Chapter 17. Learning and Memory

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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

By Benedict Carey Anyone above a certain age who has drawn a blank on the name of a favorite uncle, a friend’s phone number or the location of a house key understands how fragile memory is. Its speed and accuracy begin to slip in one’s 20s and keep slipping. This is particularly true for working memory, the mental sketch pad that holds numbers, names and other facts temporarily in mind, allowing decisions to be made throughout the day. On Monday, scientists reported that brief sessions of specialized brain stimulation could reverse this steady decline in working memory, at least temporarily. The stimulation targeted key regions in the brain and synchronized neural circuits in those areas, effectively tuning them to one another, as an orchestra conductor might tune the wind section to the strings. The findings, reported in the journal Nature Neuroscience, provide the strongest support yet for a method called transcranial alternating current stimulation, or tACS, as a potential therapy for memory deficits, whether from age-related decline, brain injury or, perhaps, creeping dementia. In recent years, neuroscientists have shown that memory calls on a widely distributed network in the brain, and it coordinates those interactions through slow-frequency, thrumming rhythms called theta waves, akin to the pulsing songs shared among humpback whales. The tACS technology is thought to enable clearer communication by tuning distant circuits to one another. The tACS approach is appealing for several reasons, perhaps most of all because it is noninvasive; unlike other forms of memory support, it involves no implant, which requires brain surgery. The stimulation passes through the skull with little sensation. Still, a widely available therapy is likely years away, as the risks and benefits are not fully understood, experts said. © 2019 The New York Times Company

Keyword: Learning & Memory; Alzheimers
Link ID: 26123 - Posted: 04.09.2019

Laura Sanders Brains have long been star subjects for neuroscientists. But the typical “brain in a jar” experiments that focus on one subject in isolation may be missing a huge part of what makes us human — our social ties. “There’s this assumption that we can understand how the mind works by just looking at individual minds, and not looking at them in interactions,” says social neuroscientist Thalia Wheatley of Dartmouth College. “I think that’s wrong.” To answer some of the thorniest questions about the human brain, scientists will have to study the mind as it actually exists: steeped in social connections that involve rich interplay among family, friends and strangers, Wheatley argues. To illustrate her point, she asked the audience at a symposium in San Francisco on March 26, during the annual meeting of the Cognitive Neuroscience Society, how many had talked to another person that morning. Nearly everybody in the crowd of about 100 raised a hand. Everyday social interactions may seem inconsequential. But recent work on those who have been isolated, such as elderly people and prisoners in solitary confinement, suggests otherwise: Brains deprived of social interaction stop working well (SN: 12/8/18, p. 11). “That’s a hint that it’s not just that we like interaction,” Wheatley says. “It’s important to keep us healthy and sane.” |© Society for Science & the Public 2000 - 2019

Keyword: Learning & Memory
Link ID: 26122 - Posted: 04.09.2019

By Carl Zimmer In 2011, Dr. Dena Dubal was hired by the University of California, San Francisco, as an assistant professor of neurology. She set up a new lab with one chief goal: to understand a mysterious hormone called Klotho. Dr. Dubal wondered if it might be the key to finding effective treatments for dementia and other disorders of the aging brain. At the time, scientists only knew enough about Klotho to be fascinated by it. Mice bred to make extra Klotho lived 30 percent longer, for instance. But scientists also had found Klotho in the brain, and so Dr. Dubal launched experiments to see whether it had any effect on how mice learn and remember. The results were startling. In one study, she and her colleagues found that extra Klotho protects mice with symptoms of Alzheimer’s disease from cognitive decline. “Their thinking, in every way that we could measure them, was preserved,” said Dr. Dubal. She and her colleagues also bred healthy mice to make extra Klotho. They did better than their fellow rodents on learning mazes and other cognitive tests. Klotho didn’t just protect their brains, the researchers concluded — it enhanced them. Experiments on more mice turned up similar results. “I just couldn’t believe it — was it true, or was it just a false positive?” Dr. Dubal recalled. “But here it is. It enhances of cognition even in a young mouse. It makes them smarter.” Five years have passed since Dr. Dubal and her colleagues began publishing these extraordinary results. Other researchers have discovered tantalizing findings of their own, suggesting that Klotho may protect against other neurological disorders, including multiple sclerosis and Parkinson’s disease. © 2019 The New York Times Company

