Chapter 17. Learning and Memory
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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
By DOUGLAS QUENQUA For recovering alcoholics, memories associated with drinking — the smell of a bar, ice clinking in a glass — are among the greatest threats to sobriety. But what if retrieval of those memories could be blocked? Using a drug typically given to organ-transplant patients, researchers at the University of California, San Francisco, reduced the incidence of relapse in rats by disrupting memories linked to past drinking. For several weeks the researchers allowed rats to binge on alcohol. Then, after 10 days of abstinence, the rats were exposed to just a drop of alcohol — enough to awaken their memories of drinking. The researchers then used brain scans to identify the neural mechanism responsible for triggering the reactivation of those memories, known as the mTORC1 signaling pathway. Rapamycin, a drug known to disrupt the pathway, was then given to some of the rats. Those that received it were significantly less likely to consume alcohol. “A single administration of this drug prevented relapse for a period of two weeks,” said Dorit Ron, a neuroscientist at the university and an author of the study, which was published in the journal Nature Neuroscience. Just how long the rats might have stayed dry is hard to say, she added, because “two weeks is when we ended the study.” Rapamycin, which is normally used to suppress transplant patients’ immune systems, is already approved by the Food and Drug Administration. But more study is required to determine whether it could help people abstain from alcohol, Dr. Ron said, adding that the drug also has significant side effects, including increased susceptibility to infection. © 2013 The New York Times Company
Helen Shen Wiping out drinking-associated memories could help those with alcohol problems to stay sober, suggests a study in rats. As with other forms of addiction, environmental cues linked to drinking — such as the smell of beer — can trigger the urge to consume alcohol and increase the risk of a relapse into abuse. Over time, these learned associations can be maddeningly difficult to break. Scientists have now identified a potential molecular target in the brains of rats that could one day lead to treatments to help people stay dry. Dorit Ron, a neuroscientist at the University of California, San Francisco (UCSF), and her team show that strategically blocking the mTORC1 signalling pathway reduces alcoholic relapse by disrupting memories linked to past drinking. This pathway controls the production of several proteins associated with learning and memory. A memory is thought to become vulnerable when it is retrieved, like a folder checked out from a library archive1. Pages can be shuffled or lost before the folder is returned to long-term storage. A number of studies have suggested that disrupting the mTORC1 pathway during this time window can destabilize the process of memory restoration and can potentially help treat post-traumatic stress disorder as well as drug addiction. © 2013 Nature Publishing Group,
Zoe Cormier By trawling through data from 35 million users of online ‘brain-training’ tools, researchers have conducted a survey of what they say is the world’s largest data set of human cognitive performance. Their preliminary results show that drinking moderately correlates with better cognitive performance and that sleeping too little or too much has a negative association. The study, published this week in Frontiers in Human Neuroscience1, analysed user data from Lumosity, a collection of web-based games made by Lumos Labs, based in San Francisco, California. Researchers at Lumos conducted the study in collaboration with scientists at two US universities as part of the Human Cognition Project, which the authors describe as “a collaborative research effort to describe the human mind”. The authors examined results from more than 600 million completed tasks — which measured players’ speed, memory capacity and cognitive flexibility — to get a snapshot of how lifestyle factors can affect cognition and how learning ability changes with age. Users who enjoyed one or two alcoholic drinks a day tended to perform better on cognitive tasks than teetotallers and heavier drinkers, whose scores dropped as the number of daily drinks increased. The optimal sleep time was seven hours, with performance worsening for every hour of sleep lost or added. The study authors also looked at performance over time for users who returned to the same brain-training tasks at least 25 times. Performance decreased with age, but the ability to learn new tasks that relied on ‘crystallized knowledge’ (such as vocabulary) did not decline as quickly as it did for those that measured ‘fluid intelligence’ (such as the ability to memorize new sets of information). © 2013 Nature Publishing Group,
Buyer beware. For US$249 a company in the United States is promising to send curious and competitive players of computer games an unusual headset. The device, the company claims, will convert electronic gamers into electronic-gamers. At the touch of a button, the headset will send a surge of electricity through their prefrontal cortex. It promises to increase brain plasticity and make synapses fire faster, to help gamers repel more space invaders and raid more tombs. And, according to the publicity shots on the website, it comes in a choice of red or black. The company is accepting orders, but says that it will not ship its first headsets to customers until next month. Some are unwilling to wait. Videos on the Internet already show people who have cobbled together their own version with a 9-volt battery and some electrical wire. If you are not fussy about the colour scheme, other online firms already promise to supply the components and instructions you need to make your own. Or you could rummage around in the garage. That’s ‘could’ as in ‘you might be able to’, by the way; not ‘could’ as in ‘it’s a good idea’. In fact, to try to boost cognitive performance in this way might be a very bad idea indeed. Would it work? It might or it might not. Nobody knows. All we know for sure is that the technology, known as transcranial direct-current stimulation (tDCS), is likely to soon get into the hands, and onto the heads, of many more people. © 2013 Nature Publishing Group
