Chapter 17. Learning and Memory
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Patricia Neighmond Losing your ability to think and remember is pretty scary. We know the risk of dementia increases with age. But if you have memory lapses, you probably needn't worry. There are pretty clear differences between signs of dementia and age-related memory loss. After age 50, it's quite common to have trouble remembering the names of people, places and things quickly, says Dr. Kirk Daffner, chief of the division of cognitive and behavioral neurology at Brigham and Women's Hospital in Boston. The brain ages just like the rest of the body. Certain parts shrink, especially areas in the brain that are important to learning, memory and planning. Changes in brain cells can affect communication between different regions of the brain. And blood flow can be reduced as arteries narrow. Simply put, this exquisitely complex organ just isn't functioning like it used to. Forgetting the name of an actor in a favorite movie, for example, is nothing to worry about. But if you forget the plot of the movie or don't remember even seeing it, that's far more concerning, Daffner says. When you forget entire experiences, he says, that's "a red flag that something more serious may be involved." Forgetting how to operate a familiar object like a microwave oven or forgetting how to drive to the house of a friend you've visited many times before can also be signs something is wrong. © 2016 npr
By R. Douglas Fields We all heard the warning as kids: “That TV will rot your brain!” You may even find yourself repeating the threat when you see young eyes glued to the tube instead of exploring the real world. The parental scolding dates back to the black-and-white days of I Love Lucy, and today concern is growing amid a flood of video streaming on portable devices. But are young minds really being harmed? With brain imaging, the effects of regular TV viewing on a child's neural circuits are plain to see. Studies suggest watching television for prolonged periods changes the anatomical structure of a child's brain and lowers verbal abilities. Behaviorally, even more detrimental effects may exist: although a cause-and-effect relation is hard to prove, higher rates of antisocial behavior, obesity and mental health problems correlate with hours in front of the set. Now a new study hits the pause button on this line of thinking. The researchers conclude that the entire body of research up to now has overlooked an important confounding variable, heredity, that could call into question the conventional wisdom that TV is bad for the brain. Further study will be needed to evaluate this claim, but the combined evidence suggests we need a more nuanced attitude toward our viewing habits. To understand the argument against television, we should rewind to 2013, when a team ofresearchers at Tohoku University in Japan, led by neuroscientist Hikaru Takeuchi, first published findings from a study in which the brains of 290 children between the ages of five and 18 were imaged. The kids' TV viewing habits, ranging from zero to four hours each day, were also taken into account. © 2016 Scientific American
By Karen Weintraub Mild cognitive impairment, or M.C.I., is not a disease in itself. Rather, it is a clinical description based on performance on a test of memory and thinking skills. Depending on its cause, mild cognitive impairment is potentially reversible. Poor performance on a cognitive test could be caused by certain medications, sleep apnea, depression or other problems, said Dr. Alvaro Pascual-Leone, a professor of neurology at Harvard Medical School and Beth Israel Deaconess Medical Center. In those cases, when the underlying disease is treated, cognitive abilities can bounce back. But in about half of people with M.C.I. – doctors are not sure of the exact number — memory problems are the first sign of impending Alzheimer’s disease. If M.C.I. progresses to Alzheimer’s, there is no recovery. Alzheimer’s is marked by an inexorable decline that is always fatal, although the path from the first signs of cognitive impairment to death may take three to 15 years, said Dr. David Knopman, a professor of neurology at the Mayo Clinic in Rochester, Minn. As many as 20 percent to 30 percent of those with M.C.I. who score below but near the cutoff for normal can cross back above in a subsequent cognitive test – perhaps because they are having a better day, he said. But someone whose score is borderline is at higher risk of developing Alzheimer’s than someone who scores higher, said Dr. Knopman, also vice chair of the medical and scientific advisory council of the Alzheimer’s Association. Doctors may be hesitant to label someone with early Alzheimer’s, which can be difficult to diagnose in the early stages, so they often call it mild cognitive impairment instead, said Dr. John C. Morris, a professor of neurology and the director of the Knight Alzheimer's Disease Research Center at Washington University School of Medicine in St. Louis. © 2015 The New York Times Company
Need to remember something important? Take a break. A proper one – no TV or flicking through your phone messages. It seems that resting in a quiet room for 10 minutes without stimulation can boost our ability to remember new information. The effect is particularly strong in people with amnesia, suggesting that they may not have lost the ability to form new memories after all. “A lot of people think the brain is a muscle that needs to be continually stimulated, but perhaps that’s not the best way,” says Michaela Dewar at Heriot-Watt University in Edinburgh, UK. New memories are fragile. They need to be consolidated before being committed to long-term storage, a process thought to happen while we sleep. But at least some consolidation may occur while we’re awake, says Dewar – all you need is a timeout. In 2012, Dewar’s team showed that having a rest helps a person to remember what they were told a few minutes earlier. And the effect seems to last. People who had a 10-minute rest after hearing a story remembered 10 per cent more of it a week later than those who played a spot-the-difference game immediately afterwards. “We dim the lights and ask them to sit in an empty, quiet room, with no mobile phones,” says Dewar. When asked what they had been thinking about afterwards, most volunteers said they had let their minds wander. Now Dewar, along with Michael Craig at the University of Edinburgh and their colleagues, have found that spatial memories can also be consolidated when we rest. © Copyright Reed Business Information Ltd.