Keyword: Learning & Memory; Alzheimers
Link ID: 26105 - Posted: 04.02.2019

Emma Yasinski In the 1970s, scientists discovered that certain neurons in the hippocampus—an area of the brain involved in learned and memory—would fire in response to particular locations. They were called “place cells,” explains Charlotte Boccara, a researcher at the University of Oslo. “They were deemed important for spatial representation . . . a bit like the ‘You Are Here’ signal’ on a map.” But it wasn’t until 2005 that researchers discovered the brain’s grid cells, which they believed function as that map. These cells, found adjacent to the hippocampus in the medial entorhinal cortex (MEC), self-organize into a pattern of hexagons that serve as coordinates to help animals make sense of their surroundings and the signals from our place cells. A pair of studies published today (March 28) in Science suggests that this map may not be as rigid as once thought. The experiments demonstrated that, in rats at least, the cellular activity within these grids changes as the animals learn and remember where they can find food rewards. “These are wonderful studies,” says György Buzsáki, a neuroscientist at New York University who was not involved in either of them. “When ideas converge from multiple, different directions, and they converge and come to the same conclusion, the result is always stronger.” In the first study, Boccara, then a researcher at the Institute of Science and Technology Austria, and her team placed rats one by one in a cheeseboard maze, a flat board drilled full of holes. They hid three food rewards in different holes then scattered food dust over the entire surface so the rats would not be able to sniff their ways to the reward. The rats explored the maze until they found the prizes and repeated the task until they learned to go straight to the food instead of foraging. The next day, the researchers conducted the same experiment but changed the locations of the rewards. © 1986 - 2019 The Scientist.

Keyword: Learning & Memory
Link ID: 26094 - Posted: 03.30.2019

Laura Sanders SAN FRANCISCO — Seizures during sleep can scramble memories — a preliminary finding that may help explain why people with epilepsy sometimes have trouble remembering. The sleeping brain normally rehashes newly learned material, a nocturnal rehearsal that strengthens those memories. Neuroscientist Jessica Creery and her colleagues forced this rehearsal by playing certain sounds while nine people with epilepsy learned where on a screen certain pictures of common objects were located. Then, while the subjects later slept, the researchers played the sounds to call up some of the associated memories. This sneaky method of strengthening memories, called targeted memory reactivation, worked as expected for five people who didn’t have seizures during the process. When these people woke up, they remembered the picture locations reactivated by a tone better than those that weren’t reactivated during sleep, said Creery, of Northwestern University in Evanston, Ill. She presented the research March 25 at the annual meeting of the Cognitive Neuroscience Society. The opposite was true, however, for four people who had mild seizures, detected only by electrodes implanted deep in the brain, while they slept. For these people, memory reactivation during sleep actually worsened memories, making the reactivated memories weaker than the memories that weren’t reactivated during sleep. The combination of seizures and memory reactivation “seems like it’s actually scrambling the memory,” Creery says, a finding that suggest that seizures somehow accelerate forgetting. |© Society for Science & the Public 2000 - 2019

Keyword: Sleep; Epilepsy
Link ID: 26083 - Posted: 03.27.2019

By Benedict Carey Whatever its other properties, memory is a reliable troublemaker, especially when navigating its stockpile of embarrassments and moral stumbles. Ten minutes into an important job interview and here come screenshots from a past disaster: the spilled latte, the painful attempt at humor. Two dates into a warming relationship and up come flashbacks of an earlier, abusive partner. The bad timing is one thing. But why can’t those events be somehow submerged amid the brain’s many other dimming bad memories? Emotions play a role. Scenes, sounds and sensations leave a deeper neural trace if they stir a strong emotional response; this helps you avoid those same experiences in the future. Memory is protective, holding on to red flags so they can be waved at you later, to guide your future behavior. But forgetting is protective too. Most people find a way to bury, or at least reshape, the vast majority of their worst moments. Could that process be harnessed or somehow optimized? Perhaps. In the past decade or so, brain scientists have begun to piece together how memory degrades and forgetting happens. A new study, published this month in the Journal of Neuroscience, suggests that some things can be intentionally relegated to oblivion, although the method for doing so is slightly counterintuitive. For the longest time, forgetting was seen as a passive process of decay and the enemy of learning. But as it turns out, forgetting is a dynamic ability, crucial to memory retrieval, mental stability and maintaining one’s sense of identity. © 2019 The New York Times Company

