Chapter 13. Memory, Learning, and Development
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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
Human DNA is 1 to 2% Neandertal, or more, depending on where your ancestors lived. Svante Pääbo, founder of the field of paleogenetics and winner of a 2016 Breakthrough Prize, explains why that matters © 2015 Scientific American
The town of Yarumal in Colombia is famous for all the wrong reasons: it has the world’s largest population of people with Alzheimer’s disease. In Yarumal and the surrounding state of Antioquia, 5000 people carry a gene mutation which causes early-onset Alzheimer’s – half of them will be diagnosed by the age of 45, and the other half will succumb by the time they are 65. Locals call the disease La Bobera, “the foolishness”, and the village bears uncanny parallels with the fictional Macondo in Gabriel Garcia Marquez’s novel One Hundred Years of Solitude, where people suffer memory disorders and hallucinations. But while Yarumal’s “curse” is well known, no one knew how the mutation first appeared. Now researchers have traced the ancestry of the mutation, concluding that it was probably introduced by a Spanish conquistador early in the 17th century. Ken Kosik at the University of California, Santa Barbara, and colleagues collected blood samples from 102 people in Antioquia and sequenced their genomes. The mutation causing this form of early-onset Alzheimer’s is called E280A and is found in a gene on chromosome 14 – 74 people had the mutation. Because Kosik’s team had information on the genome sequence around the mutation, they could use something called identity-by-descent analysis to determine how the people in the study were related. The analysis suggested the mutation arose from a common ancestor around 375 years ago. © Copyright Reed Business Information Ltd.
By Gretchen Reynolds Sturdy legs could mean healthy brains, according to a new study of British twins. As I frequently have written in this column, exercise may cause robust improvements in brain health and slow age-related declines in memory and thinking. Study after study has shown correlations between physical activity, muscular health and mental acuity, even among people who are quite old. But these studies have limitations and one of them is that some people may be luckier than others. They may have been born to have a more robust brain than someone else. Their genes and early home environment might have influenced their brain health as much as or more than their exercise habits. Their genes and early home environment also might have influenced those exercise habits, as well as how their bodies and brains responded to exercise. In other words, genes and environment can seriously confound experimental results. That problem makes twins so valuable for scientific purposes. (Full disclosure, I am a twin, although not an identical one.) Twins typically share the same early home environment and many of the same genes, and if they are identical, all their genes are the same. So if one twin’s body, brain and thinking abilities begin to differ substantially over the years from their twin’s, the cause is less likely to be solely genetic or the early environment, and more likely to be attributable to lifestyle, including exercise habits. It was that possibility that recently prompted Claire Steves, a senior lecturer in twin research at King’s College London, to consider twins and their thighs. © 2015 The New York Times Company
Link ID: 21641 - Posted: 11.18.2015
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
Laura Sanders In an unexpected twist, two antibodies designed to fight Alzheimer’s disease instead made nerve cells in mice misbehave more. The results, published online November 9 in Nature Neuroscience, highlight how little is known about how these drugs actually work, says study coauthor Marc Aurel Busche of Technical University Munich. “We need to understand what these antibodies do in the brains of patients better,” he says. The treatment approach relies on antibodies that target amyloid-beta, a protein that builds up in the brains of people with Alzheimer’s. One of the antibodies used in the new study, bapineuzumab, failed to show benefits in much-anticipated trials described in the New England Journal of Medicine in 2014. Despite that setback, some researchers say antibodies are still the best option to halt Alzheimer’s. The bapineuzumab trial was flawed, says neurologist Dennis Selkoe of Harvard Medical School and Brigham and Women’s Hospital. And the new results, which come from mice, have little relevance for ongoing tests of other antibodies in people, he says. “A-beta immunotherapy is the most promising approach right now, and nothing in their paper undercuts that,” he says. Several other antibodies have recently shown modest benefits in people with Alzheimer’s, he adds. Representatives from Eli Lilly and Biogen, pharmaceutical companies that are developing antibody treatments, declined to comment on the new study. © Society for Science & the Public 2000 - 2015
