Chapter 13. Memory, Learning, and Development
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by Bethany Brookshire Music displays all the harmony and discord the auditory world has to offer. The perfect pair of notes at the end of the Kyrie in Mozart’s Requiem fills churches and concert halls with a single chord of ringing, echoing consonance. Composers such as Arnold Schönberg explored the depths of dissonance — groups of notes that, played together, exist in unstable antagonism, their frequencies crashing and banging against each other. Dissonant chords are difficult to sing and often painful to hear. But they may get less painful with age. As we age, our brains may lose the clear-cut representations of these consonant and dissonant chords, a new study shows. The loss may affect how older people engage with music and shows that age-related hearing loss is more complex than just having to reach for the volume controls. The main mechanism behind age-related hearing loss is the deterioration of the outer hair cells in the cochlea, a coiled structure within our inner ear. When sound waves enter the ear, a membrane vibrates, pulling the hair cells to and fro and kicking off a series of events that produce electrical signals that will be sent onward to the brain. As we age, we lose some of these outer hair cells, and with them goes our ability to hear extremely high frequencies. In a new study, researchers tested how people perceive consonant pairs of musical notes, which are harmonious and generally pleasing, or dissonant ones, which can be harsh and tense. © Society for Science & the Public 2000 - 2015
|By Dwayne Godwin and Jorge Cham Our minds are veritable memory machines. © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 20734 - Posted: 03.31.2015
Nicholette Zeliadt, One afternoon in October 2012, a communication therapist from Manchester visited the home of Laura and her three children. Laura sat down at a small white table in a dimly lit room to feed her 10-month-old daughter, Bethany, while the therapist set up a video camera to record the pair’s every movement. (Names of research participants have been changed to protect privacy.) Bethany sat quietly in her high chair, nibbling on macaroni and cheese. She picked up a slimy noodle with her tiny fingers, looked up at Laura and thrust out her hand. “Oh, Mommy’s going to have some, yum,” Laura said. “Clever girl!” Bethany beamed a toothy grin at her mother and let out a brief squeal of laughter, and then turned her head to peer out the window as a bus rumbled by. “Oh, you can hear the bus,” Laura said. “Can you say ‘bus?’” “Bah!” Bethany exclaimed. “Yeah, bus!” Laura said. This ordinary domestic moment, immortalized in the video, is part of the first rigorous test of a longstanding idea: that the everyday interactions between caregiver and child can shape the course of autism1. The dynamic exchanges with a caregiver are a crucial part of any child’s development. As Bethany and her mother chatter away, responding to each other’s glances and comments, for example, the little girl is learning how to combine gestures and words to communicate her thoughts. In a child with autism, however, this ‘social feedback loop’ might go awry. An infant who avoids making eye contact, pays little attention to faces and doesn’t respond to his or her name gives parents few opportunities to engage. The resulting lack of social interaction may reinforce the baby’s withdrawal, funneling into a negative feedback loop that intensifies mild symptoms into a full-blown disorder. © 2015 Guardian News and Media Limited
Link ID: 20733 - Posted: 03.30.2015
|By Roni Jacobson As intangible as they may seem, memories have a firm biological basis. According to textbook neuroscience, they form when neighboring brain cells send chemical communications across the synapses, or junctions, that connect them. Each time a memory is recalled, the connection is reactivated and strengthened. The idea that synapses store memories has dominated neuroscience for more than a century, but a new study by scientists at the University of California, Los Angeles, may fundamentally upend it: instead memories may reside inside brain cells. If supported, the work could have major implications for the treatment of post-traumatic stress disorder (PTSD), a condition marked by painfully vivid and intrusive memories. More than a decade ago scientists began investigating the drug propranolol for the treatment of PTSD. Propranolol was thought to prevent memories from forming by blocking production of proteins required for long-term storage. Unfortunately, the research quickly hit a snag. Unless administered immediately after the traumatic event, the treatment was ineffective. Lately researchers have been crafting a work-around: evidence suggests that when someone recalls a memory, the reactivated connection is not only strengthened but becomes temporarily susceptible to change, a process called memory reconsolidation. Administering propranolol (and perhaps also therapy, electrical stimulation and certain other drugs) during this window can enable scientists to block reconsolidation, wiping out the synapse on the spot. The possibility of purging recollections caught the eye of David Glanzman, a neurobiologist at U.C.L.A., who set out to study the process in Aplysia, a sluglike mollusk commonly used in neuroscience research. Glanzman and his team zapped Aplysia with mild electric shocks, creating a memory of the event expressed as new synapses in the brain. The scientists then transferred neurons from the mollusk into a petri dish and chemically triggered the memory of the shocks in them, quickly followed by a dose of propranolol. © 2015 Scientific American