By John Bohannon In July 1984, a man broke into the apartment of Jennifer Thompson, a 22-year-old in North Carolina, and threatened her with a knife. She negotiated, convincing him to not kill her. Instead, he raped her and fled. Just hours later, a sketch artist worked with Thompson to create an image of the assailant's face. Then the police showed her a series of mug shots of similar-looking men. Thompson picked out 22-year-old Ronald Cotton, whose photograph was on file because of a robbery committed in his youth. When word reached Cotton that the police were looking for him, he walked into a precinct voluntarily. He was eventually sentenced to life in prison based on Thompson's testimony. Eleven years later, after DNA sequencing technology caught up, samples taken from Thomson's body matched a different man who finally confessed. Cotton was set free. When Thompson first identified Cotton by photo, she was not convinced of her choice. "I think this is the guy," she told the police after several minutes of hesitation. As time went on, she grew surer. By the time Thompson faced Cotton in court a year later, her doubts were gone. She confidently pointed to him as the man who raped her. Because of examples like these, the U.S. justice system has been changing how eyewitnesses are used in criminal cases. Juries are told to discount the value of eyewitness testimony and ignore how confident the witnesses may be about whom they think they saw. Now, a new study of robbery investigations suggests that these changes may be doing more harm than good. © 2015 American Association for the Advancement of Science
Keyword: Learning & Memory
Link ID: 21715 - Posted: 12.22.2015
Megan Scudellari In 1997, physicians in southwest Korea began to offer ultrasound screening for early detection of thyroid cancer. News of the programme spread, and soon physicians around the region began to offer the service. Eventually it went nationwide, piggybacking on a government initiative to screen for other cancers. Hundreds of thousands took the test for just US$30–50. LISTEN James Harkin, a researcher for the British TV trivia show QI, talks to Adam Levy about how he finds facts and myths for the show — and then runs a mini-quiz to see whether the Podcast team can discern science fact from science fiction 00:00 Across the country, detection of thyroid cancer soared, from 5 cases per 100,000 people in 1999 to 70 per 100,000 in 2011. Two-thirds of those diagnosed had their thyroid glands removed and were placed on lifelong drug regimens, both of which carry risks. Such a costly and extensive public-health programme might be expected to save lives. But this one did not. Thyroid cancer is now the most common type of cancer diagnosed in South Korea, but the number of people who die from it has remained exactly the same — about 1 per 100,000. Even when some physicians in Korea realized this, and suggested that thyroid screening be stopped in 2014, the Korean Thyroid Association, a professional society of endocrinologists and thyroid surgeons, argued that screening and treatment were basic human rights. © 2015 Nature Publishing Group,
Human memory is about to get supercharged. A memory prosthesis being trialled next year could not only restore long-term recall but may eventually be used to upload new skills directly to the brain – just like in the film The Matrix. The first trials will involve people with epilepsy. Seizures can sometimes damage the hippocampus, causing the brain to lose its ability to form long-term memories. To repair this ability, Theodore Berger at the University of Southern California and his colleagues used electrodes already implanted in people’s brains as part of epilepsy treatment to record electrical activity associated with memory. The team then developed an algorithm that could predict the neural activity thought to occur when a short-term memory becomes a long-term memory, as it passes through the hippocampus. Early next year, Berger’s team will use this algorithm to instruct the electrodes to predict and then mimic the activity that should occur when long-term memories are formed. “Hopefully, it will repair their long-term memory,” says Berger. Previous studies using animals suggest that the prosthesis might even give people a better memory than they could expect naturally. A similar approach could eventually be used to implant new memories into the brain. Berger’s team recorded brain activity in a rat that had been trained to perform a specific task. The memory prosthesis then replicated that activity in a rat that hadn’t been trained. The second rat was able to learn the task much faster than the first rat – as if it already had some memory of the task. © Copyright Reed Business Information Ltd.
