Chapter 2. Cells and Structures: The Anatomy of the Nervous System

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Helen Shen An international group of neuroscientists has sliced, imaged and analysed the brain of a 65-year-old woman to create the most detailed map yet of a human brain in its entirety (see video at bottom). The atlas, called ‘BigBrain’, shows the organization of neurons with microscopic precision, which could help to clarify or even redefine the structure of brain regions obtained from decades-old anatomical studies. “The quality of those maps is analogous to what cartographers of the Earth offered as their best versions back in the seventeenth century,” says David Van Essen, a neurobiologist at Washington University in St Louis, Missouri, who was not involved in the study. He says that the new and improved set of anatomical guideposts could allow researchers to merge different types of data — such as gene expression, neuroanatomy and neural activity — more precisely onto specific regions of the brain. The brain is comprised of a heterogeneous network of neurons of different sizes and with shapes that vary from triangular to round, packed more or less tightly in different areas. BigBrain reveals variations in neuronal distribution in the layers of the cerebral cortex and across brain regions — differences that are thought to relate to distinct functional units. The atlas was compiled from 7,400 brain slices, each thinner than a human hair. Imaging the sections by microscope took a combined 1,000 hours and generated 1 trillion bytes of data. Supercomputers in Canada and Germany churned away for years reconstructing a three-dimensional volume from the images, and correcting for tears and wrinkles in individual sheets of tissue. © 2013 Nature Publishing Group

Keyword: Brain imaging
Link ID: 18296 - Posted: 06.22.2013

Posted by Gary Marcus Aristotle thought that the function of the brain was to cool the blood. That seems ludicrous now; through neuroscience, we know more about the brain and how it works than ever before. But, over the past several years, enthusiasm has often outstripped the limits of what current science can really tell us, and the field has given rise to pop neuroscience, which attempts to explain practically everything about human behavior and culture through the brain and its functions. A backlash against pop neuroscience is now in full swing. The latest, and most cutting, critique yet is “Brainwashed: The Seductive Appeal of Mindless Neuroscience,” by Sally Satel and Scott Lilienfeld. The book, which slams dozens of inconclusive studies that have been spun into overblown and downright dubious fields, like neurolaw and neuromarketing, is a resounding call for skepticism of the most grandiose claims being made in the name of neuroscience. The authors describe it as “an exposé of mindless neuroscience: the oversimplification, interpretive license, and premature application of brain science in the legal, commercial, clinical, and philosophical domains." The book does a terrific job of explaining where and how savvy readers should be skeptical. Unfortunately, the book is also prone to being misread. This is partly because it focusses largely on neuroscience’s current limitations rather than on its progress. Some, like David Brooks in the New York Times, are using books like “Brainwashed” as an excuse to toss out neuroscience altogether. In Brooks’s view, Satel and Lilienfeld haven’t just exposed some bad neuroscience; they’ve gutted the entire field, leading to the radical conclusion that “the brain is not the mind.” Brooks goes so far as to suggest that “it is probably impossible to look at a map of brain activity and predict or even understand the emotions, reactions, hopes and desires of the mind,” and that “there appears to be no dispersed pattern of activation that we can look at and say, ‘That person is experiencing hatred.’ ” The core of his claim is the idea that, if activity is distributed throughout the brain, it cannot be understood or interpreted. © 2013 Condé Nast.

Keyword: Miscellaneous; Aggression
Link ID: 18294 - Posted: 06.22.2013

Maggie Fox, NBC News Researchers have figured out how to read your mind and tell whether you are feeling sad, angry or disgusted – all by looking at a brain scan. The experiment, using 10 acting students, showed people have remarkably similar brain activity when experiencing the same emotions. And a computer could predict how someone was feeling just by looking at the scan. The findings could be used to help treat patients with various mental health conditions, and even provide a hard, medical diagnosis for emotional disorders. It might also be used to get a window into the minds of people with developmental disorders such as autism, the researchers at Carnegie Mellon University in Pittsburgh say. And one big, immediate application – testing advertisements. “What emotion do you want to evoke with your ad for the latest BMW?” said psychology professor Marcel Just, who helped oversee the study. "This research introduces a new method with potential to identify emotions without relying on people's ability to self-report," added Karim Kassam, assistant professor of social and decision sciences at CMU, who led the study. "It could be used to assess an individual's emotional response to almost any kind of stimulus, for example, a flag, a brand name or a political candidate."

