Michael Marshall, In "one of the biggest mass deaths of cetaceans in Irish history" at least 33 whales have beached themselves on the north-west coast of County Donegal. They were found on Rutland Island near Burtonport on Saturday. It's thought they were the same group spotted in the Outer Hebrides at the end of October. The whales' deaths come just after the latest research into cetacean strandings, which suggests that stranded whales and dolphins often suffer from hearing loss. The finding is the latest salvo in the long-running controversy over whether undersea noise pollution is harming whales. David Mann of the University of South Florida and colleagues looked at eight species of cetacean, all of which had either stranded themselves or become entangled in fishing gear. 4 out of 7 of the bottlenose dolphins they looked at, and 5 out of 14 rough-toothed dolphins, had either severe or profound hearing loss, as did one short-finned pilot whale. They also looked at 7 Risso's dolphins, 2 pygmy killer whales, 1 Atlantic spotted dolphin, 1 spinner dolphin, and 1 Gervais' beaked whale. None of them had any hearing problems, so it seems hearing loss is far from the only possible cause for strandings. In total, 9 of the 34 animals had hearing problems (PLoS ONE, DOI: 10.1371/journal.pone.0013824). © Copyright Reed Business Information Ltd.

Keyword: Hearing; Animal Migration
Link ID: 14644 - Posted: 11.09.2010

by Miriam Frankel When newborn female rats are given a substance mimicking cannabis, their brains become more masculine – as does their behaviour. Margaret McCarthy from the University of Maryland in Baltimore and colleagues found that newborn female rats usually make more new cells than males in a part of their brain called the amygdala, an area that governs social and emotional behaviour. They also found that females had a smaller endocannabinoid system, involving brain receptors that react to cannabis. That correlation made them wonder whether injecting substances that mimicked cannabis would alter the rate of cell proliferation in the amygdala. To find out, the team injected newborn rats with a compound that triggers cannabinoid receptors in the brain. They also injected a chemical that allowed them to see cell division in brain tissue. To find out how these changes affected rats' behaviour, the team also studied the playing habits of the pups after four weeks. Without treatment, female rats produced between 30 and 50 per cent more glial cells – which help maintain homeostasis and protect neurons – in the amygdala than males. They also played 30 to 40 per cent less than males. But females that were given cannabinoid compounds had cell proliferation rates and play behaviour similar to those of males. "Play behaviour is similarly sex-specific in humans," says McCarthy. "The ultimate goal is now to find out whether the neurological underpinnings of this behaviour, which we are beginning to understand in this study, are similar in humans". © Copyright Reed Business Information Ltd.

Keyword: Drug Abuse; Sexual Behavior
Link ID: 14643 - Posted: 11.09.2010

By Barnabe Geisweiller Which do you like better, Coke or Pepsi? You may be surprised by the answer. The Pepsi Challenge TV commercials from the ’70s and ’80s featured people blind-tasting Pepsi or Coke. Not surprisingly, people chose Pepsi. Yet Coke continued to outsell Pepsi. In 2003, neuroscientist Read Montague decided to repeat the Pepsi Challenge with subjects lying in a functional magnetic resonance imaging (fMRI) machine, which tracks changes in blood flow related to neural activity in the brain. Most subjects in Montague’s study chose the Pepsi sample as better tasting, and Pepsi tended to produce a stronger response in the brain’s ventral putamen, a region thought to process feelings of reward. But in a second test when subjects were told which brand they were drinking, more said they preferred Coke. Montague observed that their brain activity also changed. The knowledge that they were drinking Coke increased activity in the medial prefrontal cortex, an area of the brain associated with thinking and judging. This seemed to validate the claims of marketers that they can influence consumers’ decisions. Neuro-marketing was born. Marketing is only one field in which neuro-imaging is applied. Studies done in labs across the world provide researchers with new insight into how our brains work. This knowledge could help in the treatment of diseases such as Alzheimer’s or Parkinson’s, say neuroscientists. ©2008 New York Press.

