By PAM BELLUCK The device allows people with a certain type of blindness to detect crosswalks on the street, the presence of people or cars, and sometimes even large numbers or letters. The approval of the system marks a milestone in a new frontier in vision research, a field in which scientists are making strides with gene therapy, optogenetics, stem cells and other strategies. “This is just the beginning,” said Grace Shen, a director of the retinal diseases program at the National Eye Institute, which helped finance the artificial retina research and is supporting many other blindness therapy projects. “We have a lot of exciting things sitting in the wings.” The artificial retina is a sheet of electrodes implanted in the eye. The patient is also given glasses with an attached camera and a portable video processor. This system, called Argus II, allows visual signals to bypass the damaged portion of the retina and be transmitted to the brain. With the artificial retina or retinal prosthesis, a blind person cannot see in the conventional sense, but can identify outlines and boundaries of objects, especially when there is contrast between light and dark — fireworks against a night sky or black socks mixed with white ones. “Without the system, I wouldn’t be able to see anything at all, and if you were in front of me and you moved left and right, I’m not going to realize any of this,” said Elias Konstantopolous, 74, a retired electrician in Baltimore, one of about 50 Americans and Europeans who have been using the device in clinical trials. He said it helps him differentiate curbs from roads, and detect contours of objects and people. “When you have nothing, this is something. It’s a lot.” The F.D.A. approved Argus II, made by Second Sight Medical Products, to treat people with severe retinitis pigmentosa, in which photoreceptor cells, which take in light, deteriorate. © 2013 The New York Times Company

Keyword: Vision; Robotics
Link ID: 17807 - Posted: 02.16.2013

by Hal Hodson CAN YOU imagine feeling Earth's magnetic field on the tip of your tongue? Strangely, this is now possible, using a device that converts the tongue into a "display" for output from environmental sensors. Gershon Dublon of the Massachusetts Institute of Technology devised a small pad containing electrodes in a 5 × 5 grid. Users put the pad, which Gershon calls Tongueduino, on their tongue. When hooked up to an electronic sensor, the pad converts signals from the sensor into small pulses of electric current across the grid, which the tongue "reads" as a pattern of tingles. Dublon says the brain quickly adapts to new stimuli on the tongue and integrates them into our senses. For example, if Tongueduino is attached to a sensor that detects Earth's magnetic field, users can learn to use their tongue as a compass. "You might not have to train much," he says. "You could just put this on and start to perceive." Dublon has been testing Tongueduino on himself for the past year using a range of environmental sensors. He will now try the device out on 12 volunteers. Blair MacIntyre at the Georgia Institute of Technology in Atlanta says a wireless version of Tongueduino could prove useful in augmented reality applications that deliver information to users inconspicuously, without interfering with their vision or hearing. "There's a need for forms of awareness that aren't socially intrusive," he says. Even Google's much-publicised Project Glass will involve wearing a headset, he points out. © Copyright Reed Business Information Ltd.

Keyword: Chemical Senses (Smell & Taste); Pain & Touch
Link ID: 17806 - Posted: 02.16.2013

The latest bionic superhero is a rat: its brain hooked up to an infrared detector, it's become the first animal to be given a sixth sense. Developed by Miguel Nicolelis and colleagues at Duke University in Durham, North Carolina, the system connects a head-mounted sensor to a brain region that normally processes touch sensations from whiskers. As shown in this video, the rat's brain is tricked when infrared light is detected, giving it a new sense organ. "Instead of seeing, the rats learned how to touch the light," says Nicolelis. Even though the touch-processing brain area acquires a new role, the team found that it continues to process touch sensations from whiskers, somehow dividing its time between both types of signal. "The adult brain is a lot more plastic than we thought," says Nicolelis. The finding could lead to new brain prostheses that restore sight in humans with a damaged visual cortex. By bypassing the damaged part of the brain altogether, it might be possible to wire up a video camera to a part of the brain that processes touch, letting people "touch" what the camera sees. According to Nicolelis, it could also lead to superhero powers for humans. "It could be X-rays, radio waves, anything," he says. "Superman probably had a prosthetic device that nobody knew of." © Copyright Reed Business Information Ltd.

