Chapter 17. Learning and Memory
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by Bethany Brookshire Every day sees a new research article on addiction, be it cocaine, heroin, food or porn. Each one takes a specific angle on how addiction works in the brain. Perhaps it’s a disorder of reward, with drugs hijacking a natural system that is meant to respond to food, sex and friendship. Possibly addiction is a disorder of learning, where our brains learn bad habits and responses. Maybe we should think of addiction as a combination of an environmental stimulus and vulnerable genes. Or perhaps it’s an inappropriate response to stress, where bad days trigger a relapse to the cigarette, syringe or bottle. None of these views are wrong. But none of them are complete, either. Addiction is a disorder of reward, a disorder of learning. It has genetic, epigenetic and environmental influences. It is all of that and more. Addiction is a display of the brain’s astounding ability to change — a feature called plasticity — and it showcases what we know and don’t yet know about how brains adapt to all that we throw at them. “A lot of people think addiction is what happens when someone finds a drug to be the most rewarding thing they’ve ever experienced,” says neuroscientist George Koob, director of the National Institute on Alcohol Abuse and Alcoholism in Bethesda, Md. “But drug abuse is not just feeling good about drugs. Your brain is changed when you misuse drugs. It is changed in ways that perpetuate the problem.” The changes associated with drug use affect how addicts respond to drug cues, like the smell of a cigarette or the sight of a shot of vodka. Drug abuse also changes how other rewards, such as money or food are processed, decreasing their relative value. © Society for Science & the Public 2000 - 2013
By DOUGLAS QUENQUA A tiny part of the brain keeps track of painful experiences and helps determine how we will react to them in the future, scientists say. The findings could be a boon to depression treatments. The habenula (pronounced ha-BEN-you-la), a part of the brain less than half the size of a pea, has been shown in animal studies to activate during painful or unpleasant episodes. Using M.R.I.s to produce powerful brain scans, researchers at University College London tracked the habenulas in subjects who were hooked up to electric shock machines. The subjects were presented with a series of photographs, some of which were followed by increasingly strong shocks. Soon, when the subjects were shown pictures associated with shocks, their habenulas would light up. “The habenula seems to track the associations with electric shocks becoming stronger and stronger,” said Jonathan Roiser, a neuroscientist at the college and an author of the study, published in The Proceedings of the National Academy of Sciences. The habenula appeared to have an effect on motivation, too. The subjects had been asked to occasionally press a button, just to show they were awake. They were much slower to do so when their habenula was active. In fact, the more slowly they responded, the more reliably their habenulas tracked associations with shocks. In animals, the habenula has been shown to suppress production of dopamine, a chemical that drives motivation. Perhaps, the researchers say, an overactive habenula can cause the feelings of impending doom and low motivation common in people with depression. © 2014 The New York Times Company
|By Annie Sneed It's easy to recall events of decades past—birthdays, high school graduations, visits to Grandma—yet who can remember being a baby? Researchers have tried for more than a century to identify the cause of “infantile amnesia.” Sigmund Freud blamed it on repression of early sexual experiences, an idea that has been discredited. More recently, researchers have attributed it to a child's lack of self-perception, language or other mental equipment required to encode memories. Neuroscientists Paul Frankland and Sheena Josselyn, both at the Hospital for Sick Children in Toronto, do not think linguistics or a sense of self offers a good explanation, either. It so happens that humans are not the only animals that experience infantile amnesia. Mice and monkeys also forget their early childhood. To account for the similarities, Frankland and Josselyn have another theory: the rapid birth of many new neurons in a young brain blocks access to old memories. In a new experiment, the scientists manipulated the rate at which hippocampal neurons grew in young and adult mice. The hippocampus is the region in the brain that records autobiographical events. The young mice with slowed neuron growth had better long-term memory. Conversely, the older mice with increased rates of neuron formation had memory loss. Based on these results, published in May in the journal Science, Frankland and Josselyn think that rapid neuron growth during early childhood disrupts the brain circuitry that stores old memories, making them inaccessible. Young children also have an underdeveloped prefrontal cortex, another region of the brain that encodes memories, so infantile amnesia may be a combination of these two factors. © 2014 Scientific American
