by Jennifer Viegas Roosters are genetically programmed to crow with the dawn, finds a new study that could also help to explain why dogs bark and cats meow. Previously it was unknown if crowing roosters were simply reacting to their environment. “‘Cock-a-doodle-doo’ symbolizes the break of dawn in many countries,” Takashi Yoshimura of Nagoya University, who worked on the study, was quoted as saying in a press release. “But it wasn’t clear whether crowing is under the control of a biological clock or is simply a response to external stimuli.” That’s because things like a car’s headlights can set a rooster off too, as anyone who has lived near these birds knows. To solve the mystery, Yoshimura and colleagues kept roosters under round-the-clock dim lighting. This didn’t deter the roosters. No matter what, they kept crowing each morning just before dawn. The researchers say this is proof that the vocalizing is entrained to a circadian rhythm. In short, the roosters are genetically programmed to crow at a certain time. At some point, the rising sun set the roosters’ internal clock, so now they crow every 24 hours. Most animals, and plants too, have such an internalized timing mechanism. That’s why we tend to eat, sleep, exercise and more at around the same times. By consciously being aware of the schedule, our body has a chance to adapt to it, so well-functioning circadian rhythms are often tied to good health. © 2013 Discovery Communications, LLC.

Keyword: Biological Rhythms
Link ID: 17919 - Posted: 03.19.2013

By TARA PARKER-POPE The best path to a healthy weight may be a good night’s sleep. For years researchers have known that adults who sleep less than five or six hours a night are at higher risk of being overweight. Among children, sleeping less than 10 hours a night is associated with weight gain. Now a fascinating new study suggests that the link may be even more insidious than previously thought. Losing just a few hours of sleep a few nights in a row can lead to almost immediate weight gain. Sleep researchers from the University of Colorado recruited 16 healthy men and women for a two-week experiment tracking sleep, metabolism and eating habits. Nothing was left to chance: the subjects stayed in a special room that allowed researchers to track their metabolism by measuring the amount of oxygen they used and carbon dioxide they produced. Every bite of food was recorded, and strict sleep schedules were imposed. The goal was to determine how inadequate sleep over just one week — similar to what might occur when students cram for exams or when office workers stay up late to meet a looming deadline — affects a person’s weight, behavior and physiology. During the first week of the study, half the people were allowed to sleep nine hours a night while the other half stayed up until about midnight and then could sleep up to five hours. Everyone was given unlimited access to food. In the second week, the nine-hour sleepers were then restricted to five hours of sleep a night, while the sleep-deprived participants were allowed an extra four hours. Copyright 2013 The New York Times Company

Keyword: Obesity; Sleep
Link ID: 17918 - Posted: 03.19.2013

Coaches should pull athletes with a suspected head injury immediately until a health professional trained in concussions checks them out, according to new medical guidelines. The American Academy of Neurology updated its guidelines on Monday for evaluating and managing athletes with concussion. It’s the group's first update since 1997. Demonstration of a test with patients that have suffered concussions. It's likely that concussion risk is greater for female athletes playing soccer, according to new guidelines.Demonstration of a test with patients that have suffered concussions. It's likely that concussion risk is greater for female athletes playing soccer, according to new guidelines. (Keith Srakocic/Associated Press) "If in doubt, sit it out," said Dr. Jeffrey Kutcher with the University of Michigan Medical School in Ann Arbor and a member of the academy, in a release. "Being seen by a trained professional is extremely important after a concussion. If headaches or other symptoms return with the start of exercise, stop the activity and consult a doctor. You only get one brain; treat it well." Players should return to the rink, field or pitch slowly and only after acute signs and symptoms, such as headache, sensitivity to light and sound or changes in memory and judgment, are gone. For ice hockey, the guidelines said bodychecking is likely to increase the risk of sport-related concussion. In peewee hockey, bodychecking is likely to be a risk factor for a more severe concussion that prolongs the return to play. © CBC 2013

