Links for Keyword: Brain imaging

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.

Links 81 - 100 of 269

Tiffany O'Callaghan A miniaturized positron emission tomography (PET) scanner has opened a fresh window for research into behaviour and brain function simultaneously. The 'wearable' PET, known as the RatCAP, was developed by a team of researchers led by physicist Paul Vaska at Brookhaven National Laboratory in Upton, New York, and allows scans on animals that are awake and moving around. The findings are published online today in Nature Methods. PET uses radioactive tracers to show the metabolism of chemicals in the body in real time. It is a key tool for examining organ function, evaluating blood flow, diagnosing cancer early and researching neurological conditions from Alzheimer's disease to epilepsy. But PET use for behavioural research in animals has been limited — whereas humans can lie still during a PET scan, enabling analysis while they are awake, it is a lot trickier to get animals to do as they're told. That largely limits the use of PET to anaesthetized animals, ruling out simultaneous behavioural studies. The tiny PET developed by the team attaches to the rat's head using a bracket screwed onto the skull, has an inner diameter of 38 mm and weighs just 250 g. For a rat, that is still pretty heavy — nearly the weight of an adult male rat — so to optimize the rat's movement while wearing the RatCAP, the team attached the device to a system of long springs and motion stabilisers fastened to the top of the observation chamber to reduce the weight and allow rat movement. © 2011 Nature Publishing Group,

Related chapters from BP6e: 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: 15101 - Posted: 03.14.2011

Complete circuit map of mammal brain chunk revealed

Jessica Hamzelou, reporter This overlapping rainbow of connecting cells represents new insights into how mammalian brains work. The techniques used to create this three-dimensional map of a tiny chunk of mouse brain could help neuroscientists understand the connections that make up our own brains. To create this map - which shows the neurons in a piece of mouse visual cortex just 8 thousandths of a cubic millimetre in volume - Clay Reid and his colleagues at Harvard Medical School in Boston combined two imaging techniques. First, the group measured the activity of neurons in the visual cortex of a living mouse in order to spot the cells that were excited by visual information. They then killed the mouse and cut the visual cortex into 1215 slices, before using an electron microscope to capture more than 3 million images of the slices. Finally they stitched the pictures together to form this 3D image using a computer capable of handling the 30 to 40 terabytes of information. That was the relatively easy part. Next, Reid's team painstakingly traced all of the connections made by 10 of the neurons that were active in the first stage of the study. That involved tracing 240 axons and dendrites through the tangled mess created by other axons and dendrites in the 3D image. The results are already shedding light on the detailed behaviour of the brain. The team found that neurons that inhibit brain activity received input from all the excitatory neurons in the chunk. That finding offers new insight into the debate over whether these neurons receive specific or random inputs, and may inform research into conditions characterised by a lack of brain activity inhibition, such as epilepsy, says Reid. © Copyright Reed Business Information Ltd.

Coma brain image techniques being developed in Aberdeen

Brain imaging techniques to find out more about patients in a coma are being developed by University of Aberdeen scientists. The new Aberdeen Coma Science Group - believed to be the first of its kind in Scotland - hopes to provide greater insights into coma patient awareness. This would be used to help guide treatment and provide information for relatives and clinicians. North east of Scotland patients will initially assist the research. The scanning technique is called functional MRI - fMRI. Prof Christian Schwarzbauer is leading the work, which will involve patients being given fMRI scans while exposed to stimuli such as pictures, sounds, smell and touch. He said: "Thanks to advances in medical care our chances of surviving a severe accident are much higher than they used to be. "Doctors can save the lives of many patients who suffer brain injury, but, if the injury is severe, the patient may not regain consciousness and slip into a coma. "Some will regain consciousness but others will remain in a so-called vegetative state. With their eyes open and possibly even wandering, these patients appear to be awake but show no signs of awareness of themselves or their environment." BBC © MMXI

Related chapters from BP6e: 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: 15093 - Posted: 03.10.2011

