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Yawning regulates brain-cooling

Yawning, is  considered a mark of boredom or fatigue, could serve as a method for regulating brain temperature, according to a study.

A study led by Andrew Gallup, a postdoctoral research associate in Princeton University’s Department of Ecology and Evolutionary Biology, is the first involving humans to show that yawning frequency varies with the season and that people are less likely to yawn when the heat outdoors exceeds body temperature.

This suggests that yawning could be a natural brain-cooling mechanism, Princeton University and University of Arizona researchers reported.

 Gallup and his co-author Omar Eldakar documented the yawning frequency of 160 people in the winter and summer in Tucson, Ariz., with 80 people for each season. They found that participants were more likely to yawn in the winter, as opposed to the summer when ambient temperatures were equal to or exceeding body temperature.

The researchers concluded that warmer temperatures provide no relief for overheated brains, which, according to the thermoregulatory theory of yawning, stay cool via a heat exchange with the air drawn in during a yawn.
 
Craving for junk food? Blame it on low sugar in brain
Feeding the brain with sugar could dampen our desire for high-calorie food, according to a new study led by an Indian-origin researcher.

Brain imaging scans show that when glucose levels drop, an area of the brain known to regulate emotions and impulses loses the ability to dampen desire for high-calorie food, the report said.

“Our prefrontal cortex is a sucker for glucose,” said Rajita Sinha, the Foundations Fund Professor of Psychiatry, and professor in the Department of Neurobiology and the Yale Child Study Centre, one of the senior authors of the research.

 The Yale team manipulated glucose levels intravenously and monitored changes in blood sugar levels while subjects were shown pictures of high-calorie food, low-calorie food and non-food as they underwent fMRI scans.

When glucose levels drop, an area of the brain called the hypothalamus senses the change. Other regions called the insula and striatum associated with reward are activated, inducing a desire to eat, the study found.

When glucose is lowered, the prefrontal cortex seemed to lose its ability to put the brakes upon increasingly urgent signals to eat generated in the striatum. This weakened response was particularly striking in the obese when shown high-calorie foods.

“The key seems to be eating healthy foods that maintain glucose levels,” Sinha said. “The brain needs its food.”

Sharks can protect us from dengue, yellow fever
Scientists have found that a compound initially isolated from sharks could be used as a unique broad-spectrum human antiviral agent against human viruses ranging from dengue and yellow fever to hepatitis B, C, and D.

The compound, squalamine, has been in human clinical trials for the treatment of cancer and several eye disorders, and so has a well-known safety profile, suggesting it can be quickly tested as a new class of drugs to treat infections caused by these viruses.

“Squalamine appears to protect against viruses that attack the liver and blood tissues, and other similar compounds that we know exist in the shark likely protect against respiratory viral infections, and so on,” said the study’s lead investigator, Michael Zasloff,  professor of surgery and paediatrics at Georgetown University Medical Centre and scientific director of the Georgetown Transplant Institute.

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