Saturday, January 8, 2011

STRUCTURE DEEP WITHIN THE BRAIN MAY CONTRIBUTE TO A RICH, VARIED SOCIAL LIFE

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Scientists have discovered that the amygdala, a small almond shaped structure deep within the temporal lobe, is important to a rich and varied social life among humans. The finding was published in a new study in Nature Neuroscience and is similar to previous findings in other primate species, which compared the size and complexity of social groups across those species.

"We know that primates who live in larger social groups have a larger amygdala, even when controlling for overall brain size and body size," says Lisa Feldman Barrett, PhD, of the Massachusetts General Hospital (MGH) Psychiatric Neuroimaging Research Program and a Distinguished Professor of Psychology at Northeastern University, who led the study. "We considered a single primate species, humans, and found that the amygdala volume positively correlated with the size and complexity of social networks in adult humans."

The researchers also performed an exploratory analysis of all the subcortical structures within the brain and found no compelling evidence of a similar relationship between any other subcortical structure and the social life of humans. The volume of the amygdala was not related to other social variables in the life of humans such as life support or social satisfaction.

"This link between amygdala size and social network size and complexity was observed for both older and younger individuals and for both men and women," says Bradford C. Dickerson, MD, of the MGH Department of Neurology and the Martinos Center for Biomedical Research. "This link was specific to the amygdala, because social network size and complexity were not associated with the size of other brain structures." Dickerson is an associate professor of Neurology at Harvard Medical School, and co-led the study with Dr. Barrett.

The researchers asked 58 participants to report information about the size and the complexity of their social networks by completing standard questionnaires that measured the total number of regular social contacts that each participant maintained, as well the number of different groups to which these contacts belonged. Participants, ranging in age from 19 to 83 years, also received a magnetic resonance imaging brain scan to gather information about the structure of various brain structures, including the volume of the amygdala.

A member of the Martinos Center at MGH, Barrett also notes that the results of the study were consistent with the "social brain hypothesis," which suggests that the human amygdala might have evolved partially to deal with an increasingly complex social life. "Further research is in progress to try to understand more about how the amygdala and other brain regions are involved in social behavior in humans," she says. "We and other researchers are also trying to understand how abnormalities in these brain regions may impair social behavior in neurologic and psychiatric disorders."

Massachusetts General Hospital

6 YEARS AFTER THE TSUNAMI DISASTER

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Six years after the tsunami disaster of 26/12/2004, the set-up of the German-Indonesian Tsunami Early Warning System for the Indian Ocean (GITEWS) has been completed. The project ends on 31 March 2011. After that, Indonesia accepts the sole responsibility for the overall system.

"The innovative technical approach of GITEWS is based on a combination of different sensors, whose central element is a fast and precise detection and analysis of earthquakes, supported by GPS measurements," says Professor Reinhard Hüttl, Scientific Director of the GFZ German Research Centre for Geosciences. "The GFZ-developed evaluation of Seismology via the SeisComP3 system proved to be so fast and reliable that it has now been installed in over 40 countries."

A tsunami warning takes place no more than five minutes after a submarine earthquake, based on all the available information from the 300 stations that were built throughout Indonesia in the past 6 years. These include seismometers, GPS stations, tide gauges and buoy systems. Via a tsunami-simulation system, the information is converted into a situation map providing the appropriate warning levels for the affected coastline. A key outcome of GITEWS project is, however, that the buoy systems do not contribute to this process that occurs in these first few minutes. There are therefore considerations to shift the GITEWS buoys further into the open ocean and to use them to verify an ocean-wide tsunami that could threaten other countries bordering the Indian Ocean.

The Mentawai quake on 25 October this year, however, also showed the limits of any tsunami warning. The tsunami caused by the earthquake strongly affected the upstream Pagai islands in the Sunda Arc. The first waves arrived around the same time as the triggered tsunami alert, 4 minutes 46 seconds after the quake, and demanded some 500 lives. Several teams of tsunami experts from Japan, Indonesia, Germany and the USA noted in a follow-up analysis that the warning had arrived on the islands, but there had been no time to react. For the main island of Sumatra with the larger cities of Padang and Bengkulu, the time between the warning and the arrival of the first waves amounted to about 40 minutes, but in this case the Pagai Islands acted as a perfect shield against a tsunami reaching the coast of Sumatra.

The important conclusion is that even with the extremely short premonition times off Indonesia, the GITEWS system has proven to be technically and organizationally functional. Since September 2007, four tsunami events were detected and warnings were issued for each. Especially the inhabitants of the off-shore islands, however, need to receive intensified and improved training on how to act when threatened. This includes not only the correct response during a tsunami alert, but also the correct behaviour before, during and after earthquakes.

Immediately after the disaster of 26 December 2004, the Federal Government of Germany contracted the Helmholtz Association, represented by the Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences, to develop and implement an early warning system for tsunamis in the Indian Ocean. The funds to the amount of 45 million euros are a contribution of the Federal Government from the aid-for-flood-victims pool.

A natural phenomenon like the tsunami of 2004 cannot be prevented, and such disasters will continue to claim victims, even with a perfectly working alarm system. But the repercussions of such a natural disaster can be minimized with an early warning system. This is the aim of GITEWS.

