Chapter 13. Memory, Learning, and Development
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by Clare Wilson Does this qualify as irony? Our bodies need iron to be healthy – but too much could harm our brains by bringing on Alzheimer's disease. If that's the case, measuring people's brain iron levels could help identify those at risk of developing the disease. And since we already have drugs that lower iron, we may be able to put the brakes on. Despite intense efforts, the mechanisms behind this form of dementia are still poorly understood. For a long time the main suspect has been a protein called beta-amyloid, which forms distinctive plaques in the brain, but drugs that dissolve it don't result in people improving. Not so good ferrous Studies have suggested that people with Alzheimer's also have higher iron levels in their brains. Now it seems that high iron may hasten the disease's onset. Researchers at the University of Melbourne in Australia followed 144 older people who had mild cognitive impairment for seven years. To gauge how much iron was in their brains, they measured ferritin, a protein that binds to the metal, in their cerebrospinal fluid. For every nanogram per millilitre people had at the start of the study, they were diagnosed with Alzheimer's on average three months earlier. The team also found that the biggest risk gene for Alzheimer's, ApoE4, was strongly linked with higher iron, suggesting this is why carrying the gene makes you more vulnerable. Iron is highly reactive, so it probably subjects neurons to chemical stress, says team member Scott Ayton. © Copyright Reed Business Information Ltd
Link ID: 20957 - Posted: 05.20.2015
By PAM BELLUCKM The largest analysis to date of amyloid plaques in people’s brains confirms that the presence of the substance can help predict who will develop Alzheimer’s and determine who has the disease. Two linked studies, published Tuesday in JAMA, also support the central early role in Alzheimer’s of beta amyloid, the protein that creates plaques. Data from nearly 9,500 people on five continents shows that amyloid can appear 20 to 30 years before symptoms of dementia, that the vast majority of Alzheimer’s patients have amyloid and that the ApoE4 gene, known to increase Alzheimer’s risk, greatly accelerates amyloid accumulation. The findings also confirm that amyloid screening, by PET scan or cerebral spinal fluid test, can help identify people for clinical trials of drugs to prevent Alzheimer’s. Such screening is increasingly used in research. Experts say previous trials of anti-amyloid drugs on people with dementia failed because their brains were already too damaged or because some patients, not screened for amyloid, may not have had Alzheimer’s. “The papers indicate that amyloid imaging is important to be sure that the drugs are being tested on people who have amyloid,” said Dr. Roger Rosenberg, the director of the Alzheimer’s Disease Center at the University of Texas Southwestern Medical Center at Dallas, who wrote an editorial about the studies. Dr. Samuel Gandy, an Alzheimer’s researcher at Mount Sinai Hospital, who was not involved in the research, said doctors “can feel fairly confident that amyloid is due to Alzheimer’s.” But he and others cautioned against screening most people without dementia because there is not yet a drug that prevents or treats Alzheimer’s, and amyloid scans are expensive and typically not covered by insurance. © 2015 The New York Times Company
Link ID: 20956 - Posted: 05.20.2015
by Ashley Yeager This guest post is by SN's web producer Ashley Yeager, who can't remember ever not knowing how to swim. Sometimes my brother-in-law will scoop up my 2-year-old niece and fly her around like Superwoman. She’ll start kicking her legs and swinging her arms like she’s swimming — especially when we say, “paddle, paddle, paddle.” My niece, Baby D, loves the water. She often looks like one of the kids captured in famed photographer Seth Casteel’s new book, Underwater Babies. But she probably won’t remember her first trips to the pool — she was only a few months old when her mom first took her swimming. Part of my sister’s reasoning for such an early start was standard water safety. Every day in the United States, accidental drowning claims the lives of two children under the age of 14 years. Our family spends a lot of time at the pool and the beach, so making sure Baby D is protected is a priority. But there’s another reason my sister was keen to get Baby D to the pool. Loosely based on something our mother told us, it’s that learning to swim early in life may give kids a head start in developing balance, body awareness and maybe even language and math skills. Mom may have been right. A multi-year study released in 2012 suggests that kids who take swim lessons early in life appear to hit certain developmental milestones well before their nonswimming peers. In the study, Australian researchers surveyed about 7,000 parents about their children’s development and gave 177 kids aged 3 to 5 years standard motor, language, memory and attention tests. Compared with kids who didn’t spend much time in the water, kids who had taken swim lessons seemed to be more advanced at tasks like running and climbing stairs and standing on their tiptoes or on one leg, along with drawing, handling scissors and building towers out of blocks. © Society for Science & the Public 2000 - 2015.
