harvey removed the physicist's brain and preserved it in formalin. He then took dozens of black and white photographs of it before it was cut up into 240 blocks. He then took tissue samples from each block, mounted them onto microscope slides and distributed the slides to some of the world’s best neuropathologists. The autopsy revealed that Einstein’s brain was smaller than average and subsequent analyses showed all the changes that normally occur with ageing. Nothing more was analysed, however. Harvey stored the brain fragments in a formalin-filled jar in a cider box kept under a beer cooler in his office. Decades later, several researchers asked Harvey for some samples, and noticed some unusual features when analysing them. A study done in 1985 showed that two parts of his brain contained an unusually large number of non-neuronal cells called glia for every neuron2. And one published more than a decade later showed that the parietal lobe lacks a furrow and a structure called the operculum3. The missing furrow may have enhanced the connections in this region, which is thought to be involved in visuo-spatial functions and mathematical skills such as arithmetic. © 2012 Nature Publishing Group

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 14: Attention and Consciousness
Link ID: 17496 - Posted: 11.17.2012

By Noah Hutton and Ferris Jabr "Nothing quite like it exists yet, but we have begun building it," Henry Markram wrote in the June 2012 issue of Scientific American. He was referring to a "fantastic new scientific instrument"—a biologically realistic and detailed model of a working human brain hosted on supercomputers. Markram, who directs the Brain Mind Institute at the École Polytechnique Fédérale de Lausanne in Switzerland, has been working on the Blue Brain Project, more recently known as the Human Brain Project, since 2005. "A digital brain will be a resource for the entire scientific community: researchers will reserve time on it, as they do on the biggest telescopes, to conduct their experiments," Markram wrote in SA. "They will use it to test theories of how the human brain works in health and in disease. They will recruit it to help them develop not only new diagnostic tests for autism or schizophrenia but also new therapies for depression and Alzheimer's disease. The wiring plan for tens of trillions of neural circuits will inspire the design of brainlike computers and intelligent robots. In short, it will transform neuroscience, medicine and information technology." Markram has claimed, at various times, that he can complete this ambitious project within 10 years. His critics argue that his ultimate goal is unachievable because the human brain is too complex to simultaneously simulate at every level, from the molecule to the cortex. Say one wanted to build an exact replica of a large and intricate circuit board. One would first need to map every wire linking every component and then re-create these links. In the same way, making a model of the human brain requires knowing the trillions of connections between its neurons. A map of all the connections between neurons in a brain is called a connectome, and no such map exists for the human brain. In fact, the only organism with a complete connectome is the tiny nematode C. elegans, which has 302 neurons total. The human brain has more than 80 billion neurons and 100 trillion connections between those cells. © 2012 Scientific American

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 13: Memory, Learning, and Development
Link ID: 17472 - Posted: 11.10.2012

Neuroscientists at the University of Ingberg have found a brain region that does absolutely nothing. Their research, presented at the annual Society for Neuroscience meeting, showed that a small region of the cortex located near the posterior section of the cingulate gyrus responded to ‘not one of our 46 experimental manipulations’. Dr. Ahlquist was rather surprised at the finding. “During a pilot study we noticed that this small section of the cortex did not show differential activity in any of our manipulations. Out of curiosity, we wanted to see whether it actually did anything at all. Over the months that followed we tried every we knew, with over 20 different participants. IQ tests, memory tasks, flashing lights, talking, listening, imagining juggling, but there was no response. Nothing. We got more desperate, so we tried pictures of faces, TMS, pictures of cats, pictures of sex, pictures of violence and even sexy violence, but nothing happened! Not even a decrease. No connectivity to anywhere else, not even a voodoo correlation. 46 voxels of wasted space. I know dead salmons that are more responsive. It’s an evolutionary disgrace, that’s what it is.” Some neuroscientists are disappointed by the regions’ lack of response: ‘This is exactly the type of cortical behavior that leads to this popular science nonsense about using only 10% of our brain. Frankly, I am outraged by this lazy piece of brain. It’s the cortical equivalent of a spare tyre. If anyone wants to have it lobotomized, I am happy to break out the orbitoclast and help them out. That’ll teach it.”