GFZ

MILESTONE: A METHANE-METAL MARRIAGE

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For the first time, chemists have succeeded in plugging a metal atom into a methane gas molecule, thereby creating a new compound that could be a key in opening up new production processes for the chemical industry, especially for the synthesis of organic compounds, which in turn might have implications for drug development.

The UA research group also is the first to determine the precise structure of this "metal-methane hybrid" molecule, predicted by theoretical calculations but until now never observed in the real world.

The discovery is published in the Journal of the American Chemical Society and was selected for a news spotlight in Chemical and Engineering News magazine, the weekly publication of the American Chemical Society, because of its significance.

In the chemistry world, seemingly simple actions can have big implications. For example, squeezing zinc atoms into methane gas molecules. This so-called metal-methane insertion is neither a complicated chemical reaction nor something that is likely to happen in nature, but it's very hard to do in the lab. What is even harder is figuring out what the resulting molecule looks like. But chemists like to tinker with things. And the chemical industry likes to tinker with things even more, especially when that tinkering could lead to useful products.

"There is a big push in the chemical industry and in chemistry in general, to make use of fairly common organic compounds such as methane and turn them into something that can serve as a source for a product," said Lucy Ziurys, who led the research effort. "For example, a plastic or a polymer, something that is more useful than just taking the methane and burning it."

"Our finding could make industrial applications easier, cheaper, quicker, and they could start with this simple compound, methane. They could convert it to all kinds of more complex and more valuable products."

"Gaining a better understanding of these simple reactions that we really don't understand at the basic level always has applications to more complicated systems," Ziurys added.

Ziurys is a professor of chemistry and a professor of astronomy with joint appointments in the UA's department of chemistry and biochemistry and Steward Observatory.

Methane gas, produced naturally by decaying organic matter, is familiar to many as the main ingredient in natural gas. It is also a potent greenhouse gas, more powerful than carbon dioxide. Budding chemistry students are introduced to methane as the simplest of all organic molecules. All organic molecules contain carbon and hydrogen in one way or another, which sets them apart from inorganic molecules such as table salt, which contains sodium and chloride, but no carbon or hydrogen.

When it comes to interacting with other molecules, methane is a bit anti-social. Or, as chemists put it, it is "inert," meaning one has to do a whole lot of nudging and prodding to get methane to bond with other chemicals. Chemists call this nudging and prodding "activating." And that is precisely what the tinkerers in the chemical science community and the industry would like to be able to do.

Said Ziurys: "One way to get these molecules more reactive is by what is called metal insertion. The metal inserts itself into the methane molecule and thereby activates it. It makes it more prone to reacting with something else. So you could then take this activated methane and make, say, methanol."

"Until now, there was no complete evidence that the metal actually inserts itself into the molecule bond and forms this complex. People just assumed it did," she said. "But we are the first to actually prove the existence of the complex and describe its structure to a very high degree of accuracy. It's the first time anyone has been able to do this."

The new compound is stable for a few seconds – long enough for industrial applications to immediately convert it to something else.

To create the molecule and analyze its structure, Ziurys' research group heated zinc until it vaporized in a vacuum chamber and added methane gas. An electrical discharge fed energy into the system, converting the gas mixture into glowing plasma, sparking the formation of the metal-methane molecule. Most of the experiments were done by Michael Flory, a former graduate student of Ziurys', as part of his doctoral thesis.

"We made the molecule in a gas phase, which is the only way we can really obtain a good measurement of the structure," Ziurys said. "Almost every theory paper said this couldn't be made in the gas phase, which is probably why nobody really tried it before."

"Our data show that zinc goes right in and pops into that bond that links the carbon atom to one of the four hydrogen atoms in methane. People have speculated on that, but this is the first time anyone has shown that that is what actually happens."

Because none of these processes are visible to the naked eye, the scientists used a microwave source to send electromagnetic energy at defined wavelengths through the plasma. Here is the trick: Any given molecule absorbs some of that energy at a very distinct wavelength, depending on its chemical structure. By detecting those dips in the energy inside the chamber, each species of molecule leaves its own energy dip as a telltale signature that can be picked up by a detector. This process is called direct-absorption spectroscopy.

As is often the case with scientific discoveries, Ziurys' team was after a completely different type of molecule.

"We searched in our spectra for them, but we never found them. Instead, we found our methane with zinc in it," Ziurys said. "That really surprised us. We didn't expect that to be there."

The group did the necessary experiments to confirm the structure of the elusive molecule and everything fell together, Ziurys said.

"We knew exactly what we had. Those molecules are floating around and they rotate, generating a certain spectral pattern, depending on the mass of the molecule and the bond lengths between the atoms they are made of. We then exchange the atoms for slightly different versions with different masses, and we get a slight change in inertia, which results in a changed rotational pattern. Then we apply the math and we get a structure."

Nature makes abundant use of metal atoms embedded in complex organic molecules. In fact, metals are involved in almost any sort of complicated chemical reaction in living systems. One example is hemoglobin and iron, the large protein molecule that contains iron atoms in precise arrangements to capture oxygen and transport it around in our blood stream.

"We know that metals play important roles in biology, but we don't have a very good understanding of those processes," said Ziurys. "If we did, we'd be able to use them much better."

According to Ziurys, zinc is one of the most biologically important metals, used by many enzymes to perform their jobs.

"How does Zinc react? How does it work? If we understand how it does in simple molecules like methane, eventually we should be able to generalize to much more complicated systems like enzymes."

(Photo: U. Arizona)

University of Arizona

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