Some folks who don’t seem to listen may just have a lazy ear. A new study in rats shows that short-term hearing impairments at any stage of life can lead to rewiring in the part of the brain that processes sounds, making the ear seem as if it is loafing on its duty to make sense from noise.
Ear infections and fluid buildup in the middle ear — a condition known as otitis media with effusion — can dampen incoming sound waves. These problems are extremely common in children and represent the top reason children go to the doctor. Such temporary hearing impairment can lead to lingering hearing deficits even after the infection or fluid clears up. The long-term difficulties result from a problem with how the brain adjusts to hearing changes rather than a malfunction in the ear’s ability to detect sounds, researchers report in the March 11 Neuron.
An analogous problem in which the brain has trouble processing visual signals from a perfectly functional eye is often called “lazy eye.” A lazy eye can often be retrained through practice in children up to about 8 years old.
Likewise, the new study shows that the brain’s auditory cortex remains flexible enough that it can partially rewire itself even into adulthood. This gives hope that at least some ear “laziness” problems can be corrected in adults, say study coauthors Daniel Polley, a neuroscientist at the Massachusetts Eye and Ear Infirmary in Boston, and Maria Popescu of Vanderbilt University in Nashville.
Polley and Popescu’s experiments with rats show that the brain has a number of critical windows for rewiring itself. The researchers surgically tied off the ear canal in one ear of infant, juvenile and adult rats to mimic the sound-deadening effects of fluid in the ear. After 60 days, the team measured activity of the rats’ auditory cortex cells in response to sounds of various frequencies. Blocking sound to one ear produced different changes in the rats’ brains, depending on the age when hearing was impaired, the team found.
In 2-week-old rats with blocked ears, more cells in the auditory cortex responded to low-frequency sounds and fewer cells responded to high-frequency sounds compared with rats with no ear blockage, suggesting a diminished range. The infant rats also had a strengthened response to sound signals from the open ear and a weakened response to signals from the closed ear — meaning that one side of the brain loses out in the competition to process sounds. Such losses in people could lead to subtle speech defects or other learning problems, says Takao Hensch, a neuroscientist at Children’s Hospital Boston and Harvard University.
Juvenile rats whose ear canals were tied off at age 4 weeks didn’t have more low-frequency–sensitive cells in their auditory cortex, indicating that the critical window for determining the low- and high-frequency range had already closed. But like the infant rats, the juvenile rats still showed a shift in which ear responded most to sound signals.
If the ear canal wasn’t tied off until the rats were adults, the brain cells had a weakened response to the blocked ear but didn’t strengthen the open ear’s input. That result shows that as animals age, they lose the ability to boost signals from the open ear.
The new study “opens up quite a rich system to study brain plasticity,” Hensch says. Researchers still don’t yet know how long each of the critical rewiring periods last in rats or, assuming the system is similar in humans, in people. Also unclear is exactly what effect the brain rewiring would have on hearing in people.
While there’s been little to no work done on how common lazy ear is in humans, the researchers think the new study could have important implications in medicine, especially for choosing how aggressively to treat childhood ear infections.
Since adults still retain some ability to rewire sound-processing centers, the researchers hope that just as a lazy eye can be retrained, lazy ears might also learn new work habits.
Image: maessive/Flickr
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Plastics became ubiquitous during the 20th century. They were hot topics of industrial and academic research, and saw innumerable consumer applications. While plastics can have a wide variety of mechanical properties, they are almost universally good insulators, both of heat and electricity. But a paper out of the Pappalardo Micro and Nano Engineering Laboratories reports on a novel processing technique that aligns the polymer chains of polyethylene, which results in a material that has both a high thermal capacitance and a high electrical resistance.
The researchers forced the polyethylene to form into this aligned morphology by slowly drawing the fiber out of solution using the tip of an atomic force microscope. The new fibrous form of polyethylene conducts heat well along the direction of the fibers—so well, it beats out many pure metals, including iron and platinum.The resulting fiber was about 300 times more thermally conductive than normal polyethylene. This surprising ability to move heat could find uses in any number of technologies that currently rely on metal as a heat transfer medium.