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 1: An Introduction to Brain and Behavior
Link ID: 17464 - Posted: 11.07.2012

By Laura Sanders A genetic tweak makes it easier to see neurons at work in living, breathing animals. The method, described in the Oct. 18 Neuron, capitalizes on a property of a busy neuron: When the cell fires, calcium ions flood in. Using an altered version of the protein GFP that lights up when calcium is present in a mouse’s brain, neuroscientist Guoping Feng of MIT and colleagues could see smell-sensing neurons respond to an odor, and movement neurons light up during walking. Q. Chen et al. Imaging Neural Activity Using Thy1-GCaMP Transgenic Mice. Neuron. Vol. 76, October 18,2012, p. 297. doi: 10.1016/j.neuron.2012.07.011. [Go to] © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 17435 - Posted: 10.30.2012

By Ferris Jabr Scientists have mapped, charted, modeled and visualized the human brain in many different ways. They have marked the boundaries of the organ’s four major lobes: the frontal, parietal, temporal and occipital lobes. They have divvied up the cortex into more than 50 Broadmann areas—small regions characterized by particular cell types and specific cognitive functions, such as processing speech and recognizing faces. Researchers have tagged individual neurons with fluorescent proteins, transforming gray tissue into stunning brainbows, and followed water molecules as they move through the nervous system to trace ribbons of neural tissue linking one brain region to another. More recently, some scientists have championed the importance of connectomes—detailed wiring diagrams of all the connections between neurons in a given nervous system or brain. Thoroughly understanding the brain, proponents of connectomics argue, requires precise maps of its neural circuits. The standard way of making a connectome is serial electron microscopy—chopping up an animal’s brain into thin sheets, taking photos of all the resident neurons through an electron microscope and using those photos to painstakingly reconstruct the connections between neurons. In the 1970s biologist Sydney Brenner and his colleagues began using this technique to map the 302 neurons and 7,000 neural connections, or synapses, in the nervous system of a tiny worm known as Caenorhabditis elegans. It took them more than 12 years to finish the map. So far, C. elegans is the only animal with such a thorough connectome. Since mammalian brains contain millions or billions of neurons and billions or trillions of synapses, depending on the species, researchers are searching for faster and cheaper ways to create connectomes. At Harvard University, for example, Jeff Lichtman and his colleagues have constructed an Automatic Tape-Collecting Lathe Ultramicrotome (ATLUM)—a machine that speeds up the business of slicing up brain tissue into thin sheets with conveyor-belt efficiency. © 2012 Scientific American

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17417 - Posted: 10.24.2012

By David DiSalvo Neuroscientists aren’t usually thought of as advocates for special interests. They’re a generally objective bunch, dedicated to their discipline and concerned above all with making solid contributions to understanding how our brains work. Advances in understanding and treating Alzheimer’s, Parkinson’s, multiple sclerosis, and a host of other diseases and conditions are largely attributable to the commitment of neuroscientists focused on solving some of the most difficult problems in medicine. But, over the past decade, as neuroscience—and brain imaging in particular—has become a star science attraction, the role of the impartial neuroscientist has been redefined. When the forces of marketing realized that neuroscience could assist in predicting consumer behavior, neuroscientists became a hot commodity as “consultants” to some of the biggest brands on the planet. Soon “neuromarketing” was born, and firms armed with fMRI machines started becoming mainstays at consumer focus groups for Fortune 500 companies. A similar story is playing out in the legal arena—but the stakes are much higher. When neuroscientists are recruited to weigh in on critical issues like lie detection and the alleged mental state of a defendant, people’s lives, and not just their wallets, are directly affected. But much of this technology is too new to be reliable. Furthermore, neuroscience experts aren’t just being used on the stand—they are also being paid to help select, even sway, juries, and that poses an entirely new ethical dilemma. © 2012 The Slate Group, LLC

