33 items | 2 visits
Martin Wolff's List: Brain
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Most notably, during his 43 years at Columbia, Dr. Holloway has argued that hominid brains began to evolve important anatomical alterations several million years ago, when they were ape-size and had yet to undergo the striking expansion often seen as humanity’s hallmark. We humans are rightly proud of our big brains. But most anthropologists now agree with Dr. Holloway that increases in size alone cannot explain advanced human cognition.
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Drs. Tononi and Cirelli say this weakening of the synapses is a crucial role of sleep, because it restores the brain for the next period of learning. But their ideas run counter to another theory, that brain circuits that were activated during wakefulness become reactivated during sleep, consolidating learning by making these synapses stronger. Now the Wisconsin researchers have produced experimental findings in rats that support their hypothesis.
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To understand the social intelligence of hyenas, Dr. Holekamp and her colleagues track the animals from birth to death. Their work begins in the communal dens where the cubs live for their first few months. Older spotted hyenas pay regular visits to the dens, giving the cubs an opportunity to learn about the rigid hierarchy in which they live. Spotted hyena societies have one dominant female at the top, and a series of hyenas below her. Each cub learns exactly where it fits into the hierarchy, and where all the other spotted hyenas fit as well.
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If the subprime mortgage mess has taught us anything, it is that we are leverage addicts. U.S. consumers spend more than 14 percent of their after-tax income just to stay current on household debt. The question worth asking now is: Why do we love leverage so much that it hurts?... Zweig has studied several experiments examining people's brains when they make personal finance decisions. The results, he said, are surprising. "You would expect logically that the borrowing and spending of money would be emotionally painful to people because having money is intrinsically a good thing, and having less money would have to be worse," he said. "Going from more money to less would be painful." If only that were true.
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Leave it to a vision researcher to make you feel like Mr. Magoo. When Jeremy Wolfe of Harvard Medical School wanted to illustrate how the brain sees the world and how often it fumbles the job, he naturally turned to a great work of art. He flashed a slide of Ellsworth Kelly’s “Study for Colors for a Large Wall†on the screen, and the audience couldn’t help but perk to attention. The checkerboard painting of 64 black, white and colored squares was so whimsically subtle, so poised and propulsive. We drank it in greedily, we scanned every part of it, we loved it, we owned it, and, whoops, time for a test. Dr. Wolfe flashed another slide of the image, this time with one of the squares highlighted. Was the highlighted square the same color as the original, he asked the audience, or had he altered it? Um, different. No, wait, the same, definitely the same. That square could not now be nor ever have been anything but swimming-pool blue ... could it? The slides flashed by. How about this mustard square here, or that denim one there, or this pink, or that black? By the end of the series only one thing was clear: We had gazed on Ellsworth Kelly’s masterpiece, but we hadn’t really seen it at all.
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The most promising therapies, experts say, are based on discoveries made in the last five years about the brain activity of people with tinnitus. With brain-scanning equipment like functional magnetic resonance imaging, researchers in the United States and Europe have independently discovered that the brain areas responsible for interpreting sound and producing fearful emotions are exceptionally active in people who complain of tinnitus.
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“A broad attention span may enable older adults to ultimately know more about a situation and the indirect message of what’s going on than their younger peers,†Dr. Hasher said. “We believe that this characteristic may play a significant role in why we think of older people as wiser.â€
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Jun 05, 08
To see if YOU can detect sarcasm, be sure to watch the 2-minute video associated with this article (Flash Player required).
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The magnetic resonance scans revealed that the part of the brain lost among those who failed to perceive sarcasm was not in the left hemisphere of the brain, which specializes in language and social interactions, but in a part of the right hemisphere previously identified as important only to detecting contextual background changes in visual tests. “The right parahippocampal gyrus must be involved in detecting more than just visual context — it perceives social context as well,†Dr. Rankin said. The discovery fits with an increasingly nuanced view of the right hemisphere’s role, said Dr. Anjan Chatterjee, an associate professor in the Center for Cognitive Neuroscience at the University of Pennsylvania. “The left hemisphere does language in the narrow sense, understanding of individual words and sentences,†Dr. Chatterjee said. “But it’s now thought that the appreciation of humor and language that is not literal, puns and jokes, requires the right hemisphere.â€
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Scientists have investigated such illusions for hundreds of years, looking for clues to how the brain constructs a seamless whole from the bouncing kaleidoscope of light coming through the eyes. Brain researchers today call the illusions perceptual, not optical, because the entire visual system is involved, and their theories about what is occurring can sound as exotic as anyone’s. In the current issue of the journal Cognitive Science, researchers at the California Institute of Technology and the University of Sussex argue that the brain’s adaptive ability to see into the near future creates many common illusions.
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Evolution’s recipe for making a brain more complex has long seemed simple enough. Just increase the number of nerve cells, or neurons, and the interconnections between them. A human brain, for instance, is three times the volume of a chimpanzee’s. A whole new dimension of evolutionary complexity has now emerged from a cross-species study led by Dr. Seth Grant at the Sanger Institute in England.