Keyword: Brain Injury/Concussion
Link ID: 17917 - Posted: 03.19.2013

When the mind is at rest, the electrical signals by which brain cells communicate appear to travel in reverse, wiping out unimportant information in the process, but sensitizing the cells for future sensory learning, according to a study of rats conducted by researchers at the National Institutes of Health. The finding has implications not only for studies seeking to help people learn more efficiently, but also for attempts to understand and treat post-traumatic stress disorder — in which the mind has difficulty moving beyond a disturbing experience. During waking hours, electrical signals travel from dendrites — antenna-like projections at one end of the cell — through the cell body. From the cell body, they then travel the length of the axon, a single long projection at the other end of the cell. This electrical signal stimulates the release of chemicals at the end of the axon, which bind to dendrites on adjacent cells, stimulating these recipient cells to fire electrical signals, and so on. When groups of cells repeatedly fire in this way, the electrical signals increase in intensity. Dr. Bukalo and her team examined electrical signals that traveled in reverse?from the cell’s axon, to the cell body, and out its many dendrites. The reverse firing, depicted in this diagram, happens during sleep and at rest, appearing to reset the cell and priming it to learn new information. It was previously known that, during sleep, these impulses were reversed, arising from waves of electrical activity originating deep within the brain. In the current study, the researchers found that these reverse signals weakened circuits formed during waking hours, apparently so that unimportant information could be erased from the brain. But the reverse signals also appeared to prime the brain to relearn at least some of the forgotten information. If the animals encountered the same information upon awakening, the circuits re-formed much more rapidly than when they originally encountered the information.

Keyword: Learning & Memory; Sleep
Link ID: 17916 - Posted: 03.19.2013

by Audrey Carlsen Plenty of us got our fill of green-colored food on St. Patrick's Day. (Green beer, anyone?) But for some people, associating taste with color is more than just a once-a-year experience. These people have synesthesia — a neurological condition in which stimulation of one sense (e.g., taste) produces experiences in a totally different sense (e.g., sight). According to researcher Sean Day, approximately one in 27 people has some form of synesthesia. We've covered this phenomenon in the past. And I'm a synesthete myself — I see letters and numbers in color, and associate sounds with shapes and textures. But only a very few people — maybe only 1 percent of synesthetes — have sensory crossovers that affect their relationship with food and drink. Jaime Smith is one of those people. He's a sommelier by trade, and he has a rare gift: He smells in colors and shapes. For Smith, who lives in Las Vegas, a white wine like Nosiola has a "beautiful aquamarine, flowy, kind of wavy color to it." Other smells also elicit three-dimensional textures and colors on what he describes as a "projector" in his mind's eye. This "added dimension," Smith says, enhances his ability to appraise and analyze wines. "I feel that I have an advantage over a lot of people, particularly in a field where you're judged on how good of a smeller you are," he says. ©2013 NPR

Keyword: Chemical Senses (Smell & Taste); Pain & Touch
Link ID: 17915 - Posted: 03.19.2013

A clinical trial test of a vein-opening procedure for multiple sclerosis suggests it does not improve symptoms, and in a few patients symptoms worsened. The small pilot study was designed to test the safety and effectiveness of using balloons to unblock veins in the neck and chest of people with MS. Dr. Paolo Zamboni, left, and Dr. Robert Zivadinov have studied whether multiple sclerosis is triggered by vascular problems and have suggested it can be treated by using angioplasty to unblock vessels.Dr. Paolo Zamboni, left, and Dr. Robert Zivadinov have studied whether multiple sclerosis is triggered by vascular problems and have suggested it can be treated by using angioplasty to unblock vessels. Chronic cerebro-spinal venous insufficiency or CCSVI is a hypothesis put forward by Italian vascular surgeon Dr. Paolo Zamboni. He suspects that narrowed neck veins create a backup of blood that can lead to lesions in the brain and inflammation. On Friday, researchers at the University of Buffalo discussed the findings of their clinical trial involving 10 MS patients in an initial safety trial of the real and fake procedures and 20 who were randomized to receive treatment or a placebo. "All the outcomes that we looked at — which had to do with clinical disease, functional status, quality of life, cognition — there was no appreciable difference between the two arms," principal investigator Dr. Adnan Siddiqui, an assistant professor of neurosurgery at the University of Buffalo, said in an interview. When the investigators reviewed the MRI data, Siddiqu said they found new activity in patients who received the balloon angioplasty treatment. © CBC 2013

