Chapter 17. Learning and Memory
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By Neuroskeptic According to British biochemist Donald R. Forsdyke in a new paper in Biological Theory, the existence of people who seem to be missing most of their brain tissue calls into question some of the “cherished assumptions” of neuroscience. I’m not so sure. Forsdyke discusses the disease called hydrocephalus (‘water on the brain’). Some people who suffer from this condition as children are cured thanks to prompt treatment. Remarkably, in some cases, these post-hydrocephalics turn out to have grossly abnormal brain structure: huge swathes of their brain tissue are missing, replaced by fluid. Even more remarkably, in some cases, these people have normal intelligence and display no obvious symptoms, despite their brains being mostly water. This phenomenon was first noted by a British pediatrician called John Lorber. Lorber never published his observations in a scientific journal, although a documentary was made about them. However, his work was famously discussed in Science in 1980 by Lewin in an article called “Is Your Brain Really Necessary?“. There have been a number of other more recent published cases. Forsdyke argues that such cases pose a problem for mainstream neuroscience. If a post-hydrocephalic brain can store the same amount of information as a normal brain, he says, then “brain size does not scale with information quantity”, therefore, “it would seem timely to look anew at possible ways our brains might store their information.”
Chris Woolston A study that did not find cognitive benefits of musical training for young children triggered a “media firestorm”. Researchers often complain about inaccurate science stories in the popular press, but few air their grievances in a journal. Samuel Mehr, a PhD student at Harvard University in Cambridge, Massachusetts, discussed in a Frontiers in Psychology article1 some examples of media missteps from his own field — the effects of music on cognition. The opinion piece gained widespread attention online. Arseny Khakhalin, a neuroscientist at Bard College in Annandale-on-Hudson, New York, tweeted: Mehr gained first-hand experience of the media as the first author of a 2013 study in PLoS ONE2. The study involved two randomized, controlled trials of a total of 74 four-year-olds. For children who did six weeks of music classes, there was no sign that musical activities improved scores on specific cognitive tests compared to children who did six weeks of art projects or took part in no organized activities. The authors cautioned, however, that the lack of effect of the music classes could have been a result of how they did the studies. The intervention in the trials was brief and not especially intensive — the children mainly sang songs and played with rhythm instruments — and older children might have had a different response than the four-year-olds. There are many possible benefits of musical training, Mehr said in an interview, but finding them was beyond the scope of the study. © 2015 Nature Publishing Group
Kashmira Gander Performing well at school and going on to have a complex job could lower the risk of dementia, scientists have found. On the contrary, loneliness, watching too much TV and a sedentary lifestyle can make a person’s cognitive abilities decline more quickly, according to new research being presented to experts at the international Alzheimer's Association International Conference in Washington DC. Researchers are also due to show attendees the results from trials Solanezumab – believed to be the first drug to halt the progression of the disease if a patient is diagnosed early enough. One study involving 7,500 people aged 65 and above in Sweden over a 20-year period showed that dementia rates were 21 per cent higher in those whose grades were in the bottom fifth of the population. Meanwhile, participants with complex jobs involving data and numbers saw their chance of developing the disease cut by 23 per cent. Read more: Why fish oil pills may not be so healthy after all Proof that dementia risk can be reduced by improving lifestyle Charity warns of a 'worrying' lack of support for dementia patients Dementia research: Drug firms despair of finding cure and withdraw funding after a catalogue of failures For separate study in Sweden, scientists followed the lives of 440 people aged 75 or over for nine years, and discovered that those in the bottom fifth for school grades were found to have a 50 per cent increase in the risk of developing dementia. © independent.co.uk
