Chapter 17. Learning and Memory

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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

Nell Greenfieldboyce At the Marine Biological Laboratory in Woods Hole, Mass., there's a room filled with burbling aquariums. A lot of them have lids weighed down with big rocks. "Octopuses are notorious for being able to, kind of, escape out of their enclosures," says Bret Grasse, whose official title at MBL is "manager of cephalopod operations" — cephalopods being squid, cuttlefish and octopuses. He's part of a team that's trying to figure out the best ways to raise these sea creatures in captivity, so that scientists can investigate their genes and learn the secrets of their strange, almost alien ways. For decades, much of the basic research in biology has focused on just a few, well-studied model organisms like mice, fruit flies, worms and zebrafish. That's because these critters are easy to keep in the laboratory, and scientists have worked out how to routinely alter their genes, leading to all kinds of insights into behavior, diseases and possible treatments. "With these organisms, you could understand what genes did by manipulating them," says Josh Rosenthal, another biologist at MBL. "And that really became an indispensable part of biology." But it's also meant that basic biology has ignored much of the animal kingdom, especially its more exotic denizens. "We're really missing out on, I would say, the diversity of biology's solutions to problems," Rosenthal notes. © 2019 npr

Keyword: Learning & Memory; Evolution
Link ID: 26295 - Posted: 06.04.2019

By Kenneth Miller A model of Ben Barres’ brain sits on the windowsill behind his desk at Stanford University School of Medicine. To a casual observer, there’s nothing remarkable about the plastic lump, 3-D-printed from an MRI scan. Almost lost in the jumble of papers, coffee mugs, plaques and trophies that fill the neurobiologist’s office, it offers no hint about what Barres’ actual gray matter has helped to accomplish: a transformation of our understanding of brains in general, and how they can go wrong. Barres is a pioneer in the study of glia. This class of cells makes up 90 percent of the human brain, but gets far less attention than neurons, the nerve cells that transmit our thoughts and sensations at lightning speed. Glia were long regarded mainly as a maintenance crew, performing such unglamorous tasks as ferrying nutrients and mopping up waste, and occasionally mounting a defense when the brain faced injury or infection. Over the past two decades, however, Barres’ research has revealed that they actually play central roles in sculpting the developing brain, and in guiding neurons’ behavior at every stage of life. “He has made one shocking, revolutionary discovery after another,” says biologist Martin Raff, emeritus professor at University College London, whose own work helped pave the way for those advances. Recently, Barres and his collaborators have made some discoveries that may revolutionize the treatment of neurodegenerative ailments, from glaucoma and multiple sclerosis to Alzheimer’s disease and stroke. What drives such disorders, their findings suggest, is a process in which glia turn from nurturing neurons to destroying them. Human trials of a drug designed to block that change are just beginning.

Keyword: Glia; Learning & Memory
Link ID: 26258 - Posted: 05.22.2019

By Benedict Carey The research on brain stimulation is advancing so quickly, and the findings are so puzzling, that a reader might feel tempted to simply pre-order a genius cap from Amazon, to make sense of it all later. In just the past month, scientists reported enhancing the working memory of older people, using electric current passed through a skullcap, and restoring some cognitive function in a brain-damaged woman, using implanted electrodes. Most recently, the Food and Drug Administration approved a smartphone-size stimulator intended to alleviate attention-deficit problems by delivering electric current through a patch placed on the forehead. Last year, another group of scientists announced that they, too, had created a brain implant that boosts memory storage. All the while, a do-it-yourself subculture continues to grow, of people who are experimenting with placing electrodes in their skulls or foreheads for brain “tuning.” Predicting where all these efforts are headed, and how and when they might converge in a grand methodology, is an exercise in rank speculation. Neuro-stimulation covers too many different techniques, for various applications and of varying quality. About the only certainties are the usual ones: that a genius cap won’t arrive anytime soon, and that any brain-zapping gizmo that provides real benefit also is likely to come with risk. Nevertheless, the field is worth watching because it hints at some elementary properties of brain function. Unlike psychiatric drugs, or psychotherapy, pulses of current can change people’s behavior very quickly, and reliably. Turn the current on and things happen; turn it off and the effect stops or tapers. © 2019 The New York Times Company

