Tuesday, November 24, 2009

NITROGEN LOSS THREATENS DESERT PLANT LIFE

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As the climate gets warmer, arid soils lose nitrogen as gas, reports a new Cornell study. That could lead to deserts with even less plant life than they sustain today, say the researchers.

"This is a way that nitrogen is lost from an ecosystem that people have never accounted for before," said Jed Sparks, associate professor of ecology and evolutionary biology and co-author of the study, published in the Nov. 6 issue of Science. "It allows us to finally understand the dynamics of nitrogen in arid systems"

Available nitrogen is second only to water as the biggest constraint to biological activity in arid ecosystems, but before now, ecologists struggled to understand how the inputs and outputs of nitrogen in deserts balance.

By showing that the higher temperatures cause nitrogen to escape as gas from desert soils, the Cornell researchers have balanced the nitrogen budget in deserts. They stress that most climate change models need to be altered to consider these findings.

Sparks and lead author Carmody McCalley, a graduate student, warn that temperature increases and shifting precipitation patterns due to climate change may lead to further nitrogen losses in arid ecosystems. That would make arid soils even more infertile and unable to support most plant life, McCalley warned. Although, some climate models predict more summer rainfall for desert areas, the water, when combined with heat, would greatly increase nitrogen losses, she added.

"We're on a trajectory where plant life in arid ecosystems could cease to do well," she said.

In the past, researchers focused on biological mechanisms where soil microbes near the surface produce nitrogen gas that dissipates into the air, but McCalley and Sparks found that non-biological processes (abiotic) play a bigger role in nitrogen losses. They used instruments sensitive enough to measure levels of nitrogen gases in parts per trillion that had never before been applied to soil measurements.

The researchers covered small patches of soil in the Mojave Desert with sealed containers to measure nitrogen oxide (NO), NOy (a group of more than 25 different compounds containing oxidized nitrogen) and ammonia gases that escape from desert soils. To rule out the role of light in this process, McCalley kept light constant but varied the temperatures in lab experiments.

"At 40 to 50 degrees Celsius [about 100-120 F], we found rapid increases in gases coming out of the soil" regardless of the light, McCalley said. Midday ground temperatures average about 150 F and can reach almost 200 F in the Mojave Desert.

"Any place that gets hot and dry, in all parts of the world, will likely exhibit this pattern," said Sparks.

In addition, the researchers note, more nitrogen oxides in the lower atmosphere creates ozone near the ground, which contributes to air pollution and increases the greenhouse effect that warms the planet.

With deserts accounting for 35 to 40 percent of the Earth's surface and arid and semiarid lands being the most likely areas for new human settlements, air quality issues, loss of soil fertility and further desertification need to be considered as the climate warms, the researchers said.

The researchers also point out that most climate modelers now use algorithms that only consider biological factors to predict nitrogen gases coming from soils.

"The code in climate models would have to change to account for abiotic impacts on this part of the nitrogen budget," McCalley concluded.

(Photo: Cornell U.)

Cornell University

REDUCING GREENHOUSE GASES MAY NOT BE ENOUGH TO SLOW CLIMATE CHANGE

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Georgia Tech City and Regional Planning Professor Brian Stone publishes a paper in the December edition of Environmental Science and Technology that suggests policymakers need to address the influence of global deforestation and urbanization on climate change, in addition to greenhouse gas emissions.

According to Stone’s paper, as the international community meets in Copenhagen in December to develop a new framework for responding to climate change, policymakers need to give serious consideration to broadening the range of management strategies beyond greenhouse gas reductions alone.

“Across the U.S. as a whole, approximately 50 percent of the warming that has occurred since 1950 is due to land use changes (usually in the form of clearing forest for crops or cities) rather than to the emission of greenhouse gases,” said Stone. “Most large U.S. cities, including Atlanta, are warming at more than twice the rate of the planet as a whole – a rate that is mostly attributable to land use change. As a result, emissions reduction programs – like the cap and trade program under consideration by the U.S. Congress – may not sufficiently slow climate change in large cities where most people live and where land use change is the dominant driver of warming.”

According to Stone’s research, slowing the rate of forest loss around the world, and regenerating forests where lost, could significantly slow the pace of global warming.

“Treaty negotiators should formally recognize land use change as a key driver of warming,” said Stone. “The role of land use in global warming is the most important climate-related story that has not been widely covered in the media.”

