Some migratory birds that have to navigate across continents have an extremely useful tool at their disposal–an internal compass that points unerringly towards magnetic north. Researchers already knew that some birds possess these biological compasses, but their mechanism has been unclear. “This is basically the sixth sense of biology, but no one knows how it works…. The magnetic sense is by far the least understood sense in the natural world,” [Science News], says study coauthor Henrik Mouritsen.
Now, researchers have determined that light-sensing cells in the eye convey the crucial message to a special visual center of a robin’s brain, called cluster N. Special proteins called cryptochromes in the birds’ eyes may mediate this light-dependent magnetic sensing, Mouritsen says. Light hitting the proteins produces a pair of free radicals, highly reactive molecules with unpaired electrons. These electrons have a property called spin which may be sensitive to Earth’s magnetic field. Signals from the free radicals may then move to nerve cells in cluster N, ultimately telling the birds where north is [Science News].
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Phantom limb syndrome is an eerie condition, in which amputees have the physically painful sensation that their missing limbs are still present. Now, a small new study has shown that people can twist those ghostly limbs in anatomically impossible ways, while still feeling that the limb is real and present. In essence, each amputee’s brain reshaped his understanding of where his body was. The findings show that the brain can alter how we perceive our bodies all by itself, without input from our senses [Reuters].
Researchers had patients with “vivid phantoms” try to move their wrists in a physically impossible way—a 360 degree spin of the wrist around the long axis of the forearm—and found that 4 of the 7 patients could move their wrists this way. Some patients that were able to move their wrists later reported that their phantom hands were now more difficult to move from side to side because of changes in their phantom arms’ shapes.
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Snooty wine pairing rules, such as the edict that one must only drink white wine with fish, now have a little data behind them, according to a new study. Researchers found a correlation between the high iron content of red wine and a nasty, fishy aftertaste when the reds are sipped with seafood. In the experiment, tasters ate a bit of scallop, tasted some wine and evaluated the aftertaste on a scale of 1 to 4. The diners found the unpleasant aftertaste was more intense with wines that had a higher iron content, the researchers say [Los Angeles Times]. The researchers were able to block the aftertaste by adding a compound that masks the iron.
The iron content of a wine depends on the composition of the soil in which the grapes were grown, the dust on the berry, contamination during harvesting, transportation, and crushing, and the conditions during fermentation [Telegraph]. The new research, published in Journal of Agricultural and Food Chemistry, suggests that some low-iron red wines are OK to drink with fish. While red wines tend to have more iron than whites, it varies according to the type of grape, country of origin, and vintage.
But the iron is only half the story. The researchers report that they haven’t yet isolated the compound in the scallops that reacts with the wine, but they suspect it’s an unsaturated fatty acid, which could be breaking down rapidly and releasing the decaying fish smell when exposed to iron [ScienceNOW Daily News].
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Scientists who have been investigating the link between professional football and severe brain damage have a troubling new piece of evidence: The brain of a deceased man who stopped playing football after college also showed the distinctive signs of damage. The man, the former Western Illinois wide receiver Mike Borich, died at 42 of a drug overdose in February after a downward spiral of depression and substance abuse that is generally associated with the type of tissue damage found in his brain [The New York Times].
The findings suggest that the damage isn’t only associated with professional football players who have played at the highest level of competition for years, but might be a fundamental byproduct of the sport itself. The cumulative effect of the many blows to the head that many football players experience may simply be too much for the brain to handle, researchers say.
Several neuroscientists have been investigating football players with a condition called chronic traumatic encephalopathy (C.T.E.). Scientific progress is slow because the condition can only be diagnosed after death, when the brains donated by players can be sliced, stained, and examined for protein deposits and fibrous tangles. So far, researchers have identified C.T.E. in eight NFL players who died between the ages of 36 and 52–many of whom had extreme emotional problems in their last years. It has been found in every player of those ages examined by the two groups doing such research [The New York Times].
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Researchers have found a pharmaceutical way to clear some of the cognitive fog that results from a sleepless night. In a new study using lab mice, researchers corrected the memory problems in sleep-deprived mice through a drug that suppressed levels of a certain enzyme in a brain region called the hippocampus, which plays an important role in memory and learning.
The study, published in Nature, helps tease out the specific effects of sleep deprivation on the brain. Says lead researcher Christopher Vecsey: “One of the main problems is that sleep deprivation does a lot of things to the brain, and it’s easy to get caught in a mish-mash of different effects” [Nature News].
