Chapter 17. Learning and Memory

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Diana Kwon There are approximately 5.6 million people over the age of 65 living with Alzheimer’s disease in the United States. With the population aging, that number is projected to grow to 7.1 million by 2025. Researchers know that age, a family history of the disease, and carrying a genetic variant known as APOE4 are all associated with a higher chance of developing the condition. But the biological mechanisms leading to Alzheimer’s are still largely a mystery. Over the last decade, scientists have amassed evidence for a hypothesis that, prior to developing full-blown Alzheimer’s disease, patients experience a period of hyperactivity and hyperconnectivity in the brain. Several functional magnetic resonance imaging studies have reported that people with mild cognitive impairment (MCI), a condition that often precedes Alzheimer’s, appear to have higher brain activity levels than their age-matched counterparts. Researchers have also found signs of such changes in healthy people carrying the APOE4 allele, as well as in presymptomatic stages of Alzheimer’s in rodent models of the disease. Krishna Singh, a physicist and imaging neuroscientist at the Cardiff University Brain Research Imaging Center (CUBRIC) in the UK, and his colleagues wanted to investigate this theory further. Previous studies of brain activity in young APOE4 carriers were mostly conducted using small sample sizes, according to Singh. But by the mid-2010s, his team had access to neuroimaging data from close to 200 participants studied at CUBRIC as part of an effort to build a massive dataset of healthy brains. So the researchers decided to use the data to search for signs of unusual brain activity and connectivity in people with the APOE4 allele. © 1986–2019 The Scientist

Keyword: Alzheimers
Link ID: 26709 - Posted: 10.16.2019

Angela Saini How should we remember historical figures who we know have done terrible things? It’s a dilemma we face more often, as universities and public institutions critically examine their histories, reassessing the past with 21st-century eyes. And over the last year, University College London has been in the midst of a historical inquiry into its role as the institutional birthplace of eugenics – the debunked “science” that claimed that by selectively breeding humans we could improve racial quality. We tend to associate eugenics with Nazi Germany and the Holocaust, but it was in fact developed in London. Its founder was Francis Galton, who established a laboratory at UCL in 1904. Already, some students and staff have called on the university to rename its Galton lecture theatre. Galton’s seductive promise was of a bold new world filled only with beautiful, intelligent, productive people. The scientists in its thrall claimed this could be achieved by controlling reproduction, policing borders to prevent certain types of immigrants, and locking away “undesirables”, including disabled people. University College London is investigating its role as the birthplace of eugenics. In hindsight, it’s easy to say that only a moral abyss could have given rise to such a pseudo-scientific plan, not least because we have borne witness to its horrifying consequences through the 20th century, when it was used to justify genocide and mass sterilisations. And by the standards of today, Galton does resemble a monster. He was a brilliant statistician but also a racist (not just my assessment, but that of Veronica van Heyningen, the current president of the Galton Institute). He was obsessed with human difference, and determined to remove from British society those he considered inferior. © 2019 Guardian News & Media Limited

Keyword: Genes & Behavior; Intelligence
Link ID: 26683 - Posted: 10.09.2019

By Kelly Servick WASHINGTON, D.C. —Sending a mouse through a maze can tell you a lot about how its little brain learns. But what if you could change the size and structure of its brain at will to study what makes different behaviors possible? That’s what Elan Barenholtz and William Hahn are proposing. The cognitive psychologist and computer scientist, both at Florida Atlantic University in Boca Raton, are running versions of classic psychology experiments on robots equipped with artificial intelligence. Their laptop-size robotic rovers can move and sense the environment through a camera. And they’re guided by computers running neural networks–models that bear some resemblance to the human brain. Barenholtz presented this “robopsychology” approach here last week at the American Psychological Association’s Technology Mind & Society Conference. He and Hahn told Science how they’re using their unusual new test subjects. The interview has been edited for clarity and length. Q: Why put neural networks in robots instead of just studying them on a computer? Elan Barenholtz: There are a number of groups trying to build models to simulate certain functions of the brain. But they’re not making a robot walk around and recognize stuff and carry out complex cognitive functions. William Hahn: What we want is the organism itself to guide its own behavior and get rewards. One way to think about it would be to try to build the simplest possible models. What is the minimum complexity you need to put in one of these agents so that it acts like a squirrel or it acts like a cat? © 2019 American Association for the Advancement of Science

