Monday, October 5, 2009

USE IT OR LOSE IT? STUDY SUGGESTS THE BRAIN CAN REMEMBER A FORGOTTEN LANGUAGE

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Many of us learn a foreign language when we are young, but in some cases, exposure to that language is brief and we never get to hear or practice it subsequently. Our subjective impression is often that the neglected language completely fades away from our memory. But does “use it or lose it” apply to foreign languages? Although it may seem we have absolutely no memory of the neglected language, new research suggests this “forgotten” language may be more deeply engraved in our minds than we realize.

Psychologists Jeffrey Bowers, Sven L. Mattys, and Suzanne Gage from the University of Bristol recruited volunteers who were native English speakers but who had learned either Hindi or Zulu as children when living abroad. The researchers focused on Hindi and Zulu because these languages contain certain phonemes that are difficult for native English speakers to recognize. A phoneme is the smallest sound in a language—a group of phonemes forms a word.

The scientists asked the volunteers to complete a background vocabulary test to see if they remembered any words from the neglected language. They then trained the participants to distinguish between pairs of phonemes that started Hindi or Zulu words.

As it turned out, even though the volunteers showed no memory of the second language in the vocabulary test, they were able to quickly relearn and correctly identify phonemes that were spoken in the neglected language.

These findings, which appeared in a recent issue of Psychological Science, a journal of the Association for Psychological Science, suggest that exposing young children to foreign languages, even if they do not continue to speak them, can have a lasting impact on speech perception. The authors conclude, “Even if the language is forgotten (or feels this way) after many years of disuse, leftover traces of the early exposure can manifest themselves as an improved ability to relearn the language.”

The Association for Psychological ScienceMany of us learn a foreign language when we are young, but in some cases, exposure to that language is brief and we never get to hear or practice it subsequently. Our subjective impression is often that the neglected language completely fades away from our memory. But does “use it or lose it” apply to foreign languages? Although it may seem we have absolutely no memory of the neglected language, new research suggests this “forgotten” language may be more deeply engraved in our minds than we realize.

Psychologists Jeffrey Bowers, Sven L. Mattys, and Suzanne Gage from the University of Bristol recruited volunteers who were native English speakers but who had learned either Hindi or Zulu as children when living abroad. The researchers focused on Hindi and Zulu because these languages contain certain phonemes that are difficult for native English speakers to recognize. A phoneme is the smallest sound in a language—a group of phonemes forms a word.

The scientists asked the volunteers to complete a background vocabulary test to see if they remembered any words from the neglected language. They then trained the participants to distinguish between pairs of phonemes that started Hindi or Zulu words.

As it turned out, even though the volunteers showed no memory of the second language in the vocabulary test, they were able to quickly relearn and correctly identify phonemes that were spoken in the neglected language.

These findings, which appeared in a recent issue of Psychological Science, a journal of the Association for Psychological Science, suggest that exposing young children to foreign languages, even if they do not continue to speak them, can have a lasting impact on speech perception. The authors conclude, “Even if the language is forgotten (or feels this way) after many years of disuse, leftover traces of the early exposure can manifest themselves as an improved ability to relearn the language.”

The Association for Psychological Science

BABIES SEE IT COMING

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Do infants only start to crawl once they are physically able to see danger coming? Or is it that because they are more mobile, they develop the ability to sense looming danger? According to Ruud van der Weel and Audrey van der Meer, from the Norwegian University of Science and Technology in Trondheim, infants’ ability to see whether an object is approaching on a direct collision course, and when it is likely to collide, develops around the time they become more mobile. Their findings1 have just been published online in the Springer journal Naturwissenschaften.

An approaching object on a collision course projects an expanding image on the retina, providing information that the object is approaching and how imminent the danger is. Looming stimuli create waves of neural activity in the visual cortex in adults. The authors investigated how, and where, the infant brain extracts and processes information about imminent collision.