Keyword: Learning & Memory
Link ID: 26070 - Posted: 03.23.2019

By Paul Raeburn When the brain remembers, proteins in two locations deep within the organ—the amygdala and hippocampus—encode the memory until it is stored, or “consolidated” in the vernacular. Neuroscientists once thought that a memory, when put in its place, became permanent and stable. That’s a problem for patients with post-traumatic stress disorder (PTSD), plagued by crippling, debilitating memories that they cannot shake. “We wish that we could somehow target unpleasant or pathological memories and reduce their emotional strength,” says Bryan A. Strange, founder of the Laboratory of Clinical Science at the Universidad Politécnica de Madrid. During the past two decades or so, it has become clear that these memories are not fixed and unshakable. They can be manipulated in ways that might ultimately ease the suffering of patients, not just ones with a PTSD diagnosis but also those afflicted by phobias, depression and other stress-related conditions. Strange is among the researchers looking for leads to tamp down toxic memories. He and his colleagues reported in a Science Advances paper on March 20 that the anesthetic propofol can be used to alter such recollections, if administered in the right circumstances. © 2019 Scientific American

Keyword: Stress; Learning & Memory
Link ID: 26064 - Posted: 03.22.2019

By Pam Belluck Could people’s eyes and ears help fix the damage Alzheimer’s disease does to the brain? Just by looking at flashing light and listening to flickering sound? A new study led by a prominent M.I.T. neuroscientist offers tantalizing promise. It found that when mice engineered to exhibit Alzheimer’s-like qualities were exposed to strobe lights and clicking sounds, important brain functions improved and toxic levels of Alzheimer’s-related proteins diminished. What’s more, the rapid-fire soundtrack appeared to make mice better at cognitive and memory skills, like navigating mazes and recognizing objects. Of course, mice are not people. And many drugs that have helped Alzheimer’s-engineered mice haven’t done much for people with Alzheimer’s, which affects 44 million people worldwide, including 5.5 million Americans. Also, because the technique didn’t have long-lasting effects — results faded about a week after the sensory stimulation was stopped — any therapy developed from the research might have to be repeated regularly. Still, seeing that a noninvasive daily dose of light and sound could have such significant effects in mice give some experts reason for optimism. “It’s exciting, I think,” said Dr. Lennart Mucke, director of the Gladstone Institute of Neurological Disease, who was not involved in the study. “Reading the paper made me quite enthusiastic about seeing this move forward into some well-crafted clinical trials.” The experiments were led by Li-Huei Tsai, director of MIT’s Picower Institute for Learning and Memory. She and her colleagues showed that light and sound delivered to mice at a certain frequency — 40 hertz or 40 flashes or clicks per second — appears to synchronize the rhythm of the brain’s gamma waves, which is disrupted in patients with Alzheimer’s. Gamma waves are among several types of electrical brain waves believed to be involved in concentration, sleep, perception and movement. The experiment setup where flickering light and sound were delivered to Alzheimer’s-engineered mice in the tubs.CreditPicower Institute for Learning and Memory, M.I.T. © 2019 The New York Times Company