By Elizabeth Pennisi Imagine trying to train wild sea lions—without them ever seeing you. That was Peter Cook's challenge 8 years ago when he was trying to figure out whether poisonous algae were irrevocably damaging the animals’ brains. With a lot of patience and some luck, the comparative neuroscientist from Emory University in Atlanta has succeeded, and the news isn't good. Toxins from the algae mangle a key memory center, likely making it difficult for sick animals to hunt or navigate effectively, Cook and his colleagues report today. "Sea lions can be seen as sentinels of human health," says Kathi Lefebvre, a research biologist at the Northwest Fisheries Science Center in Seattle, Washington, who was not involved with the work. As oceans warm, toxic algae proliferate and cause so-called red tides because the water looks reddish. So "understanding these toxins in wild animals is going to become more important," she says. Red tides are produced by algae called diatoms. They make a toxin called domoic acid, which is consumed by other plankton that in turn become food for fish and other organisms. Predators such as anchovies, sardines, and other schooling fish accumulate this toxin in their bodies. So when algal populations explode, say, because of warming water, domoic acid concentrations increase in these animals to a point that they affect the sea lions that feast on them. Scientists first recognized this problem in 1998, after hundreds of sea lions were found stranded or disoriented along California's coast. Since then, researchers have studied sick and dead sea lions and documented that the toxin causes seizures and damages the brain, sometimes killing the animal. © 2015 American Association for the Advancement of Science.
By Michael M. Torrice, We learn from experience: It sounds like a trite sentiment posted by a friend on Facebook, but neuroscientists would agree. Our interactions with the world around us strengthen and weaken the connections between our neurons, a process that neuroscientists consider to be the cellular mechanism of learning. Now researchers report that boosting signaling of a certain receptor in the brain with a small molecule can enhance these cellular changes and improve learning in people. The findings could lead to new treatments for patients with disorders associated with deficits in learning, such as Alzheimer’s disease and schizophrenia. Through decades of research on how synapses change in animal brains, scientists have found that the N-methyl-d-aspartate receptor (NMDAR) plays a critical role in strengthening synapses during learning. Compounds that increase NMDAR signaling can drive such changes and, as a result, help animals learn new tasks. Robert F. Asarnow at UCLA and colleagues wanted to test whether one such compound, d-cycloserine, would act similarly in people. But neuroscientists measure synapse changes in animals by sticking electrodes into slices of brain tissue to record electrical signals. “Obviously, we don’t do that to our friends,” Asarnow says. So his team used electroencephalography (EEG) to record electrical activity through electrodes stuck to the scalps of its subjects. The team monitored this activity as the subjects watched a certain pattern flash on a screen at high frequency for a couple minutes. Afterward, the subjects showed a spike in EEG activity in their visual cortex when they viewed the pattern at a later time. This suggested a population of neurons had wired themselves together by strengthening their synapses. © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 21684 - Posted: 12.09.2015
by Laura Sanders There’s only so much brainpower to go around, and when the eyes hog it all, the ears suffer. When challenged with a tough visual task, people are less likely to perceive a tone, scientists report in the Dec. 9 Journal of Neuroscience. The results help explain what parents of screen-obsessed teenagers already know. For the study, people heard a tone while searching for a letter on a computer screen. When the letter was easy to find, participants were pretty good at identifying a tone. But when the search got harder, people were less likely to report hearing the sound, a phenomenon called inattentional deafness. Neural responses to the tone were blunted when people worked on a hard visual task, but not when the visual task was easy, researchers found. By showing that a demanding visual job can siphon resources away from hearing, the results suggest that perceptual overload can jump between senses. © Society for Science & the Public 2000 - 2015
