Chapter 17. Learning and Memory
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Jason Bruck Ever been at a party where you recognize everyone’s faces but can’t think of their names? That wouldn’t happen if you were a bottlenose dolphin (Tursiops truncatus). The marine mammals can remember each other’s signature contact whistles—calls that function as names—for more than 20 years, the longest social memory ever recorded for a nonhuman animal, according to a new study. “The ability to remember individuals is thought to be extremely important to the ‘social brain,’ ” says Janet Mann, a marine mammal biologist at Georgetown University in Washington, D.C., who was not involved in the research. Yet, she notes, no one has succeeded in designing a test for this talent in the great apes—our closest kin—let alone in dolphins. Dolphins use their signature whistles to stay in touch. Each has its own unique whistle, and they learn and can repeat the whistles of other dolphins. A dolphin will answer when another dolphin mimics its whistle—just as we reply when someone calls our name. The calls enable the marine mammals to communicate over long distances—which is necessary because they live in “fission-fusion” societies, meaning that dolphins in one group split off to join other groups and later return. By whistling, they’re able to find each other again. Scientists don’t know how long dolphins are separated in the wild, but they do know the animals can live almost 50 years. So how long do the dolphins remember the calls of their friends? To find out, Jason Bruck, a cognitive ethologist at the University of Chicago in Illinois, spent 5 years collecting 71 whistles from 43 dolphins at six captive facilities, including Brookfield Zoo near Chicago and Dolphin Quest in Bermuda. The six sites belong to a consortium that rotates the marine mammals for breeding and has decades-long records of which dolphins have lived together. © 2012 American Association for the Advancement of Science
By NICK BILTON Scientists haven’t yet found a way to mend a broken heart, but they’re edging closer to manipulating memory and downloading instructions from a computer right into a brain. Researchers from the Riken-M.I.T. Center for Neural Circuit Genetics at the Massachusetts Institute of Technology took us closer to this science-fiction world of brain tweaking last week when they said they were able to create a false memory in a mouse. The scientists reported in the journal Science that they caused mice to remember receiving an electrical shock in one location, when in reality they were zapped in a completely different place. The researchers weren’t able to create entirely new thoughts, but they applied good or bad feelings to memories that already existed. “It wasn’t so much writing a memory from scratch, it was basically connecting two different types of memories. We took a neutral memory, and we artificially updated that to make it a negative memory,” said Steve Ramirez, one of the M.I.T. neuroscientists on the project. It may sound insignificant and perhaps not a nice way to treat mice, but it is not a dramatic leap to imagine that one day this research could lead to computer-manipulation of the mind for things like the treatment of post-traumatic stress disorder, Mr. Ramirez said. Technologists are already working on brain-computer interfaces, which will allow us to interact with our smartphones and computers simply by using our minds. And there are already gadgets that read our thoughts and allow us to do things like dodge virtual objects in a computer game or turn switches on and off with a thought. Copyright 2013 The New York Times Company
by Helen Thomson We all get lost sometimes. Luckily, specialised cells in the brain that help animals find their way have now been identified in humans for the first time. The discovery could lead to better treatments for people who have problems navigating. We know that animals use three cell types to navigate the world. Direction cells fire only when an animal is facing a particular direction, place cells fire only in a particular location, and grid cells fire at regular intervals as an animal moves around. To understand how grid cells work, imagine the carpet in front of you has a grid pattern of interlocking triangles. One grid cell will fire whenever you reach the corner of any triangle in that grid. Shift the grid pattern along ever so slightly to another section of the carpet, and another grid cell will be responsible for firing every time you reach the corners of that grid's triangles – and so on. Grid cells send information to place cells and both kinds of cell send information to the hippocampus – responsible for memory formation. Together, this network of activity helps form a mental representation of an animal's location in its environment. Direction and place cells have been identified in humans but the existence of grid cells has so far only been hinted at in brain scans. To find out whether these cells do exist in humans, Joshua Jacobs at Drexel University in Philadelphia, Pennsylvania, and colleagues tested 14 people who had already had electrodes implanted in their brains for epilepsy therapy. © Copyright Reed Business Information Ltd.