Keyword: Vision; Robotics
Link ID: 17805 - Posted: 02.14.2013

By Emily Chung, CBC News Among musicians who learned to play an instrument before the age of seven, earlier training was linked to more connections in the area of the brain that co-ordinates both hands.Among musicians who learned to play an instrument before the age of seven, earlier training was linked to more connections in the area of the brain that co-ordinates both hands. (Jorge Silva/Reuters) Starting piano or violin lessons before the age of seven appears to cause permanent changes to the brain that are linked to better motor skills. Those changes in brain development don't occur in people who learn to play an instrument when they are older, a new study has found. "What we think is that it doesn't mean you can't be an amazing musician if you start later — just that if you start earlier it may give you some of these specific abilities that are helpful," said Virginia Penhune, a Concordia University psychologist who co-authored the research with two of her doctoral students and McGill University neuropsychologist Robert Zatorre. The Montreal researchers gave a test of motor skills to and scanned the brains of 36 musicians who were either enrolled in a university music program or performed professionally, and who had an average of 16 years experience playing musical instruments. Half of them began their musical training between age three and seven, while the other half started between the ages of eight and 18, but both groups had a comparable level of experience. The study also tested 17 non-musicians. © CBC 2013

Keyword: Development of the Brain; Hearing
Link ID: 17804 - Posted: 02.14.2013

by Lizzie Wade When a male wasp decides it's time to settle down and start a family, he releases a chemical calling card in the form of pheromones, broadcasting his location, his availability, and, most importantly, his identity. Most other kinds of insects will either ignore his signal or be repelled by it, but female wasps of his own species will buzz over and get down to business. But how and why did different pheromone blends—and the species that prefer them—evolve in the first place? A new study offers a possible solution to this long-standing evolutionary mystery, suggesting that new sex pheromones may evolve through genetic mutation before potential mates develop the ability to detect them. Scientists have long been impressed by the perfect harmony of chemical communication among insects, especially when it comes to choosing mates by detecting and responding to the sex pheromones of only their own species. But scientists were puzzled by how such a delicate system evolved. If female wasps respond to only a specific blend of pheromones, males that produce even a subtly different blend shouldn't have much luck mating and passing on their mutant genes. It seemed that in order for males to evolve new pheromones, the female insects would need some preexisting adaptation that would cause them to prefer the new chemical blend. But how could they evolve a preference for something they had never encountered and should, logic suggests, find off-putting? In essence, the question is which came first, a new species or its sex pheromone? In order to answer this question, a team of researchers in Germany turned to the Nasonia vitripennis wasp, a species famous for its propensity to lay its parasitic eggs on doomed fly pupae. When the scientists analyzed the N. vitripennis male sex pheromone, they found it contained two important chemicals, which they call RS and RR. RS also turns up in the male sex pheromones of another species of wasp, N. giraulti, whereas RR appears to be unique. © 2010 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 17803 - Posted: 02.14.2013

By Laura Sanders Before you can run, you have to walk, and before you can walk well, you have to walk like a brand-new baby. A new study uncovers the logistics of newborns’ herky-jerky, Frankensteinian stepping action and how this early reflex morphs into refined adult locomotion. In the study, electrodes on infants’ chubby legs picked up signals from neurons that tell muscles to fire, revealing that three-day old babies tense up many of their leg muscles all at once. Toddlers, preschoolers and adults, by contrast, showed a progressively more sophisticated, selective pattern of neuron activity. From birth to adulthood, motor neurons in the spine get an overhaul as neurons in different locations along the spine become specialized for various aspects of walking, such as foot position, balance and direction, Yuri Ivanenko of the Santa Lucia Foundation in Rome and colleagues conclude in the Feb. 13 Journal of Neuroscience. © Society for Science & the Public 2000 - 2013