By Virginia Morell Children and parrot and songbird chicks share a rare talent: They can mimic the sounds that adults of their species make. Now, researchers have discovered this vocal learning skill in baby Egyptian fruit bats (Rousettus aegyptiacus, pictured), a highly social species found from Africa to Pakistan. Only a handful of other mammals, including cetaceans and certain insectivorous bats, are vocal learners. The adult fruit bats have a rich vocal repertoire of mouselike squeaks and chatter (listen to a recording here), and the scientists suspected the bat pups had to learn these sounds. To find out, they placed baby bats with their mothers in isolation chambers for 5 months and made video and audio recordings of each pair. Lacking any other adults to vocalize to, the mothers were silent, and their babies made only isolation calls and babbling sounds, the researchers report today in Science Advances. As a control, the team raised another group of bat pups with their mothers and fathers, who chattered to each other. Soon, the control pups’ babbling gave way to specific sounds that matched those of their mothers. But the isolated pups quickly overcame the vocal gap after the scientists united both sets of bats—suggesting that unlike many songbird species (and more like humans), the fruit bats don’t have a limited period for vocal learning. Although the bats’ vocal learning is simple compared with that of humans, it could provide a useful model for understanding the evolution of language, the scientists say. © 2015 American Association for the Advancement of Science
Carl Zimmer Scientists in Iceland have produced an unprecedented snapshot of a nation’s genetic makeup, discovering a host of previously unknown gene mutations that may play roles in ailments as diverse as Alzheimer’s disease, heart disease and gallstones. “This is amazing work, there’s no question about it,” said Daniel G. MacArthur, a geneticist at Massachusetts General Hospital who was not involved in the research. “They’ve now managed to get more genetic data on a much larger chunk of the population than in any other country in the world.” In a series of papers published on Wednesday in the journal Nature Genetics, researchers at Decode, an Icelandic genetics firm owned by Amgen, described sequencing the genomes — the complete DNA — of 2,636 Icelanders, the largest collection ever analyzed in a single human population. With this trove of genetic information, the scientists were able to accurately infer the genomes of more than 100,000 other Icelanders, or almost a third of the entire country. “From the technical point of view, these papers are a tour-de-force,” said David Reich, a geneticist at Harvard Medical School who was not involved in the research. While some diseases, like cystic fibrosis, are caused by a single genetic mutation, the most common ones are not. Instead, mutations to a number of different genes can each raise the risk of getting, say, heart disease or breast cancer. Discovering these mutations can shed light on these diseases and point to potential treatments. But many of them are rare, making it necessary to search large groups of people to find them. The wealth of data created in Iceland may enable scientists to begin doing that. In their new study, the researchers at Decode present several such revealing mutations. For example, they found eight people in Iceland who shared a mutation on a gene called MYL4. Medical records showed that they also have early onset atrial fibrillation, a type of irregular heartbeat. © 2015 The New York Times Company
Hannah Devlin, science correspondent Scientists have raised the alert about an antibiotic routinely prescribed for chest infections, after linking it to an increased risk of epilepsy and cerebral palsy in children whose mothers took the drug during pregnancy. Children of mothers who had taken macrolide antibiotics were found to be almost twice as likely to be affected by the conditions, prompting scientists to call for a review of their use during pregnancy. The study authors urged pregnant women not to stop taking prescribed antibiotics, however. The potential adverse effects are rare and, as yet, unproven, while infections during pregnancy are a well-established cause of health problems in babies. Professor Ruth Gilbert, a clinical epidemiologist who led the research at University College London, said: “The main message is for medicines regulators and whether they need to issue a warning about these drugs. For women, if you’ve got a bacterial infection, it’s more important to get on and treat it.” The study tracked the children of nearly 65,000 women who had been prescribed a variety of antibiotics for illnesses during pregnancy, including chest and throat infections and cystitis. There was no evidence that most antibiotics (including penicillin, which made up 67% of prescriptions), led to an increased risk of the baby developing cerebral palsy or epilepsy. However, when the antibiotics were compared head-to-head, the potential adverse effect of macrolide drugs emerged. Around 10 in 1,000 children whose mothers were given the drug had developed the conditions by the age of seven, compared to 6 in 1,000 children, for those who had other types of antibiotic. © 2015 Guardian News and Media Limited