Stone recommends slowing what he terms the “green loss effect” through the planting of millions of trees in urbanized areas and through the protection and regeneration of global forests outside of urbanized regions. Forested areas provide the combined benefits of directly cooling the atmosphere and of absorbing greenhouse gases, leading to additional cooling. Green architecture in cities, including green roofs and more highly reflective construction materials, would further contribute to a slowing of warming rates. Stone envisions local and state governments taking the lead in addressing the land use drivers of climate change, while the federal government takes the lead in implementing carbon reduction initiatives, like cap and trade programs.

“As we look to address the climate change issue from a land use perspective, there is a huge opportunity for local and state governments,” said Stone. “Presently, local government capacity is largely unharnessed in climate management structures under consideration by the U.S. Congress. Yet local governments possess extensive powers to manage the land use activities in both the urban and rural areas.”

Georgia Institute of Technology

CAUGHT IN THE ACT

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Breaking up may actually not be hard to do, say scientists who’ve found a population of butterflies that may be on its way to a split into two distinct species. What’s the cause of this particular breakup? A shift in wing color and mate preference.

In a paper published in the journal Science, the researchers at Harvard University, the University of Texas, and the University of Hawaii describe the relationship between diverging color patterns in Heliconius butterflies and the long-term divergence of populations into new and distinct species.

“Our paper provides a unique glimpse into the earliest stage of ecological speciation, where natural selection to fit the environment causes the same trait in the same population to be pushed in two different directions,” said Marcus Kronforst, a co-author of the study and a Bauer Fellow in the Center for Systems Biology at Harvard University. “If this trait is also involved in reproduction, this process can have a side effect of causing the divergent subpopulations to no longer interbreed. This appears to be the process that is just beginning among Heliconius butterflies in Ecuador.”

Heliconius species display incredible color-pattern variation across Central and South America, with closely related species usually sporting different colors. For instance, in Costa Rica, the two most closely related species differ in color: One species is white and the other yellow. In addition, both display a marked preference for others of the same color.

The Ecuadorean population examined by Kronforst and his colleagues shows the same white and yellow variation found in Costa Rica, but this population has not yet reached a level of strong reproductive isolation. The entire population lives in close proximity, and individuals of both colors come in contact with — and mate with — each other.

But by studying the Ecuadorean population in captivity, scientists found that the two colors do not mate randomly. Despite the genetic similarity between the groups — white and yellow varieties differ only at the color-determining gene — yellow Ecuadorean individuals show a preference for those of the same color. White male butterflies, most of which are heterozygous at the gene that controls color, show no color preference.

“This subtle difference in mate preference between the color forms in Ecuador may be the first step in a process that could eventually result in two species, as we see in Costa Rica,” said Kronforst, who began studies of Heliconius color pattern and behavioral genetics as a doctoral student in the laboratory of Lawrence Gilbert, professor in the section of integrative biology at the University of Texas, Austin.

Previous studies of species formation have focused on the characteristics of well-differentiated species, and the health and viability of their hybrids in particular, in an effort to identify how the species may have emerged and how they stay distinct. Heliconius provides a model for a different kind of study. The researchers considered species emergence from the opposite end, studying populations that have yet to diverge into separate species in order to identify the role of mate choice in the potential emergence of new species.

Having identified color-based mate preference in Heliconius, the researchers used a battery of genetic markers to compare the genomes of the white and yellow varieties, showing that they are genetically identical except for their different colors and preferences. The work suggests that the genes for color and preference are very close to one another in the genome; the two traits could even be caused by the same gene. The researchers’ next step is to identify the gene or genes responsible for the differences in color and mate preference.

“If we can identify this gene or genes, we can say conclusively how they influence both color and mate choice,” said Kronforst. “Subsequent work could elucidate exactly how changes in individual genes can, over long periods of time, lead to novel species.”

”This study shows the great potential of the genus Heliconius as a model system for integrating genetics, development, behavior, ecology, and evolution,” said co-author Gilbert.

(Photo: Rose Lincoln/Harvard Staff Photographer)

Harvard University

SHIFTING BLAME IS SOCIALLY CONTAGIOUS

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Merely observing someone publicly blame an individual in an organization for a problem – even when the target is innocent – greatly increases the odds that the practice of blaming others will spread with the tenacity of the H1N1 flu, according to new research from the USC Marshall School of Business and Stanford University.

Nathanael J. Fast, an assistant professor of management and organization at the USC Marshall School of Business and Larissa Tiedens, a professor of organizational behavior at Stanford, conducted four different experiments and found that publicly blaming others dramatically increases the likelihood that the practice will become viral. The reason: blame spreads quickly because it triggers the perception that one's self-image is under assault and must be protected.