Keyword: Learning & Memory; Robotics
Link ID: 26681 - Posted: 10.08.2019

By Laura Sanders A sleeping rat may look peaceful. But inside its furry, still head, a war is raging. Two types of brain waves battle over whether the rat will remember new information, or forget it, researchers report October 3 in Cell. Details of this previously hidden clash may ultimately help explain how some memories get etched into the sleeping brain, while others are scrubbed clean. By distinguishing between these dueling brain waves, the new study helps reconcile some seemingly contradictory ideas, including how memories can be strengthened (SN: 6/5/14) and weakened during the same stage of sleep (SN: 6/23/11). “It will help unite the field of sleep and learning, because everyone gets to be right,” says neuroscientist Gina Poe of the University of California, Los Angeles, who wasn’t involved in the study. Researchers led by neuroscientist and neurologist Karunesh Ganguly of the University of California, San Francisco, have been teaching rats to control a mechanical water spout with nothing but their neural activity. The team soon realized that the rats’ success with these brain-computer interfaces depended heavily on something that came after the training: sleep. To study how the new learning was strengthened during snoozing, Ganguly and his team monitored the brains of sleeping rats after they practiced moving the spout. The scientists focused on brain waves that wash over the motor cortex, the part of the brain that was controlling the external water spout, during non-REM sleep. That stage of sleep usually makes up more than half of an adult human’s night. © Society for Science & the Public 2000–2019.

Keyword: Sleep; Learning & Memory
Link ID: 26672 - Posted: 10.04.2019

By Kelly Servick The brain has a way of repurposing unused real estate. When a sense like sight is missing, corresponding brain regions can adapt to process new input, including sound or touch. Now, a study of blind people who use echolocation—making clicks with their mouths to judge the location of objects when sound bounces back—reveals a degree of neural repurposing never before documented. The research shows that a brain area normally devoted to the earliest stages of visual processing can use the same organizing principles to interpret echoes as it would to interpret signals from the eye. In sighted people, messages from the retina are relayed to a region at the back of the brain called the primary visual cortex. We know the layout of this brain region corresponds to the layout of physical space around us: Points that are next to each other in our environment project onto neighboring points on the retina and activate neighboring points in the primary visual cortex. In the new study, researchers wanted to know whether blind echolocators used this same type of spatial mapping in the primary visual cortex to process echoes. The researchers asked blind and sighted people to listen to recordings of a clicking sound bouncing off an object placed at different locations in a room while they lay in a functional magnetic resonance imaging scanner. The researchers found that expert echolocators—unlike sighted people and blind people who don’t use echolocation—showed activation in the primary visual cortex similar to that of sighted people looking at visual stimuli. © 2019 American Association for the Advancement of Science.

Keyword: Hearing; Learning & Memory
Link ID: 26663 - Posted: 10.02.2019

By Knvul Sheikh One afternoon in April 1929, a journalist from a Moscow newspaper turned up in Alexander Luria’s office with an unusual problem: He never forgot things. Dr. Luria, a neuropsychologist, proceeded to test the man, who later became known as subject S., by spouting long strings of numbers and words, foreign poems and scientific formulas, all of which S. recited back without fail. Decades later, S. still remembered the lists of numbers perfectly whenever Dr. Luria retested him. But S.’s ability to remember was also a hindrance in everyday life. He had a hard time understanding abstract concepts or figurative language, and he was terrible at recognizing faces because he had memorized them at an exact point in time, with specific facial expressions and features. The ability to forget, scientists eventually came to realize, was just as vital as the ability to remember. “We’re inundated with so much information every day, and much of that information is turned into memories in the brain,” said Ronald Davis, a neurobiologist at the Scripps Research Institute in Jupiter, Fla. “We simply cannot deal with all of it.” Researchers like Dr. Davis argue that forgetting is an active mechanism that the brain employs to clear out unnecessary pieces of information so we can retain new ones. Others have gone a step further, suggesting that forgetting is required for the mental flexibility inherent in creative thinking and imagination. A new paper, published Thursday in the journal Science, points to a group of neurons in the brain that may be responsible for helping the brain to forget. Akihiro Yamanaka, a neuroscientist at Nagoya University in Japan, and his team stumbled across the cells, known as melanin-concentrating hormone, or M.C.H., neurons, while studying sleep regulation in mice. Unlike most of the brain’s neurons, which are active when animals are awake, M.C.H. neurons in the hypothalamus start firing electrical signals most actively when a sleeping animal is in a stage called R.E.M. sleep. This phase of sleep is characterized by rapid eye movement, an elevated pulse, unique brain waves and, in humans, vivid dreams. When the researchers tracked M.C.H. signals in mice, they found that the cells were suppressing neurons in the hippocampus, a brain region known to play a role in the consolidation of memory. © 2019 The New York Times Company