by Sarah Zielinski It may not be polite to eavesdrop, but sometimes, listening in on others’ conversations can provide valuable information. And in this way, humans are like most other species in the animal world, where eavesdropping is a common way of gathering information about potential dangers. Because alarm calls can vary from species to species, scientists have assumed that eavesdropping on these calls of “danger!” requires some kind of learning. Evidence of that learning has been scant, though. The only study to look at this topic tested five golden-mantled ground squirrels and found that the animals may have learned to recognize previously unknown alarm calls. But the experiment couldn’t rule out other explanations for the squirrels’ behavior, such as that the animals had simply become more wary in general. So Robert Magrath and colleagues at Australian National University in Canberra turned to small Australian birds called superb fairy-wrens. In the wild, these birds will flee to safety when they hear unfamiliar sounds that sound like their own alarm calls, but not when they hear alarm calls that sound different from their own. There’s an exception, though: They’ll take to cover in response to the alarm calls of other species that are common where they live. That suggests the birds learn to recognize those calls. In the lab, the team played the alarm call from a thornbill or a synthetic alarm call for 10 fairy-wrens. The birds didn’t respond to the noise. Then the birds went through two days of training in which the alarm call was played as a mock predator glided overhead. Another group of birds heard the calls but there was no pretend predator. © Society for Science & the Public 2000 - 2015
By Claire Asher Even fish have role models. In a new study, researchers paired up inexperienced fathead minnows (Pimephales promelas, pictured) with two types of mentors: a minnow raised in an environment free of predators or a minnow raised in a dangerous one simulated by the odors of predatory pike and sturgeon. Fish from dangerous environments were fearful of the smell of both unknown and familiar predators, whereas fish that grew up in safety hid when they smelled a known predator but were curious about new smells. Both types of fish passed on their fears to their protégés: Minnows that spent time with fish raised in dangerous environments were scared of all smells they came across, but those that learned from fish raised in safety feared only specific predators and took new experiences in stride, the team reports online this week in the Proceedings of the Royal Society B. The authors say this is the first experiment to show that environment can influence the social transmission of fear and reveals how risk aversion can be learned. The researchers also suggest their study may shed light on how fear disorders such as post-traumatic stress disorder (PTSD) develop in humans, which research shows can be influenced by social environment; PTSD symptoms can be acquired from friends or family who have suffered trauma, for example. © 2015 American Association for the Advancement of Science
By Emily Underwood Glance at a runner's wrist or smartphone, and you'll likely find a GPS-enabled app or gadget ticking off miles and minutes as she tries to break her personal record. Long before FitBit or MapMyRun, however, the brain evolved its own system for tracking where we go. Now, scientists have discovered a key component of this ancient navigational system in rats: a group of neurons called "speed cells" that alter their firing rates with the pace at which the rodents run. The findings may help explain how the brain maintains a constantly updated map of our surroundings. In the 1970s, neuroscientist John O'Keefe, now at University College London, discovered neurons called place cells, which fire whenever a rat enters a specific location. Thirty-five years later, neuroscientists May-Britt and Edvard Moser, now at the Norwegian University of Science and Technology in Trondheim, Norway, discovered a separate group of neurons, called grid cells, which fire at regular intervals as rats traverse an open area, creating a hexagonal grid with coordinates similar to those in GPS. The Mosers and O'Keefe shared last year's Nobel Prize in Physiology and Medicine for their findings, which hint at how the brain constructs a mental map of an animal's environment. Still mysterious, however, is how grid and place cells obtain the information that every GPS system requires: the angle and speed of an object's movement relative to a known starting point, says Edvard Moser, co-author of the new study along with May-Britt Moser, his spouse and collaborator. If the brain does indeed contain a dynamic, internal map of the world, "there has to be a speed signal" that tells the network how far an animal has moved in a given period of time, he says. © 2015 American Association for the Advancement of Science.