Keyword: Learning & Memory
Link ID: 18459 - Posted: 08.05.2013
By Andrea Anderson In spring a band of brainy rodents made headlines for zipping through mazes and mastering memory tricks. Scientists credited the impressive intellectual feats to human cells transplanted into their brains shortly after birth. But the increased mental muster did not come from neurons, the lanky nerve cells that swap electrical signals and stimulate muscles. The mice benefited from human stem cells called glial progenitors, immature cells poised to become astrocytes and other glia cells, the supposed support cells of the brain. Astrocytes are known for mopping up excess neuro-transmitters and maintaining balance in brain systems. During the past couple of decades, however, researchers started suspecting astrocytes of making more complex cognitive contributions. In the 1990s the cells got caught using calcium to accomplish a form of nonelectrical signaling. Studies since then have revealed how extensively astrocytes interact with neurons, even coordinating their activity in some cases. Perhaps even more intriguing, our astrocytes are enormous compared with the astrocytes of other animals—20 times larger than rodent astrocytes—and they make contact with millions of neurons apiece. Neurons, on the other hand, are nearly identical in all mammals, from rodents to great apes like us. Such clues suggest astrocytes could be evolutionary contributors to our outsized intellect. The new study, published in March in Cell Stem Cell, tested this hypothesis. A subset of the implanted human stem cells matured into rotund, humanlike astrocytes in the animals' brains, taking over operations from the native mouse astrocytes. When tested under a microscope, these human astrocytes accomplished calcium signaling at least three times faster than the mouse astrocytes did. The enhanced mice masterfully memorized new objects, swiftly learned to link certain sounds or situations to an unpleasant foot shock, and displayed unusually savvy maze navigation—signs of mental acuity that surpassed skills exhibited by either typical mice or mice transplanted with glial progenitor cells from their own species. © 2013 Scientific American
Andrew M. Seaman, Reuters Children with an autism spectrum disorder spend about twice as much time playing video games as kids who don't have a developmental disability, according to a new study. Researchers also found that children with an autism spectrum disorder or attention deficit/hyperactivity disorder (ADHD) are at an increased risk of gaming addictions, compared to children without the disabilities. "What we found is that it looks like (addictive gaming) was largely driven by inattention," Christopher Engelhardt, one of the study's authors from the University of Missouri in Columbia, told Reuters Health. Previous studies have found that children with an autism spectrum disorder or ADHD spend more time playing video games and are at increased risk for gaming addictions than other children, write the researchers in the journal Pediatrics. No single study, however, has looked at the three groups to see whether shared features of autism and ADHD - such as inattention or hyperactivity - seem to drive video game use. For the new study, Engelhardt and his colleague surveyed the parents of 141 boys between the ages of 8 and 18 years old. Of those, 56 had an autism spectrum disorder, 44 had ADHD and 41 were developing normally. Overall, they found that kids with an autism spectrum disorder played - on average - 2.1 hours of video games per day. Children with ADHD spent about 1.7 hours per day playing video games and normally developing kids played about 1.2 hours per day.
By Darold Treffert So much of what happens to us in life is not by plan, but rather by coincidence or serendipity. Thus it was with me and my career. After completing my residency in psychiatry I was assigned the responsibility of developing a Children’s Unit at Winnebago Mental Health Institute here in Wisconsin. There were over 800 patients at the hospital, some under age 18. We gathered about 30 such children and adolescents and put them on this new unit. Three patients particularly caught my eye. One boy had memorized the bus system of the entire city of Milwaukee with exhaustive detail and precision. Another little guy, even though mute and severely disabled with autism, could put a 200 piece jig saw puzzle together—picture side down—just from the geometric shapes of the puzzle pieces. And a third lad was an expert on what happened on this day in history and even though I would study up the night before, knowing he would quiz me the next day, I could never surpass his recall of events on that day in history. Kim Peek, his father Fran Peek and Dr. Treffert meeting in Milwaukee I was stunned, and intrigued, by this jarring juxtaposition of ability and disability in the same individual and began to study all that I could about savant syndrome—“islands of genius” amidst a sea of impairment. Then in 1980 Leslie Lemke came to Fond du Lac to give a concert. Leslie–blind, cognitively impaired and with such spasticity in his hands that he could not hold a fork or spoon to eat—had become a accomplished pianist, never having had a piano lesson in his life. Somehow the hand spasticity magically disappears when he sits at the keyboard. The 1983 60 Minutes program, which many still remember, recounted in detail the astonishment of Leslie’s mother, May Lemke, one evening, when Leslie, age 14, played back Tchaikovsky’s Piano Concerto No. 1 flawlessly, having heard it earlier for the first time that evening as the soundtrack to the movie Sincerely Yours. © 2013 Scientific American
Keyword: Learning & Memory
Link ID: 18437 - Posted: 08.01.2013