The study called "Blame Contagion: The Automatic Transmission of Self-Serving Attributions" is believed to be the first to examine whether shifting blame to others is socially contagious. The results will be published in the November issue of Journal of Experimental Social Psychology.

"When we see others protecting their egos, we become defensive too," says Fast, the study's lead author. "We then try to protect our own self-image by blaming others for our mistakes, which may feel good in the moment." He adds that in the long run, such behavior could hurt one's reputation and be destructive to an organization and further to our society as a whole.

Tiedens said the study didn't specifically look at the impact of hard economic times, but it undoubtedly makes the problem worse. "Blaming becomes common when people are worried about their safety in an organization," she said. "There is likely to be more blaming going on when people feel their jobs are threatened."

Fast says that when public blaming becomes common practice – especially by leaders -- its effects on an organization can be insidious and withering: Individuals who are fearful of being blamed for something become less willing to take risks, are less innovative or creative, and are less likely to learn from their mistakes.

"Blame creates a culture of fear," Fast said, "and this leads to a host of negative consequences for individuals and for groups."

A manager can keep a lid on the behavior by rewarding employees who learn from their mistakes and by making a point to acknowledge publicly his or her own mistakes, Fast says. Managers may also want to assign blame, when necessary, in private and offer praise in public to create a positive attitude in the workplace.

Or, managers could follow the lead of companies such as Intuit, which implemented a "When Learning Hurts" session where they celebrated and learned from mistakes, rather than pointing fingers and assigning blame. The blame contagion research provides empirical evidence that such a practice can avoid negative effects in the culture of the organization.

Anyone can become a blamer, Fast says, but there are some common traits. Typically, they are more ego defensive, have a higher likelihood of being narcissistic, and tend to feel chronically insecure.

President Richard Nixon is one example the authors point to in the study. Nixon harbored an intense need to enhance and protect his self-image and, as a result, made a practice of blaming others for his shortcomings. His former aides reported that that this ego-defensiveness pervaded his administration. It was the culture of fear and blame that ultimately led to Nixon's political downfall.

The experiments showed that individuals who watched someone blame another for mistakes went on to do the same with others. In one experiment, half of the participants were asked to read a newspaper article about a failure by Governor Schwarzenegger who blamed special interest groups for the controversial special election that failed in 2005, costing the state $250 million. A second group read an article in which the governor took full responsibility for the failure.

Those who read about the governor blaming special interest groups were more likely to blame others for their own, unrelated shortcomings, compared with those who read about Schwarzenegger shouldering the responsibility.

Another experiment found that self-affirmation inoculated participants from blame. The tendency for blame to spread was completely eliminated in a group of participants who had the opportunity to affirm their self-worth.

"By giving participants the chance to bolster their self-worth we removed their need to self protect though subsequent blaming," says Fast.

The results have particularly important implications for CEOs. Executives and leaders would be wise to learn from such examples, Fast suggests, and instead display behaviors that help to foster a culture of psychological safety, learning, and innovation.

The University of Southern California

OCEANOGRAPHERS DEVELOP "SWARMS" OF ROBOTIC OCEAN EXPLORERS

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In an effort to plug gaps in knowledge about key ocean processes, the National Science Foundation (NSF)'s division of ocean sciences has awarded nearly $1 million to scientists at the Scripps Institution of Oceanography in La Jolla, Calif. The Scripps marine scientists will develop a new breed of ocean-probing instruments. Jules Jaffe and Peter Franks will spearhead an effort to design and deploy autonomous underwater explorers, or AUEs. AUEs will trace the fine details of oceanographic processes vital to tiny marine inhabitants.

While oceanographers have been skilled in detailing large-scale ocean processes, a need has emerged to zero in on functions unfolding at smaller scales. By defining localized currents, temperature, salinity, pressure and biological properties, AUEs will offer new and valuable information about a range of ocean phenomena.

"We're seeing great success in the global use of ocean profiling floats to document large-scale circulation patterns and other physical and chemical attributes of the deep and open seas," said Phillip Taylor of NSF's division of ocean sciences. "These innovative AUEs will allow researchers to sample the environments of coastal regions as well, and to better understand how small organisms operate in the complex surroundings of the oceans."

The miniature robots will aid in obtaining information needed for developing marine protected areas, determining critical nursery habitats for fish and other animals, tracking harmful algae blooms, and monitoring oil spills.