Jon Hamilton Doctors are much more likely to level with patients who have cancer than patients who have Alzheimer's, according to a report released this week by the Alzheimer's Association. The report found that just 45 percent of Medicare patients who'd been diagnosed with Alzheimer's said they were informed of the diagnosis by their doctor. By contrast, more than 90 percent of Medicare patients with cancer said they were told by their doctor. "What we found is really shocking," says Beth Kallmyer, vice president of constituent services for the Alzheimer's Association. "This is reminiscent of what happened in the 1960s and 1970s with cancer," she says. "But that's changed now, and it really needs to change for Alzheimer's as well." For years, the association's help line has been receiving complaints from family members who say that doctors are reluctant to reveal an Alzheimer's diagnosis, Kallmyer says. So the association decided to investigate by studying medical records and survey results from Medicare recipients. To make sure that Alzheimer's patients hadn't simply forgotten what a doctor said, the group also looked at Medicare survey responses from family members and other caregivers. The result wasn't much better: Just 53 percent said a doctor told them of the patient's diagnosis. © 2015 NPR
Link ID: 20721 - Posted: 03.25.2015
By Siri Carpenter “I don’t look like I have a disability, do I?” Jonas Moore asks me. I shake my head. No, I say — he does not. Bundled up in a puffy green coat, Moore, 35 and sandy-haired, doesn’t stand out in the crowd seeking refuge from the winter cold in a drafty Starbucks. His handshake is firm and his blue eyes meet mine as we talk. He comes across as intelligent and thoughtful, if perhaps a bit reserved. His disability — a form of autism — is invisible. That’s part of the problem, Moore says. Like most people with an autism spectrum disorder, he finds relationships challenging. In the past, he has been quick to anger and has had what he calls meltdowns. Those who don’t know he has autism can easily misinterpret his actions. “People think that when I do misbehave I’m somehow intentionally trying to be a jerk,” Moore says. “That’s just not the case.” His difficulty managing emotions has gotten him into some trouble, and he has had a hard time holding onto jobs — an outcome he might have avoided, he says, if his co-workers and bosses had better understood his intentions. Over time, things have gotten better. Moore has held the same job for five years, vacuuming commercial buildings on a night cleaning crew. He attributes his success to getting the right amount of medication and therapy, to time’s maturing him and to the fact that he works mostly alone. Moore is fortunate. His parents help support him financially. He has access to good mental health care where he lives in Wisconsin. And he has found a job that suits him. Many adults with autism are not so lucky.
Link ID: 20711 - Posted: 03.24.2015
By ANDREW POLLACK An experimental drug for Alzheimer’s disease sharply slowed the decline in mental function in a small clinical trial, researchers reported Friday, reviving hopes for an approach to therapy that until now has experienced repeated failures. The drug, being developed by Biogen Idec, could achieve sales of billions of dollars a year if the results from the small trial are replicated in larger trials that Biogen said it hoped to begin this year. Experts say that there are no really good drugs now to treat Alzheimer’s. Biogen’s stock has risen about 50 percent since early December, when the company first announced that the drug had slowed cognitive decline in the trial, without saying by how much. Analysts and investors had been eagerly awaiting the detailed results, some of them flying to France to hear Biogen researchers present them at a neurology meeting on Friday. The drug, called aducanumab, met and in some cases greatly exceeded Wall Street expectations in terms of how much the highest dose slowed cognitive decline. However, there was a high incidence of a particular side effect that might make it difficult to use the highest dose. Still, the net impression was positive. “Out-of-the-ballpark efficacy, acceptable safety,” Ravi Mehrotra, an analyst at Credit Suisse, wrote on Friday. Shares of Biogen rose $42.33, or 10 percent, to $475.98. Alzheimer’s specialists were impressed, but they cautioned that it was difficult to read much from a small early-stage, or Phase 1, trial that was designed to look at safety, not the effect on cognition. Also, other Alzheimer’s drugs that had looked promising in early studies ended up not working in larger trials. “It’s certainly encouraging,” said Dr. Samuel Gandy, director of the Center for Cognitive Health at Mount Sinai Hospital in New York, who was not involved in the study. He said the effect of the highest dose was “pretty impressive.” © 2015 The New York Times Company
Link ID: 20709 - Posted: 03.21.2015
by Michael Slezak What were we talking about? Oh yes, brain-training programmes may be useful for helping inattentive people focus on tasks in their daily life. At least, that's the implication of an analysis looking at one particular programme. It's the latest salvo in a field that has seen the battles lines drawn between those who believe there is no compelling scientific evidence that training the brain to do a specific task better can offer wider cognitive improvements, and those that think it can work in some cases. The party line is that brain training improves only that which it exercises, says Jared Horvath from the University of Melbourne in Australia. "What this means is, if the training programme uses a working memory game, you get better at working memory games and little else." But an analysis by Megan Spencer-Smith of Monash University in Melbourne, Australia, and Torkel Klingberg at the Karolinska Institute in Stockholm, Sweden, claims to show that there are benefits for daily life – at least for people with attention deficit hyperactivity disorder or other problems related to attentiveness. They focused on a programme called Cogmed, which Klingberg has helped develop, and combined the results of several smaller studies. Cogmed is designed to improve how much verbal or visual information you can temporarily remember and work with. © Copyright Reed Business Information Ltd.