By Nicholas Bakalar Watching television may be bad for your brain, a new study suggests. Researchers followed 3,274 people whose average age was 25 at the start of the study for 25 years, using questionnaires every five years to collect data on their physical activity and TV watching habits. At year 25, they administered three tests that measured various aspects of mental acuity. The highest level of TV watching — more than three hours a day most days — was associated with poor performance on all three tests. Compared with those who watched TV the least, those who watched the most had between one-and-a-half and two times the odds of poor performance on the tests, even after adjusting for age, sex, race, educational level, body mass index, smoking, alcohol use, hypertension and diabetes. Those with the lowest levels of physical activity and the highest levels of TV watching were the most likely to have poor test results. The authors acknowledge that their findings, published in JAMA Psychiatry, depend on self-reports, and that they had no baseline tests of cognitive function for comparison. “We can’t separate out what is going on with the TV watching,” said the lead author, Dr. Kristine Yaffe, a professor of psychiatry and neurology at the University of California, San Francisco. “Is it just the inactivity, or is there something about watching TV that’s the opposite of cognitive stimulation?” © 2015 The New York Times Company
Link ID: 21675 - Posted: 12.05.2015
By Nala Rogers If you travel with a group of friends, you might delegate navigation to the person with the best sense of direction. But among homing pigeons, the leader is whoever flies the fastest—even if that pigeon has to pick up navigation skills on the job, according to a new study. To find out how the skills of individual pigeons influence flock direction, researchers tested four flocks on journeys from three different locations, each about 5 kilometers from their home loft near Oxford, U.K. At each site, the researchers tracked the pigeons during solo flights before releasing them together for several group journeys. The fastest birds surged to the front during group flights and determined when the flock turned, despite the fact that these leaders were often poor navigators during their initial solo expeditions. But on a final set of solo flights—made after the group journeys—these same leaders chose straighter routes than followers, the researchers report today in Current Biology. Apparently, being responsible for group decisions helped pigeons learn the route, say scientists, raising questions about the two-way interplay between skills and leadership. © 2015 American Association for the Advancement of Science
By John Bohannon It may sound like a bird-brained idea, but scientists have trained pigeons to spot cancer in images of biopsied tissue. Individually, the avian analysts can't quite match the accuracy of professional pathologists. But as a flock, they did as well as trained humans, according to a new study appearing this week in PLOS ONE. Cancer diagnosis often begins as a visual challenge: Does this lumpy spot in a mammogram image justify a biopsy? And do cells in biopsy slides look malignant or benign? Training doctors and medical technicians to tell the difference is expensive and time-consuming, and computers aren't yet up to the task. To see whether a different type of trainee could do better, a team led by Richard Levenson, a pathologist and technologist at the University of California, Davis, and Edward Wasserman, a psychologist at the University of Iowa, in Iowa City, turned to pigeons. In spite of their limited intellect, the bobble-headed birds have certain advantages. They have excellent visual systems, similar to, if not better than, a human's. They sense five different colors as opposed to our three, and they don’t “fill in” the gaps like we do when expected shapes are missing. However, training animals to do a sophisticated task is tricky. Animals can pick up on unintentional cues from their trainers and other humans that may help them correctly solve problems. For example, a famous 20th century horse named Clever Hans was purportedly able to do simple arithmetic, but was later shown to be observing the reactions of his human audience. And although animals can perform extremely well on tasks that are confined to limited circumstances, overtraining on one set of materials can lead to total inaccuracy when the same information is conveyed slightly differently. © 2015 American Association for the Advancement of Science