Keyword: Learning & Memory
Link ID: 18289 - Posted: 06.20.2013
By Elizabeth Landau, CNN Philadelphia (CNN) -- Martha Farah is leaning forward, furiously typing on her thin laptop in her spacious office at the University of Pennsylvania. Awards, paintings and posters lean against the walls on the floor as she puts the final touches on a grant proposal. "I hate it, but I love it!" she exclaims, in a voice that often rises melodically to stress words with enthusiasm. "The adrenaline!" Farah, 57, built a career that has taken many exciting turns. The scope of her work in the field is impressive: She has studied vision, brain-enhancing drugs and socioeconomic influences on the brain, among other topics. Currently, she is the founding director for Penn's Center for Neuroscience and Society. "One of the things that really drew me to her was her interest in applying the tools and insights of cognitive neuroscience to socially relevant questions," said Andrea Heberlein, a former postdoctoral fellow in Farah's lab and current lecturer at Boston College. "How can we make the world better, using these tools?" After completing her undergraduate education at Massachusetts Institute of Technology, Farah studied experimental psychology in the 1970s and '80s at Harvard University, where she earned her Ph.D. The prevailing idea among scientists at the time was that the mind is like computer software and the brain is like the hardware; software would explain "cognitive" phenomena such as memory, problem-solving and information processing. CNN© 2013 Cable News Network
By Nathan Seppa Soccer players who hit the ball with their head a lot don’t score as well on a memory test as players who head the ball less often, a new study finds. Frequent headers are also associated with abnormalities in the white matter of the brain, researchers report June 11 in Radiology. “These changes are subtle,” says Inga Koerte, a radiologist at Harvard Medical School and Brigham and Women’s Hospital in Boston. “But you don’t need a concussive trauma to get changes in the microstructure of your brain.” While soccer players can get concussions from colliding with goal posts, the ground or each other, concussions are uncommon from heading the ball, even though it can move at 80 kilometers per hour, says coauthor Michael Lipton, a neuroradiologist at the Albert Einstein College of Medicine in New York City. He and his colleagues took magnetic resonance imaging scans of 28 men and nine women who played amateur soccer. The players, with an average age of 31, tallied up their games and practice sessions in the previous year and estimated how many headers they had done in each. Most players headed the ball hundreds of times; some hit thousands of headers. The MRIs revealed brain abnormalities in some players, mainly in the white matter of three regions of the brain. White matter coats nerve fibers, and bundles of fibers cross and converge in the three regions. But the areas aren’t associated with a single function, Lipton says. Attention, memory, sensory inputs and visual and spatial functions could all be processed there. © Society for Science & the Public 2000 - 2013
Scientists have discovered more about the role of an important brain protein which is instrumental in translating learning into long-term memories. Writing in Nature Neuroscience, they said further research into the Arc protein's role could help in finding new ways to fight neurological diseases. The same protein may also be a factor in autism, the study said. Recent research found Arc lacking in the brains of Alzheimer's patients. Dr Steve Finkbeiner, professor of neurology and physiology at the University of California, who led the research at Gladstone Institutes, said lab work showed that the role of the Arc protein was crucial. "Scientists knew that Arc was involved in long-term memory, because mice lacking the Arc protein could learn new tasks, but failed to remember them the next day," he said. Further experiments revealed that Arc acted as a "master regulator" of the neurons during the process of long-term memory formation. The study explained that during memory formation, certain genes must be switched on and off at very specific times in order to generate proteins that help neurons lay down new memories. The authors found that it was Arc that directed this process, from inside the nucleus. Dr Finkbeiner said people who lack the protein could have memory problems. BBC © 2013
by Emily Underwood The mushroom clouds produced by more than 500 nuclear bomb tests during the Cold War may have had a silver lining, after all. More than 50 years later, scientists have found a way to use radioactive carbon isotopes released into the atmosphere by nuclear testing to settle a long-standing debate in neuroscience: Does the adult human brain produce new neurons? After working to hone their technique for more than a decade, the researchers report that a small region of the human brain involved in memory makes new neurons throughout our lives—a continuous process of self-renewal that may aid learning. For a long time, scientific dogma held that our brains did not produce new neurons during adulthood, says Pasko Rakic, a neuroscientist at Yale University who was not involved in the study. In 1998, however, a group of Swedish researchers reported the first evidence that neurons are continually born throughout the human lifespan. The researchers injected a compound normally used to label tumor cell division into patients who had agreed to have their brains