Chapter 13. Memory, Learning, and Development
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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
Amy Standen A doctor I interviewed for this story told me something that stuck with me. He said for every person with dementia he treats, he finds himself caring for two patients. That's how hard it can be to be a caregiver for someone with dementia. The doctor is Bruce Miller. He directs the Memory and Aging Center at the University of California, San Francisco. According to Miller, 50 percent of caregivers develop a major depressive illness because of the caregiving. "The caregiver is so overburdened that they don't know what to do next," he says. "This adds a huge burden to the medical system." This burden is going increase dramatically in the coming decade. By 2025, 7 million Americans will have Alzheimer's disease, according to one recent estimate. Millions more will suffer from other types of dementia. Together these diseases may become the most expensive segment of the so-called "silver tsunami" — 80 million baby boomers who are getting older and needing more medical care. The cost of caring for Alzheimer's patients alone is expected to triple by 2050, to more than $1 trillion a year. So UCSF, along with the University of Nebraska Medical Center, is beginning a $10 million study funded by the federal Centers for Medicare & Medicaid Innovation. Researchers plan to develop a dementia "ecosystem," which aims to reduce the cost of caring for the growing number of dementia patients and to ease the strain on caregivers. © 2015 NPR
Link ID: 21104 - Posted: 06.29.2015
Sharon Darwish Bottlenose dolphins have an average brain mass of 1.6 kg, slightly greater than that of humans, and about four times the size of chimpanzee brains. Although you couldn’t really imagine a dolphin writing poetry, dolphins demonstrate high levels of intelligence and social behaviour. For example, they display mirror self-recognition, as well as an understanding of symbol-based communication systems. Research into the differing brain sizes and intellectual capabilities within the animal kingdom is fascinating. Why have some species evolved to be more intelligent than others? Does brain size affect cognitive ability? Some studies say yes, but some insist otherwise. It really depends which species we are talking about. In humans, for example, larger brains do not indicate higher intelligence – otherwise Einstein, who had an average-sized brain, may have not been quite as successful in his career. (Yes, that link was to a 23-pager on the analysis of Einstein’s brain. It makes for great bedtime reading.) Most neuroscientists now believe that it is the structure of the brain on a cellular and molecular level that determines its computational capacity. Within certain animal species however, a larger brain offers evolutionary advantage. For example, large-brained female guppies are better survivors and demonstrate greater cognitive strengths than their smaller-brained counterparts. © 2015 Guardian News and Media Limited
By Nicholas Bakalar Exposure to air pollution may hasten brain aging, a new study has found. Researchers studied 1,403 women without dementia who were initially enrolled in a large health study from 1996 to 1998. They measured their brain volume with M.R.I. scans in 2005 and 2006, when the women were 71 to 89 years old. Using residential histories and air pollution data, they estimated their exposure to air pollution from 1999 to 2006. They used data recorded at monitoring sites on exposure to PM 2.5 — tiny particulate matter that easily penetrates the lungs. Each increase of 3.49 micrograms per cubic centimeter cumulative exposure to pollutants was associated with a 6.23 cubic centimeter decrease in white matter, the equivalent of one to two years of brain aging. The association remained after adjusting for many variables, including age, smoking, physical activity, blood pressure, body mass index, education and income. Previous studies have shown that air pollution can cause inflammation and damage to the vascular system, but this study, in The Annals of Neurology, showed damage to the brain itself. “This tells us that the damage air pollution can impart goes beyond the circulatory system,” said the lead author, Dr. Jiu-Chiuan Chen, an associate professor of preventive medicine at the Keck School of Medicine at the University of Southern California. “Particles in the ambient air are an environmental neurotoxin to the aging brain.” © 2015 The New York Times Company
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
Maanvi Singh Teenagers aren't exactly known for their responsible decision making. But some young people are especially prone to making rash, risky decisions about sex, drugs and alcohol. Individual differences in the brain's working memory — which allows people to draw on and use information to make decisions — could help explain why some adolescents are especially impulsive when it comes to sex, according to a study published Wednesday in Child Development. "Working memory is the ability to keep different things in mind when you're making decisions or problem solving," explains Atika Khurana, an assistant professor of counseling psychology at the University of Oregon who led the study. Khurana and her colleagues rounded up 360 adolescents, ages 12 to 15, and assessed their working memory using a series of tests. For example, the researchers told the participants a string of random numbers and asked them to repeat what they heard in reverse order. "We basically tested their ability to keep information in mind while making decisions," Khurana says. The researchers then tracked all the participants for two years, and asked about the teens' sexual activity. And through another series of tests and surveys, the researcher tried to gauge how likely each teen was to act without thinking, to make rash decisions and take risks. There was a correlation between weaker working memory and the likelihood that a teen would have sex — including unprotected sex — at a younger age. And they were more likely to act without much deliberation. That trend held true even after the researchers accounted for the teenagers' age, socioeconomic status and gender. © 2015 NPR