For marine protected areas, AUEs will help inform debates about the best areas for habitat protection. With harmful algal blooms and oil spills, the instruments can be deployed directly into outbreak patches to gauge how they develop and change over time. In the case of an airplane crash over the ocean, AUEs should be able to track currents to determine where among the wreckage a black box may be located.

"AUEs will fill in gaps between existing marine technologies," said Jaffe. "They will provide a whole new kind of information."

AUEs work through a system in which several soccer-ball-sized explorers are deployed with many tens--or even hundreds--of pint-sized explorers. Collectively, the entire "swarm" of AUEs will track ocean currents that organisms at a small-scale, such as tiny abalone larvae, for example, experience in the ocean.

"AUEs will give us information to figure out how small organisms survive, how they move in the ocean, and the physical dynamics they experience as they get around," said Franks. "AUEs should improve ocean models and allow us to do a better job of following 'the weather and climate of the ocean,' as well as help us understand things like carbon fluxes."

Franks, who conducts research on marine phytoplankton, says that "plankton are somewhat like the balloons of the ocean floating around out there. With AUEs, we're trying to figure out how the ocean works at scales that matter to plankton.

"If we place 100 AUEs in the ocean and let them go, we'll be able to look at how they move to get a sense of the physics driving current flows."

During the pilot phase of the project, Jaffe and colleagues will build five to six of the soccer-ball-sized explorers and 20 of the smaller versions. An outreach component of the project will enlist school children in building and ultimately deploying AUEs.

(Photo: SIO)

The Scripps Institution of Oceanography

CENTRAL AFRICA'S TROPICAL CONGO BASIN WAS ARID, TREELESS IN LATE JURASSIC

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The Congo Basin — with its massive, lush tropical rain forest — was far different 150 million to 200 million years ago. At that time Africa and South America were part of the single continent Gondwana. The Congo Basin was arid, with a small amount of seasonal rainfall, and few bushes or trees populated the landscape, according to a new geochemical analysis of rare ancient soils.

The geochemical analysis provides new data for the Jurassic period, when very little is known about Central Africa's paleoclimate, says Timothy S. Myers, a paleontology doctoral student in the Roy M. Huffington Department of Earth Sciences at Southern Methodist University in Dallas.

"There aren't a whole lot of terrestrial deposits from that time period preserved in Central Africa," Myers says. "Scientists have been looking at Africa's paleoclimate for some time, but data from this time period is unique."

There are several reasons for the scarcity of deposits: Ongoing armed conflict makes it difficult and challenging to retrieve them; and the thick vegetation, a humid climate and continual erosion prevent the preservation of ancient deposits, which would safeguard clues to Africa's paleoclimate.

Myers' research is based on a core sample drilled by a syndicate interested in the oil and mineral deposits in the Congo Basin. Myers accessed the sample — drilled from a depth of more than 2 kilometers — from the Royal Museum for Central Africa in Tervuren, Belgium, where it is housed. With the permission of the museum, he analyzed pieces of the core at the SMU Huffington Department of Earth Sciences Isotope Laboratory.

"I would love to look at an outcrop in the Congo," Myers says, "but I was happy to be able to do this."

The Samba borehole, as it's known, was drilled near the center of the Congo Basin. The Congo Basin today is a closed canopy tropical forest — the world's second largest after the Amazon. It's home to elephants, great apes, many species of birds and mammals, as well as the Congo River. Myers' results are consistent with data from other low paleolatitude, continental, Upper Jurassic deposits in Africa and with regional projections of paleoclimate generated by general circulation models, he says.

"It provides a good context for the vertebrate fossils found in Central Africa," Myers says. "At times, any indications of the paleoclimate are listed as an afterthought, because climate is more abstract. But it's important because it yields data about the ecological conditions. Climate determines the plant communities, and not just how many, but also the diversity of plants."

While there was no evidence of terrestrial vertebrates in the deposits that Myers studied, dinosaurs were present in Africa at the same time. Their fossils appear in places that were once closer to the coast, he says, and probably wetter and more hospitable.

The Belgium samples yielded good evidence of the paleoclimate. Myers found minerals indicative of an extremely arid climate typical of a marshy, saline environment. With the Congo Basin at the center of Gondwana, humid marine air from the coasts would have lost much of its moisture content by the time it reached the interior of the massive continent.

"There probably wouldn't have been a whole lot of trees; more scrubby kinds of plants," Myers says.

The clay minerals that form in soils have an isotopic composition related to that of the local rainfall and shallow groundwater. The difference in isotopic composition between these waters and the clay minerals is a function of surface temperature, he says. By measuring the oxygen and hydrogen isotopic values of the clays in the soils, researchers can estimate the temperature at which the clays formed.