Keyword: Development of the Brain
Link ID: 17802 - Posted: 02.14.2013

By Melinda Wenner Moyer On the night of my 32nd birthday, my husband and I enjoyed a delicious dinner while on vacation in Orvieto, Italy. To complement my pasta, I drank a single glass of red wine, my first since learning I was pregnant four months earlier. Even now my indulgence that evening inspires periodic pangs of guilt: Did I stunt my son's potential by sipping that Sangiovese? Nobody questions the notion that heavy drinking during pregnancy is harmful. It can cause facial abnormalities, central nervous system problems and stunted growth. But evidence regarding the effects of light or occasional drinking is mixed. In five epidemiological studies published in 2012, medical psychologist Erik Mortensen of the University of Copenhagen and his colleagues found that five-year-old children born to women who had one to four drinks a week during pregnancy displayed no deficits in general intelligence, attention or other types of higher-order thinking. On the other hand, in 2011 psychiatrist Nancy Day of the University of Pittsburgh and her colleagues reported that teens born to women who averaged more than one drink a week during pregnancy were twice as likely as those born to nondrinkers to have conduct disorder, a condition characterized by theft, deceit or violence. The truth is hard to discern because research on the issue is fraught with problems. The ideal type of experiment is not ethical: scientists cannot randomly assign one group of women to drink during pregnancy and compare the outcome with those instructed to abstain. As a result, they must compare what happens to women who choose to drink during pregnancy with those who do not, and these women often differ in important ways. All things considered, having an occasional drink during those nine months—say, one or two a week—probably poses little, if any, harm. Still, some experts warn, light or sporadic drinking may have effects we do not know how to measure. © 2013 Scientific American

Keyword: Drug Abuse; Development of the Brain
Link ID: 17801 - Posted: 02.14.2013

by Kelli Whitlock Burton Having a conversation in a noisy restaurant can be difficult. For many elderly adults, it's often impossible. But with a little practice, the brain can learn to hear above the din, a new study suggests. Age-related hearing loss can involve multiple components, such as the disappearance of sensory cells in the inner ear. But scientists say that part of the problem may stem from our brains. As we get older, our brains slow down—a natural part of aging called neural slowing. One side effect of this sluggishness is the inability to process the fast-moving parts of speech, particularly consonants at the beginning of words that sound alike, such as "b," "p," "g," and "d." Add background noise to the mix and "bad" may sound like "dad," says Nina Kraus, director of the Auditory Neuroscience Laboratory at Northwestern University in Evanston, Illinois. "Neural slowing especially affects our ability to hear in a noisy background because the sounds we need to hear are acoustically less salient and because noise also taxes our ability to remember what we hear." Building on animal studies that pointed to an increase in neural speed following auditory training, Kraus and colleagues enrolled 67 people aged 55 to 70 years old with no hearing loss or dementia in an experiment. Half the group completed about 2 months of exercises with Brain Fitness, a commercially available auditory training program by Posit Science. (The team has no connection to the company.) The exercises helped participants better identify different speech sounds and distinguish between similar-sounding syllables, such as "ba" or "ta." © 2010 American Association for the Advancement of Science

