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DISCOVERIES

MIT researchers offer insights into how brains pay attention

NEUROSCIENCE
Is it quiet? Or are there distractions as you try to read this? There are, it turns out, at least two different kinds of paying attention. One is where you consciously pay attention, as you do when reading a newspaper. A second is when something grabs your attention, like a sudden flash of light. A new study from MIT shows, for the first time, that different parts of the brain are involved in the two processes. Concentrating happens up front, in the prefrontal cortex. Distraction happens in the back, in the parietal cortex. The study also found that neurons send out signals at different frequencies for the two types of attention, almost like an FM radio tuned to different stations. This suggests that focusing and ignoring distractions are two distinct processes.

BOTTOM LINE: Researchers have made progress in seeing how the brain pays attention, suggesting new avenues for understanding the biology behind attention deficit disorders.

CAUTIONS: The research, done in monkeys, tested only visual attention, so it might not apply more generally.

WHAT'S NEXT: The team will look to see if the same phenomenon applies in attention to sounds.

WHERE TO FIND IT: Science, March 30.

GARETH COOK

OBESITY

Excess weight of pregnancy may end up on child


Researchers have long been aware of the potential risk for low birth weights in babies whose mothers gain an inadequate amount of weight during pregnancy. Now, researchers at Harvard Medical School have found that babies born to mothers who gain more than the recommended amounts, or even the recommended amount of weight, are at risk for becoming overweight in early childhood. By studying data from more than 1,000 mothers, the researchers found that women who gained excess weight during pregnancy according to guidelines established in 1990 had children who were four times more likely to be overweight by age 3 than those who gained less than the recommended amount. Most surprising, according to the researchers, was that the guidelines may actually be too high. "Even the women who had weight gain that was in the range currently considered adequate had kids at a higher risk of being overweight," said Dr. Emily Oken, an instructor at Harvard Medical School and the lead author of the study. For normal-weight women, the guidelines suggest gaining 25-35 pounds; for overweight women, 15-25 pounds. It's not clear how the mother's weight gain during pregnancy results in a higher obesity risk for her baby in childhood, but Oken points to several possibilities. "Women who are gaining more weight probably have genetic tendencies or lifestyles that predispose them to gaining more weight, which is an environment they will share with their babies," she said. However, Oken and her colleagues are also exploring the possibility that the mother's weight gain somehow changes the fetal environment, "programming" a higher risk for unhealthy weight gain in the child.

BOTTOM LINE: Mothers who follow or exceed the current guidelines for weight gain during pregnancy may have children at a higher risk for becoming overweight later in childhood.

CAUTIONS: The research to date followed children only until age 3, and the long-term effects of excessive weight gain during pregnancy are unclear.

WHAT'S NEXT: The researchers plan to study to a larger group including women from other populations and to examine the risk for unhealthy weight gain beyond age 3.

WHERE TO FIND IT: American Journal of Obstetrics and Gynecology, April

MICHELLE SIPICS

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