Keyword: Sleep; Learning & Memory
Link ID: 26628 - Posted: 09.20.2019

By Jane E. Brody Late one morning in June, L.J.’s husband got a distressed call from one of his wife’s colleagues. “You’d better come here right away. Your wife is acting weird,” the colleague said. Ms. J., who had just returned from a doctor visit during which she underwent a minor painful procedure, kept asking her colleague for a password despite being told each time that there was none. Ms. J., a 61-year-old arts administrator in New York who did not want her full name used, seemed physically O.K., her colleague recalled. She knew who she was, she walked and talked properly, but what she said made no sense. Plus, Ms. J. could remember nothing that happened after she left the doctor’s office and made her way to work. When Ms. J. continued to behave oddly, the alarmed colleague called 911 and paramedics took her to Mount Sinai St. Luke’s Hospital. The next thing Ms. J. remembers is waking up hours later in a hospital bed and asking, “Where am I? Why am I here?” In the interim, Dr. Carolyn Brockington, a vascular surgeon and director of the hospital’s stroke unit, had examined her and ordered a CT scan and M.R.I. of her brain. All the results were normal. There was no physical weakness, no structural abnormality, no evidence of a stroke, seizure or transient ischemic attack. So, what had happened? A diagnosis of exclusion: Transient global amnesia, often called T.G.A. It is a temporary lapse in memory that can never be retrieved. “It’s as if the brain is on overload and takes a break to recharge,” Dr. Brockington said in an interview. She likened it to rebooting a computer to eradicate an unexplainable glitch. Those with T.G.A. do not experience any alteration in consciousness or abnormal movements. Only the ability to lay down memories is affected. All other parts of the brain appear to be working normally. © 2019 The New York Times Company

Keyword: Learning & Memory; Stroke
Link ID: 26616 - Posted: 09.16.2019

By Lateshia Beachum A Tokyo-based cashier allegedly stole credit card information from 1,300 customers. According to police, he used only his brain to take the information. Yusuke Taniguchi, 34, was arrested Thursday when police said they discovered he used the stolen information to purchase bags worth an estimated $2,600 in March, according to CNN. The police intercepted that order and delivered Taniguchi’s bags themselves to catch the alleged thief, according to Vice. People close to the investigation have told news media that Taniguchi has a “photographic memory.” Police say the part-time cashier retained customer credit card information in the short amount of time it took for them to purchase their goods, according to SoraNews24. He remembered all the details until he was able to write down the information, which he would later use to shop online, police said. But science doesn’t really back the claims of his photographic memory. Scientists have not found evidence of photographic memories, but there are people with very good memories who can recall information in astounding detail — an eidetic memory — according to Daniel Burns, a professor of psychology at Union College in New York. Most people conflate having an eidetic memory with a photographic memory, but scientists who study memory draw a hard line between the two, he said. A person with an eidetic memory is able to recall an image in great detail after seeing it once, with the ability to remember the image up to four minutes. But the eidetic image is not identical even though it has many perceptual similarities, according to Burns. Furthermore, eidetic memory is most commonly found in children between the ages of 6 and 12, and it’s hardly ever found in adults, according to research. “In our mind, a ‘photographic memory’ is being able to look at something and days later call up a picture that’s identical to the actual image,” he said. “That doesn’t seem to exist.” © 1996-2019 The Washington Post