Keyword: Learning & Memory; Alzheimers
Link ID: 26232 - Posted: 05.14.2019

By Cara Giaimo Here’s a pop quiz for you. Tom is taller than Dick. Dick is taller than Harry. Who’s taller, Harry or Tom? If you said Tom, congratulations! You just demonstrated what’s called “transitive inference” — the ability to compare things indirectly, based on previous juxtapositions. But before you pat yourself on the back too much, you should know that this skill was recently demonstrated by another creature: the humble paper wasp that might be living in your backyard right now. In the summer of 2017, researchers at the University of Michigan put two species of paper wasps through a transitive inference test. A statistically significant portion of the time, the wasps passed. Other animals — including rats, geese and cichlid fish — have also exhibited this capacity. But this study, which was published Tuesday in Biology Letters, is the first to successfully showcase it in an invertebrate (honeybees failed a similar test in 2004). Paper wasps are found on every continent except Antarctica. You might be near some right now. “They tend to nest in the eaves of houses, or inside barbecue grills,” said Elizabeth Tibbetts, the study’s lead author. In a previous study, Dr. Tibbetts showed that individual female wasps can identify one another by their distinct facial patterns, which resemble Rorschach ink blots. “When two wasps meet, they learn, ‘Oh, that’s what Suzy looks like,’” she said. “And the next time they meet, they remember who Suzy is.” In the spring, the females spend a lot of time brawling, getting in each other’s faces and trading slaps with their appendages. These matchups look like schoolyard tussles. “Some wasps will be fighting; some wasps will be watching the fights,” said Dr. Tibbetts. “It’s a very exciting time.” The wasps remember the winners and losers, and use them to establish a social hierarchy: the strongest reproduce, while the weaker ones do all the work. © 2019 The New York Times Company

Keyword: Evolution; Learning & Memory
Link ID: 26229 - Posted: 05.11.2019

By Dana G. Smith Training software that emulates brain networks to identify dog breeds or sports equipment is by now old news. But getting such an AI network to learn a process on its own that is innate to early child development is truly novel. In a paper published Wednesday in Science Advances, a neural network distinguished between different quantities of things, even though it was never taught what a number is. The neural net reprised a cognitive skill innate to human babies, monkeys and crows, among others. Without any training, it suddenly could tell the difference between larger and smaller amounts—a skill called numerosity, or number sense. Many believe number sense is an essential precursor to our ability to count and do more complex mathematics. But questions have persisted about how this ability spontaneously comes about in the young brain. To research its development, scientists from the University of Tübingen in Germany used a deep-learning system designed to mimic the human brain to see if numerosity would emerge without having to train the software. “We were trying to simulate the workings of the visual system of our brain by building a deep-learning network, an artificial neural network,” says Andreas Nieder, a professor in the Institute of Neurobiology at Tübingen and senior author on the new paper. “The big question was, how is it possible that our brain and the brain of animals can spontaneously represent the number of items in a visual scene?” © 2019 Scientific American

Keyword: Learning & Memory; Development of the Brain
Link ID: 26218 - Posted: 05.09.2019

By Veronique Greenwood You’re holed up with colleagues in a meeting room for two hours, hashing out a plan. Risks are weighed, decisions are made. Then, as you emerge, you realize it was much, much warmer and stuffier in there than in the rest of the office. Small rooms can build up heat and carbon dioxide from our breath — as well as other substances — to an extent that might surprise you. And as it happens, a small body of evidence suggests that when it comes to decision making, indoor air may matter more than we have realized. At least eight studies in the last seven years have looked at what happens specifically in a room accumulating carbon dioxide, a main ingredient in our exhalations. While the results are inconsistent, they are also intriguing. They suggest that while the kinds of air pollution known to cause cancer and asthma remain much more pressing as public health concerns, there may also be pollutants whose most detrimental effects are on the mind, rather than the body. So can you trust the decisions made in small rooms? How much does the quality of air indoors affect your cognitive abilities? And as our knowledge of indoor air’s effects grows, do we need to revise how we design and use our buildings? Buildings in the United States have grown better sealed in the last 50 years, helping reduce energy used in heating and cooling. That’s also made it easier for gasses and other substances released by humans and our belongings to build up inside. Although indoor air quality is not as well monitored as the air outdoors, scientists and ventilation professionals have extensively monitored carbon dioxide indoors. © 2019 The New York Times Company