Keyword: Alzheimers; Learning & Memory
Link ID: 26040 - Posted: 03.15.2019

Liam Drew A mouse scurries down a hallway, past walls lined with shifting monochrome stripes and checks. But the hallway isn’t real. It’s part of a simulation that the mouse is driving as it runs on a foam wheel, mounted inside a domed projection screen. While the mouse explores its virtual world, neuroscientist Aman Saleem watches its brain cells at work. Light striking the mouse’s retinas triggers electrical pulses that travel to neurons in its primary visual cortex, where Saleem has implanted electrodes. Textbooks say that these neurons each respond to a specific stimulus, such as a horizontal or vertical line, so that identical patterns of inputs should induce an identical response. But that’s not what happens. When the mouse encounters a repeat of an earlier scene, its neurons fire in a different pattern. “Five years ago, if you’d told me that, I’d have been like, ‘No, that’s not true. That’s not possible’,” says Saleem, in whose laboratory at University College London we are standing. His results, published last September1, show that cells in the hippocampus that track where the mouse has run along the hallway are somehow changing how cells in the visual cortex fire. In other words, the mouse’s neural representation of two identical scenes differs, depending on where it perceives itself to be. It’s no surprise that an animal’s experiences change how it sees the world: all brains learn from experience and combine multiple streams of information to construct perceptions of reality. But researchers once thought that at least some areas in the brain — those that are the first to process inputs from the sense organs — create relatively faithful representations of the outside world. According to this model, these representations then travel to ‘association’ areas, where they combine with memories and expectations to produce perceptions.

Keyword: Learning & Memory; Vision
Link ID: 26039 - Posted: 03.15.2019

Eating mushrooms more than twice a week could prevent memory and language problems occurring in the over-60s, research from Singapore suggests. A unique antioxidant present in mushrooms could have a protective effect on the brain, the study found. The more mushrooms people ate, the better they performed in tests of thinking and processing. But researchers said it was not possible to prove a direct link between the fungi and brain function. The National University of Singapore study's findings were based on 663 Chinese adults, aged over 60, whose diet and lifestyle were tracked from 2011 to 2017. Over the six-year study the researchers found that eating more than two portions of mushrooms a week lowered the chances of mild cognitive impairment by 50%, compared with those who ate fewer than one portion. Mild cognitive impairment (MCI) can make people forgetful, affect their memory and cause problems with language, attention and locating objects in spaces - but the changes can be subtle. It is not serious enough to be defined as dementia. The participants in the study were asked how often they ate six different types of mushrooms: oyster, shiitake, white button, dried, golden and tinned. Mushroom eaters performed better in brain tests and were found to have faster processing speed - and this was particularly noticeable in those who ate more than two portions a week, or more than 300g (10.5oz). "This correlation is surprising and encouraging," said assistant professor Lei Feng, the lead study author, from the university's department of psychological medicine. Image copyright Getty Images "It seems that a commonly available single ingredient could have a dramatic effect on cognitive decline. © 2019 BBC

Keyword: Alzheimers; Learning & Memory
Link ID: 26034 - Posted: 03.15.2019

Laura Sanders Fast waves of activity ripple in the brain a half second before a person calls up a memory. The finding, published in the March 1 Science, hint that these brain waves might be a key part of a person’s ability to remember. The results come from a study of 14 people with epilepsy who had electrodes placed on their brains as part of their treatment. Those electrodes also allowed scientists to monitor neural activity while the people learned pairs of words. One to three minutes after learning the pairs, people were given one word and asked to name its partner. As participants remembered the missing word, neuroscientist and neurosurgeon Kareem Zaghloul and his colleagues caught glimpses of fast brain waves rippling across parts of the brain at a rate of around 100 per second. These ripples appeared nearly simultaneously in two brain regions — the medial temporal lobe, which is known to be important for memory, and the temporal association cortex, which has a role in language. When a person got the answer wrong, or didn’t answer at all, these coordinated ripples were less likely to be present, the researchers found. “We see this happening, and then we see people remember,” says Zaghloul, of the National Institutes of Health in Bethesda, Md. While recalling a memory, “you mentally jump back in time and re-experience it,” Zaghloul says. Just after the ripples, the researchers saw telltale signs of that mental time travel — an echo of brain activity similar to the brain activity when the memory of the word pair was first formed. |© Society for Science & the Public 2000 - 201