Keyword: Learning & Memory
Link ID: 26613 - Posted: 09.15.2019

Ed Yong Annika Reinhold says that she likes playing with animals (she has two cats) and “doing unconventional things that no one has done before.” When the chance came up to teach rats to play hide-and-seek, she was a natural candidate. One might question the wisdom of training rats to hide, but there’s a good reason to do so. In neuroscience, animal research is traditionally about control and conditioning—training animals, in carefully regulated settings, to do specific tasks using food rewards. But those techniques aren’t very useful for studying the neuroscience of play, which is universal to humans, widespread among animals, and the antithesis of control and conditioning. Playing is about freedom and fun. How do you duplicate those qualities in a lab? After watching YouTube videos of pets and their owners, Michael Brecht, a neuroscientist at the Humboldt University of Berlin, came up with the idea of using hide-and-seek. Reinhold, a master’s student in his lab, jumped at the chance. She knew that rats are social, intelligent, and playful, and will chase, roughhouse, and wrestle with one another, much like human children do. Perhaps they’d play with her. “I was optimistic enough to try it,” she says. She began by getting six adolescent rats accustomed to a 300-square-foot room fitted with boxes and barriers behind which they (or Reinhold) could hide. She also habituated the animals to her by stroking them, chasing them with her hands, and tickling them.

Keyword: Learning & Memory; Development of the Brain
Link ID: 26610 - Posted: 09.13.2019

Cristina Robinson, Kate Snyder, Nicole Creanza Bonjour! Ni hao! Merhaba! If you move to a new country as an adult, you have to work much harder to get past that initial “hello” in the local language than if you’d moved as a child. Why does it take so much effort to learn a new language later in life? Our human ability to learn language slows down as we get older, but scientists are not sure how or why this happens. An unexpected way to understand this learning process might come from listening to birds sing. After all, songbirds have a lot to learn. They don’t hatch knowing what songs to sing, or how to sing them. Instead, they must learn their species’ song. Young birds listen to adult birds and then practice copying the adult’s song syllables until they sound right. If they fail to learn an appropriate song, male birds will have difficulty attracting mates or defending their territories. How do birds learn to sing? This process of vocal learning is remarkably similar to how humans learn language: Babies listen to their parents speaking and then practice making the same sounds by babbling. Because these processes are so similar, birds have long been used to study vocal learning. However, while these learning processes are similar, the functions of speech and song are quite different. Human speech is complex and made up of many sounds that we use to convey an infinite number of ideas to each other. Birds only need to announce their presence to mates and rivals, yet their song can also be made of a repertoire of hundreds or thousands of unique syllables. What benefit could these more elaborate songs offer males? © 2010–2019, The Conversation US, Inc.

Keyword: Animal Communication; Language
Link ID: 26570 - Posted: 09.04.2019

By Laura Sanders A honeybee that’s been promoted to forager has upgrades in her nerve cells, too. Vibration-sensing nerve cells, or neurons, are more specialized in bees tasked with finding food compared with younger, inexperienced adult bees, researchers report August 26 in eNeuro. This neural refinement may help forager bees better sense specific air vibrations produced by their fellow foragers during waggle dances — elaborate routines that share information about food location, distance and quality (SN Online: 1/24/14). Researchers compared certain neurons in adult bees that had emerged from their cells one to three days earlier to neurons of forager bees, which were older than 10 days. In the foragers, these neurons had more refined shapes, the team found. These vibration-detecting cells, called DL-INT-1 neurons, appear sparser in certain areas, with fewer message-receiving tendrils called dendrites. Refined dendrites may be a sign that these cells are more selective in their connections. And in foragers, these neurons also appear to handle information more efficiently than their counterparts in the young adult bees, experiments with electrodes reveal. These changes in shape and behavior suggest that in foragers, neurons become adept at decoding vibrations produced by other foragers’ waggle dances, say computational neuroscientist Ajayrama Kumaraswamy of the Ludwig-Maximilians-Universität München in Germany and colleagues. But it’s not clear whether foraging experience in the fields or the passage of time itself prompts these refinements. © Society for Science & the Public 2000–2019

Keyword: Learning & Memory; Animal Communication
Link ID: 26543 - Posted: 08.27.2019