Keyword: Drug Abuse; Brain imaging
Link ID: 14642 - Posted: 11.09.2010

Erin Allday, UCSF researchers are kicking off a clinical trial to test whether certain children with autism can benefit from regular doses of an enzyme to help them digest proteins, which may in turn improve their brain function and ease some symptoms of their disease. It's one of several treatments being explored that could address the root causes of autism - an incurable set of developmental problems that affects socialization, language and behavior - instead of just the symptoms of the disease. But the theory behind the enzyme is controversial, because there is little solid research demonstrating that the missing enzyme, or digestion problems in general, is a direct cause of autism. Some studies have shown that autistic children are more likely than healthy children to have gastrointestinal problems, and that a certain subgroup of autistic kids have enzyme deficiencies. But whether those problems cause autism or are just another symptom of the disease isn't known for sure. Still, some researchers say that even if there's no clear connection between the missing enzyme and autism, it's a treatment worth exploring. "I think every avenue, every potential hypothesis, should be investigated in autism," said Dr. Antonio Hardan, a pediatric psychiatrist and an autism researcher at Lucile Packard Children's Hospital who is not involved in the enzyme trial. "This is one of them, and regardless what the results show, it will be helpful to look at what they find." © 2010 Hearst Communications Inc.

Keyword: Autism
Link ID: 14641 - Posted: 11.08.2010

WRINKLES reveal how ageing has degraded your skin, but how can you tell how well your brain is coping? Measure levels of lactic acid, perhaps. It seems that a build-up of the chemical in the brain is a hallmark of the ageing process, in mice at least. The finding came when Jaime Ross from the Karolinska Institute in Stockholm, Sweden, and colleagues investigated how ageing is affected by damage to the DNA in mouse mitochondria, the energy-producing part of cells. The team modified mitochondrial DNA, producing a mouse strain that aged prematurely. In these mice and healthy controls, the time it took for levels of lactic acid in the brain to double correlated with how fast they aged. Lactic acid is a normal product of metabolism, so Ross's team speculated that age-damaged mitochondria could be affecting metabolic processes. Indeed, the brains of both types of mice showed damage to the genes responsible for lactate regulation (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1008189107). Future studies may reveal if changes in brain lactate are linked to neurodegenerative diseaseMovie Camera in humans, says Ross. Issue 2785 of New Scientist magazine © Copyright Reed Business Information Ltd.

Keyword: Development of the Brain
Link ID: 14640 - Posted: 11.08.2010

By Emily Singer Most of the robotic arms now in use by some amputees are of limited practicality; they have only two to three degrees of freedom, allowing the user to make a single movement at a time. And they are controlled with conscious effort, meaning the user can do little else while moving the limb. A new generation of much more sophisticated and lifelike prosthetic arms, sponsored by the Department of Defense's Defense Advanced Research Projects Agency (DARPA), may be available within the next five to 10 years. Two different prototypes that move with the dexterity of a natural limb and can theoretically be controlled just as intuitively--with electrical signals recorded directly from the brain--are now beginning human tests. Initial results of one of these studies--the first tests of a paralyzed human controlling a robotic arm with multiple degrees of freedom--will be presented at the Society for Neuroscience conference in November. The new designs have about 20 degrees of independent motion, a significant leap over existing prostheses, and they can be operated via a variety of interfaces. One device, developed by DEKA Research and Development, can be consciously controlled using a system of levers in a shoe. © 2010 MIT Technology Review

Keyword: Robotics
Link ID: 14639 - Posted: 11.08.2010

by James Garvey So long as people read Wittgenstein, people will read Peter Hacker. It’s hard to imagine how his work on the monumental Analytical Commentary on Wittgenstein’s Philosophical Investigations could possibly be superseded. He spent nearly twenty years on that project (ten of them in cooperation with his friend and colleague Gordon Baker), following in Wittgenstein’s footsteps, and producing a large number of important articles and books on topics in the philosophy of mind and language along the way. Nearer the end than the beginning of a distinguished career as an Oxford don, at a time of life when most academics would be happy to leave the lectern behind and collapse somewhere with a nice glass of wine, Hacker is in the middle of another huge project, this time on human nature. He also seems keen to pick a fight with almost anyone doing the philosophy of mind. This has a much to do with his view of philosophy as a contribution to human understanding, not knowledge. One might think that philosophy has the same general aim as science – securing knowledge of ourselves and the world we live in – even if its subject matter is more abstract and its methods more armchair. What is philosophy if not an attempt to secure new knowledge about the mind or events or beauty or right conduct or what have you? According to Hacker, philosophy is not a cognitive discipline. It’s something else entirely. “Philosophy does not contribute to our knowledge of the world we live in after the manner of any of the natural sciences. You can ask any scientist to show you the achievements of science over the past millennium, and they have much to show: libraries full of well-established facts and well-confirmed theories. If you ask a philosopher to produce a handbook of well-established and unchallengeable philosophical truths, there’s nothing to show.” © 2010 TPM: The Philosophers’ Magazine.