By Emilie Reas What makes for a long-lasting memory? Research has shown that emotional or important events take root deeply, whereas neutral or mundane happenings create weak impressions that easily fade. But what about an experience that initially seemed forgettable but was later shown to be important? Animal research suggested that these types of older memories could be strengthened, but scientists had not been able to replicate this finding in humans—until now. New evidence suggests that our initially weak memories are maintained by the brain for a period, during which they can be enhanced. In the recent study published in Nature, psychologists at New York University showed 119 participants a series of images of tools and animals. A few minutes later the subjects saw a new set of images, with an electric shock paired with either the tools or the animals, to increase the salience of just one of those categories. The participants' memories for both sets of images were then tested either immediately, six hours later or the next day. Participants remembered images from the first neutral series better if they belonged to the same category (tool or animal) that was later paired with the shock. The findings suggest that even if an event does not seem meaningful when it occurs, a later cue that the experience was important can enhance the old memory. Although research has not yet demonstrated this effect outside the laboratory, the scientists speculate it happens often in daily life. For example, imagine you meet several new people at a networking event. During a job interview days later, you discover that one of those acquaintances is on the hiring committee, and suddenly the details of your conversation at the networking event become vivid and memorable—whereas the conversations you had with others at the event fade with time. © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 21629 - Posted: 11.12.2015
By Erika Beras From the backseat of a cab, the moves a driver makes may at times seem, let’s say, daring. In fact, cabbies may actually be better, more agile drivers than the rest of us. Because they know their streets so well. Previous research found that the hippocampus in the brain of a typical cab driver is enlarged. That’s the part of the brain used in navigation. But now a study confirms that learning detailed navigation information does indeed cause that part of the brain to grow. The findings are in the journal NeuroImage. Researchers had young adults who were not regular gamers play a driving simulation game. Some practiced maneuvering the same route 20 times, while other players were confronted with 20 different routes. The participants’ brains were scanned before they performed the simulated driving and again after. Researchers found that subjects who kept repeating the same route increased their speed more than those driving multiple routes. The single-route drivers were also much better able to put in order a sequence of random pictures taken along the way and to draw a map of the route. The investigators also found increases in the single-route drivers in the functional connectivity between the hippocampus and other parts of the brain involved with navigation. And the amount of change was directly related to the amount of improvement each participant displayed. © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 21612 - Posted: 11.07.2015
Laura Sanders Specialized cells that make up the brain’s GPS system have an expanding job description. In addition to mapping locations, these cells can keep track of distance and time, too, scientists report in the Nov. 4 Neuron. Those specialized cells, called grid cells, were thought to have a very specific job, says neuroscientist Loren Frank of the University of California, San Francisco. But, he says, the new study says, “not so fast, everybody.” These cells’ ability to detect time and distance is unexpected. “And I think it’s important,” Frank says. The growing to-do list of grid cells shows that the brain’s navigational system is surprisingly flexible. The discovery of grid cells, found in a part of the brain called the entorhinal cortex, was recognized with the Nobel Prize last year (SN Online: 10/6/14). These brain cells fire off regular signals as animals move around in space, partially forming an internal map of the environment. Neuroscientist Howard Eichenbaum of Boston University and colleagues wondered what those cells do when an animal stays put. By training rats to run on a treadmill, the researchers had a way to study grid cells as time and distance marched forward, but location remained the same. Unlike recently discovered “speed cells” (SN: 8/8/15, p. 8), these grid cells don’t change their firing rates to correspond to changes in the rats’ swiftness, the researchers found. Instead, these cells stay tuned to distance or time, or both. © Society for Science & the Public 2000 - 2015.