Elie Dolgin The southern city of Guangzhou has long held the largest eye hospital in China. But about five years ago, it became clear that the Zhongshan Ophthalmic Center needed to expand. More and more children were arriving with the blurry distance vision caused by myopia, and with so many needing eye tests and glasses, the hospital was bursting at the seams. So the centre began adding new testing rooms — and to make space, it relocated some of its doctors and researchers to a local shopping mall. Now during the summer and winter school holidays, when most diagnoses are made, “thousands and thousands of children” pour in every day, says ophthalmologist Nathan Congdon, who was one of those uprooted. “You literally can't walk through the halls because of all the children.” East Asia has been gripped by an unprecedented rise in myopia, also known as short-sightedness. Sixty years ago, 10–20% of the Chinese population was short-sighted. Today, up to 90% of teenagers and young adults are. In Seoul, a whopping 96.5% of 19-year-old men are short-sighted. Other parts of the world have also seen a dramatic increase in the condition, which now affects around half of young adults in the United States and Europe — double the prevalence of half a century ago. By some estimates, one-third of the world's population — 2.5 billion people — could be affected by short-sightedness by the end of this decade. “We are going down the path of having a myopia epidemic,” says Padmaja Sankaridurg, head of the myopia programme at the Brien Holden Vision Institute in Sydney, Australia. The condition is more than an inconvenience. Glasses, contact lenses and surgery can help to correct it, but they do not address the underlying defect: a slightly elongated eyeball, which means that the lens focuses light from far objects slightly in front of the retina, rather than directly on it. © 2015 Nature Publishing Group
Michaeleen Doucleff Malaria is one of the oldest scourges of mankind. Yet it's been a mystery how the deadliest form of the disease kills children. One doctor in Michigan has dedicated her life to figuring that out. Now she and her team report their findings in this week's issue of the New England Journal of Medicine. The key to solving the mystery was looking inside the brain. Most of the time malaria causes a bad fever and body aches. But in rare cases — often in children — the parasite gets stuck in the capillaries of the brain. The child has a seizure, goes into a coma and can die. This all happens in only two or three days, says Dr. Terrie Taylor of Michigan State University. "These are bright, happy children who are suddenly felled by a disease that quickly renders them unconscious. And quickly kills them. It's a catastrophe." The sudden death of a child devastates not just the family but the whole community, Taylor says: "Imagine the ripple effects on their friends and their siblings. Suddenly their friends are gone. Just gone." Since 1986, Taylor has been treating children with severe malaria at Queen Elizabeth Central Hospital in Blantyre, Malawi. Seeing so many families deal with these huge losses, year after year, made Taylor focus her career on one goal: Figuring out why some children die from cerebral malaria but others soon recover. © 2015 NPR
Keyword: Development of the Brain
Link ID: 20702 - Posted: 03.19.2015
A long-term study has pointed to a link between breastfeeding and intelligence. The research in Brazil traced nearly 3,500 babies, from all walks of life, and found those who had been breastfed for longer went on to score higher on IQ tests as adults. Experts say the results, while not conclusive, appear to back current advice that babies should be exclusively breastfed for six months. But they say mothers should still have a choice about whether or not to do it. Regarding the findings - published in The Lancet Global Health - they stress there are many different factors other than breastfeeding that could have an impact on intelligence, although the researchers did try to rule out the main confounders, such as mother's education, family income and birth weight. Dr Bernardo Lessa Horta, from the Federal University of Pelotas in Brazil, said his study offers a unique insight because in the population he studied, breastfeeding was evenly distributed across social class - not something just practised by the rich and educated. Most of the babies, irrespective of social class, were breastfed - some for less than a month and others for more than a year. Those who were breastfed for longer scored higher on measures of intelligence as adults. They were also more likely to earn a higher wage and to have completed more schooling. Dr Horta believes breast milk may offer an advantage because it is a good source of long-chain saturated fatty acids which are essential for brain development. But experts say the study findings cannot confirm this and that much more research is needed to explore any possible link between breastfeeding and intelligence. © 2015 BBC.