By Nicholas Bakalar A new study has found a simple way to significantly reduce teenage smoking: raise the tobacco sales age to 21. In 2005, Needham, Mass., did just that, while surrounding communities kept their age limit at 18. Researchers surveyed 16,000 high school students in Needham and 16 surrounding communities four times between 2006 and 2012, gathering data on their smoking habits. The study is in Tobacco Control. Over the seven years, the number of children under 18 buying cigarettes in Needham decreased to 11.6 percent from 18.4 percent, while in the surrounding communities it hardly changed — down to 19 percent from 19.4. In 2006, 12.9 percent of students in Needham and 14.8 percent of students in surrounding communities reported having smoked in the past 30 days. By 2010, 6.7 percent of Needham students reported smoking, compared with 12 percent in other towns. At the end of the study in 2012, smoking had declined to 5.5 percent in Needham and 8.5 percent outside. “More than 80 percent of smokers begin before 18,” said the lead author, Shari Kessel Schneider, project director at the Education Development Center in Waltham, Mass. “Our findings provide strong support for initiatives going on all across the country to increase the sales age as a means for decreasing youth access to cigarettes, initiation of smoking, and ultimately addiction.” © 2015 The New York Times Company
By James Gallagher Health editor, BBC News website Scientists have discovered a chemical in blood that indicates whether people will have declining brain function. Looking for the earliest signs of Alzheimer's disease, they analysed levels of 1,129 proteins circulating in the blood of more than 200 twins. These were compared with data from cognitive-function tests over the next decade, in Translational Psychiatry. And levels of one protein, MAPKAPK5, tended to be lower in those people whose brains declined. MAPKAPK5 is involved in relaying chemical messages within the body, although its connection with cognitive decline is unclear. Dementia cases are expected to treble globally by 2050, but there is no cure or treatment. It can take more than a decade from the first changes in the brain to culminate in symptoms such as memory loss, confusion and personality change. And drug companies believe they need to treat patients years before symptoms appear in order to protect the brain. Dr Steven Kiddle, a Medical Research Council scientist at King's College London, told the BBC News website: "People think it may be hard to reverse 20 years of potential damage to your brain. "But if you could start much earlier in that process, then you might be able to find something that works." He said a blood test could help identify people for clinical trials. But he added: "A test you could go in to your doctor to say, 'Do I have Alzheimer's disease or not?' I think that's a long way off." © 2015 BBC
Link ID: 21064 - Posted: 06.17.2015
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 Meghan Rosen When we brought Baby S home from the hospital six months ago, his big sister, B, was instantly smitten. She leaned her curly head over his car seat, tickled his toes and cooed like a pro — in a voice squeakier than Mickey Mouse’s. B’s voice — already a happy toddler squeal — sounded as if she'd sucked in some helium. My husband and I wondered about her higher pitch. Are humans hardwired to chitchat squeakily to babies, or did B pick up vocal cues from us? (I don’t sound like that, do I?) If I’m like other mothers, I probably do. American English-speaking moms dial up their pitch drastically when talking to their children. But dads’ voices tend to stay steady, researchers reported May 19 in Pittsburgh at the 169th Meeting of the Acoustical Society of America. “Dads talk to kids like they talk to adults,” says study coauthor Mark VanDam, a speech scientist at Washington State University. But that doesn’t mean fathers are doing anything wrong, he says. Rather, they may be doing something right: offering their kids a kind of conversational bridge to the outside world. Scientists have studied infant- or child-directed speech (often called “motherese” or “parentese”) for decades. In American English, this type of babytalk typically uses high pitch, short utterances, repetition, loud volume and slowed-down speech. Mothers who speak German Japanese, French, and other languages also tweak their pitch and pace when talking to children. But no one had really studied dads, VanDam says. © Society for Science & the Public 2000 - 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