Keyword: Multiple Sclerosis
Link ID: 17914 - Posted: 03.18.2013

US researchers have found a link between working night shifts and the risk of ovarian cancer. A study of more than 3,000 women suggested that working overnight increased the risk of early-stage cancer by 49% compared with doing normal office hours. One possible explanation was disruption of the sleep hormone melatonin, the researchers said. But experts warned more work was needed and there might be other explanations. It does however follow an earlier association made between shift work and breast cancer. The International Agency for Cancer Research has previously identified working shift patterns that disrupt the body's natural "clock" as a probable cause of cancer. In the latest investigation, researchers looked at 1,101 women with advanced ovarian cancer, 389 with borderline or early disease and 1,832 women without the condition. Overall, a quarter with advanced cancer said they had worked night shifts, compared with a third of those with borderline disease and one in five of the control group. Analysis of the data showed a 24% increased risk of advanced cancer and 49% increased risk of early-stage disease for night workers compared with those who worked during the day. But the results were only significant for women over the age of 50, the researchers reported in Occupational and Environmental Medicine. And the risk did not seem to increase for those who had worked night shifts for the longest. BBC © 2013

Keyword: Biological Rhythms; Neuroimmunology
Link ID: 17913 - Posted: 03.18.2013

By Darryl Fears, Ten years have gone by since one of the weirdest discoveries in the Chesapeake Bay region, on the south branch of the Potomac River — male smallmouth bass with lady parts, eggs in places where they absolutely should not be. Over that decade, wildlife biologists have probed the bay’s tributaries, slicing open fish for more necropsies than anyone can count. And one thing is clear: They still aren’t sure why between 50 and 100 percent of bass in various locations are gender-bending, switching from male to something called intersex. Biologists say studies are falling short because of a lack of data on the type and quantity of pesticides that run into the bay from farms. This complaint, along with other factors, prompted Democrats in the Maryland House and Senate to sponsor two bills in the current legislative session that would for the first time require growers to record their use of insecticides and herbicides and submit it to the state. The pesticide-reporting rule would create a treasure trove of data that scientists could draw from for studies on human and animal health, supporters say. Scientists could use it to focus research on chemical “hot spots,” the exact moment high concentrations of pesticides hit waters where vulnerable young fish are growing, said Vicki Blazer, a biologist who studies bass for the U.S. Geological Survey. But opponents say the bills have major drawbacks. They would create a financial burden for farmers, who would be forced to purchase updated equipment such as Global Positioning System devices to log pesticide applications, said Valerie Connelly, director of government relations for the Maryland Farm Bureau. © 1996-2013 The Washington Post

Keyword: Sexual Behavior
Link ID: 17912 - Posted: 03.18.2013

By Neuroskeptic When does sadness cease to be a normal emotional response, and become a mental disorder? Can psychiatrists ‘draw the line’ between healthy and sick moods, and if so, where? An important new study offers an answer: When does depression become a disorder? Using recurrence rates to evaluate the validity of proposed changes in major depression diagnostic thresholds (free pdf). The authors, Jerome Wakefield and Mark Schmitz of New York, made use of the ECA survey, a 1980s study of almost 20,000 American adults. Participants were surveyed twice each, approximately one year apart. On each occasion, they were asked questions about their mood, emotions, and mental health symptoms. Some people reported a history of depression at the first visit. Wakefield & Schmitz wanted to find a way of predicting which of those people were most likely to end up depressed at the time of the second interview, a year later – the recurrence rate. To do this, they examined the particular patterns of symptoms reported at the first visit. It turned out that there was a strong predictor of recurrence, which the authors call “complicated” depression. People with a history of complicated depression had a 15% chance of being depressed at follow up. Only 3.4% of those who’d had “uncomplicated” symptoms, however, were depressed a year later. Given that 1.7% of people with no depression history had become unwell by Time 2, this means that “uncomplicated” depression was almost never recurrent.