Keyword: Emotions; Aggression
Link ID: 18286 - Posted: 06.20.2013

By Roland Pease BBC News "I'm a neuroengineer, and one of my goals is building brains." Prof Steven Potter was disarmingly understated as he introduced himself. It's not that tissue engineering is unusual. Nor even that doing it with neural cells should be an issue. If heart cells or skin cells can be reprogrammed, why not neurons? But "building brains" had been my flip way of labelling an intriguing, indeed unnerving, branch of science: the neurophysiology of disembodied brain-cell cultures. It was not a term I was expecting a serious scientist to turn to, as I set out on making "Build Me a Brain" for BBC Radio 4's Frontiers Programme. Yet Steven Potter, professor in the department of biomedical engineering at the Georgia Institute of Technology in the US, is insistent that words like "brain" and "mind" belong to his endeavour. "One of the ways in which I differ from a lot of neuroscientists is to believe that there's a spectrum of minds. There isn't some point where the mind suddenly is there," he said. "I think that there is a different amount of mind in different animals. And even in you, whether you've had your coffee or not, whether you're asleep or awake. "There are always different levels of how much mind you have. So you could carry it all the way down to the cultured network, there is still some sort of proto-mind in there." BBC © 2013

Keyword: Brain imaging; Aggression
Link ID: 18279 - Posted: 06.15.2013

Alison Abbott A simple brain scan may offer a way to predict which people being treated for depression will respond to drugs, and which will respond to cognitive behavioural therapy. Neurologist Helen Mayberg from Emory University in Atlanta, Georgia, and her colleagues have run the first systematic, well-controlled study to identify the first potential biomarker that distinguishes between treatment responses. The work is published in JAMA Psychiatry1. Psychiatrists are desperate for such biomarkers, because fewer than 40% of people with depression go into remission after initial treatment. “It could be fabulous,” says Steven Zalcman, chief of clinical neuroscience research at the US National Institute of Mental Health (NIMH) in Bethesda, Maryland. But he cautions that the brain-scan biomarker still has to be validated in further trials — a process that could take a couple of years. Mayberg and her colleagues selected 82 people with untreated depression, and measured glucose metabolism in their brains using positron emission tomography (PET) scans. They then randomly assigned the subjects to treatment groups. One group received the common antidepressant drug escitalopram oxalate (a selective serotonin reuptake inhibitor, or SSRI) for 12 weeks. The other group received 16 sessions of cognitive behavioural therapy over the same period. © 2013 Nature Publishing Group

Keyword: Depression; Aggression
Link ID: 18269 - Posted: 06.13.2013

By Sally Satel and Scott O. Lilienfeld By now you’ve seen the pretty pictures: Color-drenched brain scans capturing Buddhist monks meditating, addicts craving cocaine, and college sophomores choosing Coke over Pepsi. The media—and even some neuroscientists, it seems—love to invoke the neural foundations of human behavior to explain everything from the Bernie Madoff financial fiasco to slavish devotion to our iPhones, the sexual indiscretions of politicians, conservatives’ dismissal of global warming, and even an obsession with self-tanning. Brains are big on campus, too. Take a map of any major university, and you can trace the march of neuroscience from research labs and medical centers into schools of law and business and departments of economics and philosophy. In recent years, neuroscience has merged with a host of other disciplines, spawning such new areas of study as neurolaw, neuroeconomics, neurophilosophy, neuromarketing, and neurofinance. Add to this the birth of neuroaesthetics, neurohistory, neuroliterature, neuromusicology, neuropolitics, and neurotheology. The brain has even wandered into such unlikely redoubts as English departments, where professors debate whether scanning subjects’ brains as they read passages from Jane Austen novels represents (a) a fertile inquiry into the power of literature or (b) a desperate attempt to inject novelty into a field that has exhausted its romance with psychoanalysis and postmodernism. Brains are in demand. Once the largely exclusive province of neuroscientists and neurologists, the brain has now entered the popular mainstream. As a newly minted cultural artifact, the brain is portrayed in paintings, sculptures, and tapestries and put on display in museums and galleries. © 2013 The Associated Press