By Michelle Roberts Health editor, BBC News online An increasingly warped sense of humour could be an early warning sign of impending dementia, say UK experts. The University College London study involved patients with frontotemporal dementia, with the results appearing in the Journal of Alzheimer's Disease. Questionnaires from the friends and family of the 48 patients revealed many had noticed a change in humour years before the dementia had been diagnosed. This included laughing inappropriately at tragic events. Experts say more studies are now needed to understand how and when changes in humour could act as a red flag for dementia. There are many different types of dementia and frontotemporal dementia is one of the rarer ones. The area of the brain it affects is involved with personality and behaviour, and people who develop this form of dementia can lose their inhibition, become more impulsive and struggle with social situations. Dr Camilla Clark and colleagues recruited 48 patients from their dementia clinic at University College London. And they asked the friends or relatives of the patients to rate their loved one's liking for different kinds of comedy - slapstick comedy such as Mr Bean, satirical comedy such as Yes, Minister or absurdist comedy such as Monty Python - as well as any examples of inappropriate humour. Nearly all of the respondents said, with hindsight, that they had noticed a shift in the nine years before the dementia had been diagnosed. Many of the patients had developed a dark sense of humour - for example, laughing at tragic events in the news or in their personal lives. The dementia patients also tended to prefer slapstick to satirical humour, when compared with 21 healthy people of a similar age. © 2015 BBC.
Link ID: 21617 - Posted: 11.10.2015
by Laura Sanders Babies’ minds are mysterious. Thoughts might be totally different in a brain that lacks words, and sensations might feel alien in a body so new. Are babies’ perceptions like ours, or are they completely different? Even if babies could talk, words would surely fail to convey what it’s like to experience, oh, every single thing for the first time. A recent paper offers a sliver of insight into young babies’ inner lives. The study, published October 19 in Current Biology, finds an example in which 4-month-old babies are happily oblivious to the external world. The research focuses on a perceptual trick that suckers adults and 6-month-old babies alike. When the hands are crossed, people often mistake which hand feels a touch. Let’s say your left hand (now crossed over to the right side of your body) gets a tickle. Your eyes would see a hand on the right side of your body get touched — a place usually claimed by your right hand, but now occupied by your left. Those mismatches between sight, touch and expectation can thwart you from quickly and correctly saying which hand was touched. Here’s the twist: 4-month-old babies don’t fall for this trick, Andrew Bremner of Goldsmiths, University of London and his colleagues found. In the experiment, a researcher would hold infants’ legs in either a crossed position or straight, while one of two remote-controlled buzzers taped to their feet tickled one foot. The researchers then watched which foot or leg wiggled as a result. If the buzzed foot moved, that meant that the baby got it right. © Society for Science & the Public 2000 - 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
By DAVE ITZKOFF and BENEDICT CAREY For the first time in more than a year, the widow of the actor Robin Williams is speaking publicly about the circumstances that preceded Mr. Williams’s death, and sharing details about a disease he had when he died. Stories from Our Advertisers In interviews with People magazine and with ABC News, the widow, Susan Schneider Williams, laid the blame for her husband’s suicide in 2014 not on depression but on diffuse Lewy body dementia. “It was not depression that killed Robin,” Mrs. Williams said in the People magazine interview. “Depression was one of let’s call it 50 symptoms and it was a small one.” She added: “This was a very unique case and I pray to God that it will shed some light on Lewy bodies for the millions of people and their loved ones who are suffering with it. Because we didn’t know. He didn’t know.” Parts of an interview with Mrs. Williams were shown Tuesday on ABC’s “Good Morning America,” with further segments scheduled for that evening on the network’s “World News Tonight” and “Nightline” programs, and Friday on its morning talk show “The View.” Robin Williams was one of the most explosively, exhaustingly, prodigiously verbal comedians who ever lived, says film critic A. O. Scott. And the only thing faster than Williams’s mouth was his mind. By Adam Freelander on Publish Date August 12, 2014. Photo by ABC, via Associated Press. Watch in Times Video » Mr. Williams, the stand-up comic and star of “Mork & Mindy,” “Good Morning, Vietnam,” “Good Will Hunting” (for which he won an Oscar) and “Dead Poets Society,” killed himself on Aug. 11, 2014, in the home he shared with Mrs. Williams in Tiburon, Calif. He was 63. © 2015 The New York Times Company