By PAM BELLUCK What happens to forgotten memories — old computer passwords, friends’ previous phone numbers? Scientists have long held two different theories. One is that memories do not diminish but simply get overshadowed by new memories. The other is that older memories become weaker, that pulling to mind new passwords or phone numbers degrades old recollections so they do not interfere. The difference could be significant. If old memories stay strong and are merely papered over by new ones, they may be easier to recover. That could be positive for someone trying to remember an acquaintance’s name, but difficult for someone trying to lessen memories of abuse. It could suggest different strategies for easing traumatic memories, evaluating witness testimony about crimes, or helping students study for tests. Now, a study claims to provide evidence of memory’s weakening by showing that people’s ability to remember something and the pattern of brain activity that thing generates both appear to diminish when a competing memory gets stronger. Demonstrating sophisticated use of brain scans in memory research, authors of the study, published Monday in the journal Nature Neuroscience, appear to have identified neural fingerprints of specific memories, distinguishing brain activity patterns produced when viewing a picture of a necklace, say, from a picture of binoculars or other objects. The experiment, conducted by scientists in Birmingham and Cambridge, England, involved several stages with 24 participants first trained to associate words to two unrelated black and white pictures from lists of famous people, ordinary objects or scenes. © 2015 The New York Times Company
Keyword: Learning & Memory
Link ID: 20695 - Posted: 03.17.2015
By BENEDICT CAREY Behind all those canned compliments for older adults — spry! wily! wise! — is an appreciation for something that scientists have had a hard time characterizing: mental faculties that improve with age. Knowledge is a large part of the equation, of course. People who are middle-aged and older tend to know more than young adults, by virtue of having been around longer, and score higher on vocabulary tests, crossword puzzles and other measures of so-called crystallized intelligence. Still, young adults who consult their elders (mostly when desperate) don’t do so just to gather facts, solve crosswords or borrow a credit card. Nor, generally, are they looking for help with short-term memory or puzzle solving. Those abilities, called fluid intelligence, peak in the 20s. No, the older brain offers something more, according to a new paper in the journal Psychological Science. Elements of social judgment and short-term memory, important pieces of the cognitive puzzle, may peak later in life than previously thought. The postdoctoral fellows Joshua Hartshorne of M.I.T. and Laura Germine of Harvard and Massachusetts General Hospital analyzed a huge trove of scores on cognitive tests taken by people of all ages. The researchers found that the broad split in age-related cognition — fluid in the young, crystallized in the old — masked several important nuances. “This dichotomy between early peaks and later peaks is way too coarse,” Dr. Hartshorne said. “There are a lot more patterns going on, and we need to take those into account to fully understand the effects of age on cognition.” The new paper is hardly the first challenge to the scientific literature on age-related decline, and it won’t be the last. A year ago, German scientists argued that cognitive “deficits” in aging were caused largely by the accumulation of knowledge — that is, the brain slows down because it has to search a larger mental library of facts. That idea has stirred some debate among scientists. Experts said the new analysis raised a different question: Are there distinct, independent elements of memory and cognition that peak at varying times of life? © 2015 The New York Times Company
By John Horgan In 1990 The New York Times published a front-page article by Lawrence Altman, a reporter with a medical degree, announcing that scientists had discovered “a link between alcoholism and a specific gene.” The evidence for the "feel-good gene," which supposedly reduces anxiety, is flimsy, just like the evidence linking specific genes to high intelligence, violent aggression, homosexuality, bipolar disorder and countless other complex human traits and ailments. That was merely one in a string of reports in which the Times and other major media hyped what turned out to be erroneous claims linking complex traits and disorders—from homosexuality and high intelligence to schizophrenia and bipolar disorder—to specific genes. I thought those days were over, and that scientists and the media have learned to doubt extremely reductionist genetic accounts of complex traits and behaviors. I was wrong. Last Sunday, the “Opinion” section of the Times published an essay, “The Feel-Good Gene,” which states: “For the first time, scientists have demonstrated that a genetic variation in the brain makes some people inherently less anxious, and more able to forget fearful and unpleasant experiences. This lucky genetic mutation produces higher levels of anandamide–the so-called bliss molecule and our natural marijuana–in our brains. In short, some people are prone to be less anxious simply because they won the genetic sweepstakes and randomly got a genetic mutation that has nothing at all to do with strength of character.” This article, like the one touting the alcoholism gene 25 years ago, was written by a physician, Richard Friedman, professor of psychiatry at Weill Cornell Medical College. I emphasize this fact because scientific hype is often blamed on supposedly ignorant journalists like me rather than on physicians and other so-called experts. © 2015 Scientific American