By Michael Price First piloted as an experiment to reduce dental cavities in Grand Rapids, Michigan, in 1945, fluoridated drinking water has since been hailed by the U.S. Centers for Disease Control and Prevention in Atlanta as “one of public health’s greatest success stories.” Today, about two-thirds of people in the United States receive fluoridated tap water, as do many people in Australia, Brazil, Canada, New Zealand, Spain, and the United Kingdom. Now, a controversial new study links fluoridation to lower IQ in young children, especially boys whose mothers drank fluoridated water while pregnant. Longtime fluoridation critics are lauding the study, but other researchers say it suffers from numerous flaws that undercut its credibility. Either way, “It’s a potential bombshell,” says Philippe Grandjean, an environmental health researcher at Harvard University who wasn’t involved in the work. Fluoride is well-known for protecting teeth against cavities by strengthening tooth enamel. It’s found naturally in low concentrations in both freshwater and seawater, as well as in plant material, especially tea leaves. Throughout the 1940s and ’50s, public health researchers and government officials in cities around the world experimentally added fluoride to public drinking water; they found it reduced the prevalence of cavities by about 60%. Today, fluoridated water flows through the taps of about 5% of the world’s population, including 66% of Americans and 38% of Canadians. Yet skepticism has dogged the practice for as long as it has existed. Some have blamed fluoridated water for a wide range of illnesses including cancer, but most criticism has been dismissed as pseudoscience. Over the years, though, a small number of scientists have published meta-analyses casting doubt on the efficacy of water fluoridation in preventing cavities. More recently, scientists have published small-scale studies that appear to link prenatal fluoride exposure to lower IQ, although dental research groups were quick to challenge them. © 2019 American Association for the Advancement of Science.

Keyword: Development of the Brain; Intelligence
Link ID: 26516 - Posted: 08.19.2019

Ashley Yeager Drops of blood, filter paper, bacteria, a bacterial inhibitor, and a baking dish—that’s all it took for microbiologist Robert Guthrie to develop a basic test for phenylketonuria, a genetic metabolic disease that, if left untreated in infants, soon leads to neurological dysfunction and intellectual disability. The test would lay the foundation for screening newborns for diseases. In 1957, Guthrie met Robert Warner, a specialist who diagnosed individuals with mental disabilities. Warner told Guthrie about phenylketonuria (PKU), now known to affect roughly 1 in 10,000 children. The disease makes it impossible to break down the amino acid phenylalanine, so that it builds up to toxic levels in the body and disrupts neuronal communication. Once a child was diagnosed, a strict low-phenylalanine diet could prevent further damage, but Warner had no easy way to measure phenylalanine levels in his PKU patients’ blood to monitor the diet’s effects. He asked Guthrie for help. Guthrie reported back to Warner three days later with a solution. Guthrie knew from past work that the bacterial inhibitor β-2-thienylalanine blocked Bacillus subtilis from flourishing by substituting for phenylalanine in growing peptide chains, resulting in inactive proteins. He also knew that adding phenylalanine to the cell cultures restored normal protein function and spurred the bacterium’s growth. So his solution was simple: prick the skin, collect a few drops of blood on filter paper, and place the filter paper in a baking pan covered in β-2-thienylalanine. Add Bacillus subtilis to the filter paper and heat the pan overnight. If the bacterium grows exponentially, the level of phenylalanine is high. The assay worked well, so Guthrie used it as a model to develop tests for other metabolic diseases. © 1986–2019 The Scientist

Keyword: Development of the Brain; Genes & Behavior
Link ID: 26515 - Posted: 08.19.2019

Laura Sanders Seconds before a memory pops up, certain nerve cells jolt into collective action. The discovery of this signal, described in the Aug. 16 Science, sheds light on the mysterious brain processes that store and recall information. Electrodes implanted in the brains of epilepsy patients picked up neural signals in the hippocampus, a key memory center, while the patients were shown images of familiar people and places, including former President Barack Obama and the Eiffel Tower in Paris. As the participants took in this new information, electrodes detected a kind of brain activity called sharp-wave ripples, created by the coordinated activity of many nerve cells in the hippocampus. Later blindfolded, the patients were asked to remember the pictures. One to two seconds before the participants began describing each picture, researchers noticed an uptick in sharp-wave ripples, echoing the ripples detected when the subjects had first seen the images. That echo suggests that these ripples are important for learning new information and for recalling it later, Yitzhak Norman of the Weizmann Institute of Science in Rehovot, Israel, and colleagues write in the study. Earlier studies suggested that these ripples in the hippocampus were important for forming memories. But it wasn’t clear if the ripples also had a role in bringing memories to mind. In another recent study, scientists also linked synchronized ripples in two parts of the brain to better memories of word pairs (SN Online: 3/5/19). |© Society for Science & the Public 2000 - 2019