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
By Jennie Baird Last week’s news that Sesame Street was introducing the first autistic Muppet was met in my house with a resounding, “Huh?” “But there already is an autistic Muppet,” my high-functioning 14-year-old said. “Fozzie Bear.” I had never thought of Fozzie that way, but my son had a point. Fozzie is not good at taking social cues; he doesn’t read a room well and he tends to monologue and perseverate (to repeat himself long after the need has passed). He interprets figurative language as literal — remember that fork in the road in “The Muppet Movie?” He has a verbal tic he falls back on, “wokka-wokka.” And he hates to be separated from his hat for no obvious reason. I’ve tested this theory on friends and have seen the light bulb of recognition go off every time. Of course Fozzie has autism! One friend, a mother whose son is also on the spectrum even told me her family had the exact same conversation. Sesame Street hopes children will identify with their new character Julia, described as a “friend who has autism,” and appearing, for now, only in the book “We’re Amazing 1-2-3!” There is no question, the mere presence of Julia is a positive development. But she also introduces a rarely discussed complication of autism. Let’s call it the Fozzie Conundrum. I’m particularly sensitive to the Fozzie Conundrum now that my son attends regular honors classes in a regular public high school. Naturally sociable and charismatic — and with eight years of support and interventions from a team of terrific teachers and therapists at specialized schools — he can easily “pass” as a regular, funny, quirky teenager. © 2015 The New York Times Company
Link ID: 21590 - Posted: 11.02.2015
By Nicholas Bakalar Certain personality traits are often attributed to oldest, middle and youngest children. But a new study found that birth order itself had no effect on character, though it may slightly affect intelligence. Researchers analyzed three large ongoing collections of data including more than 20,000 people: a British study that follows the lives of people who were born in one particular week in 1958, a German study of private households started in 1984 and a continuing study of Americans born between 1980 and 1984. They searched for differences in extroversion, emotional stability, agreeableness, conscientiousness, self-reported intellect, IQ, imagination and openness to experience. They analyzed families with sisters and brothers, large and small age gaps and different numbers of siblings. They even looked to see if being a middle child correlated with any particular trait. But no matter how they spliced the data, they could find no association of birth order with any personality characteristic. The study, in Proceedings of the National Academy of Sciences, did find evidence that older children have a slight advantage in IQ scores, but the difference was apparent only in a large sample, with little significance for any individual. The lead author, Julia M. Rohrer, a graduate student at the University of Leipzig, said that birth order can have an effect — if your older brother bullied you, for example. “But these effects are highly idiosyncratic,” she said. “There is no such thing as a typical older, middle or younger sibling. It’s important to stop believing that you are the way you are because of birth order.” © 2015 The New York Times Company
A drug for Alzheimer’s seems to delay the point at which a person with the condition needs to be moved into a nursing home. Donepezil is usually given to people with moderate forms of the disease, but continuing to take the drug once the disease becomes more severe seems to prolong the period of time a person can remain in their own home. Previously, the drug was not thought to benefit people once they had developed more severe forms of Alzheimer’s. But a study that followed 295 people with moderate to severe Alzheimer’s disease found that those who continued to take donepezil were nearly half as likely to end up in a care home within the next year. “It could mean thousands of patients per year not going into care homes,” says Robert Howard of University College London, who led the study. His team found that those who continued to take donepezil had a 20 per cent chance of being moved into a care home within the first year of the trial, compared to 37 per cent in those who stopped taking the drug. However the effect didn’t last. The trial lasted for three years, and after the first year, those who taking donepezil were just as likely to be moved into a home than those who weren’t, suggesting that the drug does not have a longer-term effect on the care needs of those with Alzheimer’s. “For every six patients treated with donepezil for 12 months, you would prevent one moving into a nursing home,” says Howard. “It’s a modest effect, but it’s important if it’s your mother or your wife.” © Copyright Reed Business Information Ltd.
Link ID: 21577 - Posted: 10.28.2015
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.