By Jessica Schmerler Approximately one in 68 children is identified with some form of autism, from extremely mild to severe, according to the U.S. Centers for Disease Control. On average, diagnosis does not occur until after age four, yet all evidence indicates that early intervention is the best way to maximize the treatment impact. Various tests that look for signs of autism in infants have not been conclusive but a new exercise could improve early diagnosis, and also help reduce worry among parents that they did not intervene as soon as possible. The two most widely used tests to measure symptoms, the Autism Observation Scale for Infants (AOSI) and the Autism Diagnostic Observation Schedule (ADOS), cannot be used before the ages of 12 or 16 months respectively. The AOSI measures precursors to symptoms, such as a baby’s response to name, eye contact, social reciprocity, and imitation. The ADOS measures the characteristics and severity of autism symptoms such as social affectation and repetitive and restrictive behaviors. Now a group of scientists at the Babylab at Birkbeck, University of London think they have identified a marker that can predict symptom development more accurately and at an earlier age: enhanced visual attention. Experts have long recognized that certain individuals with autism have superior visual skills, such as increased visual memory or artistic talent. Perhaps the most well known example is Temple Grandin, a high-functioning woman with autism who wrote, “I used to become very frustrated when a verbal thinker could not understand something I was trying to express because he or she couldn’t see the picture that was crystal clear to me.” © 2015 Scientific American
Owning a cat as a kid could put you at risk for schizophrenia and bipolar disorder later on because of parasites found in feline feces, new research says. Previous studies have linked the parasite toxoplasma gondii (T. gondii) to the development of mental disorders, and two more research papers published recently provide further evidence. Researchers from the Academic Medical Centre in Amsterdam looked at more than 50 studies and found that a person infected with the parasite is nearly twice as likely to develop schizophrenia. The other study, led by Dr. Robert H. Yolken of Johns Hopkins University School of Medicine in Baltimore, confirmed the results of a 1982 questionnaire that found half of people who had a cat as a kid were diagnosed with mental illnesses later in life compared to 42% of those who didn't grow up with a cat. "Cat ownership in childhood has now been reported in three studies to be significantly more common in families in which the child is later diagnosed with schizophrenia or another serious mental illness," the authors said in a press release. The findings were published in Schizophrenia Research and Acta Psychiatrica Scandinavica. T. gondii, which causes the disease toxoplasma, is especially risky for pregnant women and people with weak immune symptoms. The parasite can also be found in undercooked meat and unwashed fruits and vegetables.
James Gorman When researchers found a group of brain cells in the fruit fly that function like a compass, they were very satisfied. They had found what they were looking for. But, said Vivek Jayaraman, when he and Johannes D. Seelig realized that the cells were actually arranged in a physical circle in the brain, so they looked just like a compass, they were taken aback. “It’s kind of like a cosmic joke that they are arranged like that,” he said. Dr. Jayaraman was investigating a kind of navigation called dead reckoning, or, in technical terms, angular path integration. It is the most basic way a moving creature knows where it is and where it is going. In dead reckoning, animals use visual cues, like landmarks, and also a sense of where their bodies are pointed. It is very different from other ways animals navigate, such as the use of polarized light from the sun or sensitivity to the earth’s magnetic field. The researchers published their findings in Nature last month. Dr. Jayaraman had narrowed down the likely location of directional tracking based on other research. So he expected to find activity in the ellipsoid body, a very small region of a very small brain. Dr. Jayaraman and Mr. Seelig, at the Janelia Research Campus of the Howard Hughes Medical Institute in Virginia, engineered neurons there to light up when they were active, and they recorded the activity with a microscopic technique called two-photon calcium imaging that gives a real-time visual picture of the brain in action in a living animal. © 2015 The New York Times Company
Keyword: Learning & Memory
Link ID: 21027 - Posted: 06.08.2015
By Sue Bailey, The Canadian Press Scientific studies increasingly suggest marijuana may not be the risk-free high that teens — and sometimes their parents — think it is, researchers say. Yet pot is still widely perceived by young smokers as relatively harmless, said Dr. Romina Mizrahi, director of the Focus on Youth Psychosis Prevention clinic and research program at the Centre for Addiction and Mental Health. She cites a growing body of research that warns of significantly higher incidence of hallucinations, paranoia and the triggering of psychotic illness in adolescent users who are most predisposed. "When you look at the studies in general, you can safely say that in those that are vulnerable, it doubles the risk." Such fallout is increasingly evident in the 19-bed crisis monitoring unit at the Children's Hospital of Eastern Ontario in Ottawa. "I see more and more cases of substance-induced psychosis," said Dr. Sinthu Suntharalingam, a child and adolescent psychiatrist. "The most common substance that's abused is cannabis." One or two cases a week are now arriving on average. "They will present with active hallucinations," Suntharalingam said. "Parents will be very scared. They don't know what's going on. "They'll be seeing things, hearing things, sometimes they will try to self-harm or go after other people." Potential effects need to be better understood She and Mizrahi, an associate professor in psychiatry at University of Toronto, are among other front-line professionals who say more must be done to help kids understand potential effects. "They know the hard drugs, what they can do," Suntharalingam said. "Acid, they'll tell us it can cause all these things so they stay away from it. But marijuana? They'll be: 'Oh, everybody does it."' Mizrahi said the message isn't getting through. ©2015 CBC/Radio-Canada.