(Photo: SMU)

Southern Methodist University

NEW TRANSPARENT INSULATING FILM COULD ENABLE ENERGY-EFFICIENT DISPLAYS

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Johns Hopkins materials scientists have found a new use for a chemical compound that has traditionally been viewed as an electrical conductor, a substance that allows electricity to flow through it. By orienting the compound in a different way, the researchers have turned it into a thin film insulator, which instead blocks the flow of electricity, but can induce large electric currents elsewhere. The material, called solution-deposited beta-alumina, could have important applications in transistor technology and in devices such as electronic books.

The discovery is described in the November issue of the journal Nature Materials and appears in an early online edition.

“This form of sodium beta-alumina has some very useful characteristics,” said Howard E. Katz, a professor of materials science and engineering who supervised the research team. “The material is produced in a liquid state, which means it can easily be deposited onto a surface in a precise pattern for the formation of printed circuits. But when it’s heated, it forms a solid, thin transparent film. In addition, it allows us to operate at low voltages, meaning it requires less power to induce useful current. That means its applications could operate with smaller batteries or be connected to a battery instead of a wall outlet.”

The transparency and thinness of the material (the hardened film is only on the order of 100 atoms thick) make it ideal for use in the increasingly popular e-book readers, which rely on see-through screens and portable power sources, Katz said. He added that possible transportation applications include instrument readouts that can be displayed in the windshield of an aircraft or a ground vehicle.

The emergence of sodium beta-alumina as an insulator was a surprising development, Katz said. The compound, known for decades, has traditionally been used to conduct electricity and for this reason has been considered as a possible battery component. The material allows charged particles to flow easily parallel to a two-dimensional plane formed within its distinct atomic crystalline arrangement. “But we found that current does not flow nearly as easily perpendicular to the planes, or in unoriented material,” Katz said. “The material acts as an insulator instead of a conductor. Our team was the first to exploit this discovery.”

The Johns Hopkins researchers developed a method of processing sodium beta-alumina in a way that makes use of this insulation behavior occurring in the form of a thin film. Working with the Johns Hopkins Technology Transfer staff, Katz’s team has filed for international patent protection for their discovery.

The lead author of the Nature Materials paper was Bhola N. Pal, who was a postdoctoral fellow in Katz’s laboratory. In addition to Katz, who is chair of the Department of Materials Science and Engineering in the university’s Whiting School of Engineering, the co-authors were Bal Mukund Dhar, a current doctoral student in the lab, and Kevin C. See, who recently completed his doctoral studies under Katz.

(Photo: Will Kirk, Homewoodphoto.jhu.edu)

Johns Hopkins University

AVATARS CAN SURREPTITIOUSLY AND NEGATIVELY AFFECT USER IN VIDEO GAMES, VIRTUAL WORLDS

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Although often seen as an inconsequential feature of digital technologies, one's self-representation, or avatar, in a virtual environment can affect the user's thoughts, according to research by a University of Texas at Austin communication professor.

In the first study to use avatars to prime negative responses in a desktop virtual setting, Jorge Peña, assistant professor in the College of Communication, demonstrated that the subtext of an avatar's appearance can simultaneously prime negative (or anti-social) thoughts and inhibit positive (or pro-social) thoughts inconsistent with the avatar's appearance. All of this while study participants remained unaware they had been primed. The study, co-written with Cornell University Professor Jeffrey T. Hancock and University of Texas at Austin graduate student Nicholas A. Merola, appears in the December 2009 issue of Communication Research.

In two separate experiments, research participants were randomly assigned a dark- or white-cloaked avatar, or to avatars wearing physician or Ku Klux Klan-like uniforms or a transparent avatar. The participants were assigned tasks including writing a story about a picture, or playing a video game on a virtual team and then coming to consensus on how to deal with infractions.

Consistently, participants represented by an avatar in a dark cloak or a KKK-like uniform demonstrated negative or anti-social behavior in team situations and in individual writing assignments.

Previous studies have demonstrated these uniform types to have negative effects on people's behaviors in face-to-face interactions. For example, Cornell researchers Mark Frank and Tom Gilovich showed that dark uniforms influence professional sports teams to play more aggressively on the playing field and in the laboratory. Peña's research demonstrates how these effects operate in desktop-based video games, and sheds light on the automatic cognitive processes that explain this effect.