Researchers develop ‘camera’ that will show your mind

MICHAEL POSNER Among the great enigmas of human existence, few have proven so intractable as the human brain. Neuroscientist V.S. Ramachandran says our current understanding of the body’s most complex organ approximates what we knew about chemistry in the 19th century: in short, not much. On a scale of 100, estimates Toronto psychiatrist Colin Shapiro, our comprehension of how the brain actually functions ranks at a lowly 2. Now, two Toronto doctors, a general practitioner and a medical biophysicist, are laying claim to a research innovation that could expand our knowledge exponentially. Using one of the earliest imaging technologies, the electroencephalograph (EEG), Mark Doidge and Joseph Mocanu have written software that creates dynamic, real-time, three-dimensional colour movies of the brain. If their research is validated, it could revolutionize neuroscience – and, not incidentally, make them a fortune. But while the software is proven, its application to medical treatment has yet to be clinically tested in traditional, double-blind studies. “We usually think of cameras as looking out at the world,” Dr. Doidge said. “This is a new kind of camera. It gives you a window on your mind.” It’s not a camera in the conventional sense. Instead, adapting an algorithm known as eLORETA, the software amplifies EEG signals from 32 electrodes attached to the cerebral cortex, and converts them into colour-coded movies of neuronal activity. In a brain divided in more than 6,200 voxels (3D pixels), the algorithm infers and maps where electrical events are occurring. The movie can then be watched in real time, recorded and played back on computer screens. © Copyright 2011 The Globe and Mail Inc.

Fly brain structure illuminated

Joseph Milton Fly brains have never looked so good. Spectacular images of the insects' complex neural circuitry have now been produced using a pair of techniques that allow individual nerve-cell lineages to be visualized using a range of colours. Both methods are adaptations of the 'Brainbow' techniques devised at Harvard University in Cambridge, Massachusetts, to visualize mouse neurons, and reported in Nature in 20071. "We were inspired by the elegance of the Brainbow approach," says Iris Salecker, a neuroscientist at the National Institute for Medical Research in London, who worked on one of the fruitfly methods. The new techniques, reported in two papers published online today in Nature Methods23, involve inserting strings of genes into the neurons of Drosophila melanogaster embryos. Each gene produces a different fluorescent colour, lighting up individual neurons, or even all of the cells descended from an embryonic neuron - because they will carry the same gene and therefore be the same colour. Both techniques result in colourful visualizations that allow all the nerve cells in any one lineage to be distinguished and their development traced, illuminating how neural circuits develop and interact. The string includes a selection of colour-producing genes, but only one gene is active in each modified nerve cell — the one closest to a region of DNA called a promoter. As the strings are identical, all the modified neurons would be the same colour, and would be impossible to separate visually. © 2011 Nature Publishing Group,

5 Questions for a Mind-Reader Who Ran Into the Brain's Limits

by Valerie Ross Jesse Rissman cannot read your mind—but he’s working on it. A postdoctoral memory researcher at Stanford University, Rissman is studying how much fMRI scans (which measure activity in the brain) can reveal about what a person is thinking. Along the way, he is raising a big red flag to those who want to use brain scans to peer into the heads of suspected criminals. What got you interested in brain scans in the courtroom? In India, a woman was convicted of murder using a technology that recorded electrical activity from the scalp while she was viewing or listening to materials related to the crime. When I learned more about the tests and how widely they were being used in the Indian legal system, I realized these techniques need to be evaluated in a more rigorous way. How do you look for memories? We had people study photographs of faces. Then, while they were in an fMRI scanner, we showed them those faces again, interspersed with new ones, and they had to judge whether they recognized each face. Then we used a computer algorithm to identify neural signatures associated with recognition and those associated with the experience of something new. Can you identify a person’s memories from such scans? We could tell quite reliably whether people thought each face was familiar or new, but we couldn’t tell the true status of the memory. When we tried to distinguish faces the person had seen from those he hadn’t, we were correct less than 60 percent of the time. There are many reasons memories may not properly form. The person may not be paying attention, may be under the influence of a substance, may be drowsy—and memories are forgotten over time. The idea that our brain contains a veridical record of our experiences is, I think, fanciful. Copyright © 2011, Kalmbach Publishing Co.