|By Jillian Rose Lim and LiveScience People who don't get enough sleep could be increasing their risk of developing false memories, a new study finds. In the study, when researchers compared the memory of people who'd had a good night's sleep with the memory of those who hadn't slept at all, they found that, under certain conditions, sleep-deprived individuals mix fact with imagination, embellish events and even "remember" things that never actually happened. False memories occur when people's brains distort how they remember a past event — whether it's what they did after work, how a painful relationship ended or what they witnessed at a crime scene. Memory is not an exact recording of past events, said Steven Frenda, a psychology Ph.D. student at the University of California, Irvine, who was involved in the study. Rather, fresh memories are constructed each time people mentally revisit a past event. During this process, people draw from multiple sources — like what they've been told by others, what they've seen in photographs or what they know as stereotypes or expectations, Frenda said. The new findings "have implications for people's everyday lives —recalling information for an exam, or in work contexts, but also for the reliability of eyewitnesses who may have experienced periods of restricted or deprived sleep," said Frenda, who noted that chronic sleep deprivation is on the rise. In a previous study, Frenda and his colleagues observed that people with restricted sleep (less than 5 hours a night) were more likely to incorporate misinformation into their memories of certain photos, and report they had seen video footage of a news event that didn't happen. In the current study, they wanted to see how a complete lack of sleep for 24 hours could influence a person's memory. © 2014 Scientific American
By DOUGLAS QUENQUA Like Pavlov’s dogs, most organisms can learn to associate two events that usually occur together. Now, a team of researchers says they have identified a gene that enables such learning. The scientists, at the University of Tokyo, found that worms could learn to avoid unpleasant situations as long as a specific insulin receptor remained intact. Roundworms were exposed to different concentrations of salt; some received food during the initial exposure, others did not. Later, when exposed to various concentrations of salt again, the roundworms that had been fed during the first stage gravitated toward their initial salt concentrations, while those that had been starved avoided them. But the results changed when the researchers repeated the experiment using worms with a defect in a particular receptor for insulin, a protein crucial to metabolism. Those worms could not learn to avoid the salt concentrations associated with starvation. “We looked for different forms of the receptor and found that a new one, which we named DAF-2c, functions in taste-aversion learning,” said Masahiro Tomioka, a geneticist at the University of Tokyo and an author of the study, which was published in the journal Science. “It turned out that only this form of the receptor can support learning” in roundworms. While human insulin receptors bear some resemblance to those of a roundworm, more study is needed to determine if it plays a similar role in memory and decision-making, Dr. Tomioka said. But studies have suggested a link between insulin levels and Alzheimer’s disease in humans. © 2014 The New York Times Company
By HENRY L. ROEDIGER III TESTS have a bad reputation in education circles these days: They take time, the critics say, put students under pressure and, in the case of standardized testing, crowd out other educational priorities. But the truth is that, used properly, testing as part of an educational routine provides an important tool not just to measure learning, but to promote it. In one study I published with Jeffrey D. Karpicke, a psychologist at Purdue, we assessed how well students remembered material they had read. After an initial reading, students were tested on some passages by being given a blank sheet of paper and asked to recall as much as possible. They recalled about 70 percent of the ideas. Other passages were not tested but were reread, and thus 100 percent of the ideas were re-exposed. In final tests given either two days or a week later, the passages that had been tested just after reading were remembered much better than those that had been reread. What’s at work here? When students are tested, they are required to retrieve knowledge from memory. Much educational activity, such as lectures and textbook readings, is aimed at helping students acquire and store knowledge. Various kinds of testing, though, when used appropriately, encourage students to practice the valuable skill of retrieving and using knowledge. The fact of improved retention after a quiz — called the testing effect or the retrieval practice effect — makes the learning stronger and embeds it more securely in memory. This is vital, because many studies reveal that much of what we learn is quickly forgotten. Thus a central challenge to learning is finding a way to stem forgetting. © 2014 The New York Times Company