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The next time a friend says he’s addicted to bacon, you should know he probably isn’t joking. The brains of rats fed only on junk food—like bacon, Ho Hos, cheesecake, and sausage—look similar to the brains of heroin-addicted rats, according to new a study. Pleasure centers in the brains of rats addicted to high-fat, high-calorie diets became less responsive as the binging wore on, making the rats consume more and more food [Science News]. The findings suggest that drug addiction and overeating have similar biological mechanisms, according to the scientists from the Scripps Research Institute. The work is not yet published, but was presented at the Society for Neuroscience’s annual meeting.
The rats fed on junk food displayed a hallmark of addiction. After just five days on the junk food diet, rats showed “profound reductions” in the sensitivity of their brains’ pleasure centers, suggesting that the animals quickly became habituated to the food. As a result, the rats ate more food to get the same amount of pleasure. Just as heroin addicts require more and more of the drug to feel good, rats needed more and more of the junk food [Science News]. To test the depths of the rats addiction, researchers shocked rats every time they ate junk food. Rats that had not previously binged on Ho Hos quickly stopped eating the high-fat foods. However, the fat rats kept eating junk food even though they knew the shock was coming. Now that’s an addiction.
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It sounds like a scene from an insect version of Total Recall: Using genetically engineered fruit flies and laser beams, researchers have found a way to embed false, fearful memories in the flies.
Researchers first tested normal flies in a chamber where a jets of air on either side brought two different odors into the container. The researchers delivered an electric shock each time a fly strayed into a particular odour stream, which taught the flies to prefer the other one: the flies learned to move in the direction of the shock-related odour 30 per cent less often [New Scientist].
Next, the researchers created a strain of genetically engineered flies with certain neurons that would be activated by a laser blast. Lead researcher Gero Miesenböck explains that with this technique, called optogenetics, researchers can use light to activate particular cell types that have been genetically engineered to express a light-responsive protein. When laser pulses hit the brain, cells expressing the light-sensitive protein activate. “It’s like sending a radio signal to a city but only those houses with a radios set to the right frequency will get the signal,” says Miesenböck [Nature News].
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A curious experiment has given scientists an unprecedented look into the human brain as it goes about a vital and everyday task: processing and speaking words. The study, published in Science, found that the brain carries out three steps of the task in about half a second, and that all the activity happens sequentially in the same small brain region, known as Broca’s area.
The researchers took advantage of a rare procedure in which epilepsy patients allow doctors to implant dozens of electrodes directly into their brains. While they are awake, the patients answer questions so that doctors can determine which parts of the brain are necessary to maintain language and which parts can be safely removed to treat epileptic seizures [Los Angeles Times]. Three such patients agreed to take part in the language experiment, were given long lists of verbs, and were asked to change some of them to the past or present tense before saying them out loud.
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Cracking open a cold can of Coke and taking a bubbling swig will have your taste buds dancing—and now scientists know why. A new study shows that cells in taste buds that respond to sour stimuli also seem to be the ones responsible for tasting the carbonation’s fizz [NPR].The fact that we can taste the carbon dioxide in a fizzing soda has previously puzzled scientists, since the human tongue is usually thought to only sense five flavors—bitter, sweet, salty, sour, and umami (also called savory). However, the new study, published in Science, shows that the sour taste buds have an enzyme that interacts with carbon dioxide, so it’s not the bursting bubbles that you taste, it’s the C02 itself.
The researchers discovered this tricky bit of chemistry by studying mice. They gave the animals sips of club soda or a little buzz of carbon dioxide gas and recorded how the tongue signaled the sensation to the brain. Both soda and the gas produced similar sensations. But when they tested mice bred to have no sour taste buds, the brain never got its sensory alert. Further probing uncovered the enzyme responsible [AP]. The mechanism should be the same in humans, according to the scientists.
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Here’s some gratifying news for any employees out there who are feeling bullied by a tyrannical boss: That aggressive behavior may have little to do with you, and a lot to do with your boss’s feelings of incompetence. A new study in Psychological Science found that when managers are made to feel insecure about their job performance, their aggressiveness skyrockets. “Power holders feel they need to be superior and competent. When they don’t feel they can show that legitimately, they’ll show it by taking people down a notch or two” [New Scientist], says study coauthor Nathanael Fast.
The researchers got 410 volunteers from various workplaces to fill out questionnaires about their position in the workplace hierarchy, how they felt about their job performance, and their aggressive tendencies. They also conducted a series experiments on the volunteers. In one, they manipulated the subjects’ sense of power and self-worth by asking them to write about occasions when they felt either empowered or impotent and then either competent or incompetent. Previous research has suggested that such essays cause a short-term bump or drop in feelings of power and capability [New Scientist]. Next they asked the volunteers to set the level of punishment for (imaginary) university students who got wrong answers on a test. Those people who felt more powerful and more incompetent picked the harshest punishments, the study found.