Keyword: Learning & Memory
Link ID: 26003 - Posted: 03.05.2019

Laura Sanders People often fret about television time for children. A new study examines the habit at the other end of life. The more television older people watched, the worse they recalled a list of words, researchers report online February 28 in Scientific Reports. But the study describes only a correlation; it can’t say that lots of TV time actually causes the memory slips. Researchers examined data on 3,590 people collected as part of the English Longitudinal Study of Aging, a long-running study of English people aged 50 and older. In 2008 and 2009, participants reported how many hours a day, on average, they spent watching television. In addition to the surveys, participants listened to a recording of 10 common words, one word every two seconds. Then, people tried to remember as many words as they could, both immediately after hearing the words and after a short delay. Six years later, people took the same tests. People who watched more than 3.5 hours of TV daily back in 2008 or 2009 were more likely to have worse verbal memory scores six years later, the researchers found. Television “dose” seemed to matter: Beyond that 3.5-hour threshold, the more TV people watched, the bigger their later verbal memory scores declined. It’s not known whether television time actually causes verbal memory problems. The reverse could be true: People who have worse memories might be more likely to watch more television. Still, the researchers suggest that TV might cause a certain kind of mental stress that might contribute to memory trouble. |© Society for Science & the Public 2000 - 2019

Keyword: Learning & Memory
Link ID: 26000 - Posted: 03.02.2019

By Perri Klass, M.D. A major international study provides new reassurance around the question of whether young children who have anesthesia are more likely to develop learning disabilities The issue has troubled pediatric anesthesiologists and parents for well over a decade, after research on animals suggested that there was a connection. Do the drugs that make it possible to perform vital surgical procedures without pain cause lasting damage to the developing human brain? Several large studies have found ways to tease out the effects of actual surgeries and anesthetic exposures on children. The new study, in the British journal The Lancet, is a randomized controlled trial involving more than 700 infants who needed hernia repairs. The babies, at 28 hospitals in seven countries, were randomly assigned to receive either general anesthesia or regional (spinal) anesthesia for these short operations — the mean duration of general anesthesia was 54 minutes. The study, called the GAS study — for general anesthesia compared to spinal — compared neurodevelopmental outcomes at 5 years of age, and found no significant difference in the children’s performance in the two groups. Dr. Andrew Davidson, a professor in the department of anesthesia at the Royal Children’s Hospital of Melbourne and one of the two lead investigators on the trial, said that this prospective, randomized design allows researchers to avoid many confounding factors that have complicated previous studies, and answer a very specific question. Preliminary data from testing the children at age 2 had shown no significant differences between the groups, and the children were then evaluated at the age of school entry. “If you have an hour of anesthesia as a child, then you are at no greater risk of deficits of cognition at the age of 5,” Dr. Davidson said. “It doesn’t increase the risk of poor neurodevelopmental outcome.” © 2019 The New York Times Company

Keyword: Development of the Brain; Learning & Memory
Link ID: 25972 - Posted: 02.18.2019

Bruce Bower WASHINGTON — Beliefs among some university professors that intelligence is fixed, rather than capable of growth, contribute to a racial achievement gap in STEM courses, a new study suggests. Those professors may subtly communicate stereotypes about blacks, Hispanics and Native Americans allegedly being less intelligent than Asians and whites, say psychologist Elizabeth Canning of Indiana University in Bloomington and her colleagues. In turn, black, Hispanic and Native American undergraduates may respond by becoming less academically motivated and more anxious about their studies, leading to lower grades. Even small dips in STEM grades — especially for students near pass/fail cutoffs — can accumulate across the 15 or more science, technology, engineering and math classes needed to become a physician or an engineer, Canning says. That could jeopardize access to financial aid and acceptance to graduate programs. “Our work suggests that academic benefits could accrue over time if all students, and particularly underrepresented minority students, took STEM classes with faculty who endorse a growth mind-set,” Canning says. Underrepresented minority students’ reactions to professors with fixed or flexible beliefs about intelligence have yet to be studied. But over a two-year period, the disparity in grade point averages separating Asian and white STEM students from black, Hispanic and Native American peers was nearly twice as large in courses taught by professors who regarded intelligence as set in stone, versus malleable, Canning’s team reports online February 15 in Science Advances. |© Society for Science & the Public 2000 - 2019.