Keyword: Learning & Memory
Link ID: 19861 - Posted: 07.21.2014
Emily A. Holmes, Michelle G. Craske & Ann M. Graybiel How does one human talking to another, as occurs in psychological therapy, bring about changes in brain activity and cure or ease mental disorders? We don't really know. We need to. Mental-health conditions, such as post-traumatic stress disorder (PTSD), obsessive–compulsive disorder (OCD), eating disorders, schizophrenia and depression, affect one in four people worldwide. Depression is the third leading contributor to the global burden of disease, according to the World Health Organization. Psychological treatments have been subjected to hundreds of randomized clinical trials and hold the strongest evidence base for addressing many such conditions. These activities, techniques or strategies target behavioural, cognitive, social, emotional or environmental factors to improve mental or physical health or related functioning. Despite the time and effort involved, they are the treatment of choice for most people (see ‘Treating trauma with talk therapy’). For example, eating disorders were previously considered intractable within our life time. They can now be addressed with a specific form of cognitive behavioural therapy (CBT)1 that targets attitudes to body shape and disturbances in eating habits. For depression, CBT can be as effective as antidepressant medication and provide benefits that are longer lasting2. There is also evidence that interpersonal psychotherapy (IPT) is effective for treating depression. Ian was filling his car with petrol and was caught in the cross-fire of an armed robbery. His daughter was severely injured. For the following decade Ian suffered nightmares, intrusive memories, flashbacks of the trauma and was reluctant to drive — symptoms of post-traumatic stress disorder (PTSD). © 2014 Nature Publishing Group,
By Emily Anthes The women that come to see Deane Aikins, a clinical psychologist at Wayne State University, in Detroit, are searching for a way to leave their traumas behind them. Veterans in their late 20s and 30s, they served in Iraq and Afghanistan. Technically, they’d been in non-combat positions, but that didn’t eliminate the dangers of warfare. Mortars and rockets were an ever-present threat on their bases, and they learned to sleep lightly so as not to miss alarms signaling late-night attacks. Some of the women drove convoys of supplies across the desert. It was a job that involved worrying about whether a bump in the road was an improvised explosive device, or if civilians in their path were strategic human roadblocks. On top of all that, some of the women had been sexually assaulted by their military colleagues. After one woman was raped, she helped her drunk assailant sneak back into his barracks because she worried that if they were caught, she’d be disciplined or lose her job. These traumas followed the women home. Today, far from the battlefield, they find themselves struggling with vivid flashbacks and nightmares, tucking their guns under their pillows at night. Some have turned to alcohol to manage their symptoms; others have developed exhausting routines to avoid any people or places that might trigger painful memories and cause them to re-live their experiences in excruciating detail. © 2014 Nautilus,
Fearful memories can be dampened by imagining past traumas in a safe setting. The "extinction" of fear is fragile, however, and surprising or unexpected events can cause fear memories to return. Inactivating brain areas that detect novelty prevents relapse of unwanted fear memories. Traumatic and emotional experiences often lead to debilitating mental health disorders, including post-traumatic stress disorder (PTSD). In the clinic, it is typical to use behavioral therapies such as exposure therapy to help reduce fear in patients suffering from traumatic memories. Using these approaches, patients are asked to remember the circumstances and stimuli surrounding their traumatic memory in a safe setting in order to "extinguish" their fear response to those events. While effective in many cases, the loss of fear and anxiety achieved by these therapies is often short-lived—fear returns or relapses under a variety of conditions. Many years ago, the famous Russian physiologist Ivan Pavlov noted that simply exposing animals to novel or unexpected events could cause extinguished responses (such as salivary responses to sounds) to return. Might exposure to novelty also cause extinguished fear responses to return? In a recent study (Maren, 2014), rats first learned that an innocuous tone predicted an aversive (but mild) electric shock to their feet. The subsequent fear response to the tone was then extinguished by presenting the stimulus to the animals many times without the shock. After the fear response to the tone was reduced with the extinction procedure, they were then presented with the tone in either a new location (a novel test box) or in a familiar location, but in the presence of an unexpected sound (a noise burst). In both cases, fear to the tone returned as Pavlov predicted: the unexpected places and sounds led to a disinhibition of fear—in other words, fear relapsed. © 2014 Publiscize