So what’s to be done with a bullying boss? Coauthor Serena Chen says a little ego stroking may make life easier for everyone. “Make them feel good about themselves in some way,” Chen said, suggesting this might mean complimenting a hobby or nonwork activity provided it is “something plausible that doesn’t sound like you’re sucking up” [San Francisco Chronicle].
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Humans typically feel uneasy when they see a very realistic human-looking robot or computer avatar, a phenomenon called the “uncanny valley” response. According to a new study performed with monkeys, that reaction might have an evolutionary basis.
Researchers hypothesize that the response stems from almost realistic images that signal HUMAN! to us, but then fail to live up to the initial excitement. The uncanny valley response has been documented in humans since the 1970s, and has been blamed for the unpopularity of some CGI films with realistic characters [like The Polar Express and Final Fantasy], and it is touted as the reason Pixar stuck to characters with cartoonish features [New Scientist].
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Inside the brain of someone who’s learning to juggle, some interesting changes take place. Researchers used MRI scans to study the brains of people before and after a six-week training course in juggling, and say they saw a 5% increase in white matter – the cabling network of the brain [BBC News].
The study, published in Nature Neuroscience, follows up on previous work that found changes in the more famous gray matter of the brain, which consists of the cell bodies of the neurons where processing and computation take place. The white matter, which consists mostly of the axons that stretch away from the cell bodies, can be thought of as the brain’s wiring, and researchers say this is the first time that changes have been observed in the white matter of a healthy adult.
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Two researchers have reviewed the body of research on the effects of birth control pills on both women and men’s perceptions of attractiveness, and have come to some provocative conclusions. Women on the pill are less attracted to hyper-masculine men, they found, and don’t show the typical propensity towards men who are genetically dissimilar from themselves. In addition, women on the pill may lack the attractiveness edge that’s associated with ovulation, the study found.
An alarmist, tabloid-esque summary of the findings might read like this: Pill-taking women aren’t hotties, and they pick girlie men who are likely to give them ugly babies. But of course, there’s a lot more complexity to the findings. The contraceptive pill alters monthly fluctuations in hormones associated with the menstrual cycle, mimicking the more stable hormonal conditions associated with pregnancy [New Scientist]. While mounting evidence suggests that having one’s hormonal levels smoothed out in this way alters some of the laws of attraction between men and women, scientists hasten to add that hormones aren’t everything.
The new study (pdf), published in Trends in Ecology and Evolution, looked first at research that’s been conducted on women’s preferences for men. Women who aren’t on the pill have shown a preference for certain types of men while they’re ovulating: they prefer men with more traditionally masculine facial features, and have also been shown to prefer the smell of men who are genetically dissimilar (which in humanity’s earlier days, when inbreeding was a danger, would have been an advantage). Women on the pill don’t show these same preferences. But many would argue that personality is a far better way to choose a life partner than what they smell like. One recent study involving speed-dating experiments suggested that although women might say they prefer the scent of men with dissimilar immune systems, this doesn’t correspond with the men they actually chose to go out with [New Scientist].
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It wasn’t quite as dramatic as a slow-motion movie action sequence or a slo-mo instant reply, but researchers have successfully slowed down people’s manipulation of a computer joystick by boosting one type of brain wave. The researchers generated a small electrical current in the brains of 14 healthy volunteers using scalp electrodes. The current increased the activity of normal beta waves [New Scientist], and slowed the volunteers’ reaction times by 10 percent. The study, published in Current Biology, has implications for Parkinson’s Disease, in which patients have trouble with voluntary motions.
Brain waves are generated naturally when groups of neurons fire in a certain rhythm. Lead researcher Peter Brown explains that the low-frequency beta waves were already known to play a role in movement. “Different parts of the brain work together and generate certain frequencies,” he explained, “and the movement areas of the brain come together in beta activity. That activity is suppressed just prior to and during movement, so we think the body gets rid of it to prepare to make a new movement” [BBC News].
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Scientists have found another reason why the fizz in a glass of champagne is so important: Besides tickling the tongue and pleasing the eye, the bubbles also release aromatic compounds that they’ve dragged up from the liquid in the glass. A new study found that concentrations of certain chemical compounds are higher in the air just above the glass than in the actual champagne.
Wine expert Jamie Goode comments: “In the past, we thought that the carbon dioxide in the bubbles just gave the wine an acidic bite and a little tingle on the tongue, but this study shows that it is much more than this” [BBC News]. Smelling the chemical compounds enhances the overall flavor of the champagne, researchers say.
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