Keyword: Learning & Memory
Link ID: 21178 - Posted: 07.16.2015
OLIVER SACHGAU Marc Lewis spends a lot of his time thinking about addiction. He has good reason to: In his 20s he struggled with his own addiction to opiates. He was eventually able to quit, and began researching addiction and neuroscience. Mr. Lewis became a professor of developmental psychology at the University of Toronto in 1989, and moved to Radboud University in the Netherlands in 2010. His new book, The Biology of Desire: Why Addiction is Not a Disease, looks at the neuroscience of addiction, mixing personal narratives with scientific data. The book will be released in Canada on Aug. 4. You argue addiction is not a disease, but an example of very normal brain activity. What do you mean? [It’s] an exaggerated form of learning. Let’s put it that way. People in neuroscience agree that addiction corresponds with brain changes, and that’s the basis of the disease argument: That addiction changes the brain, or hijacks the brain, as they say. As though it were a pathology or disease process. Whereas I argue that all learning changes – the brain is designed to change – but when you have highly motivated learning, especially something that gets repeated over and over, then the learning curve rises extremely rapidly, and you have a kind of exaggerated learning phenomenon, where the learning is deep and specialized, and blots out other available habits or other available perceptions. You chose to mix hard scientific data with these anecdotal stories. How come? I love that way of writing. It seems to me so amazing that brain changes are going on at the same time as lived experiences: The moment-to-moment changes of thoughts and feelings are completely yoked to changes and activity in your brain, but it’s almost impossible to tell both stories at the same time, because one is under the skin, in terms of cell firings and electrochemical impulses and stuff, and the other one is in terms of behavior and human values and norms and so forth. © Copyright 2015 The Globe and Mail Inc
Zoë Corbyn Jesper Noehr, 30, reels off the ingredients in the chemical cocktail he’s been taking every day before work for the past six months. It’s a mixture of exotic dietary supplements and research chemicals that he says gives him an edge in his job without ill effects: better memory, more clarity and focus and enhanced problem-solving abilities. “I can keep a lot of things on my mind at once,” says Noehr, who is chief technology officer for a San Francisco startup. The chemicals he takes, dubbed nootropics from the Greek “noos” for “mind”, are intended to safely improve cognitive functioning. They must not be harmful, have significant side-effects or be addictive. That means well-known “smart drugs” such as the prescription-only stimulants Adderall and Ritalin, popular with swotting university students, are out. What’s left under the nootropic umbrella is a dizzying array of over-the-counter supplements, prescription drugs and unclassified research chemicals, some of which are being trialled in older people with fading cognition. There is no official data on their usage, but nootropics as well as other smart drugs appear popular in the Silicon Valley. “I would say that most tech companies will have at least one person on something,” says Noehr. It is a hotbed of interest because it is a mentally competitive environment, says Jesse Lawler, a LA based software developer and nootropics enthusiast who produces the podcast Smart Drug Smarts. “They really see this as translating into dollars.” But Silicon Valley types also do care about safely enhancing their most prized asset – their brains – which can give nootropics an added appeal, he says. © 2015 Guardian News and Media Limited
By Sarah C. P. Williams The next time you forget where you left your car keys, you might be able blame an immune protein that builds up in your blood as you age. The protein impairs the formation of new brain cells and contributes to age-related memory loss—at least in mice, according to a new study. Blocking it could help prevent run-of-the-mill memory decline or treat cognitive disorders, the researchers say. “The findings are really exciting,” says neurologist Dena Dubal of the University of California, San Francisco (UCSF), who was not involved in the study. “The importance of this work cannot be underestimated as the world’s population is aging rapidly.” Multiple groups of scientists have shown that adding the blood of older mice to younger animals’ bodies makes them sluggish, weaker, and more forgetful. Likewise, young blood can restore the memory and energy of older mice. Neuroscientist Saul Villeda of UCSF homed in on one actor he thought might be responsible for some of that effect: β2 microglobulin (B2M), an immune protein normally involved in distinguishing one’s own cells from invading pathogens. B2M has also been found at increased levels in patients with Alzheimer’s disease and other cognitive disorders. Villeda and his colleagues first measured B2M levels in the blood of both people and mice of different ages; they found that those levels increased with age. When the researchers injected B2M into 3-month-old mice, the young animals suddenly had trouble remembering how to complete a water maze, making more than twice as many errors after they’d already been trained to navigate the maze. Moreover, their brains had fewer new neurons than other mice. Thirty days later, however, when the protein had been cleared from their bodies, the animals' memory troubles were gone as well, and the number of newly formed brain cells was back to normal. © 2015 American Association for the Advancement of Science