Related chapters from BP6e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 14956 - Posted: 02.05.2011

Brain Scan Can Tell if You'll Quit Smoking

Researchers have found a way to predict how successful a smoker will be at quitting by using an MRI scan to look for activity in a region of the brain associated with behavior change. The scans were performed on 28 heavy smokers who had joined an anti-smoking program, according to the study published Monday in the peer-reviewed journal Health Psychology. Participants were asked to watch a series of commercials about quitting smoking while a magnetic resonance imaging machine scanned their brains for activity. After each ad, subjects in the study "rated how it affected their intention to quit, whether it increased their confidence about quitting, and how much they related to the message," researchers explained. Those who showed activity in the medial prefrontal cortex during the ads were "significantly linked to reductions in smoking behavior" in the month that followed, regardless of how the people said they were affected by the ad. "What is exciting is that by knowing what is going on in someone's brain during the ads, we can do twice as well at predicting their future behavior, compared to if we only knew their self-reported estimate of how successful they would be or their intention to quit," said lead author Emily Falk. "It seems that our brain activity may provide information that introspection does not," added Falk, director of the Communication Neuroscience Laboratory at the University of Michigan. 4 © 2011 Discovery Communications, LLC.

Neuroscience: Thought experiment

David Cyranoski In a room full of psychiatrists in downtown Tokyo, I prepare to have my mental health assessed. No probing questions are asked. Instead, I don an odd type of swimming cap, criss-crossed with cables and studded with red and blue knobs. At the flick of a switch, the 17 red knobs send infrared light 2 to 3 centimetres into my brain, where it is absorbed or scattered by neurons. Photoreceptors in the 16 blue knobs retrieve whatever light bounces back to the surface. Buried in the signals, say the researchers operating the system, are clues that can distinguish depression, bipolar disorder, schizophrenia and a normal state of mind. More than 1,000 people have already been subjects of the technique, called near-infrared spectroscopy (NIRS) and developed by Masato Fukuda, a psychiatrist and neuroscientist at Gunma University Hospital in Maebashi, and the Hitachi Medical Corporation in Tokyo. Most of those were research subjects. But since April 2009, when NIRS was approved by the health ministry as an "advanced medical technology" to assist psychiatric diagnoses, more than 300 people have paid ¥13,000 (US$160) out of their own pocket to access the technique. The University of Tokyo Hospital, one of eight leading Japanese research hospitals now offering NIRS diagnostic neuroimaging, found demand for it to be so high that the hospital stopped taking appointments twice. Gunma University Hospital is fully booked to the end of March. "We've been overwhelmed by requests," says Fukuda. The appeal of NIRS is its promise of fast, clear-cut diagnoses of psychiatric conditions which, with their messily overlapping symptoms, are frequently diagnosed wrongly or not diagnosed at all. US studies, for example, found that some 70% of bipolar patients were initially misdiagnosed1,2. As for patients, says Fukuda, "They want some kind of hard evidence," especially when they have to explain absences from work. © 2011 Nature Publishing Group,

Lost your libido? Let's try a little neuro-realism, madam

Ben Goldacre When the BBC tells you, in a headline, that libido problems are in the brain and not in the mind, you might find yourself wondering what the difference between the two is supposed to be, and whether a science article can really be assuming – in 2010 – that its readers buy into a strange Cartesian dualism in which the self is contained by a funny little spirit entity in constant and elaborate pneumatic connection with the corporeal realm. But first let's consider the experiment they're reporting on. As far as we know (because this experiment has not yet been published, only presented at a conference), some researchers took seven women with a "normal" sex drive, and 19 women diagnosed with "hypoactive sexual desire disorder". Participants watched a series of erotic films in a scanner while an MRI machine took images of blood flow in their brains: the women with a normal sex drive had an increased flow of blood to some parts of their brain associated with emotion, while those with low libido did not. Dr Michael Diamond, one of the researchers, tells the Mail: "Being able to identify physiological changes, to me provides significant evidence that it's a true disorder as opposed to a societal construct". In the Metro, he goes further: "Researcher Dr Michael Diamond said the findings offer 'significant evidence' that persistent low sex drive – known as hypoactive sexual desire disorder (HSDD) – is a genuine physiological disorder and not made up." © Guardian News and Media Limited 2010

Related chapters from BP6e: Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 2: Cells and Structures: The Anatomy of the Nervous System; Chapter 8: Hormones and Sex
Link ID: 14617 - Posted: 11.02.2010