Keyword: Hearing; Development of the Brain
Link ID: 17800 - Posted: 02.14.2013

Regina Nuzzo People with dyslexia are often taught to work through reading by ‘slowing down and sounding it out’. Results from a computerized training program, however, suggest that ‘hurrying up and getting on with it’ might be a better practice. Accelerated training could improve both reading fluency and comprehension, with lasting benefits. The training protocol speeds up reading by displaying a sentence and then systematically erasing it, letter by letter, in the direction of reading. It then asks questions to test the reader's comprehension. If the questions are answered correctly, the software moves on to the next sentence but gives the reader 2 milliseconds — the duration of an eyeblink — less reading time per letter. “We essentially tell the brain, ‘Hey, you can do better,’” says Zvia Breznitz, a psychologist at the University of Haifa in Israel and lead author of the study. “We slowly break the cycle of bad reading.” After training with the programme for three 20-minute sessions per week for two months, students with dyslexia read about 25% faster than before and comprehended more, even when allowed to read at their own pace. Their test scores ended up statistically indistinguishable from those of typical readers who had not gone through training, and the gains were still apparent six months after training ended. Typical readers also benefited from the training, but their gains were neither as significant nor as long-lasting as the dyslexics'. The findings are published today in Nature Communications1. “The results are exciting,” says Guinevere Eden, a neuroscientist at Georgetown University in Washington DC. Dyslexia is thought to affect between 5 and 10% of the world’s population2, but there is no gold-standard method for treating it. © 2013 Nature Publishing Group

Keyword: Dyslexia
Link ID: 17799 - Posted: 02.13.2013

By RAPHAEL SATTER, Associated Press LONDON (AP) — When it comes to mating, guppies treasure their ugly friends — because they look so good by comparison. An article published Wednesday by Britain's Royal Society says that male guppies prefer to associate with their drab-colored counterparts when females were around. "Males actively choose the social context that maximizes their relative attractiveness," the article said. Or, as lead author Clelia Gasparini put it, "If you are surrounded by ugly friends, you look better." Gasparini and her colleagues at Italy's University of Padua built their theory on a kind of guppy dating game. An aquarium was set up with one female in partition on either end. Guppy bachelorette No. 1 had two attractive, brightly-colored males placed on either side of her. Guppy bachelorette No. 2 was stuck with uglier, drab-colored fish. When a male guppy was put in the middle of the tank, and given the choice of which female to sidle up to, Bachelorette No. 2 was the more popular pick, with male guppies spending about 62 percent of their time hanging around her side of the aquarium. What's more, the researchers found that the time guppies spent with bachelorette No. 2 correlated with their unattractiveness. The uglier the guppy, the less likely it was that he would hang around the brightly colored fish placed next to bachelorette No. 1. © 2013 Hearst Communications Inc.

Keyword: Sexual Behavior
Link ID: 17798 - Posted: 02.13.2013

Matt Kaplan The astounding warning colours of the nudibranchs, a diverse group of sea slugs, are certainly enough to attract attention — but even they pale in comparison to the gripping news that one species of the soft-bodied molluscs has a habit of discarding its penis. Nudibranchs are hermaphrodites, meaning that they carry both male and female reproductive organs. Moreover, when they mate, they can perform the male role of donating sperm and the female role of receiving sperm at the same time. This process involves two penises and two vagina-like organs, and sperm transmission effectively happens simultaneously during the encounter. This is a relatively standard arrangement among nudibranchs, so the creatures' sexual organs might all be expected to look roughly the same. But the animals show incredible sex-organ diversity, and it was during an exploration of this diversity in the species Chromodoris reticulata that researchers made their jaw-dropping discovery. A Japanese team led by Ayami Sekizawa at Osaka City University and Yasuhiro Nakashima at Nihon University in Tokyo went scuba diving off the coast of Okinawa to collect the sea slugs. They then placed the creatures in aquaria in pairs. In some cases both members of a pair had been isolated from others for 24 hours; in other cases a recently-mated animal was placed with one that had been in isolation. © 2013 Nature Publishing Group,