Keyword: Depression
Link ID: 17911 - Posted: 03.18.2013

By LAURIE EDWARDS TO the list of differences between men and women, we can add one more: the drug-dose gender gap. Doctors and researchers increasingly understand that there can be striking variations in the way men and women respond to drugs, many of which are tested almost exclusively on males. Early this year, for instance, the Food and Drug Administration announced that it was cutting in half the prescribed dose of Ambien for women, who remained drowsy for longer than men after taking the drug. Women have hormonal cycles, smaller organs, higher body fat composition — all of which are thought to play a role in how drugs affect our bodies. We also have basic differences in gene expression, which can make differences in the way we metabolize drugs. For example, men metabolize caffeine more quickly, while women metabolize certain antibiotics and anxiety medications more quickly. In some cases, drugs work less effectively depending on sex; women are less responsive to anesthesia and ibuprofen for instance. In other cases, women are at more risk for adverse — even lethal — side effects. These differences are particularly important for the millions of women living with chronic pain. An estimated 25 percent of Americans experience chronic pain, and a disproportionate number of them are women. A review published in the Journal of Pain in 2009 found that women faced a substantially greater risk of developing pain conditions. They are twice as likely to have multiple sclerosis, two to three times more likely to develop rheumatoid arthritis and four times more likely to have chronic fatigue syndrome than men. As a whole, autoimmune diseases, which often include debilitating pain, strike women three times more frequently than men. © 2013 The New York Times Company

Keyword: Pain & Touch; Sexual Behavior
Link ID: 17910 - Posted: 03.18.2013

By Stephani Sutherland Treating the brain with magnets went mainstream a few years ago, when the technique proved successful at relieving major depression. Now the procedure, repetitive transcranial magnetic stimulation (rTMS), shows promise for another mysterious, hard-to-treat disorder: chronic pain. Until now, pain seemed out of reach for rTMS because the regions involved in pain perception lie very deep within the brain. The other disorders helped by rTMS all involve brain areas close to the skull. To treat depression, for example, a single magnetic coil directs a magnetic field at the dorsolateral prefrontal cortex, a region of the brain's outer folds. When aimed at different areas of these outer folds, rTMS improves the motor symptoms of Parkinson's disease, staves off the damage of stroke, lessens the discomfort that follows nerve injury and treats obsessive-compulsive disorder. The magnetic field affects the electrical signaling used by neurons to communicate, but how exactly it improves symptoms is unclear—scientists suspect rTMS may redirect the activity of select cells or even entire brain circuits. To extend the technique's reach, David Yeomans, a neuroscientist at Stanford University, and his colleagues used four magnets rather than one and employed high-level math to steer the resulting complex fields. Their target was an area called the anterior cingulate cortex (ACC), an area active in the experience of all types of pain, regardless of its source or nature. © 2013 Scientific American

Keyword: Pain & Touch
Link ID: 17909 - Posted: 03.18.2013

Peter Fimrite Scientists at Stanford University have tapped into the mind of the mouse and are now circulating information about how the pesky rodents think. A team of Stanford researchers planted tiny probes inside the brains of mice to detect what were essentially mouse memories, according to a study published last month in the online edition of Nature Neuroscience. The experiment involved the insertion of a needlelike microscope into the hippocampus - a part of the brain associated with spatial and episodic memory. The microscope detected cellular activity and broadcast digital images through a cell phone camera sensor that fit like a hat over the heads of the critters as they scampered around an enclosure. "We're not really reading their minds," said the lead researcher, Mark Schnitzer, who is an associate professor of biology and applied physics at Stanford. "What is the mind of a mouse, anyway? I don't know. What we're doing is reading a spatial map in the brain. It is one little component of many, many processes that are going on inside." Over the course of a month, the scientists were able to document patterns of activity in some 700 neurons and pinpoint areas of the brain where mice store long-term information. It is important, Schnitzer said, because long-term memory is an area of the brain that researchers are struggling to understand as they attempt to develop new therapies for neurodegenerative diseases, including Alzheimer's disease. "Those are clearly diseases in which information storage has been impaired," Schnitzer said. "Now that we can look at the neural code for how the spatial information is stored, it opens the door directly to subsequent experiments. That's the logical next step." © 2013 Hearst Communications Inc.