"When you step into a virtual environment, you can potentially become 'Mario' or whatever other character you are portraying," said Peña, who studies how humans think, behave and feel online. "Oftentimes, the connotations of our own virtual character will subtly remind us of common stereotypes, such as 'bad guys wear black or dress up in hooded robes.' This association may surreptitiously steer users to think and behave more antisocially, but also inhibit more pro-social thoughts and responses in a virtual environment."

According to Peña, these findings can be particularly useful to video game and combat simulation developers.

"By manipulating the appearance of the avatar, you can augment the probability of people thinking and behaving in predictable ways without raising suspicion," said Peña. "Thus, you can automatically make a virtual encounter more competitive or cooperative by simply changing the connotations of one's avatar."

University of Texas

WORDS, GESTURES ARE TRANSLATED BY SAME BRAIN REGIONS

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In a study published in Early Edition of Proceedings of the National Academy of Sciences (PNAS), researchers have shown that the brain regions that have long been recognized as a center in which spoken or written words are decoded are also important in interpreting wordless gestures. The findings suggest that these brain regions may play a much broader role in the interpretation of symbols than researchers have thought and, for this reason, could be the evolutionary starting point from which language originated.

"In babies, the ability to communicate through gestures precedes spoken language, and you can predict a child's language skills based on the repertoire of his or her gestures during those early months," said James F. Battey, Jr., M.D., Ph.D., director of the NIDCD. "These findings not only provide compelling evidence regarding where language may have come from, they help explain the interplay that exists between language and gesture as children develop their language skills."

Scientists have known that sign language is largely processed in the same regions of the brain as spoken language. These regions include the inferior frontal gyrus, or Broca's area, in the front left side of the brain, and the posterior temporal region, commonly referred to as Wernicke's area, toward the back left side of the brain. It isn't surprising that signed and spoken language activate the same brain regions, because sign language operates in the same way as spoken language does — with its own vocabulary and rules of grammar.

In this study, NIDCD researchers, in collaboration with scientists from Hofstra University School of Medicine, Hempstead, N.Y., and San Diego State University, wanted to find out if non-language-related gestures — the hand and body movements we use that convey meaning on their own, without having to be translated into specific words or phrases — are processed in the same regions of the brain as language is. Two types of gestures were considered for the study: pantomimes, which mimic objects or actions, such as unscrewing a jar or juggling balls, and emblems, which are commonly used in social interactions and which signify abstract, usually more emotionally charged concepts than pantomimes. Examples include a hand sweeping across the forehead to indicate "it's hot in here!" or a finger to the lips to signify "be quiet."

While inside a functional MRI machine, 20 healthy, English-speaking volunteers — nine males and 11 females — watched video clips of a person either acting out one of the two gesture types or voicing the phrases that the gestures represent. As controls, volunteers also watched clips of the person using meaningless gestures or speaking pseudowords that had been chopped up and randomly reorganized so the brain would not interpret them as language. Volunteers watched 60 video clips for each of the six stimuli, with the clips presented in 45-second time blocks at a rate of 15 clips per block. A mirror attached to the head enabled the volunteer to watch the video projected on the scanner room wall. The scientists then measured brain activity for each of the stimuli and looked for similarities and differences as well as any communication occurring between individual parts of the brain.

The researchers found that for the gesture and spoken language stimuli, the brain was highly activated in the inferior frontal and posterior temporal areas, the long-recognized language regions of the brain.

"If gesture and language were not processed by the same system, you'd have spoken language activating the inferior frontal and posterior temporal areas, and gestures activating other parts of the brain," said Allen Braun, M.D., senior author on the paper, "But in fact we found virtual overlap."

Current thinking in the study of language is that, like a smart search engine that pops up the most suitable Web site at the top of its search results, the posterior temporal region serves as a storehouse of words from which the inferior frontal gyrus selects the most appropriate match. The researchers suggest that, rather than being limited to deciphering words alone, these regions may be able to apply meaning to any incoming symbols, be they words, gestures, images, sounds, or objects. According to Dr. Braun, these regions also may present a clue into how language evolved.

"Our results fit a longstanding theory which says that the common ancestor of humans and apes communicated through meaningful gestures and, over time, the brain regions that processed gestures became adapted for using words," he said. "If the theory is correct, our language areas may actually be the remnant of this ancient communication system, one that continues to process gesture as well as language in the human brain."

Dr. Braun adds that developing a better understanding of the brain systems that support gestures and words may help in the treatment of some patients with aphasia, a disorder that hinders a person's ability to produce or understand language.

National Institutes of Health

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