Obese women may have a "food learning impairment" that could explain their attitude to food, research from Yale School of Medicine suggests. Tests on groups of obese and healthy-weight people found that the obese women performed worst when asked to remember a sequence of food picture cards. Writing in Current Biology, Yale researchers tested 135 men and women. The findings could lead to new ways to tackle obesity, the study says. Study author Ifat Levy, assistant professor at Yale School of Medicine, said the difference in the performance of the obese women compared with the other groups was "really striking" and "significant". The tests looked at an individual's ability to learn and predict the appearance of pictures of food or money on coloured cards. The participants were told they would be given whatever appeared on these "reward" cards. In the first phase, the reward cards always followed a particular coloured card in a sequence. Later, the order was changed and the reward cards appeared following a different coloured card. During this time, participants were asked to predict the likelihood of a reward card appearing as the cards were shown one by one. The results showed that obese women performed worst because they overestimated how often the pictures of food, including pretzels or chocolate, appeared. Even after researchers had accounted for other factors, there was still a large difference in their learning performance. Prof Levy said: "This is not a general learning impairment, as obese women had no problem learning when the reward was money rather than food. BBC © 2014
Kelly Servick If you’re a bird enthusiast, you can pick out the “chick-a-DEE-dee” song of the Carolina chickadee with just a little practice. But if you’re an environmental scientist faced with parsing thousands of hours of recordings of birdsongs in the lab, you might want to enlist some help from your computer. A new approach to automatic classification of birdsong borrows techniques from human voice recognition software to sort through the sounds of hundreds of species and decides on its own which features make each one unique. Collectors of animal sounds are facing a data deluge. Thanks to cheap digital recording devices that can capture sound for days in the field, “it’s really, really easy to collect sound, but it’s really difficult to analyze it,” say Aaron Rice, a bioacoustics researcher at Cornell University, who was not involved in the new work. His lab has collected 6 million hours of underwater recordings, from which they hope to pick out the signature sounds of various marine mammals. Knowing where and when a certain species is vocalizing might help scientists understand habitat preferences, track their movements or population changes, and recognize when a species is disrupted by human development. But to keep these detailed records, researchers rely on software that can reliably sort through the cacophony they capture in the field. Typically, scientists build one computer program to recognize one species, and then start all over for another species, Rice says. Training a computer to recognize lots of species in one pass is “a challenge that we’re all facing.” © 2014 American Association for the Advancement of Science.
Keyword: Learning & Memory
Link ID: 19849 - Posted: 07.19.2014
By BENEDICT CAREY The 8-year-old juggling a soccer ball and the 48-year-old jogging by, with Japanese lessons ringing from her earbuds, have something fundamental in common: At some level, both are wondering whether their investment of time and effort is worth it. How good can I get? How much time will it take? Is it possible I’m a natural at this (for once)? What’s the percentage in this, exactly? Scientists have long argued over the relative contributions of practice and native talent to the development of elite performance. This debate swings back and forth every century, it seems, but a paper in the current issue of the journal Psychological Science illustrates where the discussion now stands and hints — more tantalizingly, for people who just want to do their best — at where the research will go next. The value-of-practice debate has reached a stalemate. In a landmark 1993 study of musicians, a research team led by K. Anders Ericsson, a psychologist now at Florida State University, found that practice time explained almost all the difference (about 80 percent) between elite performers and committed amateurs. The finding rippled quickly through the popular culture, perhaps most visibly as the apparent inspiration for the “10,000-hour rule” in Malcolm Gladwell’s best-selling “Outliers” — a rough average of the amount of practice time required for expert performance. Scientists begin to shed light on the placenta, an important organ that we rarely think of; virtual reality companies work out the kinks in their immersive worlds; research shows that practice may not be as important as once thought. The new paper, the most comprehensive review of relevant research to date, comes to a different conclusion. Compiling results from 88 studies across a wide range of skills, it estimates that practice time explains about 20 percent to 25 percent of the difference in performance in music, sports and games like chess. In academics, the number is much lower — 4 percent — in part because it’s hard to assess the effect of previous knowledge, the authors wrote. © 2014 The New York Times Company
