Archive for the ‘PNAS’ Category


Chinese children are lined up in Tiananmen Square in 2003 for photos with the overseas families adopting them. The children in the new study were adopted from China at an average age of 12.8 months and raised in French-speaking families.

You may not recall any memories from the first year of life, but if you were exposed to a different language at the time, your brain will still respond to it at some level, a new study suggests.

Brain scans show that children adopted from China as babies into families that don’t speak Chinese still unconsciously recognize Chinese sounds as language more than a decade later.

“It was amazing to see evidence that such an early experience continued to have a lasting effect,” said Lara Pierce, lead author of the study just published in the journal Proceedings of the National Academy of Sciences, in an email to CBC News.

The adopted children, who were raised in French-speaking Quebec families, had no conscious memory of hearing Chinese.

“If you actually test these people in Chinese, they don’t actually know it,” said Denise Klein, a researcher at McGill University’s Montreal Neurological Institute who co-authored the paper.

But their brains responded to Chinese language sounds the same way as those of bilingual children raised in Chinese-speaking families.


Children exposed to Chinese as babies display similar brain activation patterns as children with continued exposure to Chinese when hearing Chinese words, fMRI scans show.

“In essence, their pattern still looks like people who’ve been exposed to Chinese all their lives.”

Pierce, a PhD candidate in psychology at McGill University, working with Klein and other collaborators, scanned the brains of 48 girls aged nine to 17. Each participant lay inside a functional magnetic resonance imaging machine while she listened to pairs of three-syllable phrases. The phrases contained either:

■Sounds and tones from Mandarin, the official Chinese dialect.
■Hummed versions of the same tones but no actual words.

Participants were asked to tell if the last syllables of each pair were the same or different. The imaging machine measured what parts of the brain were active as the participants were thinking.

“Everybody can do the task — it’s not a difficult task to do,” Klein said. But the sounds are processed differently by people who recognize Chinese words — in that case, they activate the part of the brain that processes language.

Klein said the 21 children adopted from China who participated in the study might have been expected to show patterns similar to those of the 11 monolingual French-speaking children. After all, the adoptees left China at an average age of 12.8 months, an age when most children can only say a few words. On average, those children had not heard Chinese in more than 12 years.

The fact that their brains still recognized Chinese provides some insight into the importance of language learning during the first year of life, Klein suggested.

Effect on ‘relearning’ language not known

But Klein noted that the study is a preliminary one and the researchers don’t yet know what the results mean.

For example, would adopted children exposed to Chinese in infancy have an easier time relearning Chinese later, compared with monolingual French-speaking children who were learning it for the first time?

Pierce said studies trying to figure that out have had mixed results, but she hopes the findings in this study could generate better ways to tackle that question.

She is also interested in whether the traces of the lost language affect how the brain responds to other languages or other kinds of learning. Being able to speak multiple languages has already been shown to have different effects on the way the brain processes languages and other kinds of information.

http://www.cbc.ca/news/technology/adoptees-lost-language-from-infancy-triggers-brain-response-1.2838001

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manflu_2774361b

New study suggests that men may actually suffer more when they have influenza because high levels of testosterone can weaken immune response.

For years women have cried “man flu” when men make a fuss over a few sniffles.

But a new study suggests that men may actually suffer more when they are struck down with flu – because high levels of testosterone can weaken their immune response.

The study by Stanford University School of Medicine, examined the reactions of men and women to vaccination against flu.

It found women generally had a stronger antibody response to the jab than men, giving them better protection against the virus.

Men with lower testosterone levels also had a better immune response, more or less equivalent to that of women.

It has long been suggested that men might be more susceptible to bacterial, viral, fungal and parasitic infection than women are.

The study published in the Proceedings of the National Academy of Sciences, found women had higher blood levels of signaling proteins that immune cells pass back and forth, when the body is under threat.

Previous research has found that testosterone has anti-inflammatory properties, suggesting a possible interaction between the male sex hormone and immune response.

Professor of microbiology and immunology Mark Davis said: “This is the first study to show an explicit correlation between testosterone levels, gene expression and immune responsiveness in humans.

“It could be food for thought to all the testosterone-supplement takers out there.”

Scientists said they were left perplexed as why evolution would designed a hormone that enhances classic male sexual characteristics – such as muscle strength, beard growth and risk-taking propensity – yet left them with a weaker immune system.

Previous studies have found that while women may accuse men of exaggerating when they have flu, females who are more likely to admit to having sniffles and sneezes.

The research, carried out by London School of Hygiene and Tropical Medicine last winter, shows that women are are 16 per cent more likely to say they are ill.

http://www.telegraph.co.uk/health/healthnews/10536083/Man-flu-the-truth-that-women-dont-want-to-hear.html

monogamy

Social monogamy – when a male and female of the species stick together for the long term, although may mate with others – is rare in mammals generally. However, it occurs in over a quarter of primate species, including humans, gibbons and many New World monkeys, such as titis.

To investigate what originally drove us to establish such pair bonds, a team led by Kit Opie of University College London and Susanne Shultz from the University of Manchester, UK, gathered data on the mating behaviour of 230 primate species. They selected behavioural traits associated with several possible evolutionary drivers of monogamy, including the risk of infanticide, the need for paternal care and the potential for guarding female mates.

Using data on the genetic relationships between the species, the team ran millions of computer simulations of the evolution of these traits to work out which came first.

All three were linked to the evolution of monogamy but only behaviours associated with infanticide actually preceded it, suggesting that this was the driver. Suckling infants are most likely to be killed by unrelated males, in order to bring the mother back into ovulation.

With pair-bonding in place, not only would a mother have a male to help protect the infant from marauding males, but there would then be the opportunity for the male to help care for it by providing extra resources. This means the infant can be weaned earlier, again reducing the chance of it being killed.

“Until recently, reconstructing how behaviour evolves has been very tricky as there are few behavioural traces in the fossil record. The statistical approach we have used allows us to bring the fossils to life and to understand the factors that have led to the evolution of monogamy in humans and other primates,” says Shultz.

Carel van Schaik, a primatologist at the University of Zurich in Switzerland says the results are solid but questions whether they can be extrapolated to humans. He says evidence suggests that humans were never really monogamous and that the monogamy we see today in many cultures is socially imposed.

Shultz counters that there is fossil evidence pointing to monogamy in australopithecines, the hominin genus from which modern humans descended.

“Although we suggest that infanticide may help explain the evolution of monogamy in humans, we do not argue that it is the only factor nor that monogamy is universal,” Shultz says. “I would suggest that where infanticide risk is high, as it would be with our ancestors, having a father provide protection and care would facilitate the evolution of the modern human extended childhood.”

Journal reference: PNAS, DOI: 10.1073/pnas.1307903110