This new method differs from previous attempts at creating a more heat-conductive plastic in that it transforms the morphology of the underlying material instead of using an additive. These prior attempts, while scalable, resulted in only modest gains, since there was high thermal resistance at the interface between the plastic and additive.
It's not currently known how well, if at all, the process will be able to scale up to production. So far, the team has only produced single fibers in the laboratory, but they hope to be able to scale up to macro-scale production of entire sheets of this material.
Nature Nanotechnology, 2010. DOI: 10.1038/NNANO.2010.27 (About DOIs).
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It feels like quantum computers have barely been invented, and scientists are already testing how extensible the current technology is. A paper published in Nature Photonics this week describes how researchers are beginning to push the bandwidth limits of quantum memory. Using photon pulses and cesium vapor has provided bandwidths on par with broadband connections, rates 100 times those of other quantum memory systems currently being tested. However, the system's efficiency is still very low, and advances will have to be made in other fields before it can be improved.
Since many quantum computing implementations operate on photons, a quantum memory that doesn’t involve converting photons into other media, like electrical pulses, would be ideal. Unfortunately, current photon-based media suffers from problems with storage time, retrieval efficiency, and bandwidth. The paper tackles the last issue, as current quantum systems are limited to a data rate of a few megahertz at most.
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This week two news events featured nuclear power. In the US the Dept. of Energy announced a fairly small, on the atomic scale, grant for study of new, more efficient high temperature “next generation” reactors. In France President Sarkozy waved the flag for gallic technology to help fill expected international orders for hundreds of new reactors in coming decades.
The U.S. news got coverage, but one hopes it will get deeper in coming days or weeks. The essence is simple: About $40 million to the General Atomics Co., and to Toshiba-owned Westinghouse Electric Co., to refine “Next Generation Nuclear Plant” designs. Such reactors, cooled by helium, would run at higher temperatures than standard reactors and, some say, would be more efficient and inherently more stable than water-cooled ones now widely in use. This is an opening into whether high-temperature, so-called “fast” reactors are also going to go on a faster track. Such things use a fuel cycle that burns, or transmutes, most of the radioactive waste that make long-term disposal such a headache. They also are complex, and may make weapons proliferation harder to control, worry some. But of that, nothing here in these tidbits:
Stories:
Grist for the Mill: DOE Press Release ;
And from France the bigger story – the offense by the government, featured at a conference in Paris, to encourage a rapid expansion of nuclear power, including in developing countries.
And finally, a news that isn’t the news that it means to be news – nukes in Israel:
Pic: older illus of General Atomics Helium Cooled Gas Turbine Reactor;
- Charlie Petit
SALT LAKE CITY — Nearly two decades after vets began returning from the Middle East complaining of Gulf War Syndrome, the federal government has yet to formally accept that their vague jumble of symptoms constitutes a legitimate illness. Here, at the Society of Toxicology annual meeting, yesterday, researchers rolled out a host of brain images — various types of magnetic-resonance scans and brain-wave measurements — that they say graphically and unambiguously depict Gulf War Syndrome.
Or syndromes. Because Robert Haley of the University of Texas Southwestern Medical Center in Dallas and the research team he heads have identified three discrete subtypes. Each is characterized by a different suite of symptoms. And the new imaging linked each illness with a distinct — and different — series of abnormalities in the brain.
Men with the same symptoms exhibited similar brain changes, features starkly different from healthy vets their age who had served in the same battalions. (That said, a few vets’ symptoms seemed to encompass more than one syndrome. And in such instances, imaging confirmed their brains showed impairments that extended beyond those associated with a single syndrome.)
Since the early 1990s, some 175,000 U.S. troops have returned from service in the first Gulf War reporting a host of vague complaints, notes Richard Briggs, a physical chemist at UT Southwestern involved in the new imaging. Their symptoms ranged from mental confusion, difficulty concentrating, attacks of sudden vertigo and intense uncontrollable mood swings to extreme fatigue and sometimes numbness — or the opposite, constant body pain.
With funding from the Departments of Defense and Veterans Affairs, Haley has assembled a team of roughly 140 researchers. Many work with patients. Others are developing new animal, biochemical and genetic studies to identify the biological perturbations underlying Gulf War Illness. But the vast majority — two-thirds of these scientists — are now involved in brain imaging.