Keyword: Learning & Memory
Link ID: 26216 - Posted: 05.07.2019

/ By Elizabeth Svoboda As he neared his 50s, Anthony Andrews realized that living inside his own head felt different than it used to. The signs were subtle at first. “My wife started noticing that I wasn’t getting through things,” Andrews says. Every so often, he’d experience what he calls “cognitive voids,” where he’d get dizzy and blank out for a few seconds. It wasn’t just that he would lose track of things, as if the thought bubble over his head had popped. Over time, Andrews’ issues became more pronounced. It wasn’t just that he would lose track of things, as if the thought bubble over his head had popped. A dense calm had descended on him like a weighted blanket. “I felt like I was walking through the swamp,” says Andrews, now 54. He had to play internet chess each morning to penetrate the mental murk. In 2016, Anthony Andrews and his wife Mona were told he likely had CTE, a neurodegenerative disorder caused by repeated head impacts. With his wife, Mona, by his side, Andrews went to doctor after doctor racking up psychiatric diagnoses. One told him he had ADHD. Another thought he was depressed, and another said he had bipolar disorder. But the drugs and therapies they prescribed didn’t seem to help. “After a month,” Andrews recalls of these treatments, “I knew it’s not for me.” Copyright 2019 Undark

Keyword: Learning & Memory; Brain Injury/Concussion
Link ID: 26215 - Posted: 05.07.2019

By Gretchen Reynolds A single, moderate workout may immediately change how our brains function and how well we recognize common names and similar information, according to a promising new study of exercise, memory and aging. The study adds to growing evidence that exercise can have rapid effects on brain function and also that these effects could accumulate and lead to long-term improvements in how our brains operate and we remember. Until recently, scientists thought that by adulthood, human brains were relatively fixed in their structure and function, especially compared to malleable tissues, like muscle, that continually grow and shrivel in direct response to how we live our lives. But multiple, newer experiments have shown that adult brains, in fact, can be quite plastic, rewiring and reshaping themselves in various ways, depending on our lifestyles. Exercise, for instance, is known to affect our brains. In animal experiments, exercise increases the production of neurochemicals and the numbers of newborn neurons in mature brains and improves the animals’ thinking abilities. Similarly, in people, studies show that regular exercise over time increases the volume of the hippocampus, a key part of the brain’s memory networks. It also improves many aspects of people’s thinking. But substantial questions remain about exercise and the brain, including the time course of any changes and whether they are short-term or, with continued training, become lasting. That particular issue intrigued scientists at the University of Maryland. They already had published a study in 2013 with older adults looking at the long-term effects of exercise on portions of the brain involved in semantic-memory processing. © 2019 The New York Times Company

Keyword: Learning & Memory
Link ID: 26199 - Posted: 05.02.2019

Yao-Hua Law When it comes to migration science, birds rule. Although many mammals — antelopes, whales, bats — migrate, too, scientists know far less about how those animals do it. But a new device, invented by animal navigation researcher Oliver Lindecke, could open a new way to test how far-ranging bats find their way. Lindecke, of Leibniz Institute for Zoo and Wildlife Research in Germany, has been studying bat migration since 2011. He started with analyzing different forms of hydrogen atoms in wild bats to infer where they had flown from. But figuring out how the bats knew where to go was trickier. Lindecke needed a field setup that let him test what possible cues from nature helped bats navigate across vast distances. The first step was studying in which direction the bats first take flight. Such experiments on birds typically involve confining the animals in small, enclosed spaces. But that doesn’t work for bats, which tend to fall asleep in such spaces. So he invented what he calls the circular release box: a flat-bottom, funnel-shaped container topped by a wider lid. To escape, the bat crawls up the wall and takes off from the edge. Bat tracks in a layer of chalk (Lindecke says he was inspired by a snow-covered Berlin street) indicate where the bat took off. In August 2017, Lindecke captured 54 soprano pipistrelle bats (Pipistrellus pygmaeus) in a large, 50-meter-wide trap at the Pape Ornithological Research Station in Latvia as the animals were migrating along the coast of the Baltic Sea toward Central Europe. Experiments with the new device showed that the adult bats flew straight in the direction in which they took off, Lindecke and colleagues report online March 1 in the Journal of Zoology. |© Society for Science & the Public 2000 - 2019