Keyword: Brain imaging
Link ID: 18250 - Posted: 06.10.2013

by David Robson NO CREVICE of the human experience is safe. Our deepest fears and desires, our pasts and our futures – all have been revealed, and all in the form of colourful images that look like lava bubbling under the skull. That, at least, is the popular conception of neuroscience – and it's worth big money. The USMovie Camera and the European Union are throwing billions of dollars at two new projects to map the human brain. Yet there is also a growing anxiety that many of neuroscience's findings don't stand up to scrutiny. It's not just sensational headlines reporting a "dark patch" in a psychopath's brain, there are now serious concerns that some of the methods themselves are flawed. The intrepid outsider needs expert guidance through this rocky terrain – and there's no better place to start than Brainwashed by Sally Satel and Scott O. Lilienfeld. Satel, a practising psychiatrist, and Lilienfeld, a clinical psychologist, are terrific sherpas. They are clear-sighted, considered and forgiving of the novice's ignorance. Their first stop is the fMRI scan – a staple of much brain research. Worryingly, the statistical techniques used to construct the images sometimes create a mirage of activity where none should exist. They have a telling example: one research team watching a salmon in an fMRI scanner as images of human faces were flashed at it saw its brain spark into life in certain shots – even though it was dead. © Copyright Reed Business Information Ltd.

Keyword: Brain imaging
Link ID: 18222 - Posted: 06.04.2013

Rebecca J. Rosen What would you draw if somebody told you to draw a neuron? According to a new study, your sketch will depend on how much science education you have, but not in the way you'd expect. In the image above, the top row -- those detailed, labeled, neat renderings -- are the work of undergraduates. The bottom row, with their janky, sparse lines, come from the leaders of neuroscience research laboratories. That martini-glass looking thing over there on the left? That's a neuron, as drawn by a professional scientist. The middle row, some intermediary step, shows drawings from postdocs and graduate students. These drawings come from a new study published in the journal Science Education. Its authors, a team at King's College London led by education professor David Hay, found that nearly every single undergraduate student they studied (all but three of 126) faithfully reproduced textbook-style neurons, something akin to a canonical image from an 1899 book detailing the brain, which, the authors say, "has enjoyed an unusually pervasive influence." These drawings are "typified by a multipolar cell body and truncated, feathery dendritic processes around a clearly demarcated nucleus." Many of the drawings were annotated. For the "trainee scientists" -- those in PhD programs or completing a postdoc -- the neurons appeared more like what would be seen in a microscope image. Nuclei were excluded, the number of dendrites was reduced, and orientation was inconsistent -- all characterizing neurons as you would see them "in nature" not in the pages of a textbook. © 2013 by The Atlantic Monthly Group

Keyword: Brain imaging; Aggression
Link ID: 18218 - Posted: 06.03.2013

Kerri Smith When Karl Deisseroth moved into his first lab in 2004, he found himself replacing a high-profile tenant: Nobel-prizewinning physicist Steven Chu. “His name was still on the door when I moved in,” says Deisseroth, a neuroscientist, of the basement space at Stanford University in California. The legacy has had its benefits. When chemistry student Feng Zhang dropped by looking for Chu, Deisseroth convinced him to stick around. “I don't think he knew who I was. But he got interested enough.” Deisseroth is now a major name in science himself. He is associated with two blockbuster techniques that allow researchers to show how intricate circuits in the brain create patterns of behaviour. The development of the methods, he says, came from a desire to understand mechanisms that give rise to psychiatric disease — and from the paucity of techniques to do so. “It was extremely clear that for fundamental advances in these domains I would have to spend time developing new tools,” says Deisseroth. His measured tone and laid-back demeanour belie the frenzy that his lab's techniques are generating in neuroscience. First came optogenetics1, which involves inserting light-sensitive proteins from algae into neurons, allowing researchers to switch the cells on and off with light. Deisseroth developed the method shortly after starting his lab, working with Zhang and Edward Boyden, a close collaborator at the time. Optogenetics has since been adopted by scientists around the world to explore everything from the functions of neuron subtypes to the circuits altered in depression or autism. Deisseroth has lost count of how many groups are using it. “We sent clones to thousands of laboratories,” he says. © 2013 Nature Publishing Group

Keyword: Brain imaging
Link ID: 18210 - Posted: 05.30.2013

By Stan Alcorn After decades languishing in jars in the closet of an animal lab at the University of Texas, approximately 90 brains removed from mental patients are finally being documented--by a photographer and by college freshmen. Photographer Adam Voorhes found the collection a few years ago when he came to Dr. Tim Schallert's lab at UT Austin in search of a brain to help illustrate a Scientific American article. "It was something about `protecting your brain' or `barriers for the brain,'" Voorhes told me. "They wanted to photograph a human brain in like a bell jar or a case or armor. Anything to show a brain being protected." Voorhes got the normal brain he needed, and was about to take it back to his studio to photograph, when Dr. Schallert asked if he wanted to see some more abnormal brains. Voorhes described being led through an animal research facility to a storage closet with one wall lined with chemicals, and another wall lined with jars full of brains unlike any he had ever seen before. "Some of them are huge, some of them are really tiny. There was one that had no wrinkles at all," he said. "I don't even know how to explain it." The brains had been amassed over the course of 30 years by a medical pathologist at the Austin State Hospital, who preserved them after routine autopsies. When they were discovered in the mid-1980s, they were the subject of a high-profile battle , as institutions vied to house and study them. "Harvard Scientists Lose Minds: University of Texas Wins Brain Collection" ran one headline. © 2013 Scientific American