by Helen Thomson For the first time, scientists have discovered a mechanism in humans that could explain how your lifestyle choices may impact your children and grandchildren's genes. Mounting evidence suggests that environmental factors such as smoking, diet and stress, can leave their mark on the genes of your children and grandchildren. For example, girls born to Dutch women who were pregnant during a long famine at the end of the second world war had twice the usual risk of developing schizophrenia. Likewise, male mice that experience early life stress give rise to two generations of offspring that have increased depression and anxiety, despite being raised in a caring environment. This has puzzled many geneticists, as genetic information contained in sperm and eggs is not supposed to be affected by the environment, a principle called the August Weismann barrier. But we also know the activity of our own genes can be changed by our environment, through epigenetic mechanisms . These normally work by turning a gene on or off by adding or subtracting a methyl group to or from its DNA. These methyl groups can inactivate genes by making their DNA curl up, so that enzymes can no longer access the gene and read its instructions. Such epigenetic mechanisms are high on the list of suspects when it comes to explaining how environmental factors that affect parents can later influence their children, such as in the Dutch second world war study, but just how these epigenetic changes might be passed on to future generations is a mystery. © Copyright Reed Business Information Ltd.
By Fiona Kumfor, Sicong Tu and The Conversation The brain is truly a marvel. A seemingly endless library, whose shelves house our most precious memories as well as our lifetime’s knowledge. But is there a point where it reaches capacity? In other words, can the brain be “full”? The answer is a resounding no, because, well, brains are more sophisticated than that. A study published in Nature Neuroscience earlier this year shows that instead of just crowding in, old information is sometimes pushed out of the brain for new memories to form. Previous behavioural studies have shown that learning new information can lead to forgetting. But in this study, researchers used new neuroimaging techniques to demonstrate for the first time how this effect occurs in the brain. The experiment The paper’s authors set out to investigate what happens in the brain when we try to remember information that’s very similar to what we already know. This is important because similar information is more likely to interfere with existing knowledge, and it’s the stuff that crowds without being useful. To do this, they examined how brain activity changes when we try to remember a “target” memory, that is, when we try to recall something very specific, at the same time as trying to remember something similar (a “competing” memory). Participants were taught to associate a single word (say, the word sand) with two different images—such as one of Marilyn Monroe and the other of a hat. © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 21013 - Posted: 06.03.2015
Rebecca Hersher Greg O'Brien sees things that he knows aren't there, and these visual disturbances are becoming more frequent. That's not uncommon; up to 50 percent of people who have Alzheimer's disease experience hallucinations, delusions or psychotic symptoms, recent research suggests. At first, he just saw spider-like forms floating in his peripheral vision, O'Brien says. "They move in platoons." But in the last year or so, the hallucinations have been more varied, and often more disturbing. A lion. A bird. Sprays of blood among the spiders. Over the past five months, O'Brien has turned on an audio recorder when the hallucinations start, in hopes of giving NPR listeners insight into what Alzheimer's feels like. For now, he says, "I'm able to function. But I fear the day, which I know will come, when I can't." Interview Highlights [It's] St. Patrick's Day, about 9 o'clock in the morning in my office, and they're coming again. Those hallucinations. Those things that just come into the mind when the mind plays games. And then I see the bird flying in tighter and tighter and tighter circles. And all of a sudden, the bird — beak first — it darted almost in a suicide mission, exploding into my heart. Today I'm just seeing this thing in front of me. It looks like a lion, almost looks like something you'd see in The Lion King, and there are birds above it. It's floating, and it disintegrates ... it disintegrates ... it disintegrates.
by Jessica Hamzelou Memories that seem to be lost forever may be lurking in the brain after all, ready to be reawakened. The finding, based on experiments in mice, could eventually give us a way to revive memories in people with Alzheimer's or amnesia. When we learn something, sets of neurons in the brain strengthen their mutual connections to lay down lasting memories. Or at least that's the theory. Susumu Tonegawa and his colleagues at the Massachusetts Institute of Technology decided to put it to the test. The team first developed a clever technique to selectively label the neurons representing what is known as a memory engram – in other words, the brain cells involved in forming a specific memory. They did this by genetically engineering mice so they had extra genes in all their neurons. As a result, when neurons fire as a memory is formed, they produce red proteins visible under a microscope, allowing the researchers to tell which cells were part of the engram. They also inserted a gene that made the neurons fire when illuminated by blue light. To mimic memory loss, some of the mice were given a drug that blocks the strengthening of connections between neurons. This made the animals forget their fear of the cage. But the telltale red proteins allowed Tonegawa's team to work out which neurons had been involved in storing the fear memory. They then attempted to reactivate just these neurons using blue light. Sure enough, after the engram had been reactivated, the mice again acted as if they were afraid of the cage. © Copyright Reed Business Information Ltd.
Keyword: Learning & Memory
Link ID: 21001 - Posted: 05.30.2015