Keyword: Miscellaneous
Link ID: 14638 - Posted: 11.08.2010

by Jennifer Carpenter Need to improve your math skills or do your taxes faster? Try zapping your brain with electricity. Researchers have shown that administering a small electrical charge to the brain may enhance a person's ability to process numbers for up to 6 months. The team says the approach, which it claims is harmless, could one day restore numerical skills in people suffering from degenerative diseases or stroke, and it may even improve the math abilities of the general population. The brain's math center appears to be the right side of the parietal lobe, a region that sits beneath the crown of the head. People with injuries to this region have difficulty counting, and it's unusually active in young children learning their 1, 2, 3s. Those findings made Roi Cohen Kadosh, a cognitive neuroscientist at the University of Oxford in the United Kingdom, wonder if stimulating this part of the brain could improve a person's ability to manipulate numbers. Cohen Kadosh and colleagues recruited 15 university students and trained them to learn the value of nine made-up symbols, including shapes that looked like triangles and staples (see picture). To replicate what children go through when they first learn numbers, the researchers presented the volunteers with two symbols at a time and asked them which one had a higher value. At first, the volunteers had to guess, because they had never seen the symbols before. But as the training progressed, those volunteers who remembered their correct guesses began to learn the relative value of all nine symbols. © 2010 American Association for the Advancement of Science.

Keyword: Learning & Memory; Attention
Link ID: 14637 - Posted: 11.06.2010

By LISA SANDERS, M.D. “My arm — something is biting my arm!” The 26-year-old woman struggled to sit up in bed. What’s wrong? her husband asked, alarmed and suddenly wide awake. His wife didn’t seem to hear him. Suddenly, her whole body began to jerk. Although he had never seen a seizure, the young man knew immediately that this was one. After a long and terrifying minute the jerking stopped and his wife lay quiet with her eyes closed, as if she were asleep. When he couldn’t wake her, he picked up the phone and dialed 911. In the emergency room, the young woman was sleepy and confused. She didn’t remember the seizure. All she knew was that she felt bad earlier that day. Her shoulders ached and she had these strange shooting pains that ran up her neck, into her skull. She had a wicked headache too. Although she had this headache for months, it was much worse that day. At home she took a long hot bath and went to bed. She woke up in the ambulance. She’d had no fever, she told the E.R. doctor, and hadn’t felt sick — just sore. And now she felt fine. Her arm didn’t hurt — in fact she couldn’t remember that it had ever hurt. She still had the headache, though. She didn’t smoke, didn’t drink and took no medications. She moved to Boston from Bolivia several years earlier to get married and now had 15-month-old. Other than mild confusion, the patient’s physical exam was normal. The E.R. doctor ordered blood tests to look for evidence of infection along with a CT scan of her head to look for a tumor. Copyright 2010 The New York Times Company

Keyword: Pain & Touch; Epilepsy
Link ID: 14636 - Posted: 11.06.2010

by Michael Marshall Evolutionary wars of the sexes are less easily resolved than previously thought. Even when such genetic conflicts appear to have been settled, knock-on effects can still disadvantage the other sex. Some physical traits are advantageous to one sex but harmful to the other, leading to a tug-of-war pushing evolution in opposite directions. This battle can sometimes seem to be resolved by a disputed trait evolving so that it only appears in the sex it benefits, such as the flamboyant tails that male peacocks use to attract mates. "But no one had actually looked to see if that resolved the conflict," says David Hosken of the University of Exeter, UK. Hosken and his colleagues have now shown the battle continues even when strikingly different physical traits evolve in different sexes – at least in broad-horned flour beetles. Males of this species use their large mandibles for fighting, and those with the biggest mandibles win more fights and attract more mates. Females have much smaller ones – for them, large mandibles would be dead weight. Hosken bred 12 generations of beetles to create three groups with small, large and average-sized mandibles. As expected, males with larger mandibles won more fights and reproduced more frequently. However their female descendants produced fewer offspring, even though their mandibles were the same size as those of other females. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Evolution
Link ID: 14635 - Posted: 11.06.2010