Keyword: Animal Migration
Link ID: 26159 - Posted: 04.20.2019

In a study of healthy volunteers, National Institutes of Health researchers found that our brains may solidify the memories of new skills we just practiced a few seconds earlier by taking a short rest. The results highlight the critically important role rest may play in learning. “Everyone thinks you need to ‘practice, practice, practice’ when learning something new. Instead, we found that resting, early and often, may be just as critical to learning as practice,” said Leonardo G. Cohen, M.D., Ph.D., senior investigator at NIH’s National Institute of Neurological Disorders and Stroke and a senior author of the paper published in the journal Current Biology. “Our ultimate hope is that the results of our experiments will help patients recover from the paralyzing effects caused by strokes and other neurological injuries by informing the strategies they use to ‘relearn’ lost skills.” The study was led by Marlene Bönstrup, M.D., a postdoctoral fellow in Dr. Cohen’s lab. Like many scientists, she held the general belief that our brains needed long periods of rest, such as a good night’s sleep, to strengthen the memories formed while practicing a newly learned skill. But after looking at brain waves recorded from healthy volunteers in learning and memory experiments at the NIH Clinical Center, she started to question the idea. The waves were recorded from right-handed volunteers with a highly sensitive scanning technique called magnetoencephalography. The subjects sat in a chair facing a computer screen and under a long cone-shaped brain scanning cap. The experiment began when they were shown a series of numbers on a screen and asked to type the numbers as many times as possible with their left hands for 10 seconds; take a 10 second break; and then repeat this trial cycle of alternating practice and rest 35 more times. This strategy is typically used to reduce any complications that could arise from fatigue or other factors.

Keyword: Learning & Memory; Brain imaging
Link ID: 26137 - Posted: 04.13.2019

By Gina Kolata Allan Gallup, a retired lawyer and businessman, grew increasingly forgetful in his last few years. Eventually, he could no longer remember how to use a computer or the television. Although he needed a catheter, he kept forgetting and pulling it out. It was Alzheimer’s disease, the doctors said. So after Mr. Gallup died in 2017 at age 87, his brain was sent to Washington University in St. Louis to be examined as part of a national study of the disease. But it wasn’t just Alzheimer’s disease, the researchers found. Although Mr. Gallup’s brain had all the hallmarks — plaques made of one abnormal protein and tangled strings of another — the tissue also contained clumps of proteins called Lewy bodies, as well as signs of silent strokes. Each of these, too, is a cause of dementia. Mr. Gallup’s brain was typical for an elderly patient with dementia. Although almost all of these patients are given a diagnosis of Alzheimer’s disease, nearly every one of them has a mixture of brain abnormalities. For researchers trying to find treatments, these so-called mixed pathologies have become a huge scientific problem. Researchers can’t tell which of these conditions is the culprit in memory loss in a particular patient, or whether all of them together are to blame. Another real possibility, noted Roderick A. Corriveau, who directs dementia research programs at the National Institute of Neurological Disorders and Stroke, is that these abnormalities are themselves the effects of a yet-to-be-discovered cause of dementia. These questions strike at the very definition of Alzheimer’s disease. And if you can’t define the condition, how can you find a treatment? © 2019 The New York Times Company

Keyword: Alzheimers; Brain imaging
Link ID: 26125 - Posted: 04.09.2019