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17388 - Posted: 10.20.2012

The human brain is big and complicated. There has been a map for gene expression in mice brains available for a number of years but human brains are a thousand times bigger and a little harder to come by for post-mortem research. But published today is a high-resolution 3D atlas of the human brain created by an international team led by Michael Hawrylycz of the Allen Institute for Brain Science in Seattle. The project was launched in March 2008 with a budget of $55 million. Working with just two whole male brains and a single hemisphere from a third, the team used around 900 precise subdivisions and 60,000 gene expression probes to create the atlas. This image is a 3D rendering of just one of the genes in internal brain structures overlaid onto an MRI scan. The level of gene expression at the different points on the map is indicated on a colour scale, with blue dots reflecting relatively low expression and red dots reflecting high expression. The aim of the project is to provide a platform for further study into gene expression in the brain and how it is involved in normal and abnormal brain function. The Allen Brain Atlas is freely accessible online. Journal reference: Nature, DOI: 10.1038/nature11405 © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 13: Memory, Learning, and Development
Link ID: 17288 - Posted: 09.22.2012

by Molly Docherty The brain drain is real. There is a network of previously unrecognised vessels that rid the brain of unwanted extracellular fluids and other substances, including amyloid-beta – a peptide that accumulates in the brain of people with Alzheimer's. The new discovery looks set to add to our understanding of the disease. Jeffrey Iliff at the University of Rochester Medical Center, New York, and his colleagues, were intrigued by the fact that there are no obvious lymphatic vessels in the brain. Among other things, the lymphatic system removes waste interstitial fluids from body tissue. "It seemed strange that such an important and active organ wouldn't have a specialised waste-removal system," says Iliff. When the researchers added fluorescent and radioactive tracers to the cerebrospinal fluid of live mice, the tracers quickly spread throughout the rodents' brains. Using two-photon microscopy to visualise the movement in real-time, the team saw cerebrospinal fluid permeating the entire brain through 'pipes' surrounding blood vessels, similar to the lymphatic system that services all other organs. The pipes work on hydraulic principles, though, and so the system breaks upon opening, making it hard to identify it outside living organisms. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17174 - Posted: 08.16.2012

By Sandra Upson All elite athletes train hard, possess great skills and stay mentally sharp during competition. But what separates a gold medalist from an equally dedicated athlete who comes in 10th place? A small structure deep in the brain may give winners an extra edge. Recent studies indicate that the brain's insular cortex may help a sprinter drive his body forward just a little more efficiently than his competitors. This region may prepare a boxer to better fend off a punch his opponent is beginning to throw as well as assist a diver as she calculates her spinning body's position so she hits the water with barely a splash. The insula, as it is commonly called, may help a marksman retain a sharp focus on the bull's-eye as his finger pulls back on the trigger and help a basketball player at the free-throw line block out the distracting screams and arm-waving of fans seated behind the backboard. The insula does all this by anticipating an athlete's future feelings, according to a new theory. Researchers at the OptiBrain Center, a consortium based at the University of California, San Diego, and the Naval Health Research Center, suggest that an athlete possesses a hyper-attuned insula that can generate strikingly accurate predictions of how the body will feel in the next moment. That model of the body's future condition instructs other brain areas to initiate actions that are more tailored to coming demands than those of also-rans and couch potatoes. This heightened awareness could allow Olympians to activate their muscles more resourcefully to swim faster, run farther and leap higher than mere mortals. In experiments published in 2012, brain scans of elite athletes appeared to differ most dramatically from ordinary subjects in the functioning of their insulas. © 2012 Scientific American

Related chapters from BP7e: Chapter 11: Motor Control and Plasticity; Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17088 - Posted: 07.25.2012