By Susan Milius “Do my hair before you touch my baby” is the rule among mother vervet monkeys and sooty mangabeys when it comes to sharing their infants with their neighbors. Like some other primate infants, monkey babies attract crowds of females eager to touch, hold and make silly lip-smacking noises at the little ones, says primatologist Cécile Fruteau of Tilburg University in the Netherlands. Her novel study of infant-touching etiquette in the vervets and mangabeys adds them to the short list of animals known to have “markets” for baby fondling. The moms have to be groomed for a sufficient time before they let the groomer touch the baby. What makes this exchange a market is the way sufficient grooming time changes with the baby supply, Fruteau and her colleagues explain in a paper now posted online in Animal Behaviour. The price for access to a group’s solitary infant, measured in grooming time for mom, fell when other females gave birth and increased the number of little cuties available for cuddling. Price is sensitive to other variables as well, says Fruteau, who documented for the first time that age makes a difference in how much grooming a baby can bring to a mom. Newborns earn their mothers the longest grooming sessions. One newborn mangabey, for example, the only baby in its group at the time, earned about 10 minutes of fur cleaning and combing for its mom. In contrast another lone baby didn’t even earn four minutes of grooming once it had reached the advanced age of almost 3 months. © Society for Science & the Public 2000 - 2010

Keyword: Sexual Behavior; Emotions
Link ID: 14634 - Posted: 11.06.2010

By Tina Hesman Saey WASHINGTON — Whether people sleep a lot or a little may depend in part on a gene that also determines whether fruit flies snooze all night. Geneticists studying sleep duration in people scanned the DNA of more than 4,200 Europeans, looking for genes associated with a person’s average nightly sleep time. The team found that people who have one version of a gene called SUR2 sleep about 28 minutes longer than people who have another version of the gene, said Karla Allebrandt of the University of Munich, who presented the research November 5 at the annual meeting of the American Society of Human Genetics. In order to determine whether SUR2 really affects sleep or was just found by coincidence, the researchers then examined the gene’s function in fruit flies. The team removed the gene from the brains of two strains of fruit flies and then recorded how well the flies slept. Flies without SUR2 didn’t sleep as long at night as flies that have it, Allebrandt said. The gene encodes a protein that forms part of a channel that transports potassium in and out of cells. Last year researchers from the University of California, San Francisco reported that a rare variation in DEC2, a gene involved in regulating the body’s daily rhythms, is associated with sleeping almost two hours a night less than average (SN: 9/12/10, p. 11). © Society for Science & the Public 2000 - 2010

Keyword: Sleep; Genes & Behavior
Link ID: 14633 - Posted: 11.06.2010

Taking vitamin E could slightly increase the risk of a particular type of stroke, a study says. The British Medical Journal study found that for every 1,250 people there is the chance of one extra haemorrhagic stroke - bleeding in the brain. Researchers from France, Germany and the US studied nine previous trials and nearly 119,000 people. But the level at which vitamin E becomes harmful is still unknown, experts say. The study was carried out at Harvard Medical School, Boston, and INSERM in Paris. Haemorrhagic strokes are the least common type and occur when a weakened blood vessel supplying the brain ruptures and causes brain damage. Researchers found that vitamin E increased the risk of this kind of stroke by 22%. The study also found that vitamin E could actually cut the risk of ischaemic strokes - the most common type of stroke - by 10%. Ischaemic strokes account for 70% of all cases and happen when a blood clot prevents blood reaching the brain. Experts found vitamin E could cut the risk, equivalent to one ischaemic stroke prevented per 476 people taking the vitamin. BBC © MMX

Keyword: Stroke
Link ID: 14632 - Posted: 11.06.2010

by Jennifer Couzin-Frankel Omega-3 fatty acids get good reviews as potent brain food: They're talked up for improving cognitive function in everyone from newborns to senior citizens. But Alzheimer's patients don't see these benefits, according to a new study. The work follows a paper published 2 weeks ago with the same disappointing result in babies born to women taking the supplements. That doesn’t mean omega-3s are useless: Other research has found that they may help the heart and other body systems. But when it comes to the brain, researchers concede, it looks like these fatty acids may not live up to their billing. Both failed studies followed optimistic observational research and animal work. People who eat lots of fish are less likely to develop dementia or cognitive problems late in life. Observational studies have also found that taking omega-3s during pregnancy can reduce postpartum depression and improve neurodevelopment in children. What's more, animals with an Alzheimer's-like condition are helped by docosahexaenoic acid (DHA), one of several omega-3 fatty acids. And DHA disappears from the brains of people with Alzheimer's. All of this suggested that certain populations would benefit from upping their dose of DHA, says neurologist Joseph Quinn of Oregon Health and Science University in Portland. But does the supplement really help? To find out, Quinn and his colleagues tested DHA's effects on Alzheimer's by recruiting 402 people with mild and moderate disease. They randomly assigned the volunteers to take DHA or a placebo. Just 295 people completed the study. Quinn thinks the slightly higher than expected dropout rate "was driven by a perception that this intervention was ineffective." Even so, the team still had enough data to conclude that DHA hadn't helped. Those taking it were no better off than those taking placebos, the team reports today in The Journal of the American Medical Association (JAMA). © 2010 American Association for the Advancement of Science.