As a result of these studies, Briggs says, “In the last two years we have learned more about Gulf War Illness than we did in the previous 15.”
What’s emerged is evidence to suggest “that there are three major syndromes responsible for Gulf War Illness,” he says. They appear loosely linked to at least three different types of agents to which many troops were exposed: sarin nerve gas, a nerve gas antidote (pyridostigmine bromide) that presented its own risks and military-grade pesticides to prevent illness from sand flies and other noxious pests. But Briggs acknowledges that no one knows for sure which combination of agents or environmental conditions might have conspired to trigger Gulf War illness.
What is clear, he says, is that “our data now clearly show, beyond a shadow of a doubt, that there are brain abnormalities — physiological differences — between ill veterans and normal ones.” And from the new scans, “we can tell the ill veterans from the well veterans. And we can distinguish syndromes one, two and three from each other.”
The new neuroimaging on a subset of 57 Gulf War vets was completed eight months ago. Yesterday’s presentations represent an unveiling of the complex statistical analyses of data gleaned from those functional MRI scans (or fMRIs), brain-wave recordings and other magnetic resonance tools.
Some testing employed old-style technologies. For instance, about a dozen years ago, Haley’s team performed magnetic resonance spectroscopy, also known as MRS, to study the chemical composition of various regions in the brains of Gulf War vets. And these tests uncovered the first solid indicators that there were physiological abnormalities in men complaining of Gulf War Illness. Such as a perturbation in the ratio of two chemicals active in the brain’s basal ganglia: n-acetyl aspartate (or NAA) and creatine.
Don’t know what that means? I didn’t either. So Briggs explained.
“The basal ganglia is sort of the switching system of the brain. It’s where a lot of communication between the left and right hemispheres occurs.” Because it crosses the midbrain region, he says, “it’s heavily involved in a lot of these decisionmaking and attention/inhibition networks” – processing centers that, if messed up, could explain many symptoms reported by sick vets.
NAA is a biomarker of healthy nerve cells. So any decrease is a bad sign. The concentration of creatine, which comprises the fuel for brain activities, tends to remain constant, Briggs says, so “it’s often used as an internal standard” against which to compare things like NAA.
The Gulf War syndromes are each associated with a roughly 10 percent lower than normal NAA-to-creatine ratio in the left and right basal ganglia, Briggs says — “an indicator of either sick or dead neurons.”
After Haley’s team initially published evidence in the late ’90s of the diminished NAA-to-creatine ratio in sick vets, two other labs confirmed this characteristic MRS feature in sick Gulf War veterans, Briggs notes. More recently, when one of those labs failed to reconfirm those changes during a followup study, the UT Southwestern team began to wonder whether it had erred the first time it had conducted the pioneering tests. Or whether the sick vets had simply gotten well over the past 10 years.
“Our new follow-up [MRS] tests now show our initial findings were right,” Haley says, “and that the soldiers haven’t gotten better with time.”
Many of scans that his team unveiled here at SOT rely on a technology (fMRI) that was not available in the late ’90s. So it provides new evidence of what sets sick vets apart.
This technology allows researchers to identify which areas are active as the brain works. Haley’s multicenter team designed a series of fMRI tests that required subjects to look at threatening pictures of a battlefield, or imagine the theme behind two words to come up with a third (”desert” and “humps” might be the clues given to suggest “camel”), or to learn words and recall faces.
In healthy veterans, appropriate parts of the brain lit up as they thought, reasoned, viewed — even experienced extremes of temperature. But in men suffering from Gulf War Illness, Haley says, “a different part would often light up as their brain attempted to work around its damage.”
Affected areas of the brain in each test varied. The thalamus, for example, is involved in attention and inhibition, Briggs explains. “It is activated differently in syndrome two versus controls,” he notes. Not surprisingly, people with that particular syndrome have problems with those traits. The researchers also correlated what combinations of areas in the brain respond in concert during particular tasks. And sometimes, the collection of brain locales that lit up in sick vets differed markedly from those in healthy vets (see images above).