On a quest to map the brain’s hidden territory

By Carolyn Y. Johnson The black-and-white brain scans that have become a routine part of medicine reveal a curved gray structure folded around large lakes of white — a map that helps doctors diagnose, treat, and understand disease. But to some scientists, these images are crude and incomplete, akin to medieval maps of the world in which unexplored regions were filled in with sea monsters or dragons. “It’s like there’s a continent there, and we are nibbling along the shores,’’ said Dr. Van Wedeen, a physicist and radiologist at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital. He is helping to lead an effort to develop a superscanner that can reveal that unknown territory and provide new insight into the brain. On a recent morning, Wedeen pulled up images created with the new technology, in which the lakes of white were crisscrossed by colorful, ropy bundles of fibers, revealing an elegant, three-dimensional architecture. Looking more like art than anatomy, these strands form the connections in the brain — the “connectome.’’ They are neural highways crucial for brain function, including thoughts, movements, and sensations. “This isn’t just statistical stuff, or mush, or steel wool, or chaotic spaghetti,’’ Wedeen said. “This is as important a structure as you’re ever going to meet, and this thing had to be designed by evolution.’’ © 2010 NY Times Co.

Mapping the Brain on a Massive Scale

By Emily Singer A massive new project to scan the brains of 1,200 volunteers could finally give scientists a picture of the neural architecture of the human brain and help them understand the causes of certain neurological and psychological diseases. The National Institutes of Health announced $40 million in funding this month for the five-year effort, dubbed the Human Connectome Project. Scientists will use new imaging technologies, some still under development, to create both structural and functional maps of the human brain. The project is novel in its size; most brain-imaging studies have looked at tens to hundreds of brains. Scanning so many people will shed light on the normal variability within the brain structure of healthy adults, which will in turn provide a basis for examining how neural "wiring" differs in such disorders as autism and schizophrenia. The researchers also plan to collect genetic and behavioral data, testing participants' sensory and motor skills, memory, and other cognitive functions, and deposit this information along with brain scans in a public database (although the patients' personal information will be stripped out). Scientists around the world can then use the database to search for the genetic and environmental factors that influence the structure of the brain. © 2010 Technology Review.

Mind-reading marketers have ways of making you buy

by Graham Lawton and Clare Wilson Why ask people what they think of a product when you can just scan their brains instead? New Scientist explores the brave new world of neuromarketing TAKE A look at the cover of this week's New Scientist magazine (right). Notice anything unusual? Thought not, but behind the scenes your brain is working overtime, focusing your attention on the words and images and cranking up your emotions and memory. How do we know? Because we tested it with a brain scanner. In what we suspect is a world first, this week's cover was created with the help of a technique called neuromarketing, a marriage of market research and neuroscience that uses brain-imaging technology to peek into people's heads and discover what they really want. You may find that sinister. What right does anyone have to try to read your mind? Or perhaps you are sceptical and consider the idea laughable. But neuromarketing, once dismissed as a fad, is becoming part and parcel of modern consumer society. So we decided to take a good look at it - and try it out ourselves. That is how several New Scientist readers ended up in a darkened room in London, wired up to an electroencephalograph (EEG) machine and being shown various magazine cover designs. Our aim - with the help of the European arm of neuromarketing company NeuroFocus, based in Berkeley, California - was to observe their reactions on a level that would not normally be possible. "I've been involved in market research for about 25 years," says Thom Noble, managing director of NeuroFocus Europe. "Every few years a new methodology comes out. Frankly, they're incrementally different. This is transformationally different." © Copyright Reed Business Information Ltd.

After Stroke Scans, Patients Face Serious Health Risks

By WALT BOGDANICH When Alain Reyes’s hair suddenly fell out in a freakish band circling his head, he was not the only one worried about his health. His co-workers at a shipping company avoided him, and his boss sent him home, fearing he had a contagious disease. Only later would Mr. Reyes learn what had caused him so much physical and emotional grief: he had received a radiation overdose during a test for a stroke at a hospital in Glendale, Calif. Other patients getting the procedure, called a CT brain perfusion scan, were being overdosed, too — 37 of them just up the freeway at Providence Saint Joseph Medical Center in Burbank, 269 more at the renowned Cedars-Sinai Medical Center in Los Angeles and dozens more at a hospital in Huntsville, Ala. The overdoses, which began to emerge late last summer, set off an investigation by the Food and Drug Administration into why patients tested with this complex yet lightly regulated technology were bombarded with excessive radiation. After 10 months, the agency has yet to provide a final report on what it found. But an examination by The New York Times has found that radiation overdoses were larger and more widespread than previously known, that patients have reported symptoms considerably more serious than losing their hair, and that experts say they may face long-term risks of cancer and brain damage. Copyright 2010 The New York Times Company