By Michael T. Ullman and Mariel Y. Pullman The human brain possesses an incredible capacity to adapt to new conditions. This plasticity enables us not only to constantly learn but also to overcome brain injury and loss of function. Take away one capability, and little by little we often compensate for these deficits. Our brain may be especially well suited to overcome limitations in the case of psychiatric or neurological conditions that originate early in life, what clinicians call neurodevelopmental disorders. Given the brain's considerable plasticity during early years, children with these disorders may have particular advantages in learning compensatory strategies. It now appears that a single brain system—declarative memory—can pick up slack for many kinds of problems across multiple neurodevelopmental disorders. This system, rooted in the brain's hippocampus, is what we typically refer to when we think of learning and memory. It allows us to memorize facts and names or recall a first grade teacher or a shopping list. Whereas other memory systems are more specialized—helping us learn movements or recall emotional events, for instance—declarative memory absorbs and retains a much broader range of knowledge. In fact, it may allow us to learn just about anything. Given declarative memory's powerful role in learning, one might expect it to help individuals acquire all kinds of compensatory strategies—as long as it remains functional. Indeed, research suggests that it not only remains largely intact but also compensates for diverse impairments in five common conditions that are rarely studied in conjunction: autism spectrum disorder, obsessive-compulsive disorder (OCD), Tourette's syndrome, dyslexia and developmental language disorder (which is often referred to as specific language impairment, or SLI). © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 21143 - Posted: 07.07.2015
By David Robson William’s internal clock is eternally jammed at 13:40 on 14 March 2005 – right in the middle of a dentist appointment. A member of the British Armed Forces, he had returned to his post in Germany the night before after attending his grandfather’s funeral. He had gym in the morning, where he played volleyball for 45 minutes. He then entered his office to clear a backlog of emails, before heading to the dentist’s for root-canal surgery. “I remember getting into the chair and the dentist inserting the local anaesthetic,” he tells me. After that? A complete blank. It is as if all new memories are being written in invisible ink that slowly disappears. Since then, he has been unable to remember almost anything for longer than 90 minutes. So while he can still tell me about the first time he met the Duke of York for a briefing at the Ministry of Defence, he can’t even remember where he’s living now; he wakes up every morning believing he is still in Germany in 2005, waiting to visit the dentist. Without a record of new experiences, the passing of time means nothing to him. Today, he only knows that there is a problem because he and his wife have written detailed notes on his smartphone, in a file labelled “First thing – read this”. It is as if all new memories are being written in invisible ink that slowly disappears. How could minor dental work have affected his brain in such a profound way? This real-life medical mystery offers a rare glimpse at the hidden depths of the brain’s workings. © 2015 BBC.
Keyword: Learning & Memory
Link ID: 21137 - Posted: 07.06.2015
By SINDYA N. BHANOO Learning can be traced back to individual neurons in the brain, according to a new study. “What we wanted to do was see if we could actually create a new association — a memory — and see if we would be able to see actual change in the neurons,” said Matias Ison, a neuroscientist at the University of Leicester in England and one of the study’s authors. He and his colleagues were able to monitor the brain activity of neurosurgical patients at UCLA Medical Center. The patients already had electrodes implanted in their medial temporal lobes for clinical reasons. The patients were first presented with images of notable people — like Jennifer Aniston, Clint Eastwood and Halle Berry. Then, they were shown images of the same people against different backdrops — like the Eiffel Tower, the Leaning Tower of Pisa and the Sydney Opera House. The same neurons that fired for the images of each of the actors also fired when patients were shown the associated landmark images. In other words, the researchers were able to watch as the patients’ neurons recorded a new memory — not just of a particular person, but of the person at a particular place. © 2015 The New York Times Company
Keyword: Learning & Memory
Link ID: 21126 - Posted: 07.02.2015