The background volume of blood flowing through the brain also varied substantially in sick vets, Haley notes, “which suggests decreased [brain] function.” But even more importantly, blood flow varied in unpredictable ways when the sick Gulf War veterans were administered a drug meant to stimulate parts of the brain susceptible to chemical damage, such as nerve-gas-type agents.
In healthy vets and those suffering from syndrome one, blood flow to affected regions of the brain diminished, although not comparably; the drop in syndrome-one vets was about five times that in the healthy men. But among individuals suffering from Gulf War syndromes two and three, blood flow inappropriately spiked after administration of the drug.
Other tests probed for faults in the integrity of the circuitry connecting deep gray matter — where the brain performs unconscious calculations and processing — with the layer of white matter that performs conscious reasoning. In vets with syndrome two, the most seriously ill of the groups, a special form of scans showed signs that the insulating sheath covering the “wires” connecting the gray and white-matter regions was seriously impaired.
Concludes Briggs: “This tells us very clearly that in the syndrome twos — unlike either of the other syndromes, or the controls — their wiring is flawed.”
The panoply of quantitative changes being revealed by brain imaging “is demystifying Gulf War Syndrome,” says Haley. Indeed, before long, he predicts, “we’re going to come up with tests whereby doctors can diagnose affected vets.” And one day, he hopes, the information emerging from these images may actually point toward treatments.
Image: Healthy brain (left) shows response to pain from heat on the forearm. Different regions (right) respond to that heat in vets with Gulf War syndrome.
(English intro to Spanish lang. post) The Chilean Earthquake might become the most scientifically studied earthquake ever. We’ve read stories about the state of seismic predictions, changes in Earth axis, non-relation with other recent earthquakes, increased interest in monitoring risk in some Latin American countries… today many newspapers talk about the 3 meters movement of the city of Concepción and others in Argentina. But we have also found a really interesting story analyzing the possible increase in volcanism activity in the region. An expert alerted that this has frequently happened in the past. The journalist consults a geologist form Chile who says they haven’t perceived any anomalies yet, and that this only happens when the volcanoes are “ready” to erupt.
El terremoto de Chile va camino de convertirse en el más estudiado científicamente de la historia. Y seguramente, el que más notas de ciencia diferentes genere. Ya hablamos del ligero cambio de eje terrestre que provocó, de si el seísmo podía o no predecirse, de cuál es el riesgo en otros países latinoamericanos, de si disminuye las posibilidades chilenas de alojar el gran telescopio europeo, y de si la mayor actividad sísmica reciente es casualidad. Hoy todas las secciones de ciencia recogen la noticia de los 3 metros que se desplazó la ciudad de Concepción. Y todavía encontramos otra interesante aproximación: ¿Aumenta el riesgo de vulcanismo tras el terremoto?. Hagamos un repaso, empezando por esta última nota.
La Nación (Chile), presenta un detallado reportaje de Cristina Espinoza: “Advierten peligro de erupciones tras terremoto”. Un vulcanólogo estadounidense advirtió que tras grandes seísmos, suele haber un aumento de las erupciones volcánicas. Al menos, esto es lo que sugieren los registros históricos, y bien podría ocurrir en Chile. Cristina recoge este dato, pero lo contrasta con geólogos de la Red de Vigilancia Volcánica de Chile. “Si, si… lo sabemos. Empezamos a monitorizar nuestros volcanes de inmediato y seguiremos alerta durante un tiempo, pero de momento no hemos registrado ninguna anomalía”, viene a decir un experto. “De hecho, esta estadística es un poco frágil. Sólo ocurre si los volcanes estás listos para una pronta erupción”, opina otro. Buen texto, y buen gráfico con los volcanes “al acecho”.
Respecto los tres metros que se desplazó al oeste la ciudad de Concepción, los 27 cm de Santiago, los 4 de Buenos Aires, y los 13 de Mendoza, en La Nación (Argentina) , Sebastián Ríos abre su texto con una gran frase: “Cuando el suelo bajo nuestros pies se mueve a 8,8 grados en la escala de Richter, las cosas no siempre aparecen en el mismo lugar en el que se encontraban antes del terremoto”. Entrevistando a un científico local, consigue otra que tampoco tiene desperdicio: “La tierra firme, para nosotros los geólogos, no existe” (en referencia al movimiento de placas tectónicas). La noticia se recoge con buen detalle en BBC Mundo, y aparece en gran cantidad de medios como La Jornada (Mex), ElSalvador.com, La Tercera (Chile) El correo (Perú), Juventud Rebelde (Cuba), etc… en Clarín, Sibila Camps explica que los desplazamientos son algo natural, y ya los observó Darwin durante su viaje en el Beagle.