Keyword: Learning & Memory
Link ID: 26512 - Posted: 08.19.2019

By Brooke N. Dulka As you read this article, your brain has begun a series of complicated chemical steps in order to form a memory. How long you keep this memory may well depend on whether you are a man or a woman. Some scientists think that the reason for this difference may be estrogens. Women are disproportionately affected by Alzheimer’s disease, dementia and memory loss. In fact, almost two thirds of Americans living with Alzheimer’s are women. While researchers across the globe are still working to uncover the basic mechanisms of learning and memory, it is now known that estrogens help to regulate memory formation in both males and females. From a cultural and societal standpoint, when people think of estrogen they probably imagine pregnancy, periods and woman-fueled rage. Most people probably don’t consider memory; but maybe it’s time we all start thinking about estrogens’ role in memory a little more. Karyn Frick, a professor of psychology at the University of Wisconsin-Milwaukee, studies the connection between estrogens and memory. She and her students are among the scientists working to uncover the basic cellular and molecular mechanisms underlying memory formation. Part of Frick’s research focuses on how estrogens enhance memory, particularly through their action in the hippocampus. © 2019 Scientific American

Keyword: Hormones & Behavior; Learning & Memory
Link ID: 26470 - Posted: 07.31.2019

By Jocelyn Kaiser U.S. scientists who challenged a new rule that would require them to register their basic studies of the human brain and behavior in a federal database of clinical trials have won another reprieve. The National Institutes of Health (NIH) in Bethesda, Maryland, says it now understands why some of that kind of research won’t easily fit the format of ClinicalTrials.gov, and the agency has delayed for the reporting requirements for another 2 years. The controversy dates back to 2017, when behavioral and cognitive researchers realized that new requirements for registering and reporting results from NIH-funded clinical studies would also cover even basic studies of human subjects, experiments that did not test drugs or other potential treatments. The scientists protested that including such studies would confuse the public and create burdensome, unnecessary paperwork. A year ago, NIH announced it would delay the requirement until September and seek further input. The responses prompted NIH staff to examine published papers from scientists conducting basic research. They agreed it would be hard to include some of these studies into the rigid informational format used by ClinicalTrials.gov—for example, because the authors didn’t specify the outcome they expected before the study began, or they reported results for individuals and not the whole group. In other cases, the authors did several preliminary studies to help them design their experiment. © 2019 American Association for the Advancement of Science

Keyword: Attention; Learning & Memory
Link ID: 26450 - Posted: 07.25.2019

By Gretchen Reynolds Weight training may have benefits for brain health, at least in rats. When rats lift weights, they gain strength and also change the cellular environment inside their brains, improving their ability to think, according to a notable new study of resistance training, rodents and the workings of their minds. The study finds that weight training, accomplished in rodents with ladders and tiny, taped-on weights, can reduce or even reverse aspects of age-related memory loss. The finding may have important brain-health implications for those of us who are not literal gym rats. Most of us discover in middle age, to our chagrin, that brains change with age and thinking skills dip. Familiar names, words and the current location of our house keys begin to elude us. But a wealth of helpful past research indicates that regular aerobic exercise, such as walking or jogging, can prop up memory and cognition. In these studies, which have involved people and animals, aerobic exercise generally increases the number of new neurons created in the brain’s memory center and also reduces inflammation. Unchecked, inflammation in the brain may contribute to the development of dementia and other neurodegenerative conditions. Far less has been known, though, about whether and how resistance training affects the brain. A few studies with older people have linked weight training to improved cognition, but the studies have been small and the linkages tenuous. While researchers know that lifting weights builds muscle, it is not yet clear how, at a molecular level, it would affect the cells and functions of the brain. © 2019 The New York Times Company