Keyword: Learning & Memory
Link ID: 17908 - Posted: 03.18.2013

By GINIA BELLAFANTE Under the category “Summer Rentals That Have Gone Terribly Wrong,” there are perhaps few parallels to the experience of Charles Henry Warren, a Manhattan banker who, in 1906, took a house in Oyster Bay on Long Island’s North Shore. By the end of the season, Mr. Warren’s young daughter had developed typhoid. She was soon followed in illness by Mr. Warren’s wife, a second daughter, two maids and a gardener. At the time, typhoid, a bacterial illness spread through contaminated food and water, was largely a disease of the urban poor. The property’s owner, George Thompson, concerned that the house, on which he relied for rental income, would become associated with tenement filth in the minds of wealthy New Yorkers, invited a sanitary engineer to determine the source of the outbreak. What the medical investigator, George Soper, discovered was that the Warrens’ cook, Mary Mallon, an Irish immigrant, had left an imprint of malady in other quarters of upper-class Manhattan and its summer enclaves. Typhoid, he wrote, had erupted in every household in which Mallon had worked over the previous decade. An asymptomatic carrier of the disease, Ms. Mallon would be known to history as Typhoid Mary and spend most of the remainder of her life quarantined on North Brother Island in the East River, having failed to abide by a promise to cease working in the city’s kitchens. The events supply the narrative of “Fever,” a new novel by Mary Beth Keane, which arrives at a time when we are once again debating the parameters of public health policy’s encroachments on our behaviors. Last week, a State Supreme Court justice in Manhattan used the words “arbitrary and capricious” in striking down the Bloomberg administration’s efforts to limit the size of sugary drinks (which pertained to certain sweetened beverages but not others, and some retail environments but not all). The phrase, though, could have been similarly applied a century ago to the city’s treatment of Ms. Mallon, given that officials were not in the habit of isolating other healthy carriers whom they had identified as ignoring ordinances against the spread of the disease. © 2013 The New York Times Company

Keyword: Obesity
Link ID: 17907 - Posted: 03.18.2013

By Charles Q. Choi and Txchnologist Scientists scanning the human brain can now tell whom a person is thinking of, the first time researchers have been able to identify what people are imagining from imaging technologies. Work to visualize thought is starting to pile up successes. Recently, scientists have used brain scans to decode imagery directly from the brain, such as what number people have just seen and what memory a person is recalling. They can now even reconstruct videos of what a person has watched based on their brain activity alone. Cornell University cognitive neuroscientist Nathan Spreng and his colleagues wanted to carry this research one step further by seeing if they could deduce the mental pictures of people that subjects conjure up in their heads. “We are trying to understand the physical mechanisms that allow us to have an inner world, and a part of that is how we represent other people in our mind,” Spreng says. His team first gave 19 volunteers descriptions of four imaginary people they were told were real. Each of these characters had different personalities. Half the personalities were agreeable, described as liking to cooperate with others; the other half were less agreeable, depicted as cold and aloof or having similar traits. In addition, half these characters were described as outgoing and sociable extroverts, while the others were less so, depicted as sometimes shy and inhibited. The scientists matched the genders of these characters to each volunteer and gave them popular names like Mike, Chris, Dave or Nick, or Ashley, Sarah, Nicole or Jenny. © 2013 Scientific American