Keyword: Learning & Memory
Link ID: 19835 - Posted: 07.15.2014
By Gary Stix Popular neuroscience books have made much in recent years of the possibility that the adult brain is capable of restoring lost function or even enhancing cognition through sustained mental or physical activities. One piece of evidence often cited is a 14-year-old study that that shows that London taxi drivers have enlarged hippocampi, brain areas that store a mental map of one’s surroundings. Taxi drivers, it is assumed, have better spatial memory because they must constantly distinguish the streets and landmarks of Shepherd’s Bush from those of Brixton. A mini-industry now peddles books with titles like The Brain that Changes Itself or Rewire Your Brain: Think Your Way to a Better Life. Along with self-help guides, the value of games intended to enhance what is known as neuroplasticity are still a topic of heated debate because no one knows for sure whether or not they improve intelligence, memory, reaction times or any other facet of cognition. Beyond the controversy, however, scientists have taken a number of steps in recent years to start to answer the basic biological questions that may ultimately lead to a deeper understanding of neuroplasticity. This type of research does not look at whether psychological tests used to assess cognitive deficits can be refashioned with cartoonlike graphics and marketed as games intended to improve mental skills. Rather, these studies attempt to provide a simple definition of how mutable the brain really is at all life stages, from infancy onward into adulthood. One ongoing question that preoccupies the basic scientists pursuing this line of research is how routine everyday activities—sleep, wakefulness, even any sort of movement—may affect the ability to perceive things in the surrounding environment. One of the leaders in these efforts is Michael Stryker, who researches neuroplasticity at the University of California San Francisco. Stryker headed a group that in 2010 published a study on what happened when mice run on top of a Styrofoam ball floating on air. They found that neurons in a brain region that processes visual signals—the visual cortex—nearly doubled their firing rate when the mice ran on the ball. © 2014 Scientific American
By BENEDICT CAREY PHILADELPHIA — The man in the hospital bed was playing video games on a laptop, absorbed and relaxed despite the bustle of scientists on all sides and the electrodes threaded through his skull and deep into his brain. “O.K., that’s enough,” he told doctors after more than an hour. “All those memory tests, it’s exhausting.” The man, Ralph, a health care worker who asked that his last name be omitted for privacy, has severe epilepsy; and the operation to find the source of his seizures had provided researchers an exquisite opportunity to study the biology of memory. The Department of Defense on Tuesday announced a $40 million investment in what has become the fastest-moving branch of neuroscience: direct brain recording. Two centers, one at the University of Pennsylvania and the other at the University of California, Los Angeles, won contracts to develop brain implants for memory deficits. Their aim is to develop new treatments for traumatic brain injury, the signature wound of the wars in Iraq and in Afghanistan. Its most devastating symptom is the blunting of memory and reasoning. Scientists have found in preliminary studies that they can sharpen some kinds of memory by directly recording, and stimulating, circuits deep in the brain. Unlike brain imaging, direct brain recording allows scientists to conduct experiments while listening to the brain’s internal dialogue in real time, using epilepsy patients like Ralph or people with Parkinson’s disease as active collaborators. The technique has provided the clearest picture yet of how neural circuits function, and raised hopes of new therapies for depression and anxiety as well as cognitive problems. But experts also worry about the possible side effects of directly tampering with memory. © 2014 The New York Times Company