NIH Launches the Human Connectome Project to Unravel the Brain’s Connections

The National Institutes of Health Blueprint for Neuroscience Research is launching a $30 million project that will use cutting-edge brain imaging technologies to map the circuitry of the healthy adult human brain. By systematically collecting brain imaging data from hundreds of subjects, the Human Connectome Project (HCP) will yield insight into how brain connections underlie brain function, and will open up new lines of inquiry for human neuroscience. Investigators have been invited to submit detailed proposals to carry out the HCP, which will be funded at up to $6 million per year for five years. The HCP is the first of three Blueprint Grand Challenges, projects that address major questions and issues in neuroscience research. The Blueprint Grand Challenges are intended to promote major leaps in the understanding of brain function, and in approaches for treating brain disorders. The three Blueprint Grand Challenges to be launched in 2009 and 2010 address: * The connectivity of the adult, human brain * Targeted drug development for neurological diseases * The neural basis of chronic pain disorders Scientists have studied the relationship between the structure and function of the human brain since the 1800s. Some parts of the brain serve basic functions such as movement, sensation, emotion, learning and memory. Others are more important for uniquely human functions such as abstract thinking. The connections between brain regions are important for shaping and coordinating these functions, but scientists know little about how different parts of the human brain connect.

The Scan That Didn’t Scan

By GINA KOLATA This is a story about M.R.I.’s, those amazing scans that can show tissue injury and bone damage, inflammation and fluid accumulation. Except when they can’t and you think they can. I found out about magnetic resonance imaging tests when I injured my forefoot running. All of a sudden, halfway through a run, my foot hurt so much that I had to stop. But an M.R.I. at a local radiology center found nothing wrong. That, of course, was what I wanted to hear. So I spent five days waiting for it to feel better, taking the anti-inflammatory drugs ibuprofen and naproxen, using an elliptical cross-trainer, and riding my road bike with its clipless pedals that attach themselves to my bicycling shoes. By then, my foot hurt so much I had to walk on my heel. I was beginning to doubt that scan: it was hard to believe nothing was wrong. So I went to the Hospital for Special Surgery in New York for a second opinion from Dr. John G. Kennedy, an orthopedist who specializes in sports-related lower-limb injuries. And there I had another M.R.I. It showed a serious stress fracture, a hairline crack in a metatarsal bone in my forefoot. It was so serious, in fact, that Dr. Kennedy warned that I risked surgery if I continued activities like cycling and the elliptical cross-trainer, which make such injuries worse. And I had to stop taking anti-inflammatory drugs, since they impede bone healing. Copyright 2008 The New York Times Company

Scientists Identify the Brain’s Activity Hub

By BENEDICT CAREY The outer layer of the brain, the reasoning, planning and self-aware region known as the cerebral cortex, has a central clearinghouse of activity below the crown of the head that is widely connected to more-specialized regions in a large network similar to a subway map, scientists reported Monday. The new report, published in the free-access online journal PLoS Biology, provides the most complete rough draft to date of the cortex’s electrical architecture, the cluster of interconnected nodes and hubs that help guide thinking and behavior. The paper also provides a striking demonstration of how new imaging techniques focused on the brain’s white matter — the connections between cells, rather than the neurons themselves — are filling in a dimension of human brain function that has been all but dark. In previous studies, scientists have used magnetic resonance imaging to identify peaks and valleys of neural activity when people are doing various things, like making decisions, reacting to frightening images or reliving painful memories. But these studies, while provocative, revealed virtually nothing about the underlying neural networks involved — about which brain regions speak to one another and when. Previous estimates of network structure, based on such imaging, have been sketchy. The new findings, while not conclusive, give scientists what is essentially a wiring diagram that they can test and refine. Copyright 2008 The New York Times Company

Related chapters from BP6e: 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: 11762 - Posted: 06.24.2010