Keyword: Learning & Memory; Neurogenesis
Link ID: 26447 - Posted: 07.24.2019

Katarina Zimmer About two years ago, 29 people visited a neuroscience lab in the Netherlands to sing karaoke. Wearing muffled headphones so they could hear the music but not their own voices, it was almost inevitable that they would sing “Silent Night” or the Dutch national anthem out of tune. Dutch researchers recorded each individual sing, then played the recording back to him or her. Listening to themselves sing solo evoked feelings of shame and embarrassment and sparked higher-than-normal activity in the subjects’ amygdalae. Fortunately for some study participants, a good night’s sleep was enough to lessen the amygdala’s response when they listened to the recording again the next day. But others who had experienced restless sleep—specifically poor-quality REM, or rapid eye movement, sleep—experienced the opposite: their amygdalae were just as sensitive, if not more, to the recording the next day. The findings suggest that poor-quality REM sleep can interfere with the amygdala’s ability to process emotional memories overnight, the scientists who conducted the study say. They posit that this has implications for people with psychological disorders linked to disturbed REM sleep patterns, such as depression, anxiety, and post-traumatic stress disorder (PTSD). The research appears today (July 11) in Current Biology. © 1986–2019 The Scientist.

Keyword: Sleep; Learning & Memory
Link ID: 26414 - Posted: 07.13.2019

By Bret Stetka The hippocampus is a small curl of brain, which nests beneath each temple. It plays a crucial role in memory formation, taking our experiences and interactions and setting them in the proverbial stone by creating new connections among neurons. A report published on June 27in Science reveals how the hippocampus learns and hard wires certain experiences into memory. The authors show that following a particular behavior, the hippocampus replays that behavior repeatedly until it is internalized. They also report on how the hippocampus tracks our brain’s decision-making centers to remember our past choices. Previous research has shown that the rodent hippocampus replays or revisits past experiences during sleep or periods of rest. While a rat navigates a maze, for example, so-called place cells are activated and help the animal track its position. Following their journey through the maze, those same cells are reactivated in the exact same pattern. What previously happened is mentally replayed again. The authors of the new study were curious whether this phenomenon only applies to previous encounters with a particular location or if perhaps this hippocampal replay also applies to memory more generally, including mental and nonspatial memories. It turns out it does. In the study, 33 participants were presented with a series of images containing both a face and a house. They had to judge the age of either one or the other. If during the second trial, the age of the selected option remained the same, the judged category also did not change in the subsequent trial. If the ages differed, the judged category flipped to the other option in the next round. © 2019 Scientific American

Keyword: Attention; Learning & Memory
Link ID: 26367 - Posted: 06.28.2019

By Simon Makin Better Memory through Electrical Brain Ripples Hippocampus Neuron, computer illustration Credit: Kateryna Kon Getty Images Specific patterns of brain activity are thought to underlie specific processes or computations important for various mental faculties, such as memory. One such “brain signal” that has received a lot of attention recently is known as a “sharp wave ripple”—a short, wave-shaped burst of high-frequency oscillations. Researchers originally identified ripples in the hippocampus, a region crucially involved in memory and navigation, as central to diverting recollections to long-term memory during sleep. Then a 2012 study by neuroscientists at the University of California, San Francisco, led by Loren Frank and Shantanu Jadhav, the latter now at Brandeis University, showed that the ripples also play a role in memory while awake. The researchers used electrical pulses to disrupt ripples in rodents’ brains, and showed that, by doing so, performance in a memory task was reduced. However, nobody had manipulated ripples to enhance memory—until now, that is. Researchers at NYU School of Medicine led by neuroscientist György Buzsáki have now done exactly that. In a June 14 study in Science, the team showed that prolonging sharp wave ripples in the hippocampus of rats significantly improved their performance in a maze task that taxes working memory—the brain’s “scratch pad” for combining and manipulating information on the fly. “This is a very novel and impactful study,” says Jadhav, who was not involved in the research. “It’s very hard to do ‘gain-of-function’ studies with physiological processes in such a precise way.” As well as revealing new details about how ripples contribute to specific memory processes, the work could ultimately have implications for efforts to develop interventions for disorders of memory and learning. © 2019 Scientific American

Keyword: Learning & Memory
Link ID: 26330 - Posted: 06.15.2019