Keyword: Sexual Behavior
Link ID: 17797 - Posted: 02.13.2013

By Luciana Gravotta If cupid had studied neuroscience, he’d know to aim his arrows at the brain rather than the heart. Recent research suggests that for love to last, it’s best he dip those arrows in oxytocin. Although scientists have long known that this hormone is essential for monogamous rodents to stay true to their mates, and that it makes humans more trusting toward one another, they are now finding that it is also crucial to how we form and maintain romantic relationships. A handful of new studies show that oxytocin makes us more sympathetic, supportive and open with our feelings—all necessary for couples to celebrate not just one Valentine’s Day, but many. These findings have led some researchers to investigate whether oxytocin can be used in couple therapy. The first bit of evidence that points to oxytocin as nature’s love glue comes from researchers who measured the hormone in couples. Psychology professor Ruth Feldman at Bar-Ilan University in Israel, spent years studying oxytocin’s role in the mother–child bond and recently decided to dive into the uncharted waters of romantic bonds by comparing oxytocin levels in new lovers and singles. “The increase in oxytocin during the period of falling in love was the highest that we ever found,” she says of a study she and her colleagues published in Psychoneuroendocrinology. New lovers had double the amount Feldman usually sees in pregnant women. Oxytocin was also correlated with the longevity of a relationship. Couples with the highest levels were the ones still together six months later. They were also more attuned to each other than the low-oxytocin couples when Feldman asked them to talk about a shared positive experience. © 2013 Scientific American,

Keyword: Sexual Behavior; Hormones & Behavior
Link ID: 17796 - Posted: 02.13.2013

By BENEDICT CAREY The young men who opened fire at Columbine High School, at the movie theater in Aurora, Colo., and in other massacres had this in common: they were video gamers who seemed to be acting out some dark digital fantasy. It was as if all that exposure to computerized violence gave them the idea to go on a rampage — or at least fueled their urges. Social scientists have been studying and debating the effects of media violence on behavior since the 1950s, and video games in particular since the 1980s. The issue is especially relevant today, because the games are more realistic and bloodier than ever, and because most American boys play them at some point. Girls play at lower rates and are significantly less likely to play violent games. A burst of new research has begun to clarify what can and cannot be said about the effects of violent gaming. Playing the games can and does stir hostile urges and mildly aggressive behavior in the short term. Moreover, youngsters who develop a gaming habit can become slightly more aggressive — as measured by clashes with peers, for instance — at least over a period of a year or two. Yet it is not at all clear whether, over longer periods, such a habit increases the likelihood that a person will commit a violent crime, like murder, rape, or assault, much less a Newtown-like massacre. (Such calculated rampages are too rare to study in any rigorous way, researchers agree.) “I don’t know that a psychological study can ever answer that question definitively,” said Michael R. Ward, an economist at the University of Texas, Arlington. “We are left to glean what we can from the data and research on video game use that we have.” © 2013 The New York Times Company

Keyword: Aggression
Link ID: 17795 - Posted: 02.13.2013

Nearly 400 years after William Shakespeare asked, "What is love?," brain imaging studies are allowing scientists to give at least a partial answer. As our calendars get closer to Feb. 14, a day when passion is deeply associated with the heart, love will in fact be in the mind. A recent study shows love is a complex emotion triggered by 12 specific areas of the brain — the network of love. Love is in the mind, not in the heart © 1996-2013 The Washington Post

Keyword: Sexual Behavior; Emotions
Link ID: 17794 - Posted: 02.13.2013

By Laura Sanders Immune cells that help heal injuries in the adult brain may have a second job early in life, a study in mice reveals. The brain crusaders unexpectedly moonlight as sculptors, shaping a region of the brain into a male-specific form. The cells, called microglia, are mobile garbage disposals that travel around the brain and gobble up damaged cells and infectious agents. But the new study, published in the Feb. 13 Journal of Neuroscience, emphasizes that these cells have diverse functions, says neuroscientist Jean Harry of the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., who was not involved in the work. Earlier results hinted that parts of the immune system have a role in building sex differences into the brain, so Kathryn Lenz and her colleagues at the University of Maryland, Baltimore decided to test whether microglia are pulling double duty. The team focused on the preoptic area of the mouse brain—“a place where you see a ton of sex differences,” Lenz says. Early in life, this brain area gets shaped by sex hormones including molecules called estradiol and prostaglandin E2, which work on the male mouse brain. In males, the preoptic area is larger, and the cells there have more elaborate shapes than in females. Scientists think those brain differences drive mating behaviors. Lenz and her colleagues found another difference in the preoptic area between males and females: Young males had about twice as many active microglia as females did. What’s more, a dose of estradiol or prostaglandin E2 in the first few days of life caused female animals to produce the male number of active microglia. © Society for Science & the Public 2000 - 2013