Neural Light Show: Scientist Use Genetics to Map and Control Brain Functions

By Gero Miesenböck In 1937 the great neuroscientist Sir Charles Scott Sherrington of the University of Oxford laid out what would become a classic description of the brain at work. He imagined points of light signaling the activity of nerve cells and their connections. During deep sleep, he proposed, only a few remote parts of the brain would twinkle, giving the organ the appearance of a starry night sky. But at awakening, “it is as if the Milky Way entered upon some cosmic dance,” Sherrington reflected. “Swiftly the head-mass becomes an enchanted loom where millions of flashing shuttles weave a dissolving pattern, always a meaningful pattern though never an abiding one; a shifting harmony of subpatterns.” Although Sherrington probably did not realize it at the time, his poetic metaphor contained an important scientific idea: that of the brain revealing its inner workings optically. Understanding how neurons work together to generate thoughts and behavior remains one of the most difficult open problems in all of biology, largely because scientists generally cannot see whole neural circuits in action. The standard approach of probing one or two neurons with electrodes reveals only tiny fragments of a much bigger puzzle, with too many pieces missing to guess the full picture. But if one could watch neurons communicate, one might be able to deduce how brain circuits are laid out and how they function. This alluring notion has inspired neuroscientists to attempt to realize Sherrington’s vision. © 1996-2008 Scientific American Inc

Scanning Dead Salmon in fMRI Machine Highlights Risk of Red Herrings

By Alexis Madrigal Email Author Neuroscientist Craig Bennett purchased a whole Atlantic salmon, took it to a lab at Dartmouth, and put it into an fMRI machine used to study the brain. The beautiful fish was to be the lab’s test object as they worked out some new methods. So, as the fish sat in the scanner, they showed it “a series of photographs depicting human individuals in social situations.” To maintain the rigor of the protocol (and perhaps because it was hilarious), the salmon, just like a human test subject, “was asked to determine what emotion the individual in the photo must have been experiencing.” The salmon, as Bennett’s poster on the test dryly notes, “was not alive at the time of scanning.” methodsIf that were all that had occurred, the salmon scanning would simply live on in Dartmouth lore as a “crowning achievement in terms of ridiculous objects to scan.” But the fish had a surprise in store. When they got around to analyzing the voxel (think: 3-D or “volumetric” pixel) data, the voxels representing the area where the salmon’s tiny brain sat showed evidence of activity. In the fMRI scan, it looked like the dead salmon was actually thinking about the pictures it had been shown. “By complete, random chance, we found some voxels that were significant that just happened to be in the fish’s brain,” Bennett said. “And if I were a ridiculous researcher, I’d say, ‘A dead salmon perceiving humans can tell their emotional state.’” © 2009 Cond� Nast Digital.

Mind-reading with a brain scan

Kerri Smith Scientists have developed a way of ‘decoding’ someone’s brain activity to determine what they are looking at. “The problem is analogous to the classic ‘pick a card, any card’ magic trick,” says Jack Gallant, a neuroscientist at the University of California in Berkeley, who led the study. But while a magician uses a ploy to pretend to ‘read the mind’ of the subject staring at a card, now researchers can do it for real using brain-scanning instruments. “When the deck of cards, or photographs, has about 120 images, we can do better than 90% correct,” says Gallant. The technique is a step towards being able to see the contents of someone’s visual experiences. “You can imagine using this for dream analysis, or psychotherapy,” says Gallant. Already the results are helping to provide neuroscientists with a more accurate model of how the human visual system works. If the work can be broadened to developing more general models of how the brain responds to things beyond visual stimuli, such brain scans could help to diagnose disease or monitor the effects of therapy. © 2008 Nature Publishing Group

Brain scans now catch chemicals too

by Ewen Callaway A chemical produced during sex and linked to addiction has been visualised in a scanner as it washes across rats' brains. The feat means that functional magnetic resonance imaging (fMRI), a workhorse of neuroscience, can now be used to observe the flow of brain chemicals, not just oxygen-rich blood. By pinpointing increases in blood oxygenation in the brain in response to different events – a sign that specific groups of neurons are active – fMRI is responsible for some of the hottest findings about the brain. Now Alan Jasanoff at the Massachusetts Institute of Technology and colleagues have extended its power. His team repeatedly mutated a magnetic, iron-containing enzyme that "lights up" in fMRI readings. With each mutation, the researchers tested its tendency to bind to dopamine, a learning and reward chemical in the brain involved in sex and addictive behaviours. Mutations that increased this tendency were combined, resulting in a molecule that was both magnetic and strongly attracted to dopamine. The team injected the molecule into the brains of rats, in a region laden with dopamine-producing cells. When given a chemical that triggers dopamine release, that area "lit up" under fMRI. Because the molecule must be injected into the brain, this kind of chemical-based fMRI won't be applied to humans anytime soon, says Jasanoff, but it could be used to probe addiction and disease using animals. © Copyright Reed Business Information Ltd

Previous Page | Next Page

Links By Chapter:

Links for Keyword: Brain imaging