Keyword: Brain imaging
Link ID: 18205 - Posted: 05.30.2013

By Gary Stix The Obama administration’s Big Brain project—$100 million for a map of some sort of what lies beneath the skull—has captured the attention of the entire field of neuroscience. The magnitude of the cash infusion can’t help but draw notice, eliciting both huzzahs mixed with gripes that the whole effort might sap support for other perhaps equally worthy neuro-related endeavors. The Brain Activity Map Project—or the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative—is intended to give researchers tools to elicit the real-time functioning of neural circuits, providing a better picture of what happens in the brain when immersed in thought or when brain cells are beset by a degenerative condition like Parkinson’s or Alzheimer’s. Current technologies are either too slow or lack the resolution to achieve these goals. One strength of the organizers—perhaps a portent of good things to come—is that they don’t seem to mind opening themselves to public critiques. At a planning meeting earlier this month, George Whitesides, the eminent Harvard chemist and veteran of big government ventures in support of nanotechnology, weighed in on how the project appeared to an informed outsider. Edited excerpting of some of his comments follows. This posting is a bit long, but Whitesides is eloquent and it’s worth reading what he has to say because his views apply to any large-scale sci-tech foray. Whitesides began his talk after listening to a steady cavalcade of big-name neuroscientists furnish their personal wish lists for the program: ultrasound to induce focal lesions, more fruit fly studies to find computational nervous system primitives, more studies on zebra fish, studies on wholly new types of model organisms, avoiding too much emphasis on practical applications and so on. © 2013 Scientific American

Keyword: Brain imaging
Link ID: 18200 - Posted: 05.30.2013

By Neuroskeptic Newly discovered papers have shed light on a fascinating episode in the history of neuroscience: Weighing brain activity with the balance The story of the early Italian neuroscientist Dr Angelo Mosso and his ‘human circulation balance’ is an old one – I remember reading about it as a student, in the introductory bit of a textbook on fMRI – but until now, the exact details were murky. In the new paper, Italian neuroscientists Sandrone and colleagues report that they’ve unearthed Mosso’s original manuscripts from an archive in Milan. Mosso worked in the late 19th century, an era that was – in retrospect – right at the dawn of modern neuroscience. A major question at that time was the relationship between brain function and blood flow. His early work included studies of the blood pressure in the brains of individuals with skull defects. His most ambitious project, however, was his balance – or as he sometimes called it, according to his daughter, his ‘metal cradle’ or ‘machine to weigh the soul’. It was in essence just a large balance. A volunteer lay on a table, their head on one side of the scale’s pivot and their feet on the other. It was carefully adjusted so that the two sides were perfectly balanced. The theory was that if mental activity caused increased brain blood flow, it ought to increase the weight of the head relative to the rest of the body, so that side of the balance would fall.

Keyword: Brain imaging
Link ID: 18188 - Posted: 05.23.2013

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

Keyword: Glia; Aggression
Link ID: 18139 - Posted: 05.11.2013

Posted by Helen Shen More than 150 neuroscientists descended on Arlington, Virginia this week to begin planning the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative—an ambitious but still hazy proposal to understand how the brain works by recording activity from an unprecedented numbers of neurons at once. President Barack Obama announced the initiative on 2 April, which will be carried out by three federal agencies—the National Institutes of Health (NIH), the National Science Foundation (NSF), and the Defense Advanced Research Projects Agency (DARPA)—alongside a handful of private foundations. Most neuroscientists have relished the attention on their field, but have also been left wondering what it means in scientific terms to “understand” the brain, what it will take to get there, and how much will be feasible in the programme’s projected 10-year lifespan. They gathered at an inaugural NSF planning meeting taking place from 5-6 May to discuss their ideas and concerns. “The belief is we’re ready for a leap forward,” says Van Wedeen, a neurobiologist at Harvard Medical School in Boston, Massachusetts, and one of the NSF meeting organizers. “Which leap and in which direction is still being debated.” The NSF group invited researchers representing neuroscience, computer science, and engineering — as many as would fit in the hotel conference room. Another estimated 200 or so followed the meeting by live webcast on Monday. Roughly 75 participants accepted NSF’s open invitation to submit one-page documents outlining the major © 2013 Nature Publishing Group,