Rebecca Goldin, Ph.D., Cindy S. Merrick With the news media telling us that neuroscience – and brain scans – can explain everything from a global pandemic of Justin Bieber fever to whether you are likely to stay with your spouse, we investigate what neuroscience can and can’t tell us about who we are and why we do the things we do. In the first part of an ongoing series, we look at functional magnetic resonance imaging, and whether it’s really the window on the mind that some in the media – and science – would have us believe. Gone are the days when the only people who believed in technologies that could read minds were distinguishable from the rest of us by their tin foil hats. With the advent of functional magnetic resonance imaging (fMRI), we are able to see, in near-video quality, the ebb and flow of a live mind at work. Or so it seems. Something, for certain, is at work, and there are lots of people willing to tell you they know exactly how to interpret what we can see. Certainly this new technology has already produced fascinating results: surgeons use it real-time to avoid critical regions while operating on brain tumors; physicians use it to look for changes in the brain activity of stroke victims as they experience physical rehabilitation; and fMRI data showing activity in the brains of patients thought to be in a vegetative state may be blurring the line that defines consciousness. Along with these advances, though, have appeared many somewhat less credible stories. The media reports claims ranging from fMRI’s ability to detect lies to its predicting future addictive behavior or determining whether or not you really love your spouse, or, maybe, your iPhone. Already, attempts have been made to use fMRI as admissible evidence of lie detection in court (so far, they have failed); and in another court case, fMRI results and a neuroscientist’s testimony were admitted in the sentencing hearing. The data were used as evidence that the defendant, a violent offender, was psychopathic.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17047 - Posted: 07.17.2012

Will Ferguson, reporter You can't visit this tropical jungle. It's a forest of neurons snaking through a pig's brain. The brain cells, enlarged and coloured here, are being investigated to give scientists a clearer view of the mechanics of brain matter when it is hit hard. Michel Destrade, an applied mathematician at the National University of Ireland, Galway, and colleagues obtained samples of pig brains from a local slaughterhouse to study the mechanics of brain matter undergoing rapid impacts. With the aim of improving the treatment of traumatic head injuries, they used the samples to create computer models of electrical signals inside the brain. But during the course of the experiment, Destrade's student Badar Rashid decided to find out what white and grey matter inside a brain look like. He started with an image of neuron bundles taken using scanning electron microscopy, and blew it up to 4,000 times its actual size. He then added colour to the black and white result according to his own aesthetic. The image appears in Physics Today (DOI:10.1063/PT.3.1651). © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17042 - Posted: 07.16.2012

By Mahir Ozdemir Hardly a week passes without some sensational news about brain scans unleashing yet another secret of our cognitive faculties. Very recently I stumbled upon the news that according to recent research neuroscientists can tell, depending on your brain responses, whether you and your significant one will still be together in a few years: “You might hide it from friends and family. But you can’t hide it from neuroscientists”. The technique at the bottom of the study, just like the majority of studies making a big splash, is functional magnetic resonance imaging, fMRI. Researchers have been struggling to unfold ‘what’s under the hood’ through the lens of Neuroscience and they have been finding all sorts of insights into human behavior. They have been looking at everything from how multitasking is harder for seniors to how people love talking about themselves. Neural basis of love and hatred, compassion and admiration have all been studied with fMRI, yielding colored blobs representing the corresponding love or hatred centers in our brains. First a brief background: The fMRI technique measures brain activity indirectly via changes in blood oxygen levels in different parts of the brain as subjects participate in various activities. While lying down with head immobilized in a small confined chamber of the notoriously noisy MR scanner, subjects are shown experimental stimuli. They wear earplugs to reduce at least some part of the noise while performing these cognitive tasks. © 2012 Scientific American

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 17005 - Posted: 07.07.2012

By Daisy Yuhas At right is a picture of someone’s brain as seen through functional magnetic resonance imaging or fMRI. This particular subject is taxing his neurons with a working memory task—those sunny orange specks represent brain activity related to the task. fMRI images show the brain according to changes in blood oxygen level, a proxy for degree of mental activity. It’s a pretty amazing tool; it has validated a lot of assumptions about brain regions and helped us make comparisons between groups of people, shedding light on addiction, development and disease. Some scientists believe it can help us read minds (more on that later) or even predict the future. But fMRI doesn’t actually provide detail at the level of a cell. The 3-dimensionsal image it provides is built up in units called voxels. Each one represents a tidy cube of brain tissue—a 3-D image building block analogous to the 2-D pixel of computers screens, televisions or digital cameras. Each voxel can represent a million or so brain cells. Those orange blobs in the image above are actually clusters of voxels—perhaps tens or hundreds of them. fMRI is also too slow to capture all of the changes in the brain. Each scan requires a second or two, enough time for a neuron to fire more than a hundred times. That means it can’t provide a clear sense of precisely when things happen. Trying to explain whether activity in one spot causes activity in another is not possible through fMRI alone. Furthermore, you have to be careful with your conclusions. Just because voxels corresponding to one region ‘light up’ when your subject sees a terrifying tiger doesn’t mean that every time this region appears active, your subject is frightened. Many of the brain’s regions are quite complex and involved in multiple processes. © 2012 Scientific American