By Julie Hecht AFTER A LONG DAY of being a dog, no dog in existence has ever curled up on a comfy couch to settle in with a good book. Dogs just don’t roll like that. But that shouldn’t imply that human words don’t or can’t have meaning for dogs. Chaser, a Border Collie from South Carolina, first entered the news in 2011 when a Behavioral Processes paper reported she had learned and retained the distinct names of over 1,000 objects. But that’s not all. When tested on the ability to associate a novel word with an unfamiliar item, she could do that, too. She also learned that different objects fell into different categories: certain things are general “toys,” while others are the more specific “Frisbees” and, of course, there are many, many exciting “balls.” She differentiates between object labels and action commands, interpreting “fetch sock” as two separate words, not as the single phrase “fetchsock.” Fast forward two years. Chaser and her owner and trainer Dr. John Pilley, an emeritus professor of psychology at Wofford College, appeared again in a scientific journal. This time, the study highlighted Chaser’s attention to the syntactical relationships between words, for example, differentiating “to ball take Frisbee” from “to Frisbee take ball.” I’ve been keeping an eye on Chaser, and I’ve been keeping an eye on Rico, Sofia, Bailey, Paddy and Betsy, all companion dogs whose way with human language has been reported in scientific journals. Most media reports tend to focus on outcomes: what these dogs can — or can’t — do with our words. But I think these reports are missing the point. Learning the names of over 1,000 words doesn’t just happen overnight. What does the behind-the-scenes learning and training look like? How did Chaser develop this intimate relationship with human language? © 2013 Scientific American
By Jason Castro It’s the premise of every third sci-fi thriller. Man wakes up to his normal seeming life, but of course it isn’t. At first, just the little things are off – the dog won’t eat and the TV keeps looping some strange video – but whatever. A few cuts later, with only his granddad’s rusty brass knuckles and a steely-eyed contempt for authority, our hero reveals a conspiracy that kicks up straight to the top. There were deals. Some blackmailing. A probe or two. But in the end, what’s most important is that everything he thought he knew was wrong. Because the scientists (Noooo!!) got to him with one of those electrode caps and rewrote his memory. Everything – the job, the daughter, the free parking – is a lie. The dramatic ploy works on us because memory seems inviolable, or at least, we desperately hope that it is. We allow that our memories may fade and fail a bit, but otherwise, we go on the sanity-preserving assumption that there is one reason why we remember a particular thing: because we were there, and it actually happened. Now, a new set of experiments, led by MIT neuroscientists Steve Ramirez and Xu Liu in Susumu Tonegawa’s lab, shows that this needn’t be the case. Using a stunning set of molecular neuroscience techniques (no electrode caps involved), these scientists have captured specific memories in mice, altered them, and shown that the mice behave in accord with these new, false, implanted memories. The era of memory engineering is upon us, and naturally, there are big implications for basic science and, perhaps someday, human health and society. © 2013 Scientific American,
Keyword: Learning & Memory
Link ID: 18432 - Posted: 07.31.2013
Kelly Servick Our imperfect memory is inconvenient at the grocery store and downright dangerous on the witness stand. In extreme cases, we may be confident that we remember something that never happened at all. Now, a group of neuroscientists say that they’ve identified a potential mechanism of false memory creation and have planted such a memory in the brain of a mouse. Neuroscientists are only beginning to tackle the phenomenon of false memory, says Susumu Tonegawa of the Massachusetts Institute of Technology in Cambridge, whose team conducted the new research. “It’s there, and it’s well established,” he says, “but the brain mechanisms underlying this false memory are poorly known.” With optogenetics—the precise stimulation of neurons with light—scientists can seek out the physical basis of recall and even tweak it a bit, using mouse models. Like us, mice develop memories based on context. When a mouse returns to an environment where it felt pain in the past, it recalls that experience and freezes with fear. Tonegawa’s team knew that the hippocampus, a part of the brain responsible for establishing memory, plays a role in encoding context-based experiences, and that stimulating cells in a part of the hippocampus called the dentate gyrus can make a mouse recall and react to a mild electric shock that it received in the past. The new goal was to connect that same painful shock memory to a context where the mouse had not actually received a shock. © 2012 American Association for the Advancement of Science
Keyword: Learning & Memory
Link ID: 18416 - Posted: 07.27.2013
Researchers in Canada and Ireland have discovered that blood pressure drugs, known as ACE inhibitors, can improve brain function while slowing down the onset of dementia. ACE inhibitors, known by names such as ramipril and perindopril, have been already been shown in previous studies to delay the onset of dementia. What the medical community didn’t know was that these drugs may also enhance cognitive function. The study, published in the British Medical Journal, concludes that the use of ACE inhibitors could become useful in the management of dementia. The study examined 361 patients, all of whom had been diagnosed with Alzheimer’s, vascular dementia (triggered by lack of blood supply to the brain) or a mix of the two. Many Alzheimer's patients suffer dementia, which can affect memory, thinking, reasoning, planning and the ability to speak. Eighty-five of the patients were already taking the ACE inhibitors while the rest were not. Researchers also separately tested 30 patients, put on the drugs for the first time, for changes in their brain function. The average age was 77 and participants were followed for one year. © CBC 2013