by Bethany Brookshire One day when I came in to the office, my air conditioning unit was making a weird rattling sound. At first, I was slightly annoyed, but then I chose to ignore it and get to work. In another 30 minutes, I was completely oblivious to the noise. It wasn’t until my cubicle neighbor Meghan Rosen came in and asked about the racket that I realized the rattle was still there. My brain had habituated to the sound. Habituation, the ability to stop noticing or responding to an irrelevant signal, is one of the simplest forms of learning. But it turns out that at the level of a brain cell, it’s a far more complex process than scientists previously thought. In the June 18 Neuron, Mani Ramaswami of Trinity College Dublin proposes a new framework to describe how habituation might occur in our brains. The paper not only offers a new mechanism to help us understand one of our most basic behaviors, it also demonstrates how taking the time to integrate new findings into a novel framework can help push a field forward. Our ability to ignore the irrelevant and familiar has been a long-known feature of human learning. It’s so simple, even a sea slug can do it. Because the ability to habituate is so simple, scientists hypothesized that the mechanism behind it must also be simple. The previous framework for habituation has been synaptic depression, a decrease in chemical release. When one brain cell sends a signal to another, it releases chemical messengers into a synapse, the small gap between neurons. Receptors on the other side pick up this excitatory signal and send the message onward. But in habituation, neurons would release fewer chemicals, making the signal less likely to hit the other side. Fewer chemicals, fewer signals, and you’ve habituated. Simple. But, as David Glanzman, a neurobiologist at the University of California, Los Angeles points out, there are problems with this idea. © Society for Science & the Public 2000 - 2013
Keyword: Learning & Memory
Link ID: 19772 - Posted: 06.25.2014
By DOUGLAS QUENQUA When it comes to forming memories that involve recalling a personal experience, neuroscientists are of two minds. Some say that each memory is stored in a single neuron in a region of the brain called the hippocampus. But a new study is lending weight to the theory of neuroscientists who believe that every memory is spread out, or distributed, across many neurons in that part of the brain. By watching patients with electrodes in their brains play a memory game, researchers found that each such memory is committed to cells distributed across the hippocampus. Though the proportion of cells responsible for each memory is small (about 2 percent of the hippocampus), the absolute number is in the millions. So the loss of any one cell should not have a noticeable effect on memory or mental acuity, said Peter N. Steinmetz, a research neurologist at the Dignity Health Barrow Neurological Institute in Phoenix and senior author of the study. “The significance of losing one cell is substantially reduced because you’ve got this whole population that’s turning on” when you access a memory, he said. The findings also suggest that memory researchers “need to use techniques that allow us to look at the whole population of neurons” rather than focus on individual cells. The patients in the study, which is published in Proceedings of the National Academy of Sciences, first memorized a list of words on a computer screen, then viewed a second list that included those words and others. When asked to identify words they had seen earlier, the patients displayed cell-firing activity consistent with the distributed model of memory. © 2014 The New York Times Company
Keyword: Learning & Memory
Link ID: 19763 - Posted: 06.24.2014
by Lauren Hitchings Our brain's ability to rapidly interpret and analyse new information may lie in the musical hum of our brainwaves. We continuously take in information about the world but establishing new neural connections and pathways – the process thought to underlie memory formation – is too slow to account for our ability to learn rapidly. Evan Antzoulatos and Earl Miller at the Massachusetts Institute of Technology decided to see if brainwaves – the surges of electricity produced by individual neurons firing en masse – play a role. They used EEG to observe patterns of electrical activity in the brains of monkeys as they taught the animals to categorise patterns of dots into two distinct groups. At first, they memorised which dots went where, but as the task became harder, they shifted to learning the rules that defined the categories. Humming brainwaves The researchers found that, initially, brainwaves of different frequencies were being produced independently by the prefrontal cortex and the striatum – two brain regions involved in learning. But as the monkeys made sense of the game, the waves began to synchronise and "hum" at the same frequency – with each category of dots having its own frequency. Miller says the synchronised brainwaves indicate the formation of a communication circuit between the two brain regions. He believes this happens before anatomical changes in brain connections take place, giving our minds time to think through various options when presented with new information before the right one gets laid down as a memory. Otherwise, the process is too time-consuming to account for the flexibility and speed of the human mind, says Miller. © Copyright Reed Business Information Ltd.