Keyword: Sexual Behavior; Neuroimmunology
Link ID: 17793 - Posted: 02.13.2013

by Nic Halverson By studying a magic trick that has been around for thousands of years, neuroscientists have shed light on human attention and visual systems -- as well as on the trick, itself. "Magicians, in particular, are very intellectual performance artists. They are very interested in the mind and how behavior happens," Dr. Stephen Macknik, director of the Laboratory of Behavioral Neurophysiology at the Barrow Neurological Institute(BNI), told Discovery News. "What scientists are doing when we study perception is pretty much the same thing, except we're using the scientific method." The hope is that magicians' intuitive insight could help instruct the field of neuroscience and perhaps, even be applied in medicine to help people with attention deficit issues. In their study, recently published in the inaugural issue of PeerJ, the researchers focused upon a famous trick by a pair of very famous magicians. Penn & Teller's 10-year run at The Rio All-Suite Hotel & Casino has made them one of the longest-running and most beloved acts in Las Vegas history. Their trick, "Cups and Balls," is a classic illusion performed by Roman magicians as far back as 2,000 years ago when gladiators still battled in the Colosseum. While the trick has many derivatives, the most common uses three brightly colored balls and three opaque cups. Using sleight-of-hand, the magician seemingly makes the balls pass through the bottoms of cups, jump from cup to cup, disappear and reappear elsewhere or turn into entirely different objects. In Penn & Teller's case, that different object is often a potato. © 2013 Discovery Communications, LLC. T

Keyword: Attention
Link ID: 17792 - Posted: 02.13.2013

By Scicurious When it comes down to it, most humans are pretty optimistic. Yeah, we know the Titanic sank, but our boat is better. We know that driving a car is really pretty dangerous, but we’re more careful, it won’t happen to us. This is not just a cultural thing, we generally tend to place more importance on positive information about something than on negative. We’re more optimistic than we should be on everything, from the future of our current relationship to the stock market. But what is it that makes us so optimistic? And what happens when it goes wrong? Because not everyone is optimistic. People with major depressive disorder, for example, are more pessimistic (sometimes they are just pessimistic enough to be realistic, but they can also be unrealistically pessimistic). What is it that determines how optimistic we are? It’s time to take another look at dopamine. I often talk about the neurotransmitter dopamine in the context of addiction. But dopamine is a much more subtle signal than just the “reward” or “pleasure” you see thrown around in the media. Dopamine is extremely important in detecting prediction errors: when you’ve made the wrong choice. Basically, dopamine can spike in the presence of reward, and can spike when a reward is expected. Conversely, you often see decreases in dopamine when something unexpected happens and you fail to get your reward, like with a Rickroll. That’s a prediction error, you predicted a reward and it didn’t happen. © 2013 Scientific American