by Virginia Morell The next time your dog digs a hole in the backyard after watching you garden, don't punish him. He's just imitating you. A new study reveals that our canine pals are capable of copying our behavior as long as 10 minutes after it's happened. The ability is considered mentally demanding and, until this discovery, something that only humans and apes were known to do. Scientists first discovered that dogs are excellent at imitating their owners in 2006. Or at least, one dog had the talent: Philip, a 4-year-old Belgian Tervuren working with József Topál, a behavioral ethologist at the Hungarian Academy of Sciences in Budapest. Topál adapted the method (called "Do as I do") that Keith and Catherine Hayes developed in the 1950s for teaching an infant chimpanzee to copy their actions. Philip was already a trained assistant dog for his disabled owner and readily followed Topál's commands. First, Topál told him to stay, and then commanded "Do as I do." The researcher then performed a simple action, such as jumping in place, barking, putting an object in a box, or carrying it to Philip's owner. Next, Topál ordered, "Do it!", and Philip responded by matching the scientist's actions. The experiment was designed to explore dog's imitative abilities, not to measure how long Philip's memory lasted; but his owner used Philip's skill to teach him how to do new, useful behaviors, such as fetching objects or putting things away. Despite Philip's abilities, "nobody really cared, or saw that it could be useful for investigating how dogs learn or see their world," says Ádám Miklósi, a behavioral ethologist at Eötvös Loránd University in Budapest who was part of Topál's team. And in 2009, another team concluded that dogs were only able to correctly imitate if there was no more than a 5-second delay between watching the action and repeating it. With such a short retention span, dogs' vaunted imitation skills seemed useless. © 2010 American Association for the Advancement of Science
by Virginia Morell A single cue—the taste of a madeleine, a small cake, dipped in lime tea—was all Marcel Proust needed to be transported down memory lane. He had what scientists term an autobiographical memory of the events, a type of memory that many researchers consider unique to humans. Now, a new study argues that at least two species of great apes, chimpanzees and orangutans, have a similar ability; in zoo experiments, the animals drew on 3-year-old memories to solve a problem. Their findings are the first report of such a long-lasting memory in nonhuman animals. The work supports the idea that autobiographical memory may have evolved as a problem-solving aid, but researchers caution that the type of memory system the apes used remains an open question. Elephants can remember, they say, but many scientists think that animals have a very different kind of memory than our own. Many can recall details about their environment and routes they've traveled. But having explicit autobiographical memories of things "I" did, or remembering events that occurred in the past, or imagining those in the future—so-called mental time travel—are considered by many psychologists to be uniquely human skills. Until recently, scientists argued that animals are stuck in time, meaning that they have no sense of the past or future and that they aren't able to recall specific events from their lives—that is, they don't have episodic memories, the what-where-when of an event that happened. © 2010 American Association for the Advancement of Science
By PAM BELLUCK The man complained of memory problems but seemed perfectly normal. No specialist he visited detected any decline. “He insisted that things were changing, but he aced all of our tests,” said Rebecca Amariglio, a neuropsychologist at Brigham and Women’s Hospital in Boston. But about seven years later, he began showing symptoms of dementia. Dr. Amariglio now believes he had recognized a cognitive change so subtle “he was the only one who could identify it.” Patients like this have long been called “the worried well,” said Creighton Phelps, acting chief of the dementias of aging branch of the National Institute on Aging. “People would complain, and we didn’t really think it was very valid to take that into account.” But now, scientists are finding that some people with such complaints may in fact be detecting early harbingers of Alzheimer’s. Studies presented Wednesday at an Alzheimer’s Association conference in Boston showed that people with some types of cognitive concerns were more likely to have Alzheimer’s pathology in their brains, and to develop dementia later. Research presented by Dr. Amariglio, for example, found that people with more concerns about memory and organizing ability were more likely to have amyloid, a key Alzheimer’s-related protein, in their brains. And, in a significant shift highlighted at the conference, leading Alzheimer’s researchers are identifying a new category called “subjective cognitive decline,” which is people’s own sense that their memory and thinking skills are slipping even before others have noticed. © 2013 The New York Times Company