Keyword: Alzheimers
Link ID: 14631 - Posted: 11.04.2010

By Stephanie Pappas Fruit flies that eat high-fat diets get fat, according to a new study. More important, fruit fly obesity looks much like human obesity, with symptoms including high cholesterol and blood sugar imbalances. Researchers use fruit flies as model organisms for studying many medical and biological questions, but much obesity research has been done on mice. Doing similar research on fruit flies would be easier and cheaper, since their life spans are shorter and their care is less expensive. But first, researchers have to be sure fruit flies are similar enough to humans for the results to be useful. In 2009, researchers pinpointed neurons in the flies' brains that sense and manipulate the insects' fat stores. The findings, reported in the journal Neuron, paralleled findings about the control of fat storage in mammalian brains. Like last year's research, the new study finds parallels between flies and people. The results indicate that the disease of obesity goes way back, said study researcher Sean Oldham of the Sanford-Burnham Medical Research Institute in La Jolla, Calif. "The capacity for this disease has been around for 500 million years," Oldham said in a statement. To fatten up the fruit flies in their study, Oldham and his colleagues fed the insects a diet consisting of 30 percent fat in the form of coconut oil. Due to their hard exoskeletons, fruit flies can only gain so much, but the high-fat diet flies did put on weight. © 2010 LiveScience.com.

Keyword: Obesity; Genes & Behavior
Link ID: 14630 - Posted: 11.04.2010

By Gregory Park , David Lubinski and Camilla P. Benbow Ninety years ago, Stanford psychologist Lewis Terman began an ambitious search for the brightest kids in California, administering IQ tests to several thousand of children across the state. Those scoring above an IQ of 135 (approximately the top 1 percent of scores) were tracked for further study. There were two young boys, Luis Alvarez and William Shockley, who were among the many who took Terman’s tests but missed the cutoff score. Despite their exclusion from a study of young “geniuses,” both went on to study physics, earn PhDs, and win the Nobel prize. How could these two minds, both with great potential for scientific innovation, slip under the radar of IQ tests? One explanation is that many items on Terman’s Stanford-Binet IQ test, as with many modern assessments, fail to tap into a cognitive ability known as spatial ability. Recent research on cognitive abilities is reinforcing what some psychologists suggested decades ago: spatial ability, also known as spatial visualization, plays a critical role in engineering and scientific disciplines. Yet more verbally-loaded IQ tests, as well as many popular standardized tests used today, do not adequately measure this trait, especially in those who are most gifted with it. Spatial ability, defined by a capacity for mentally generating, rotating, and transforming visual images, is one of the three specific cognitive abilities most important for developing expertise in learning and work settings. Two of these, quantitative and verbal ability, are quite familiar due to their high visibility in standardized tests like the Scholastic Aptitude Test (SAT). A spatial ability assessment may include items involving mentally rotating an abstract image or reasoning about an illustrated mechanical device functions. All three abilities are positively correlated, such that someone with above average quantitative ability also tends to have above average verbal and spatial ability. © 2010 Scientific American

Keyword: Intelligence; Attention
Link ID: 14629 - Posted: 11.04.2010

Deborah Blum, IN THE summer of 1991, neuroscientist Simon LeVay published a paper that would make him famous. It reported a study that clearly demonstrated a structural difference between the brains of gay and straight men. For nearly two decades since, LeVay has been in pursuit of more evidence to support the study's core implication: that sexual orientation derives from biology, not from personal choice. Gay, Straight, and the Reason Why is the third popular book that he has published on the topic, and its publication raises two different but equally important questions. First, how far has the science of sexual orientation advanced since LeVay's seminal paper? Second, how far has the research - and effort by advocates like LeVay to spread its message - increased acceptance of gay people by the straight majority? The answer to the first is: not as much as we could hope. I was dismayed to discover that many of the most influential studies cited here spring from previous decades. I'm all for historical context, but when a chapter on the importance of biology in sexuality contains 32 citations and 23 of them date to the year 2000 or earlier, a book can feel a bit dated. I would venture to guess that the dearth of notable recent findings is due in part to the political climate of the last decade, which has not been particularly eager to fund sex research. Thankfully, though, there are some very good recent studies in human development, gender and, more sparsely, sexual orientation. LeVay does a deft job of pulling these varying threads together into his own theory of homosexuality, which nicely balances solid science and common sense. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior
Link ID: 14628 - Posted: 11.04.2010