They used high-density electroencephalography to measure brain activity in 18 five- to eleven-month-old infants, when a growing multicolored dot on a screen (the looming stimulus) approached the infants at three different speeds. The researchers also recorded the gaze of both eyes.

They found that infants’ looming-related brain activity clearly took place in the visual cortex. The more mature infants (ten to eleven months old) were able to process the information much quicker than the younger infants aged five to seven months. These findings suggest that there are well-established neural networks for registering impending collision in ten- to eleven-month-olds, but not yet in five- to seven-month-olds. For the eight- to nine-month-old infants, they are somewhere in between.

The authors comment: “This could be interpreted as a sign that appropriate neural networks are in the process of being established and that the age of eight to nine months would be an important age for doing so. Coincidentally, this is also the average age at which infants start crawling. This makes sense from a perspective where brain and behavioral development go hand in hand. Namely, as infants gain better control of self-produced locomotion, their perceptual abilities for sensing looming danger improve.”

(Photo: Springer)

Springer Science+Business Media

ROOM'S AMBIENCE FINGERPRINTED BY PHONE

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Your smart phone may soon be able to know not only that you're at the mall, but whether you're in the jewelry store or the shoe store.

Duke University computer engineers have made use of standard cell phone features – accelerometers, cameras and microphones – to turn the unique properties of a particular space into a distinct fingerprint. While standard global positioning systems (GPS) are only accurate to 10 meters (32 feet) and do not work indoors, the new application is designed to work indoors and can be as precise as telling if a user is on one side of an interior wall or another.

The system, dubbed SurroundSense, uses the phone's built-in camera and microphone to record sound, light and colors, while the accelerometer records movement patterns of the phone's user. This information is sent to a server, which knits the disparate information together into a single fingerprint.

"You can't tell much from any of the measurements individually, but when combined, the optical, acoustic and motion information creates a unique fingerprint of the space," said Ionut Constandache, graduate student in computer science. He presented the details of SurroundSense at the 15th International Conference on Mobile Computing and Networking in Bejing on Sept. 25.

For example, in a bar, people spend little time moving and most time sitting, while the room is typically dark and noisy. In contrast, a Target store will be brightly lit with vibrant colors – especially red – with movement up and down aisles. SurroundSense can tell these differences.

Students of Romit Roy Chouhury, Duke assistant professor of electrical and computer engineering and senior member of the research team, fanned out across Durham, N.C. with their cell phones, collecting data in different types of businesses. So that they would not bias the measurements, the students "mirrored" the actions of selected customers.

"We went to 51 different stores and found that SurroundSense achieved an average accuracy of about 87 percent when all of the sensing capabilities were used," Constandache said.

As more people use the application, it gets "smarter."

"As the system collects and analyzes more and more information about a particular site, the fingerprint becomes that much more precise," said Roy Choudhury. "Not only is the ambience different at different locations, but also can be different at different times at the same location."

SurroundSense collects data at different time points, so it would be able to distinguish a Starbucks store at the morning rush when there are many customers from the slower period in mid-afternoon.

"We believe that SurroundSense is an early step toward a long-standing challenge of improving indoor localization," Roy Choudhury said.

Currently, in order for the phone to collect data, it must be held with the camera facing down, though the researchers are working on strategies for the application to work if the phone is in a pocket, case or handbag. However, as the researchers pointed out, phones are now coming onto the market that are worn on the wrist or around the neck on a necklace.

As in many technical advances, it appears that batteries can be an Achilles' heel. The Duke researchers are now considering the tradeoffs between having the application "on" all the time, which drains the battery faster, or having it take measurements at regular intervals. They are also trying to determine whether the entire application should be housed on the server, the phone, or some combination of the two.