Keyword: Brain imaging; Attention
Link ID: 17906 - Posted: 03.15.2013

By Christie Aschwanden, A lawyer contacted Beatrice Golomb, a physician at the VA San Diego Healthcare Center, because he could no longer follow a normal conversation with his clients. A radiologist told Golomb that he found himself suddenly unable to distinguish left from right. A third person told her he had grown so forgetful that his doctor assumed he had Alzheimer’s. All three had developed their memory problems after taking a cholesterol-lowering statin drug, and the symptoms improved after they stopped the medication. The statin revolution began in 1987, when lovastatin was approved by the Food and Drug Administration. Since then, this class of drugs has transformed cardiac medicine, says Allen Taylor, chief of cardiology at MedStar Georgetown University Hospital. “Cardiovascular disease affects one in two people. This is the one drug that works.” But these drugs are not without risks. Golomb has amassed thousands of reports at her Web site Statineffects.com, detailing adverse reactions from statins. She says that cognitive problems are the second-most-common side effect reported in her database, after muscle pain. In a 2009 report in the journal Pharmacotherapy, Golomb described 171 patients who’d reported cognitive problems after taking statins. The idea that a cholesterol-lowering drug could make your brain fuzzy might sound crazy, and Golomb says the notion was greeted with suspicion at first. But eventually the FDA received enough such reports that last February it ordered drug companies to add a new warning label about possible memory problems. © 1996-2013 The Washington Post

Keyword: Learning & Memory
Link ID: 17905 - Posted: 03.15.2013

By GINA KOLATA The Food and Drug Administration plans to loosen the rules for approving new treatments for Alzheimer’s disease. Drugs in clinical trial would qualify for approval if people at very early stages of the disease subtly improved their performance on memory or reasoning tests, even before they developed any obvious impairments. Companies would not have to show that the drugs improved daily, real-world functioning. For more than a decade, the only way to get Alzheimer’s drugs to market was with studies showing that they improved the ability of patients not only to think and remember, but also to function day to day at activities like feeding, dressing or bathing themselves. The proposal, published online Wednesday in The New England Journal of Medicine, could help millions of people at risk of developing the disease by speeding the development and approval of drugs that might slow or prevent it. The proposed policy could also be a boon for the pharmaceutical industry and researchers. They have often felt stymied by regulations that left them uncertain of how to get drugs tested and approved for marketing to people early in the course of Alzheimer’s, when the medications are most likely to be useful. Several studies are being planned for people at high risk of developing Alzheimer’s, and the proposed regulations should lead to even more clinical trials, said Dr. P. Murali Doraiswamy, an Alzheimer’s researcher and professor of psychiatry at Duke University School of Medicine. © 2013 The New York Times Company

Keyword: Alzheimers
Link ID: 17904 - Posted: 03.15.2013

By Scicurious I think we can all say that we prefer praise. I’d much rather be told that I was peerless and perspicacious than that I was a pathetic peripatetic. But whether we get praise or censure, as social humans we receive a lot of social feedback. People are always telling us, either directly or indirectly, how we are ‘doing’ socially, and how we are perceived. But getting that information, and what you do with it, are very different things indeed. And while we all like to think that we see our own good and bad points for what they are and take in criticism as well as praise….well, it turns out we’re a little biased in our own favor. When most studies want to look at things like social feedback or social processing, they often do fMRI studies with “games” that you play with other “people” (who aren’t real people, just a computer, but you don’t know that). But this has several disadvantages. First, you can’t rate people on various personality traits, you only know if you get socially accepted or rejected. And secondly, you can’t really get good social feedback from a computer. So to look at social feedback, the authors of this study had people meet each other in PERSON. On the first day, a group of five people who had never met before met in the lab to play an hour or so of Monopoly (hopefully if you’re only in the first hour you avoid a lot of the social rancor that I associate with my family’s Monopoly games). © 2013 Scientific American,