Keyword: Brain imaging
Link ID: 18126 - Posted: 05.07.2013

Distinct patterns of brain activity are linked to greater rates of relapse among alcohol dependent patients in early recovery, a study has found. The research, supported by the National Institutes of Health, may give clues about which people in recovery from alcoholism are most likely to return to drinking. "Reducing the high rate of relapse among people treated for alcohol dependence is a fundamental research issue," said Kenneth R. Warren, Ph.D., acting director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of NIH. "Improving our understanding of the neural mechanisms that underlie relapse will help us identify susceptible individuals and could inform the development of other prevention strategies." Using brain scans, researchers found that people in recovery from alcoholism who showed hyperactivity in areas of the prefrontal cortex during a relaxing scenario were eight times as likely to relapse as those showing normal brain patterns or healthy controls. The prefrontal brain plays a role in regulating emotion, the ability to suppress urges, and decision-making. Chronic drinking may damage regions involved in self-control, affecting the ability to regulate cravings and resist relapse. Findings from the study, which was funded by NIAAA, appear online at the JAMA Psychiatry website.

Keyword: Drug Abuse; Aggression
Link ID: 18106 - Posted: 05.02.2013

by Sara Reardon An electronic patch can analyse complex brainwaves and listen in on a fetus’s heart MIND reading can be as simple as slapping a sticker on your forehead. An "electronic tattoo" containing flexible electronic circuits can now record some complex brain activity as accurately as an EEG. The tattoo could also provide a cheap way to monitor a developing fetus. The first electronic tattoo appeared in 2011, when Todd Coleman at the University of California, San Diego, and colleagues designed a transparent patch containing electronic circuits as thin as a human hairMovie Camera. Applied to skin like a temporary tattoo, these could be used to monitor electrophysiological signals associated with the heart and muscles, as well as rudimentary brain activity. To improve its usefulness, Coleman's group has now optimised the placement of the electrodes to pick up more complex brainwaves. They have demonstrated this by monitoring so-called P300 signals in the forebrain. These appear when you pay attention to a stimulus. The team showed volunteers a series of images and asked them to keep track of how many times a certain object appeared. Whenever volunteers noticed the object, the tattoo registered a blip in the P300 signal. The tattoo was as good as conventional EEG at telling whether a person was looking at the target image or another stimulus, the team told a recent Cognitive Neuroscience Society meeting in San Francisco. © Copyright Reed Business Information Ltd.

Keyword: Brain imaging; Aggression
Link ID: 18075 - Posted: 04.27.2013

by Scicurious Mmmmm beer! Just a sip is enough to prime the brain's dopamine addiction circuits, if reports of a new study are to be believed. Photograph: Johnny Green/PA It's been a long day at work, followed by a long workout. I'm tired, and all I really want is to relax with a beer. I grab one out of the fridge and take a sip. I feel better already. A new study tells us that this is due to dopamine, a neurotransmitter that plays an important role in things like motivation and reward. Drugs of abuse, such as cocaine, increase dopamine levels in areas of the brain associated with the expectation of reward, such as the ventral striatum, and this increase is part of what makes them feel so good, and do so bad. But dopamine can also signal the expectation of something that might be rewarding. This means that as we learn that some things are rewarding, like, say, beer, we begin to respond, not only to the alcohol, but to the cues that alcohol is coming: to the beer bottles, the glass, or the taste. And taste is what this study looked at. The authors took 49 male beer drinkers and divided them up into three groups: those with a family history of alcoholism, those without, and those who didn't know. They used positron emission tomography (PET) to examine how the dopamine in their brains responded to a taste of beer. The big effect? The mere taste of your favourite beer (15 millilitres – not enough to get any effects of the alcohol) produces an increase in dopamine in the ventral striatum, as well as an increased desire to … drink more beer. This suggests that a cue (the taste) produces a sign of reward expectation long before the alcohol hits your system. And the effect of the taste of beer on dopamine in the ventral striatum was larger in people who had a family history of alcohol abuse. What's not to love! It's beer! It's dopamine! It's brain scans! Of course the media got excited. © 2013 Guardian News and Media Limited