Keyword: Attention; Learning & Memory
Link ID: 25970 - Posted: 02.18.2019

By Pallab Ghosh Science correspondent, BBC News, Washington DC New results suggest ageing brains can potentially be rejuvenated, at least in mice, according to researchers. Very early-stage experiments indicate that drugs can be developed to stop or even reverse mental decline. The results were presented at the 2019 meeting of the American Association for the Advancement of Science. The US and Canadian researchers took two new approaches to trying to prevent the loss of memory and cognitive decline that can come with old age. One team, from the University of California, Berkeley, showed MRI scans which indicated that mental decline may be caused by molecules leaking into the brain. Blood vessels in the brain are different from those in other parts of the body. They protect the organ by allowing only nutrients, oxygen and some drugs to flow through into the brain, but block larger, potentially damaging molecules. This is known as the blood-brain barrier. The scans revealed that this barrier becomes increasingly leaky as we get older. For example, 30-40% of people in their 40s have some disruption to their blood-brain barrier, compared with 60% of 60-year-olds. The scans also showed that the brain was inflamed in the leaky areas. Prof Daniela Kaufer, who leads the Berkeley group, said that young mice altered to have leaky blood-brain barriers showed many signs of aging. She discovered a chemical that stops the damage to the barrier from causing inflammation to the brain. Prof Kaufer told BBC News that not only did the chemical stop the genetically altered young mice from showing signs of aging, it reversed the signs of aging in older mice. © 2019 BBC

Keyword: Alzheimers; Learning & Memory
Link ID: 25966 - Posted: 02.15.2019

Ian Sample Science editor An experimental drug that bolsters ailing brain cells has raised hopes of a treatment for memory loss, poor decision making and other mental impairments that often strike in old age. The drug could be taken as a daily pill by over-55s if clinical trials, which are expected to start within two years, show that the medicine is safe and effective at preventing memory lapses. Tests in the lab showed that old animals had far better memory skills half an hour after receiving the drug. After two months on the treatment, brain cells which had shrunk in the animals had grown back, scientists found. Etienne Sibille, at the Centre for Addiction and Mental Health in Toronto, said the treatment was aimed not only at the “normal” cognitive decline that leads to senior moments, but at memory loss and mental impairments that commonly afflict people with depression, schizophrenia and Alzheimer’s disease. If the drug did well in human trials, Sibille said it was possible that “anybody over the age of 55-60 who may be at risk of cognitive problems later on could benefit from this treatment”. “Our findings have direct implications for poor cognition in normal ageing,” he said, with the drug potentially improving learning, memory, decision making and essential life planning. “But we see this deficiency across disorders from depression to schizophrenia and Alzheimer’s.” © 2019 Guardian News & Media Limited

Keyword: Alzheimers; Learning & Memory
Link ID: 25964 - Posted: 02.14.2019

Shawna Williams Watch a bacterium chase down the source of an enticing molecular trail using chemo-taxis, and it’s clear that its sensory and navigation abilities are tightly linked. But could the same be true for humans? In 2014, Louisa Dahmani, then a graduate student at McGill University in Montreal, set out to answer that question. After having reviewed the literature on studies of spatial memory and olfaction in people, “I realized that the two functions seemed to rely on similar brain regions,” she explains. “But no one had actually looked at it directly and tested the same sample of participants on an olfaction and on a spatial memory task.” Dahmani, her advisor Véronique Bohbot, and their colleagues set out to rectify that. The group recruited 60 volunteers and tested their ability to identify 40 odors, from menthol to cucumber to lavender. The researchers also had the subjects do a computer-based task in which they moved through a virtual town. After their exploration, the subjects navigated through the virtual town from one of its eight landmarks to a different destination via the shortest route possible. “People who are better at finding their way are also better at identifying smells,” Dahmani says, summing up the study’s biggest takeaway. The scientists also imaged participants’ brains using MRI and found that a larger medial orbitofrontal cortex—a brain region known to be associated, along with the hippocampus, with spatial navigation—correlated with both better smell identification and fewer errors on the navigation task (Nat Comm, 9:4162, 2018). © 1986 - 2019 The Scientist.

Keyword: Chemical Senses (Smell & Taste); Learning & Memory
Link ID: 25963 - Posted: 02.14.2019