También interesante en El País cómo Alicia Rivera explica que “El terremoto de Chile no era una sorpresa”, pues los sismólogos llevaban años midiendo el movimiento de placas, habían advertido acumulación de tensiones, y registrado terremotos grandes en las costas Chilenas cada 8-10 años, pero a excepción del área de Concepción que sufrió su último gran seísmo en 1835. Lejos de Chile pero cercano a los tsunamis, en ABC Judith de Jorge presenta a “El hombre que puede evitar catástrofes”. Interesante cómo este experto en mecánica de fluidos investiga para ser capaces de predecir con mayor antelación tsunamis, inundaciones, incendios, o roturas de diques.
Con un tono ligeramente alarmista, Diario de las Américas titula un artículo de Sergio Bofelli “El próximo terremoto en Managua”, y tras entrevistar a un experto concluye que la posibilidad de que en los próximos 3 a 6 años se produzca un terremoto en la capital Nicaragüense es de entre el 50 y el 100%. Y debido a el mal estado arquitectónico, causaría 35.000 muertos. Qué precisión…
Veremos cómo continúa la inercia informativa sobre los terremotos.
- Pere Estupinyà
Try deconstructing this sentence, the lede to a WaPost story today by Joel Achenbach, which on its face seems to say one thing but could mean quite another: “Harrison Schmitt’s credentials as a space policy analyst include several days of walking on the moon.”
Hmm, well okay. Plus, as Achenbach adds, he is a former Senator. But really, walking on the moon makes one a space policy analyst … or merely an advocate? One might as well write, “Al Unser Jr.’s credentials as a mass transit analyst include a victory in the Indy 500.” Which is to say, Achenbach could be making a sly point about lack of credentials. Or not. Hard to say.
The story is about the intense reaction, including by Schmitt, against the administration’s drive to pole-ax NASA’s new human-rated rockets before they even reach the launch pad, and to re-think the whole return to the Moon and then on-to-Mars plan it inherited from the last administration.
The evasive tone of the lede fits an article that doesn’t overtly lead where one might expect. It starts with accounts of the powerful forces and emotions working against the proposed alteration of focus at NASA. But then it says the fight is over public relations, hardly a metric for substance. Following along are some calmly recited budget facts and other factors that tend to defuse some arguments from the protesters. We read that much of it is about jobs, and about the ability to carry Florida by any who can be linked by party to the President.
And finally, to get back to the story’s top, the first quote from Schmitt is his distress that Obama seems not to believe in American exceptionalism. That, too, is a term that, depending on whom one consults, may have little to do with rational analysis and a lot to do with hubris and emotion. The ending is provided by private entrepreneur Elon Musk, he of SpaceX and a nice new launcher that may or may not work in an upcoming test – and who is eager to try to fill the void left by any designed-to-NASA specs (and some would therefore snort, “socialist”) rocket. Does Musk represent a new and better, entrepreneurial future? A foe of exceptionalism? What?
The story is entertaining to me because it seems mischievous, hard to judge, a chameleon – it’s meaning likely to shift widely and according to the perception and background of the reader.
Minor, interesting Grist for the Mill:
SpaceX update on an abort to a static test yesterday for the new Falcon 9 launcher.
Pic: Falcon9 on pad, source ;
- Charlie Petit
Chicken sex doesn’t work like ours. No, not that sex — but the process by which an embryo becomes a recognizably male or female animal.
Unlike mammals, it’s not hormones that dictate a chicken’s sex. It’s a fundamental property of the cells themselves. But this only became apparent when biologists investigated several odd chickens that were half male and half female, as if a line were drawn down the center of their bodies.