Keyword: Emotions
Link ID: 17903 - Posted: 03.15.2013

By NICHOLAS BAKALAR Compared with the rest of the population, people with mental illness may be at sharply increased risk of dying by homicide, a new study has found. Researchers used Swedish government registries to determine psychiatric diagnoses and causes of death among the entire adult population of 7.2 million from 2001 to 2008. There were 615 murders in the period, 141 of them of people with mental disorders. (The homicide rate in Sweden is about one-fifth that of the United States.) After controlling for age, education level, income and other factors, they found that people with mental illness were almost five times as likely to be a victim of murder as a person without a psychiatric diagnosis. The study appeared online last week in the journal BMJ. The risk was highest among those with substance use disorders — nine times that of the general population. Those with personality disorders had three times the risk, people with depression two and a half times, and those with anxiety or schizophrenia about twice the risk of being murdered, compared with people without mental illness. The lead author, Dr. Casey Crump, a clinical assistant professor of medicine at Stanford, said the findings were consistent with those from smaller studies done in the United States. Interestingly, he said, “these results extended to all the most common mental disorders.” Copyright 2013 The New York Times Company

Keyword: Schizophrenia
Link ID: 17902 - Posted: 03.15.2013

By Jon Lieff Traditionally, we have understood the immune system and the nervous system as two distinct and unrelated entities. The former fights disease by responding to pathogens and stimulating inflammation and other responses. The latter directs sensation, movement, cognition and the functions of the internal organs. For some, therefore, the recent discovery that left-sided brain lesions correlate with an increased rate of hospital infections is difficult to understand. However, other recent research into the extremely close relationship between these two systems makes this finding comprehensible. A study, published in the March 2013 issue of Archives of Physical Medicine and Rehabilitation, looked at more than 2,000 hospital patients with brain lesions from either stroke or traumatic brain injury. They looked at how many of these brain-injured patients contracted infections within 2 to 3 days of admission. Of those patients who developed infections, 60% had left-sided lesions. The authors concluded that an unknown left-sided brain/immune network might influence infections. But why would the left side of the brain affect immunity? The nervous and immune systems are quite different in their speed and mode of action. The two major immune systems, innate and adaptive, are both wireless—they communicate through cell-to-cell contact, secreted signals, and antigen-antibody reactions. The innate system is the first responder, followed by the slower adaptive response. The nervous system, on the other hand, is wired for much more rapid communication throughout the body. It turns out that the two work surprisingly closely together. © 2013 Scientific American

Keyword: Neuroimmunology; Stroke
Link ID: 17901 - Posted: 03.15.2013

by Lizzie Wade Hundreds of millions of years ago, the Earth's seas teemed with trilobites, hard-shelled critters that resembled spiny aquatic cockroaches. Because their exoskeletons lent themselves to fossilization, scientists know a lot about what the outside of their bodies looked like. Their inner workings, however, have remained mysterious. Now, a new study has revealed the structure of the trilobite eye, bringing researchers one step closer to understanding the evolution of vision. Like today's insects and crustaceans, trilobites had compound eyes, with many different lenses focusing light onto clusters of sensory cells lying below them. The resulting image was put together a lot like a picture on your computer screen, with each lens producing one "pixel" of the whole. Because the lenses themselves were made of the mineral calcite, they often fossilized along with the rest of the trilobite's tough exoskeleton. The sensory cells underneath the lenses, however, were ephemeral, and scientists had always assumed that they had decayed without a trace. So imagine Brigitte Schoenemann's surprise when she spotted fossilized versions of these delicate sensory cells while x-raying a long dead trilobite with a computed tomography (CT) scanner. "I expected that we would see [something] in the lens of trilobites, but then suddenly we saw structures of cells below the lens," recalls Schoenemann, a physiologist at the University of Bonn and the University of Cologne, both in Germany. Inspired, she applied to take more fossils to the European Synchrotron Radiation Facility in Grenoble, France, where she could use a particle accelerator's high energy x-rays to peer deeper into the trilobites' eyes. Now, she says, she's created images of the extinct animal's entire visual system, down to the level of fossilized individual cells. © 2010 American Association for the Advancement of Science

Keyword: Vision; Evolution
Link ID: 17900 - Posted: 03.15.2013