by Debora MacKenzie Groups in Germany and the US have been testing electronic implants aimed at restoring vision to people with retinal dystrophy. The condition is hereditary or age-related, and causes degeneration of the photoreceptors – light-sensitive cells in the retina – leading to blindness. It affects 15 million people worldwide. Eberthart Zrenner and colleagues at the University of Tübingen in Germany have developed a microchip carrying 1500 photosensitive diodes that slides into the retina where the photoreceptors would normally be. The diodes respond to light, and when connected to an outside power source through a wire into the eye, can stimulate the nearby nerves that normally pass signals to the brain, mimicking healthy photoreceptors. The team reports that their first three volunteers could all locate bright objects. One could recognise normal objects and read large words. Nerves in the eye normally adapt to visual input and stop transmitting signals after a short time. Tiny movements of the eye overcome this by constantly projecting the image back and forth between neighbouring nerve cells so that each has time to recover and resume transmitting signals. Because the implant is inside the eye, this mechanism worked normally in the trials. Another device being tested sends images from a head-mounted camera to ocular nerves, but as the image forms outside the eye the tiny movements cannot maintain it and patients must rapidly shake their head instead. © Copyright Reed Business Information Ltd.

Keyword: Robotics; Vision
Link ID: 14627 - Posted: 11.04.2010

by Karen Heyman One-third of stroke survivors never recover enough brain function to live on their own. Now scientists think they know why. Once a stroke kills a swath of brain cells, a neurotransmitter known as GABA impairs the surviving, apparently healthy, brain tissue. Targeting GABA could help a stroke-afflicted brain better overcome its damage, the researchers suggest. When a stroke hits, physicians have few options. If they catch it early enough, they can administer the clot-busting drug tPA to keep even more brain cells from dying—but tPA is not appropriate for all types of stroke. Physicians can also prescribe physical therapy, which can occasionally help recover impaired motor function. Yet there are no approved drugs that help the brain heal. For its part, the brain appears to try a sort of natural drug therapy to limit the spread of damage. It releases extra amounts of GABA, which reduces the firing of neurons. GABA initially prevents stroke-damaged brain tissue from becoming overexcited and dying. But University of California, Los Angeles (UCLA), investigators led by Thomas Carmichael, a specialist in stroke, and Istvan Mody, an expert in inhibition, wondered whether GABA might also interfere with the brain's plasticity, the ability of healthy regions to take over for injured ones. Previous studies had tried to address this question, but they produced confusing results. The UCLA team hypothesized that others had failed to distinguish between two types of inhibition—phasic, in which GABA acts upon specific receptors at nerve cell sites called synapses, and tonic, in which the neurotransmitter acts on other receptors elsewhere on the nerve cell. © 2010 American Association for the Advancement of Science.

Keyword: Stroke; Brain imaging
Link ID: 14626 - Posted: 11.04.2010

By Nathan Seppa MRI scans of stroke patients can indicate when the stroke occurred, a revelation that could allow more aggressive treatment to limit brain damage, French researchers report online November 2 in Radiology. For a person arriving at a hospital with a stroke, the clock is ticking. When a clot obstructs an artery in the brain, millions of neurons are lost with each passing minute as tissue is starved of blood and oxygen. A clot-busting drug called tPA, or tissue plasminogen activator, can often dissolve the clot and free up the vessel. But the drug is generally considered safe to administer only in the first three to 4½ hours after a stroke begins (SN: 10/25/08, p. 16). Stoke patients typically get a CT scan, which enables doctors to discern whether the stroke results from a blood clot or, less commonly, from a hemorrhage, which shows up as a dark mass on the CT, says neurologist Andrew Barreto of the University of Texas Medical School at Houston. MRI, or magnetic resonance imaging, is used much less often and usually only at large medical centers. Unfortunately, a CT scan cannot pinpoint when a stroke began. Neither can many patients, either because they can’t recall exactly when their symptoms first appeared or because they woke up already in the throes of a stroke. In such cases, doctors “guesstimate” the stroke’s onset, Barreto says, but hesitate to give tPA if too many hours might have passed. Giving tPA too late won’t help tissue that’s already dead and risks causing a brain bleed. After the tPA window closes there is little doctors can do but monitor the patient. © Society for Science & the Public 2000 - 2010

Keyword: Stroke; Brain imaging
Link ID: 14625 - Posted: 11.04.2010