Jon Hamilton If you run into an old friend at the train station, your brain will probably form a memory of the experience. And that memory will forever link the person you saw with the place where you saw them. For the first time, researchers have been able to see that sort of link being created in people's brains, according to a study published Wednesday in the journal Neuron. The process involves neurons in one area of the brain that change their behavior as soon as someone associates a particular person with a specific place. "This type of study helps us understand the neural code that serves memory," says Itzhak Fried, an author of the paper and head of the Cognitive Neurophysiology Laboratory at UCLA. It also could help explain how diseases like Alzheimer's make it harder for people to form new memories, Fried says. The research is an extension of work that began more than a decade ago. That's when scientists discovered special neurons in the medial temporal lobe that respond only to a specific place, or a particular person, like the actress Jennifer Aniston. The experiment used a fake photo of actor Clint Eastwood and Pisa's leaning tower to test how the brain links person and place. More recently, researchers realized that some of these special neurons would respond to two people, but only if the people were connected somehow. For example, "a neuron that was responding to Jennifer Aniston was also responding to pictures of Lisa Kudrow," [another actress on the TV series Friends], says Matias Ison of the University of Leicester in the U.K. © 2015 NPR
By Erika Beras Marijuana is the drug of choice for people who drink alcohol. And people who use both are twice as likely to do so at the same time than to indulge in just one or the other. That’s according to a study in the journal Alcoholism: Clinical and Experimental Research. [Meenakshi S. Subbaraman and William C. Kerr, Simultaneous Versus Concurrent Use of Alcohol and Cannabis in the National Alcohol Survey The data came from self-reported answers that more than 8,600 people provided to what’s called the National Alcohol Surveys, done by phone in 2005 and 2010. People who used pot and alcohol were about twice as likely to drive drunk than those who just drank. And they doubled their chances of what are referred to as negative social consequences, such as arrests, fights and job problems. Meanwhile, another new study finds that if you’re chronically stoned, you’re more likely to remember things differently from how they happened, or not at all. Researchers showed a series of words to people who do not use marijuana and to regular pot users who had not partaken in a month. A few minutes later, all participants were shown the same list of words along with other words. The volunteers were then asked to identify only the original words. The pot smokers thought more of the new words were in the original list than did the nonusers. And brain scans revealed that the regular pot users showed less activity in brain regions associated with memory and cognitive resources than did the nonusers. The study is in the journal Molecular Psychiatry. [J. Riba et al, Telling true from false: cannabis users show increased susceptibility to false memories] © 2015 Scientific American
By Ariana Eunjung Cha One of the most heartbreaking things about Alzheimer's is that it has been impossible for doctors to predict who will get it before symptoms begin. And without early detection, researchers say, a treatment or cure may be impossible. Governments, drug companies and private foundations have poured huge amounts of money into trying to come up with novel ways to detect risk through cutting-edge technologies ranging from brain imaging, protein analysis of cerebrospinal fluid and DNA profiling. Now a new study, published in the journal Neurology, shows that perhaps something more old-fashioned could be the answer: a memory test. The researchers tracked 2,125 participants in four Chicago neighborhoods for 18 years, giving them tests of memory and thinking every three years. They found that those who scored lowest on the tests during the first year were 10 times more likely to be diagnosed with Alzheimer's down the road -- indicating that cognitive impairment may be affecting the brain "substantially earlier than previously established," the researchers wrote.
By Sunnie Huang, CBC News The story of a Newfoundland man who was struck by a moose but doesn't remember it is not just a curious tale of luck. It also highlights the complex underpinnings of human memory, a neuroscience expert says. Stephen Bromley, from Conche, N.L., struck a moose with his car on Monday, but said he had no recollection it, even days after the collision. It's not the first time that something was amiss about human memory after a moose encounter. hi-moose-car-2012 Michelle Higgins said the roof of her car was peeled back "like a sardine can" after she struck a moose. Another Newfoundlander drove about 40 kilometres with her car's roof peeled back "like a sardine can" after crashing into a moose in 2012. Three years later, she said she still can't recall the incident. The blackout doesn't surprise Scott Watter, a McMaster University professor who specializes in neuroscience, psychology and behaviour. "They are lucky in that sense, but it doesn't seem like a thing that breaks the rules of everything we know about how brains work," he told CBC News. People who sustain head trauma often have poor memory of the event, especially when tested on specific details, Watter said. Also, the more severe the injury gets, the further back the memory loss extends, Watter said. The system at the heart of our memory is a seahorse-shaped section of the brain called the hippocampus, Watter explained. It's responsible for linking different parts of human experience to form a coherent memory. In the most severe — but rare — cases of hippocampus damage, the person can no longer create or retain new memory, as seen in Christopher Nolan's 2000 box office hit Memento. ©2015 CBC/Radio-Canada.