Duke University

PERUVIAN GLACIAL RETREATS LINKED TO EUROPEAN EVENTS OF LITTLE ICE AGE

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A new study that reports precise ages for glacial moraines in southern Peru links climate swings in the tropics to those of Europe and North America during the Little Ice Age approximately 150 to 350 years ago. The study, published in the journal Science, "brings us one step closer to understanding global-scale patterns of glacier activity and climate during the Little Ice Age," says lead author Joe Licciardi, associate professor of Earth sciences at the University of New Hampshire. "The more we know about our recent climate past, the better we can understand our modern and future climate."

The study, "Holocene glacier fluctuations in the Peruvian Andes indicate northern climate linkages," was borne of a convergence of a methodological breakthrough in geochronological techniques and Licciardi's chance encounter with well-preserved glacial moraines in Peru.

On vacation in 2003, Licciardi was hiking near the well-known Inca Trail when he noticed massive, well-preserved glacial moraines – ridges of dirt and rocks left behind when glaciers recede -- along the way, about 25 kilometers from the ruins of Machu Picchu. "They very clearly mark the outlines of formerly expanded valley glaciers at various distinct times in the recent past," he says. But Licciardi, who had no geologic tools with him at the time, did not take any samples.

Two years later, coauthor David Lund, assistant professor of geology at the University of Michigan and a friend of Licciardi's from graduate school, was in the same region and offered to chisel off some samples of the salt-and-pepper colored granitic rock. "Dave also recognized the potential of this site and shared my enthusiasm for initiating a study," says Licciardi. "That was the catalyst for turning our ideas into an actual project." Licciardi returned in 2006 to the slopes of Nevado Salcantay, a 20,000-foot-plus peak that is the highest in the Cordillera Vilcabamba range. Over the next two years, he and his graduate student Jean Taggart, also a coauthor, collected more rock samples from the moraines.

The researchers analyzed the samples using a surface exposure dating technique -- measuring the tiny amounts of the chemical isotope beryllium-10 that is formed as cosmic rays bombard exposed surfaces -- to place very precise dates on these relatively young glacial fluctuations. Licciardi and Taggart, who received a master's degree from UNH last month, worked with coauthor Joerg Schaefer, a geochemist at Columbia University's Lamont-Doherty Earth Observatory, to produce some of the youngest ages ever obtained from the beryllium isotope dating method.

"The ability to measure such young and precise ages with this method provides us with an exciting new way to establish the timing of recent glacier fluctuations in places far afield from where we have historical records," says Licciardi. Because the Little Ice Age – from about 1300 AD to 1860 AD -- coincides with historical accounts and climate observations in Europe and North America, the event is well documented in the Northern Hemisphere. In remote and sparsely inhabited areas like the Peruvian Andes, however, chronologies of Little Ice Age glacial events are very scarce.

A key finding of the study is that while glaciers in southern Peru moved at similar times as glaciers in Europe, the Peruvian record differs from the timing of glacier fluctuations in New Zealand's Southern Alps during the last millennium, as reported in another recent study in Science led by Schaefer.

"This finding helps identify interhemispheric linkages between glacial signals around the world. It increases our understanding of what climate was like during the Little Ice Age, which will in turn help us understand climate drivers," says Taggart.

"If the current dramatic warming projections are correct, we have to face the possibility that the glaciers may soon disappear," adds Schaefer.

Licciardi and his colleagues will continue working in Peru toward a more complete understanding of glacial expansion during the Little Ice Age – and their subsequent retreat. "Our new results point to likely climate processes that can explain why these glaciers expanded and retreated when they did, but there are still many open questions," he says. "For example, what's the relative importance of temperature change versus precipitation change on the health of these glaciers?" The research team plans to explore this question using coupled climate-glacier models that evaluate the sensitivity of glaciers in southern Peru to the two main factors that drive glacier expansion – cold temperatures and abundant snowfall.

(Photo: Joe Licciardi)

CRACKING THE BRAIN'S NUMERICAL CODE

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By carefully observing and analyzing the pattern of activity in the brain, researchers have found that they can tell what number a person has just seen. They can similarly tell how many dots a person has been presented with, according to a report published online on September 24th in Current Biology, a Cell Press publication.