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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, scientists reported. 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. “This is just about the coolest paper I’ve seen in a long time, and forward-looking in terms of where the science is going,†said Dr. Marcus E. Raichle, a professor of neurology and radiology at Washington University in St. Louis, who was not involved in the research. He added, “They’ve found in the brain what looks like a hub map of the airline system for the United States.â€
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If you want to glimpse the handiwork of one of your body’s unsung sensory heroes, try this little experiment. Hold your index finger a few inches in front of your face and sweep it back and forth at a rate of maybe once or twice a second. What do you see? A blurry finger. Now hold your finger steady and instead shake your head back and forth at the same half-second pace. This time, no blur. The finger stays in focus even as your head vigorously pantomimes its denial. And it’s a good thing, too. If the brain couldn’t distinguish between movements of the viewer and movements of the view, if every time you turned around or walked across the room the scenery appeared to smear or the walls to lurch your way, you soon might cease to move at all, uncertain of external threats, unaided by any internal compass marked You. Essential to a fully embodied sense of self is the vestibular system, a paired set of tiny sensory organs tucked deep into the temporal bone on either side of the head, right near the cochlea of the inner ear.
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As you are reading this article, are you listening to music or the radio? If you are looking at it online, are you e-mailing or instant-messaging at the same time? Since the 1990s, we’ve accepted multitasking without question. Virtually all of us spend part or most of our day either rapidly switching from one task to another or juggling two or more things at the same time. While multitasking may seem to be saving time, psychologists, neuroscientists and others are finding that it can put us under a great deal of stress and actually make us less efficient. Although doing many things at the same time — reading an article while listening to music, switching to check e-mail messages and talking on the phone — can be a way of making tasks more fun and energizing, “you have to keep in mind that you sacrifice focus when you do this,†said Edward M. Hallowell, a psychiatrist and author of “CrazyBusy: Overstretched, Overbooked, and About to Snap!†“Multitasking is shifting focus from one task to another in rapid succession. It gives the illusion that we’re simultaneously tasking, but we’re really not. It’s like playing tennis with three balls.â€
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Dr. Rodolfo Llinás, the chairman of neuroscience and physiology at the New York University School of Medicine, believes that abnormal brain rhythms help account for a variety of serious disorders, including Parkinson’s disease, schizophrenia, tinnitus and depression. His theory may explain why the technique called deep brain stimulation — implanting electrodes into particular regions of the brain — often alleviates the symptoms of movement disorders like Parkinson’s... Unlike neuroscientists who study the brain’s outer layer, or cortex, he has focused his attention on the thalamus, a paired structure in the midbrain. He has found that each walnut-size thalamus has 30 or more nuclei, each of which specializes in one type of information collected from the senses — sights, sounds, movements, external touches, internal feelings and so on.
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Deceitful behavior has a long and storied history in the evolution of social life, and the more sophisticated the animal, it seems, the more commonplace the con games, the more cunning their contours. In a comparative survey of primate behavior, Richard Byrne and Nadia Corp of the University of St. Andrews in Scotland found a direct relationship between sneakiness and brain size.
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The man, a doctor left blind by two successive strokes, refused to take part in the experiment. He could not see anything, he said, and had no interest in navigating an obstacle course — a cluttered hallway — for the benefit of science. Why bother? When he finally tried it, though, something remarkable happened. He zigzagged down the hall, sidestepping a garbage can, a tripod, a stack of paper and several boxes as if he could see everything clearly. “You just had to see it to believe it,†said Beatrice de Gelder, a neuroscientist at Harvard and Tilburg University in the Netherlands, who with an international team of brain researchers reported on the patient in the journal Current Biology.
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Spikes in blood sugar can take a toll on memory by affecting the dentate gyrus, an area of the brain within the hippocampus that helps form memories, a new study reports. Researchers said the effects can be seen even when levels of blood sugar, or glucose, are only moderately elevated, a finding that may help explain normal age-related cognitive decline, since glucose regulation worsens with age.
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Researchers at the University of British Columbia conducted tests with 600 people to determine whether cognitive performance varied when people saw red or blue. Participants performed tasks with words or images displayed against red, blue or neutral backgrounds on computer screens.
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Most human vices have enough sense to be very, very tempting. One vice, however, dispenses with any hedonistic trappings and instead feels so painful you would think it was a virtue, except that there’s no gain in lean muscle mass at the end: envy. Skulking at sixth place on traditional lists of the seven deadly sins, right between wrath and pride, envy is the deep, often hostile resentment you feel toward somebody who has something you want, like wealth, beauty, a promotion or the admiration of peers. “Envy is corrosive and ugly, and it can ruin your life,†said Richard H. Smith, a professor of psychology at the University of Kentucky who has written about envy. “If you’re an envious person, you have a hard time appreciating a lot of the good things that are out there, because you’re too busy worrying about how they reflect on the self.†Now researchers are gleaning insights into the neural and evolutionary underpinnings of envy, and why it can feel like a bodily illness or a physical blow. They’re also tracing the pathway of envy’s equally petty foil, the sensation of schadenfreude — taking pleasure when those whom you envied are themselves brought down low.
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Humans operate in a tiny range of preferred internal temperatures. We can tolerate overcooling, routinely recovering from long periods of hypothermia with body temperatures diving 20 or more degrees below normal. But we have little tolerance for even brief overheating: the brain malfunctions with six or seven degrees of fever, and an internal temperature of 110, barely a dozen degrees above normal, is often cited as the upper limit compatible with life.
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