By Maggie Fox Teenagers who use marijuana heavily grow up to have poor memories and also have brain abnormalities, a new study shows. The study cannot say which came first — the brain structure differences or the pot use. But it suggests there could be long-term effects of heavy marijuana use. A team at Northwestern University looked at 97 volunteers with and without mental illness. The dope smokers said they'd used marijuana daily starting at age 16 or 17, and said they had not used other drugs. The daily marijuana users had an abnormally shaped hippocampus and performed about 18 percent more poorly on long-term memory tasks, the researchers reported in the journal Hippocampus. The hippocampus is a part of the brain used in storing long-term memory. "The memory processes that appear to be affected by cannabis are ones that we use every day to solve common problems and to sustain our relationships with friends and family," said Dr. John Csernansky, who worked on the study. Previous research by the same Northwestern team showed heavy pot smokers had poor short-term and working memory and abnormally shaped brain structures including the striatum, globus pallidus and thalamus. "It is possible that the abnormal brain structures reveal a pre-existing vulnerability to marijuana abuse," Matthew Smith, who led the study, said in a statement.
By Emily Underwood From imaging babies to blasting apart kidney stones, ultrasound has proved to be a versatile tool for physicians. Now, several research teams aim to unleash the technology on some of the most feared brain diseases. The blood-brain barrier, a tightly packed layer of cells that lines the brain's blood vessels, protects it from infections, toxins, and other threats but makes the organ frustratingly hard to treat. A strategy that combines ultrasound with microscopic blood-borne bubbles can briefly open the barrier, in theory giving drugs or the immune system access to the brain. In the clinic and the lab, that promise is being evaluated. This month, in one of the first clinical tests, Todd Mainprize, a neurosurgeon at the University of Toronto in Canada, hopes to use ultrasound to deliver a dose of chemotherapy to a malignant brain tumor. And in some of the most dramatic evidence of the technique's potential, a research team reports this week in Science Translational Medicine that they used it to rid mice of abnormal brain clumps similar to those in Alzheimer's disease, restoring lost memory and cognitive functions. If such findings can be translated from mice to humans, “it will revolutionize the way we treat brain disease,” says biophysicist Kullervo Hynynen of the Sunnybrook Research Institute in Toronto, who originated the ultrasound method. Some scientists stress that rodent findings can be hard to translate to humans and caution that there are safety concerns about zapping the brain with even the low-intensity ultrasound used in the new study, which is similar to that used in diagnostic scans. © 2015 American Association for the Advancement of Science.
Link ID: 20685 - Posted: 03.12.2015
|By Daisy Yuhas The brain is a hotbed of electrical activity. Scientists have long known that brain cells communicate via electrical missives, created by charged atoms and molecules called ions as they travel across the membranes of those cells. But a new study suggests that in the days and weeks that lead up to a brain forming in an embryo or fetus, altering the electrical properties of these cells can dramatically change how the ensuing brain develops. Researchers at Tufts University and the University of Minnesota have investigated how the difference in charge on either side of a resting cell’s membrane—its electrical potential—helps build the brain. In previous work Tufts University developmental biologist Michael Levin found that patterns of electrical potentials in the earliest stages of an embryo’s development can direct how an animal’s body grows, and that manipulating those potentials can cause a creature to sprout extra limbs, tails or functioning eyes. Now, Levin’s group has investigated how these potentials shape the brain. Working with frog embryos the researchers first used dyes to see the patterns of electrical potentials that precede brain development. They noticed that before the development of a normal brain the cells lining the neural tube, a structure that eventually becomes the brain and spinal cord, have extreme differences in ionic charge within and outside the membrane that houses the cells. In other words, these cells are extremely polarized. © 2015 Scientific American
Keyword: Development of the Brain
Link ID: 20684 - Posted: 03.12.2015