examined after death. When the scientists examined the postmortem brain tissue, they found that new neurons had indeed sprung forth during adulthood. The cells were located in a part of the hippocampus—a pair of seahorse-shaped structures located deep within the brain and involved in memory and learning. The compound was later found to be toxic, however, and the experiment was never repeated. Since 1998, a number of studies have demonstrated that new neurons are generated in the same small region of the hippocampus in mice and appear to play an important role in memory and learning, says Kirsty Spalding, a molecular biologist at the Karolinska Institute in Stockholm and lead author of the new study. Because the 1998 work was never confirmed by independent research, however, scientists have fiercely argued over whether the neuron birth seen in mice also occurs in people. © 2010 American Association for the Advancement of Science
By Aiden Arnold “…henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union between the two will preserve an independent reality.” This now iconic quote spoken by Hermann Minkowski in 1906 captured the spirit of Albert Einstein’s recently published special theory of relativity. Einstein, in a stroke of mathematical genius, had shown that both space and time as independent mathematical constructs were mere illusions in the equations of relativity, conceding instead to a 4-dimensional construct which Minkowski adroitly termed space-time. While most people are familiar with the ensuing influence Einstein’s ideas had on both the academic and public conception of the physical universe, few people are aware a similar revolution against space and time is underway in the fields of experimental psychology and neuroscience. Spatial cognition is the study of how the mind’s cognitive architecture perceives, organizes and interacts with physical space. It has long been of interest to philosophers and scientists, with perhaps the biggest historical step towards our modern ideas occurring within Immanuel Kant’s Critique of Pure Reason (1781/1787). Kant argued that space as we know it is a preconscious organizing feature of the human mind, a scaffold upon which we’re able to understand the physical world of objects, extension and motion. In a sense, space to Kant was a window into the world, rather than a thing to be perceived in it. © 2013 Scientific American
By Ian Chant Kids are wildly better than adults at most types of learning—most famously, new languages. One reason may be that adults' brains are “full,” in a way. Creating memories relies in part on the destruction of old memories, and recent research finds that adults have high levels of a protein that prevents such forgetting. Whenever we learn something, brain cells become wired together with new synapses, the connections between neurons that enable communication. When a memory fades, those synapses weaken. Researchers led by Joe Tsien, a neuroscientist at the Medical College of Georgia, genetically engineered mice to have high levels of NR2A, part of a receptor on the surface of some neurons that regulates the flow of chemicals such as magnesium and calcium in and out of a cell. NR2A is known to be more prevalent in the brains of mammals as they age. The engineered mice, though young, had adult levels of NR2A, and they showed some difficulty forming long-term memories. More dramatically, their brains could barely weaken their synapses, a process that allows the loss of useless information in favor of more recent data. A similar process may govern short-term memories as well. When you hear a friend ask for coffee, the details of her order don't just slip away in your mind—your brain must produce a protein that actively destroys the synapses encoding that short-term memory, according to a 2010 paper in Cell. Much psychological research supports the idea that forgetting is essential to memory and emotional health. Tsien's new work, published January 8 in Scientific Reports, suggests that older brains hold on to their connections more dearly—which helps to explain why learning is more laborious as we age and why memory trouble later in life so often involves the accidental recall of outdated information. © 2013 Scientific American
By Stuart McMillen A classic experiment into drug addiction science. Would rats choose to take drugs if given a stimulating environment and social company?
Karen Ravn Babies learn to babble before they learn to talk, at first simply repeating individual syllables (as in ba-ba-ba), and later stringing various syllables together (as in ba-da-goo). Songbirds exhibit similar patterns during song-learning, and the capacity for this sort of syllable sequencing is widely believed to be innate and to emerge full-blown — a theory that is challenged by a paper published on Nature's website today1. A study of three species — zebra finches, Bengalese finches and humans — reports that none of the trio has it that easy. Their young all have to learn how to string syllables together slowly, pair by pair. “We discovered a previously unsuspected stage in human vocal development,” says first author Dina Lipkind, a psychologist now at Hunter College in New York. The researchers began by training young zebra finches (Taeniopygia guttata) to sing a song in which three syllables represented by the letters A, B and C came in the order ABC–ABC. They then trained the birds to sing a second song in which the same syllables were strung together in a different order, ACB–ACB. Eight out of seventeen birds managed to learn the second song, but they did not do so in one fell swoop. They learned it as a series of syllable pairs, first, say, learning to go from A to C, then from C to B and finally from B to A. And they didn’t do it overnight, as the innate-sequencing theory predicts. Instead, on average, they learned the first pair in about ten days, the second in four days and the third in two days. © 2013 Nature Publishing Group