Keyword: Drug Abuse; Emotions
Link ID: 17791 - Posted: 02.12.2013

By NICHOLAS BAKALAR Being physically fit in midlife is associated with a lower risk of dementia in old age, a new study reports. Between 1971 and 2009, 19,458 healthy adults younger than age 65 took a treadmill fitness test as part of a broader health examination. Researchers followed the subjects through their Medicare records for an average of 24 years. After adjusting for age, smoking, diabetes, cholesterol and other health factors, the researchers found that compared with those in the lowest 20 percent for fitness in midlife, those in the highest 20 percent had a 36 percent reduced risk of dementia. The reason for the association is unclear, but it was independent of cardiovascular and cerebrovascular risk factors for dementia, suggesting that both vascular and nonvascular mechanisms may be involved. “Dementia is a disease with no cure and no good therapies,” said the lead author, Dr. Laura F. DeFina, the interim chief scientific officer at the Cooper Institute in Dallas. Physical activity may be “a preventive way to address dementia instead of addressing the costs of a disabled elder.” The study population was largely white and highly educated, and the researchers acknowledge that their findings, published last week in The Annals of Internal Medicine, cannot be generalized to other populations. They emphasize that the study is observational and does not prove causation. Copyright 2013 The New York Times Company

Keyword: Alzheimers
Link ID: 17790 - Posted: 02.12.2013

By PAM BELLUCK A type of brain stimulation caused by a mild electric current that appears to have minimal negative side effects is showing promise as a potential treatment for major depression, according to several studies. The experimental therapy, known as transcranial direct current stimulation, or tDCS, involves a low-level charge about one-400th of that used in electroshock treatment. Unlike electroshock (also called electroconvulsive therapy or ECT), which is administered for a few seconds to patients under anesthesia, tDCS is given for 20 to 30 minutes continuously while patients are conscious. While doctors do not see it replacing electroshock, considered the most effective approach for major depression that has been treatment-resistant and requires urgent attention, tDCS does not appear to cause memory loss as electroshock can. Because it is inexpensive and easily administered, scientists say it might become an alternative or additional treatment for people whose depression is not completely helped by medication. “I think tDCS could be tried before ECT,” said Dr. Andre R. Brunoni, a psychiatrist at the University of São Paulo in Brazil and an author of a study published last week in The Journal of the American Medical Association-Psychiatry. Or, he said, it could be used “for avoiding drug treatment in patients that cannot use drugs.” Researchers said Dr. Brunoni’s study is the largest to date of about half a dozen studies in recent years. It is the first comparing tDCS with another treatment — in this case, sertraline, or Zoloft. The study, involving 120 patients, found that tDCS appeared to work about as well as a low dose of Zoloft, and that combined with Zoloft, it worked better than the drug or the stimulation alone. Zoloft and tDCS were equally safe. A few patients became manic, and some developed redness where electrodes were applied. Copyright 2013 The New York Times Company

Keyword: Depression
Link ID: 17789 - Posted: 02.12.2013

If optimists see the world through rose-colored lenses, some birds see it through ultraviolet ones. Avians have evolved ultraviolet vision quite a few times in history, a new study finds. Birds depend on their color vision for selecting mates, hunting or foraging for food, and spotting predators. Until recently, ultraviolet vision was thought to have arisen as a one-time development in birds. But a new DNA analysis of 40 bird species, reported Feb. 11 in the journal BMC Evolutionary Biology, shows the shift between violet (shorter wavelengths on the electromagnetic spectrum) and ultraviolet vision has occurred at least 14 times. "Birds see color in a different way from humans," study co-author Anders Ödeen, an animal ecologist at Uppsala University in Sweden, told LiveScience. Human eyes have three different color receptors, or cones, that are sensitive to light of different wavelengths and mix together to reveal all the colors we see. Birds, by contrast, have four cones, so "they see potentially more colors than humans do," Ödeen said. Birds themselves are split into two groups based on the color of light (wavelength) that their cones detect most acutely. Scientists define them as violet-sensitive or ultraviolet-sensitive, and the two groups don't overlap, according to Ödeen. Birds of each group would see the same objects as different hues. The specialization of color vision has its advantages. For instance, a bird with ultraviolet-sensitive vision might have spectacularly bright plumage in order to impress a female, but that same plumage might appear dull to predator birds that see only in the violet range. © 2013 Discovery Communications, LLC.

Keyword: Vision; Genes & Behavior
Link ID: 17788 - Posted: 02.12.2013