Keyword: Learning & Memory
Link ID: 19746 - Posted: 06.19.2014
by Bethany Brookshire When a cartoon character gets an idea, you know it. A lightbulb goes on over Wile E. Coyote’s head, or a ding sounds as Goofy puts two and two together. While the lightbulb and sound effects are the stuff of cartoons, scientists can, in a way, watch learning in action. In a new study, a learning task in rats was linked to increases in activity patterns in groups of brain cells. The results might help scientists pin down what learning looks like at the nerve cell level, and give us a clue about how memories are made. Different areas of the brain communicate with each other, transferring information from one area to another for processing and interpretation. Brain cell meets brain cell at connections called synapses. But to transfer information between areas often takes more than one neuron firing a lonely signal. It takes cortical oscillations — networks of brain cells sending electrical signals in concert — over and over again for a message to transmit from one brain area to another. Changes in electrical fields increase the probability that neurons in a population will fire. These cortical oscillations are like a large crowd chanting. Not all voices may be yelling at once, some people may be ahead or behind, some may even be whispering, but you still hear an overwhelming “USA! USA!” Cortical oscillations can occur within a single brain area, or they can extend from one area to another. “The oscillation tells you what the other brain area is likely to ‘see’ when it gets that input,” explains Leslie Kay, a neuroscientist at the University of Chicago. Once the receiving area ‘sees’ the incoming oscillation, it may synchronize its own population firing, joining in the chant. “A synchronized pattern of oscillations in two separate brain regions serves to communicate between the two regions,” says Kei Igarashi, a neuroscientist at the Norwegian University of Science and Technology in Trondheim. © Society for Science & the Public 2000 - 2013
Keyword: Learning & Memory
Link ID: 19742 - Posted: 06.17.2014
Virginia Morell Teaching isn’t often seen in animals other than humans—and it’s even more difficult to demonstrate in animals living in the wild rather than in a laboratory setting. But researchers studying the Australian superb fairy-wren (Malurus cyaneus) in the wild think the small songbirds (a male is shown in the photo above) practice the behavior. They regard a female fairy-wren sitting on her nest and incubating her eggs as the teacher, and her embryonic chicks as her pupils. She must teach her unhatched chicks a password—a call they will use after emerging to solicit food from their parents; the better they learn the password, the more they will be fed. Since 1992, there’s been a well-accepted definition of teaching that consists of three criteria. First, the teacher must modify his or her behavior in the presence of a naive individual—which the birds do; the mothers increase their teaching (that is, the rate at which they make the call) when their chicks are in a late stage of incubation. Second, there must be a benefit to the pupil, which there clearly is. Scientists reported online yesterday in Behavioral Ecology that the fairy-wrens also pass the third criteria: There must be a cost to the teacher. And for the small birds, there can be a hefty price to pay. The more often a female repeats the password, the more likely she is to attract a parasitical cuckoo, which will sneak in and lay its eggs in her nest. From careful field observations, the scientists discovered that at nests that were parasitized, the females had recited their password 20 times an hour. But at nests that were not parasitized, the females had called only 10 times per hour. Superb fairy-wrens thus join a short but growing list of animal-teachers, such as rock ants, meerkats, and pied babblers. © 2014 American Association for the Advancement of Science.
by Ashley Yeager Being put under anesthesia as an infant may make it harder for a person to recall details or events when they grow older. Previous studies on animals had shown that anesthesia impairs parts of the brain that help with recollection. But it was not clear how this type of temporary loss of consciousness affected humans. Comparing the memory of 28 children ages 6 to 11 who had undergone anesthesia as infants to 28 children similar in age who had not been put under suggests that the early treatment impairs recollection later in life, researchers report June 9 in Neuropsychopharmacology. The team reported similar results for a small study on rats and notes that early anesthesia did not appear to affect the children's familiarity with objects and events or their IQ. © Society for Science & the Public 2000 - 2013.