Keyword: Learning & Memory
Link ID: 21106 - Posted: 06.29.2015
Children who have a good memory are better at telling lies, say child psychology researchers. They tested six and seven-year-olds who were given an opportunity to cheat in a trivia game and then lie about their actions. Children who were good liars performed better in tests of verbal memory - the number of words they could remember. This means they are good at juggling lots of information, even if they do tell the odd fib. Writing in the Journal of Experimental Child Psychology, researchers from the Universities of North Florida, Sheffield and Stirling, recruited 114 children from four British schools for their experiment. Using hidden cameras during a question-and-answer game, they were able to identify the children who peeked at the answer to a fictitious question, even though they were told not to. A potentially surprising finding (for parents) is that only a quarter of the children cheated by looking at the answer. Further questioning allowed the researchers to work out who was a good liar or a bad liar. They were particularly interested in children's ability to maintain a good cover story for their lie. In separate memory tests, the good liars showed they had a better working memory for words - but they didn't show any evidence of being better at remembering pictures (visuo-spatial memory). The researchers said this was because lying involves keeping track of lots of verbal information, whereas keeping track of images is less important. © 2015 BBC
Helen Shen Boosting activity in neurons that have stored happy memories might help to treat depression — at least according to results in mice. In a study published today (17 June) in Nature, neuroscientist Susumu Tonegawa and his colleagues at the Massachusetts Institute of Technology in Cambridge report how they reversed a depression-like state in rodents by using light to stimulate clusters of brain cells believed to have stored memories of a positive experience1. The findings are preliminary, but they hint that areas of the brain involved in storing memories could one day be a target to treat mental disorders in humans, says Tonegawa. “I want to be very careful not to give false expectations to patients. We are doing very basic science,” he adds. “This is exactly the type of work that psychiatry needs right now,” says Robert Malenka, a behavioural scientist at Stanford University in California. “This is an elegant paper.” The work has grown out of studies by Tonegawa’s lab and others that aimed to locate the memory ‘engram’ — the physical trace of a memory, thought to be encoded in an ensemble of neurons2–6. In 2012, Tonegawa and his team provided one of the clearest demonstrations of an engram. They engineered mice with light-sensitive proteins that were expressed when neurons fired. As a result, they could track any neurons that activated while the mice were given a fearful memory by being trained with repeated electric shocks to be scared of a cage3. The researchers later used blue flashes of light to make the same neurons fire again — a technique known as optogenetics — and found that they could make the animals freeze up, presumably because the fearful memory had been reawoken. © 2015 Nature Publishing Group
You remember your first kiss. You remember your childhood phone number, where you parked your car, and the last time you got really drunk. You probably remember the digits of pi, or at least the first three of them (slacker). Each day you accumulate fresh memories—kissing new people, acquiring different phone numbers and (possibly) competing in pi-memorizing championships (we would root for you). With all those new adventures stacking up, you might start worrying that your brain is growing full. But, wait—is that how it works? Can your brain run out of space, like a hard drive? It depends on what kind of memory you’re talking about. “It’s not like each memory takes a cell and then that cell is used up,” says Nelson Cowan, cognitive psychologist at the University of Missouri. Over the long term, memories are encoded in neural patterns—circuits of connected neurons. And your brain’s ability to knit together new patterns is limitless, so theoretically the number of memories stored in those patterns is limitless as well. Memories don’t always keep to themselves, though. They can crossbreed, like similar but distinct species, creating the recollection equivalent of a mule. If you can’t remember it, a memory is pretty much worthless—and similar memories can interfere with each other, getting in the way of surfacing the right one. Though memory interference is well documented, researchers like Cowan are still guessing at the phenomenon’s neural mechanics.
Keyword: Learning & Memory
Link ID: 21061 - Posted: 06.17.2015
By Nicholas Bakalar Statins, the widely used cholesterol-lowering drugs, have been blamed for memory loss, but a new study suggests that the association is an illusion. The report, in JAMA Internal Medicine, found that the apparent association was likely a result of detection bias — visiting the doctor and starting a new medicine makes people more acutely aware of health issues they might otherwise not notice. Researchers compared 482,543 statin users with the same number of people using no lipid-lowering drugs and with 26,484 people using non-statin lipid lowering drugs. Use of statin drugs was associated with an increase in memory loss during the first 30 days of starting the drugs compared with people who did not take cholesterol-lowering drugs. But so was use of non-statin lipid-lowering drugs. After accounting for many health and behavioral variables, the scientists concluded that either all lipid lowering drugs, statins or not, cause memory loss or, more likely, that previous findings were based on the expectations of the patients rather than any physiological effect of the medicine. “As you think about whether you should be taking statins, there are questions about uncommon side effects worth raising,” said the lead author, Dr. Brian L. Strom, chancellor of Rutgers Biomedical and Health Sciences. “But the question of impairing memory is a nonissue.” © 2015 The New York Times Company
Keyword: Learning & Memory
Link ID: 21047 - Posted: 06.15.2015