by Jennifer Viegas The memory of dogs is more human-like than previously thought, allowing our furry pals to copy our actions, even after delays. The discovery, outlined in the latest issue of Animal Cognition, means that dogs possess what’s known as “declarative memory,” which refers to memories which can be consciously recalled, such as facts or knowledge. Humans, of course, have this ability, as anyone playing a trivia game demonstrates. But it had never fully been scientifically proven in dogs before, although dog owners and canine aficionados have likely witnessed the skill first-hand for years. Claudia Fugazza and Adám Miklósi of Eötvös Loránd University in Hungary conducted the study. A LOT of dog studies happen in Hungary, where people really love their pooches and some of the world’s leading canine researchers live. The team investigated if dogs could defer imitation, which in this case meant copying what their owners were doing. Eight adult pet dogs were trained using the “Do As I Do” method. (Fugazza is a leading expert on this training method for dogs.) The tasks included copying their owners walking around a bucket and ringing a bell. Can dogs then successfully replicate what they learned after a 10 or so minute distracting break? The owner, Valentina, got her dog Adila to pay attention to her. She then demonstrated an activity, like ringing a bell with her hand. © 2013 Discovery Communications, LLC
By Susan Gaidos For nearly a decade, neuroscientist Li-Huei Tsai and her colleagues have been studying senile mice. In a lab at MIT her team has genetically fast-forwarded the mice into a condition much like dementia: They have problems making new memories and retrieving old ones. The mice forget how to navigate water mazes they had mastered; they don’t recognize signs of imminent danger they had once responded to fearfully. Last year, Tsai’s group found a way to reverse the process. When given a drug known to strengthen nerve cell connections in the brain, the mice not only gained back the ability to learn new tasks, but also remembered many forgotten behaviors. On the opposite coast, researchers are using a similar drug to rewire long-held memories in mice facing another kind of mental challenge: drug addiction. Neurobiologist Marcelo Wood of the University of California, Irvine coaxes cocaine-seeking mice to view the sights and sounds they’ve learned to associate with getting cocaine. He then creates a new, harmless memory around those cues. After a single treatment, mice placed near their drug den forget their cravings. Though Tsai and Wood use different drugs in their studies, both draw on research showing that the ability to learn and remember can be influenced by subtle changes to DNA — changes that affect how genes turn on and off without altering the underlying genetic information. Such epigenetic modifications, it turns out, might have a profound impact on long-term memory. Exploring these methods has opened a growing field of research, called neuroepigenetics, aimed at finding ways to boost memory in humans. Results so far offer the prospect of new types of medication to improve memory and even restore long-forgotten information in disorders such as Alzheimer’s disease, Huntington’s disease or other types of dementia. © Society for Science & the Public 2000 - 2013
By Michelle Roberts Health editor, BBC News online Late nights and lax bedtime routines can blunt young children's minds, research suggests. The findings on sleep patterns and brain power come from a UK study of more than 11,000 seven-year-olds. Youngsters who had no regular bedtime or who went to bed later than 21:00 had lower scores for reading and maths. Lack of sleep may disrupt natural body rhythms and impair how well the brain learns new information say the study authors. They gathered data on the children at the ages of three, five and then seven to find out how well they were doing with their learning and whether this might be related to their sleeping habits. Erratic bedtimes were most common at the age of three, when around one in five of the children went to bed at varying times. By the age of seven, more than half the children had a regular bedtime of between 19:30 and 20:30. Overall, children who had never had regular bedtimes tended to fare worse than their peers in terms of test scores for reading, maths and spatial awareness. The impact was more obvious throughout early childhood in girls than in boys and appeared to be cumulative. BBC © 2013
Research from the National Institutes of Health has identified neural circuits in mice that are involved in the ability to learn and alter behaviors. The findings help to explain the brain processes that govern choice and the ability to adapt behavior based on the end results. Researchers think this might provide insight into patterns of compulsive behavior such as alcoholism and other addictions. “Much remains to be understood about exactly how the brain strikes the balance between learning a behavioral response that is consistently rewarded, versus retaining the flexibility to switch to a new, better response,” said Kenneth R. Warren, Ph.D., acting director of the National Institute on Alcohol Abuse and Alcoholism. “These findings give new insight into the process and how it can go awry.” The study, published online in Nature Neuroscience, indicates that specific circuits in the forebrain play a critical role in choice and adaptive learning. Like other addictions, alcoholism is a disease in which voluntary control of behavior progressively diminishes and unwanted actions eventually become compulsive. It is thought that the normal brain processes involved in completing everyday activities become redirected toward finding and abusing alcohol. Researchers used a simple choice task in which mice viewed images on a computer touchscreen and learned to touch a specific image with their nose to get a food reward. Using various techniques to visualize and record neural activity, researchers found that as the mice learned to consistently make a choice, the brain’s dorsal striatum was activated. The dorsal striatum is thought to play an important role in motivation, decision-making, and reward.