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 16957 - Posted: 06.23.2012

Neuroscientist and friend of the blog Bradley Voytek has a terrific piece about the relationship between popular science writing and neuroscience that’s well worth your time. In brief, he says, the primary problem are neuroscientists themselves. Or at least, some of the assumptions that neuroscientists make. The problem, he notes, is a problem that long term readers here are familiar with – the confusion of cause and effect, as well as an over-reductionist view of the brain. Namely, that imaging studies showing a portion of the brain “lighting up” when something happens means that that area of the brain is directly involved in the activity. Something that he analogizes to “like how when your arms swing faster when you run that means that your arms are ‘where running happens’.” Voytek also provides what I think is one of the best analogies I’ve read about the problem inherent in trying to isolate “which part of the brain does X”: Imagine asking “where is video located in my computer?” That doesn’t make any sense. Your monitor is required to see the video. Your graphics card is required to render the video. The software is required to generate the code for the video. But the “video” isn’t located anywhere in the computer. This is something that I think is exactly right. The best neuroscientists out there are, I think, very aware of this problem, but I think part of what’s going on here is the inherent limitations of our ability to experiment. Take fMRI’s, for example, which have provided an interesting look into what kinds of activity is going on in the brain while the person being imaged is doing or thinking something. It’s one of the best pieces of equipment available, but it’s very nature can be deceiving. Because it’s one of the few ways available to figure out what’s going on in the brain, it can be tempting to see what is measured by an fMRI image as definitive. 2012 Forbes.com LLC™

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 16927 - Posted: 06.19.2012

By Jane Dreaper Health correspondent, BBC News Multiple CT scans in childhood can triple the risk of developing brain cancer or leukaemia, a study suggests. The Newcastle University-led team examined the NHS medical records of almost 180,000 young patients. But writing in The Lancet the authors emphasised that the benefits of the scans usually outweighed the risks. They said the study underlined the fact the scans should only be used when necessary and that ways of cutting their radiation should be pursued. During a CT (computerised tomography) scan, an X-ray tube rotates around the patient's body to produce detailed images of internal organs and other parts of the body. In the first long-term study of its kind, the researchers looked at the records of patients aged under 21 who had CT scans at a range of British hospitals between 1985 and 2002. Because radiation-related cancer takes time to develop, they examined data on cancer cases and mortality up until 2009. The study estimated that the increased risk translated into one extra case of leukaemia and one extra brain tumour among 10,000 CT head scans of children aged under ten. BBC © 2012

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 13: Memory, Learning, and Development
Link ID: 16883 - Posted: 06.07.2012

by Linda Geddes SECOND by second changes in the brain's pH can be visualised for the first time. This ability may provide fresh insights into learning, memory and disease. Oxygen deprivation can alter the brain's pH, and even normal brain signals from acidic neurotransmitters or metabolic by-products such as lactic acid may lead to local changes in pH. Studies in mice have also uncovered pH-sensitive receptors in brain areas involved in emotion and memory - although their function is something of a mystery. "If these receptors are activated by pH change, it's possible that abnormalities in this system could lead to changes in learning, memory and mood," says Vincent Magnotta at the University of Iowa in Iowa City. A common way of studying the brain is with an MRI scanner, which detects differences in the spin of protons in tissues according to water content. Although brain pH can be measured using a form of MRI called MR spectroscopy, it only detects changes that occur over minutes - not fast enough to keep up with the rapid pace of the brain. T1ρ MRI analyses the interaction between spinning protons and other ions in a solution, which changes under different pHs. By tweaking the technique so that multiple measurements could be taken simultaneously, Magnotta and his colleagues have found that T1ρ MRI can detect changes in brain acidity happening over seconds. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System
Link ID: 16845 - Posted: 05.26.2012