“We assumed this was caused by one side of the body having some kind of sex chromosome anomaly,” said Michael Clinton, a University of Edinburgh developmental biologist and co-author of the study, described March 10 in Nature. “But when we looked at them closely, they were composed of entirely normal cells. We realized that birds don’t follow the mammalian model.”
In mammals, there are two types of sex-determining chromosomes, X and Y. Each cell in an embryo has a pair of chromosomes, either XX or XY, but the cells are otherwise identical. Then, early in development, in response to some environmental cue, a group of cells that will someday become ovaries or testes start to produce hormones that cause other cells to develop in male- or female-specific ways. It’s the hormones that matter: Exposed to lots of testosterone and deprived of estrogen, cells with female chromosomes will form masculine tissues, and vice versa.
There are a few oddball species such as the duck-billed platypus which has a whopping 10 sex chromosomes, making males XYXYXYXYXY. But the mammalian system was thought to represent a general rule among vertebrate species. And though birds have Z and W chromosomes rather than X and Y, and ZZ is male rather than female, they were thought to follow this rule, too.
That’s why Clinton, along with fellow Edinburgh biologists Debiao Zhao and Derek McBrid, expected to find chromosomal malfunction in their half-female, half-male chickens, known as gynandromorphs. But the cells were perfectly normal. They just happened to be organized according to sex: cells with ZZ chromosomes on the male side, and cells with ZW chromosomes on the female side.
As cells on both sides of the body were exposed to the same hormones, it wasn’t hormones that mattered to gender, as with mammals. Gender was a fundamental property of the cells.
“These funky chickens, oddities of nature that they are, will provide new perspectives on questions of sexual identity long thought to have been resolved,” wrote Duke University cell biologists Lindsey Barske and Blanche Capel in a Nature commentary accompanying the findings.
About one in 10,000 birds is gynandromorphic, but biologists assumed the mammal model applied to all vertebrates, said Clinton.
To test the proposition, the researchers transplanted male cells into a female embryo, and female cells into a male embryo. In both cases, the cells continued to express their sex-specific hormones. Their fate was already set.
The findings expand on earlier research by University of California, Los Angeles biologist Arthur Arnold, who has studied the brains of gynandromorphic zebra finches. They also fit with long-established observations that heavy hormone doses can only change the sex of chicken embryos, but only as long as the dose is maintained. Take the hormones away, and the chickens revert to their intended form.
The big question is whether this kind of cell-based sexual identity will turn out to be a common sex-determining system in other vertebrates, write Barske and Capel.
Clinton suspects it will. “We believe now that certainly all birds, and possibly lower vertebrates, will have a cellular identity,” he said. “Remnants of this cellular system may still exist in mammals, but it’s overridden by the effects of hormones.”
Images: 1) Gyandromorph chicken reflected in mirror; male side white, female side brown./Roslin Institute, University of Edinburgh. 2) Gyandromorph chicken./Roslin Institute, University of Edinburgh.
Thanks to Ed Yong for “half-cocked.”
See Also:
Citations: “Somatic sex identity is cell autonomous in the chicken.” By D. Zhao, D. McBride, S. Nandi, H. A. McQueen, M. J. McGrew, P. M. Hocking, P. D. Lewis, H. M. Sang & M. Clinton. Nature, Vol. 464 No. 7285, March 11, 2010.
“An avian sexual revolution.” By Lindsey A. Barske and Blanche Capel. Nature, Vol. 464 No. 7285, March 11, 2010.
Brandon Keim’s Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points.
Several outlets jumped out with advance word today that the UN is set to unveil an independent panel that will check the way the Intergovernmental Panel on Climate Change sizes up global warming. Just guessing here – but one suspects that the effort by the InterAcademy Council (umbrella group to national academies around the world) will be solid; one suspects also that unless it decides global warming is a fraud, the results will have no impact on doubters who figure that if the panel’s membership has outstanding experts and they give the IPCC any kind of pass, that just means they all along were in on the “scam.”
If and when that happens, the challenge for reporters will be to pay close attention to the reviewer’s credentials and analytical data process, and to compare those with the tools employed by any who reject the panel’s eventual findings.
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Somewhat Related Astrology News:
- Charlie Petit
Estos son textos publicados antes aquí.
These are text published before here.