By Jessica Schmerler Young brains are plastic, meaning their circuitry can be easily rewired to promote learning. By adulthood, however, the brain has lost much of its plasticity and can no longer readily recover lost function after, say, a stroke. Now scientists have successfully restored full youthful plasticity in adult mice by transplanting young neurons into their brain—curing their severe visual impairments in the process. In a groundbreaking study published in May in Neuron, a team of neuroscientists led by Sunil Gandhi of the University of California, Irvine, transplanted embryonic mouse stem cells into the brains of other mice. The cells were primed to become inhibitory neurons, which tamp down brain activity. Prior to this study, “it was widely doubted that the adult brain would allow these cells to disperse, integrate and reactivate plasticity,” says Melissa Davis, first author of the study. Scientists have been attempting such a feat for years, refining their methods along the way, and the Irvine team finally saw success: the cells were integrated in the brain and caused large-scale rewiring, restoring the high-level plasticity of early development. In visually impaired mice, the transplant allowed for the restoration of normal vision, as demonstrated by tests of visual nerve signals and a swimming maze test. The scientists have not yet tested the transplanting technique for other neurological disorders, but they believe the technique has potential for many conditions and injuries depending on how, exactly, the new neurons restore plasticity. It is not yet known whether the proliferation of the transplanted cells accounts for the restored plasticity or if the new cells trigger plasticity in existing neurons. If the latter, the treatment could spur the rewiring and healing of the brain following traumatic brain injury or stroke. © 2015 Scientific American
By GINA KOLATA Three diseases, leading killers of Americans, often involve long periods of decline before death. Two of them — heart disease and cancer — usually require expensive drugs, surgeries and hospitalizations. The third, dementia, has no effective treatments to slow its course. So when a group of researchers asked which of these diseases involved the greatest health care costs in the last five years of life, the answer they found might seem surprising. The most expensive, by far, was dementia. The study looked at patients on Medicare. The average total cost of care for a person with dementia over those five years was $287,038. For a patient who died of heart disease it was $175,136. For a cancer patient it was $173,383. Medicare paid almost the same amount for patients with each of those diseases — close to $100,000 — but dementia patients had many more expenses that were not covered. On average, the out-of-pocket cost for a patient with dementia was $61,522 — more than 80 percent higher than the cost for someone with heart disease or cancer. The reason is that dementia patients need caregivers to watch them, help with basic activities like eating, dressing and bathing, and provide constant supervision to make sure they do not wander off or harm themselves. None of those costs were covered by Medicare. For many families, the cost of caring for a dementia patient often “consumed almost their entire household wealth,” said Dr. Amy S. Kelley, a geriatrician at Icahn School of Medicine at Mt. Sinai in New York and the lead author of the paper published on Monday in the Annals of Internal Medicine. © 2015 The New York Times Company
Link ID: 21571 - Posted: 10.27.2015
By Dina Fine Maron Early-life exposure to anesthesia does not appear to lead to long-term cognitive problems, researchers announced today. New evidence from the first, randomized anesthesia trial in kids provides the strongest indication yet that exposing young children to anesthesia—at least for a brief time—will not saddle them with developmental deficits. The news comes just a couple of weeks after a medical advisory group reiterated its concerns about such exposures among children younger than four years. Previously, multiple animal and human studies have linked such exposure with cognitive impairment, but none of the information on humans came from a gold-standard, randomized study design that could help eliminate other reasons to explain such a connection. This is a “reassuring finding, but it is not the final answer,” says Dean Andropoulos, anesthesiologist in chief at Texas Children’s Hospital and an expert who was not involved in the work. The new study assesses only what happens to youngsters after a relatively brief bout with anesthetics, so it is possible that longer or repeated exposures to such chemicals may still cause neurodevelopmental issues. There may also be deficits in anesthesia-exposed children that are not measurable until later in life. The study followed more than 500 infants undergoing hernia repair across the U.S., Australia, the U.K., Canada, the Netherlands, New Zealand and Italy. The surgeries lasted an average of roughly an hour. About half of the children were randomly selected to be put under with general anesthesia, and the other half stayed awake during the surgery and received targeted anesthesic in a specific body region. The kids in the study were all younger than 60 weeks and were matched by where they had the surgery and whether they were born prematurely. © 2015 Scientific American