Keyword: Drug Abuse; Aggression
Link ID: 18053 - Posted: 04.20.2013

By Puneet Kollipara Brain research has been on a lot of minds lately in the nation’s capital. After offering a brief shout-out to Alzheimer’s research in his February State of the Union address, President Barack Obama went a step further in April by announcing a decade-long effort to develop advanced tools for tracking human brain activity. The administration dubbed it the Brain Research through Advancing Innovative Neurotechnologies initiative, and proposed spending $100 million on the program in the 2014 fiscal year. Scientists have discussed such an endeavor for years, and pushed hard for it in the past few months. Writing March 15 in Science, researchers say the project would develop technologies to probe brain activity on a far greater scale and with higher resolution than is now possible. Current tools can monitor only small numbers of individual neurons at a time or capture blurry, bird’s-eye views of brain activity. The new tools would enable real-time mapping of how the thousands or millions of neurons in coordinated groups, known as circuits, work together. Brain functions — and, in many cases, dysfunctions — are thought to emerge from this still poorly described circuit level. “There’s no way to build a map until you develop the tools,” says Rafael Yuste, a neuroscientist at Columbia University’s Kavli Institute for Brain Science and one of the project’s proponents. Researchers call for developing three sets of tools to better understand brain circuits. One focus is on the creation of tools to measure the activities of all the individual neurons in a circuit. Another is on technologies to experimentally manipulate these neurons. The third tool set would store, analyze and make the data accessible to all researchers. © Society for Science & the Public 2000 - 2013

Keyword: Brain imaging
Link ID: 18046 - Posted: 04.20.2013

By Neuroskeptic A new paper could prompt a rethink of a technique that’s become very hot in neuroscience lately: Confounds in multivariate pattern analysis The authors are Princetonians Michael T. Todd and colleagues, and the method in question is multivariate pattern analysis (MVPA). I’ve written about this before and there’s a blog dedicated to it. MVPA searches for relatively subtle patterns of brain activity, most commonly in fMRI data. For example, a conventional fMRI study might compare activity when someone’s looking at a picture, compared to a blank screen, and would find increases of activity in the visual cortex. But MVPA might take two different pictures, and see if there’s a pattern of activity that’s unique to one picture over the other – even if overall activity in the visual cortex is the same. Neuroscientists have fallen in love with MVPA (and related methods) over the past 5 years, mainly I think because it’s promised to let us ‘read’ the brain: to not just see where in the brain things happen, but to glimpse what information is being represented. In the new paper, Todd et al make a very simple point: all MVPA really shows is that there are places where, in most people’s brain, activity differs when they’re doing one thing as opposed to another. But there infinite reasons why that might be the case, many of them rather trivial. The authors give the example of two very similar tasks, A and B. We’ll say these are imagining apples and imagining bananas. You scan some people doing A and B. You run a standard fMRI analysis, and find that nowhere in the brain shows a difference in activity, on average, between the two (as expected – they are similar.)

Keyword: Brain imaging
Link ID: 18045 - Posted: 04.20.2013

A study by researchers at the National Institutes of Health gives insight into changes in the reward circuitry of the brain that may provide resistance against cocaine addiction. Scientists found that strengthening signaling along a neural pathway that runs through the nucleus accumbens — a region of the brain involved in motivation, pleasure, and addiction — can reduce cocaine-seeking behavior in mice. Research suggests that about 1 in 5 people who use cocaine will become addicted, but it remains unclear why certain people are more vulnerable to drug addiction than others. “A key step in understanding addiction and advancing treatment is to identify the differences in brain connectivity between subjects that compulsively take cocaine and those who do not,” said Ken Warren, Ph.D., acting director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA). Researchers at NIAAA, part of NIH, conducted the study. “Until now, most efforts have focused on finding traits associated with vulnerability to develop compulsive cocaine use. However, identifying mechanisms that promote resilience may prove to have more therapeutic value,” said the paper’s senior author, Veronica Alvarez, Ph.D., acting chief of the Section on Neuronal Structure in the NIAAA Laboratory for Integrative Neuroscience. The study is available on the Nature Neuroscience website ahead of print. In the study, mice were conditioned to receive an intravenous dose of cocaine each time they poked their nose into a hole in their enclosure. Cocaine was then made unavailable for periods of time during the day. Some of the mice would stop seeking the drug once it was removed while others would obsessively continue to poke the hole in an effort to obtain the drug.

Keyword: Drug Abuse; Aggression
Link ID: 18041 - Posted: 04.16.2013