Keyword: Learning & Memory
Link ID: 21606 - Posted: 11.05.2015
Sara Reardon Military-service members can suffer brain injury and memory loss when exposed to explosions in enclosed spaces, even if they do not sustain overt physical injury. A strategy designed to improve memory by delivering brain stimulation through implanted electrodes is undergoing trials in humans. The US military, which is funding the research, hopes that the approach might help many of the thousands of soldiers who have developed deficits to their long-term memory as a result of head trauma. At the Society for Neuroscience meeting in Chicago, Illinois, on 17–21 October, two teams funded by the Defense Advanced Research Projects Agency presented evidence that such implanted devices can improve a person’s ability to retain memories. By mimicking the electrical patterns that create and store memories, the researchers found that gaps caused by brain injury can be bridged. The findings raise hopes that a ‘neuroprosthetic’ that automatically enhances flagging memory could aid not only brain-injured soldiers, but also people who have had strokes — or even those who have lost some power of recall through normal ageing. Because of the risks associated with surgically placing devices in the brain, both groups are studying people with epilepsy who already have implanted electrodes. The researchers can use these electrodes both to record brain activity and to stimulate specific groups of neurons. Although the ultimate goal is to treat traumatic brain injury, these people might benefit as well, says biological engineer Theodore Berger at the University of Southern California (USC) in Los Angeles. That is because repeated seizures can destroy the brain tissue needed for long-term-memory formation. © 2015 Nature Publishing Group
By Michelle Roberts Health editor, BBC News online Brain training - playing online games that give memory and reasoning skills a workout - is beneficial for older people, a large-scale study has concluded. Researchers at King's College London found the mental exercises kept minds sharp and helped people with everyday skills such as shopping and cooking. Nearly 7,000 people aged 50 and over signed up for the six-month experiment, launched by BBC TV's Bang Goes The Theory. Longer studies are now beginning. The volunteers were recruited from the general population by a partnership between the BBC, the Alzheimer's Society and the Medical Research Council. As far as the investigators were aware, none had any problems with memory or cognition when they signed up to the experiment. Some of the volunteers were encouraged to play online brain training games for 10 minutes at a time, as often as they wished. The others - the control group - were asked to do simple internet searches. The researchers tested the subjects on a series of medically recognised cognitive tests at baseline and then again at three months and six months to see if there was any detectable difference between the groups. The researchers found after six months, those who played "brain training" games for reasoning and problem-solving kept their broader cognitive skills better than those who did not. The benefit appeared to kick in when people played the games at least five times a week. And people over 60 who played these games reported better scores for carrying out essential everyday tasks, the Journal of Post-acute and Long Term Care Medicine reports. © 2015 BBC
When we hear speech, electrical waves in our brain synchronise to the rhythm of the syllables, helping us to understand what’s being said. This happens when we listen to music too, and now we know some brains are better at syncing to the beat than others. Keith Doelling at New York University and his team recorded the brain waves of musicians and non-musicians while listening to music, and found that both groups synchronised two types of low-frequency brain waves, known as delta and theta, to the rhythm of the music. Synchronising our brain waves to music helps us decode it, says Doelling. The electrical waves collect the information from continuous music and break it into smaller chunks that we can process. But for particularly slow music, the non-musicians were less able to synchronise, with some volunteers saying they couldn’t keep track of these slower rhythms. Rather than natural talent, Doelling thinks musicians are more comfortable with slower tempos because of their musical training. As part of his own musical education, he remembers being taught to break down tempo into smaller subdivisions. He suggests that grouping shorter beats together in this way is what helps musicians to process slow music better. One theory is that musicians have heard and played much more music, allowing them to acquire “meta-knowledge”, such as a better understanding of how composers structure pieces. This could help them detect a broader range of tempos, says Usha Goswami of the University of Cambridge. © Copyright Reed Business Information Ltd.
Richard A. Friedman YOU can increase the size of your muscles by pumping iron and improve your stamina with aerobic training. Can you get smarter by exercising — or altering — your brain? Stories from Our Advertisers This is hardly an idle question considering that cognitive decline is a nearly universal feature of aging. Starting at age 55, our hippocampus, a brain region critical to memory, shrinks 1 to 2 percent every year, to say nothing of the fact that one in nine people age 65 and older has Alzheimer’s disease. The number afflicted is expected to grow rapidly as the baby boom generation ages. Given these grim statistics, it’s no wonder that Americans are a captive market for anything, from supposed smart drugs and supplements to brain training, that promises to boost normal mental functioning or to stem its all-too-common decline. The very notion of cognitive enhancement is seductive and plausible. After all, the brain is capable of change and learning at all ages. Our brain has remarkable neuroplasticity; that is, it can remodel and change itself in response to various experiences and injuries. So can it be trained to enhance its own cognitive prowess? The multibillion-dollar brain training industry certainly thinks so and claims that you can increase your memory, attention and reasoning just by playing various mental games. In other words, use your brain in the right way and you’ll get smarter. A few years back, a joint study by BBC and Cambridge University neuroscientists put brain training to the test. Their question was this: Do brain gymnastics actually make you smarter, or do they just make you better at doing a specific task? For example, playing the math puzzle KenKen will obviously make you better at KenKen. But does the effect transfer to another task you haven’t practiced, like a crossword puzzle? © 2015 The New York Times Company