By Jessica Wright and SFARI.org With the right incentive, such as winning a prize, children with autism do fairly well at inferring the thoughts and beliefs of others, according to a study published in the May issue of Developmental Science. Research has shown that children with autism usually struggle with a widely used test designed to gauge this ability, called theory of mind. The new study suggests that they are able to grasp theory of mind, but don’t have a strong motivation to give the correct answer when taking the classic test. The particulars of the test vary, but children are generally told a story in which two characters (often called Sally and Ann) place an object in a basket. After Sally leaves the room, Ann moves the item into a box. The child passes the test if he or she knows that Sally will look for the item in the basket and not the box. Typical children struggle with this test as 3-year-olds, but most pass it by 5 years of age. The majority of children with autism continue to fail the test well into their teenage years. Adults with autism are usually able to pass the Sally-Ann test, as it is often called, but struggle with more subtle examples of theory of mind. In the new study, the researchers revised the Sally-Ann test into a game. For typically developing children, the motivation to answer a question correctly may be tied to a desire for social interactions. In contrast, children with autism may use theory of mind when they want something concrete, for example when competing for things with a sibling, the researchers say. © 2013 Scientific American,
By Helen Briggs BBC News Keeping mentally active by reading books or writing letters helps protect the brain in old age, a study suggests. A lifetime of mental challenges leads to slower cognitive decline after factoring out dementia's impact on the brain, US researchers say. The study, published in Neurology, adds weight to the idea that dementia onset can be delayed by lifestyle factors. An Alzheimer's charity said the best way to lower dementia risk was to eat a balanced diet, exercise and stay slim. In a US study, 294 people over the age of 55 were given tests that measured memory and thinking, every year for about six years until their deaths. They also answered a questionnaire about whether they read books, wrote letters and took part in other activities linked to mental stimulation during childhood, adolescence, middle age, and in later life. After death, their brains were examined for evidence of the physical signs of dementia, such as brain lesions and plaques. The study found that after factoring out the impact of those signs, those who had a record of keeping the brain busy had a rate of cognitive decline estimated at 15% slower than those who did not. Dr Robert Wilson, of Rush University Medical Center in Chicago, who led the study, said the research suggested exercising the brain across a lifetime was important for brain health in old age. BBC © 2013
By Christie Aschwanden, It’s a thought that crosses many middle-aged minds when a word is forgotten or a set of keys misplaced: Is this a fluke, or the first sign of dementia? “Most of us will experience some cognitive changes with age,” says Molly Wagster, chief of the behavioral and systems neuroscience branch of the National Institute on Aging, who likens the mental change to the slowing of a marathon runner’s times with advancing years. The ability to call up words is one of the first things to slip. “You might find it more difficult to recall someone’s name or the name of a book you read or favorite movie. Eventually, you’ll remember it, but it takes a little longer,” Wagster says. Such problems are irritating and frustrating, but they’re usually not a sign that your mind is going, Wagster says. “There are a lot of things that have some evidence behind them, but it’s hard to find interventions that have convincing evidence behind them,” says Victor Henderson, a neurologist who studies cognitive aging at Stanford University Medical School. Physical activity seems like the most promising thing you can do to keep your brain at its best, Henderson says. The evidence comes mostly from observational studies rather than the randomized, controlled trials that are considered the gold standard, but it’s consistent: People who engage in aerobic activity — for instance, walking several times per week — show improvements in their cognitive function, particularly in their ability to switch quickly from task to task, Wagster says. © 1996-2013 The Washington Post