These findings confirm the notion that numbers are encoded in the brain via detailed and specific activity patterns and open the door to more sophisticated exploration of humans' high-level numerical abilities. Although "number-tuned" neurons have been found in monkeys, scientists hadn't managed to get any farther than particular brain regions before now in humans.

"It was not at all guaranteed that with functional imaging it would be possible to pick this up," said Evelyn Eger of INSERM in France. "In the monkey, neurons preferring one or the other numerosity appear highly intermixed among themselves as well as with neurons responding to other things, so it might seem highly unlikely that with fMRI [functional magnetic resonance imaging] at 1.5 mm resolution—where one voxel contains many thousands of neurons—one would be able to detect differences in activity patterns between individual numbers. The fact that this worked means that there is probably a somewhat more structured layout of preferences for individual numbers that has yet to be revealed by neurophysiological methods."

The researchers presented ten study participants with either number symbols or dots while their brains were scanned with fMRI. They then used a multivariate analysis method to devise a way of decoding the numbers or number of dots people had observed.

Although the brain patterns corresponding to number symbols differed somewhat from those for the same number of objects, the numerosity of dot sets can be predicted above chance from the brain activation patterns evoked by digits, the researchers show. That doesn't work the other way around, however.

At least for small numbers of dots, the researchers did find that the patterns change gradually in a way that reflects the ordered nature of the numbers—allowing one to conclude that 6 is between 5 and 7, for instance. In the case of digits, the researchers could not detect that same gradual change, suggesting that their methods are not yet sensitive enough or that digits are in fact coded as more precise, discrete entities.

The methods used in the new study may ultimately help to unlock how the brain makes more sophisticated calculations, the researchers say.

"With these codes, we are only beginning to access the most basic building blocks that symbolic math probably relies on," Eger said. "We still have no clear idea of how these number representations interact and are combined in mathematical operations, but the fact that we can resolve them in humans gives hope that at some point we can come up with paradigms that let us address this."

Cell Press

PAPER BATTERY MAY POWER ELECTRONICS IN CLOTHING AND PACKAGING MATERIAL

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Imagine a gift wrapped in paper you really do treasure and want to carefully fold and save. That's because the wrapping paper lights up with words like "Happy Birthday" or "Happy Holidays," thanks to a built in battery — an amazing battery made out of paper. That's one potential application of a new battery made of cellulose, the stuff of paper, being described in the October 14 issue of ACS' Nano Letters, a monthly journal.

Albert Mihranyan and colleagues note in the report that scientists are trying to develop light, ecofriendly, inexpensive batteries consisting entirely of nonmetal parts. The most promising materials include so-called conductive polymers or "plastic electronics." One conductive polymer, polypyrrole (PPy), shows promise, but was often regarded as too inefficient for commercial batteries. The scientists realized, however, that by coating PPy on a large surface area substrate and carefully tailoring the thickness of the PPy coating, both the charging capacity and the charging (discharging) rates can be drastically improved. The secret behind the performance of this battery is the presence of the homogeneous, uninterrupted, nano-thin coating — about 1/50,000th the thickness of a human hair — of PPy on individual cellulose fibers which in turn can be molded into paper sheets of exceptionally high internal porosity. It was special cellulose, extracted from a certain species of green algae, with 100 times the surface area of cellulose found in paper. That surface area was key to allowing the new device to hold and discharge electricity very efficiently.

The innovative design of the battery cell was surprisingly simple yet very elegant since both of the electrodes consist of identical pieces of the composite paper separated by an ordinary filter paper soaked with sodium chloride serving as the electrolyte. The potential difference is solely due to differences between the oxidized and reduced forms of the functional PPy layer. The battery recharged faster than conventional rechargeable batteries and appears well-suited for applications involving flexible electronics, such as clothing and packaging, the scientists say. Alternatively, low-cost very large energy storage devices having electrodes of several square yards in size could potentially be made in the future.

(Photo: The American Chemical Society)

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