An octopus filmed off the coast of Kalaoa in Hawaii has shown that even cephalopods can get into a game of peekaboo. In the footage, shot last month by the GoPro camera of diver Timothy Ewing, the octopus bobs up and down behind a rock as a Ewing does the same in an effort to take the animal's picture. It's clear from the video that the octopus is wary of Ewing and his big, light-equipped camera — but the animal is also very curious. “Octopus are one of the more intelligent creatures in the ocean. Sometimes they are too curious for their own good. If you hide from them they will come out and look for you," the diver wrote in his online posting of the video. Ewing explained to CaliforniaDiver.com that the encounter wasn't limited to the time captured on his GoPro. "I was interacting with that octopus for about 10 minutes before I took the video," Ewing told CaliforniaDiver.com. "I normally mount my GoPro to my big camera housing, however I always carry a small tripod with me to use with the GoPro for stationary shots like this or selfie videos." The octopus, found worldwide in tropical, subtropical and temperate areas, is known for its smarts and striking ability to camouflage itself. When it feels threatened, pigment cells in its skin allow it to change color instantly to blend in with its surroundings. The animals can also adapt their skin texture and body posture to further match their background. © 2015 Discovery Communications, LLC.
By James Gorman and Robin Lindsay Before human ancestors started making stone tools by chipping off flakes to fashion hand axes and other implements, their ancestors may have used plain old stones, as animals do now. And even that simple step required the intelligence to see that a rock could be used to smash open a nut or an oyster and the muscle control to do it effectively. Researchers have been rigorous in documenting every use of tools they have found find in animals, like crows, chimpanzees and dolphins. And they are now beginning to look at how tools are used by modern primates — part of the scientists’ search for clues about the evolution of the kind of delicate control required to make and use even the simplest hand axes. Monkeys do not exhibit human dexterity with tools, according to Madhur Mangalam of the University of Georgia, one of the authors of a recent study of how capuchin monkeys in Brazil crack open palm nuts. “Monkeys are working as blacksmiths,” he said, “They’re not working as goldsmiths.” But they are not just banging away haphazardly, either. Mr. Mangalam, a graduate student who is interested in “the evolution of precise movement,” reported in a recent issue of Current Biology on how capuchins handle stones. His adviser and co-author was Dorothy M. Fragaszy, the director of the Primate Behavior Laboratory at the university. Using video of the capuchins’ lifting rocks with both hands to slam them down on the hard palm nuts, he analyzed how high a monkey lifted a stone and how fast it brought it down. He found that the capuchins adjusted the force of a strike according to the condition of the nut after the previous strike. © 2015 The New York Times Company
Monica Tan The age-old question of whether human traits are determined by nature or nurture has been answered, a team of researchers say. Their conclusion? It’s a draw. By collating almost every twin study across the world from the past 50 years, researchers determined that the average variation for human traits and disease is 49% due to genetic factors and 51% due to environmental factors. University of Queensland researcher Beben Benyamin from the Queensland Brain Institute collaborated with researchers at VU University of Amsterdam to collate 2,748 studies involving more than 14.5 million pairs of twins. “Twin studies have been conducted for more than 50 years but there is still some debate in terms of how much the variation is due to genetic or environmental factors,” Benyamin said. He said the study showed the conversation should move away from nature versus nature, instead looking at how the two work together. “Both are important sources of variation between individuals,” he said. While the studies averaged an almost even split between nature and nurture, there was wide variation within the 17,800 separate traits and diseases examined by the studies. For example, the risk for bipolar disorder was found to be 68% due to genetics and only 32% due to environmental factors. Weight maintenance was 63% due to genetics and 37% due to environmental factors. In contrast, risk for eating disorders was found to be 40% genetic and 60% environmental, whereas the risk for mental and behavioural disorders due to use of alcohol was 41% genetic and 59% environmental. © 2015 Guardian News and Media Limited
Keyword: Genes & Behavior
Link ID: 20948 - Posted: 05.19.2015
RACHEL MARTIN, HOST: For most of her life, Cole Cohen had a hard time with all kinds of things. She'd get lost all of the time. She couldn't do math to save her life. The whole concept of time was hard for her to grasp. Her parents took her to doctor after doctor, and there were all kinds of tests and experiments with medication, but no real diagnosis until she was 26 years old. Cole Cohen got her first MRI and finally, there was an explanation. There was a hole in her brain; a hole in her brain the size of a lemon. Her memoir, titled "Head Case," is a darkly funny exploration of what that discovery meant to her. Cole Cohen joins us now. Thanks so much for being with us. COLE COHEN: Thank you for having me, Rachel. MARTIN: Let's talk about what life was like before this revelation. I mentioned your propensity to get lost. We're not talking about being in a new place and getting confuses as a lot of us might do. You got lost in, like, big box stores that you had been to before. Can you describe that sensation, that feeling of not knowing where you are in a situation like that? COHEN: Yeah. I know that sensation every time I go grocery shopping. You know, you want to get a jar of peanut butter. You have a memory of where that jar of peanut butter is, and I just don't have that in my brain. I don't store that information. So it's like a discovery every time. MARTIN: I'd love for you to read an example of one of the symptoms. You have a hard time with numbers, even references to numbers. And you write about this in the book when you're taking driver's ed. Do you mind reading that bit? © 2015 NPR
Keyword: Learning & Memory
Link ID: 20942 - Posted: 05.18.2015
By JIM DWYER The real world of our memory is made of bits of true facts, surrounded by holes that we Spackle over with guesses and beliefs and crowd-sourced rumors. On the dot of 10 on Wednesday morning, Anthony O’Grady, 26, stood in front of a Dunkin’ Donuts on Eighth Avenue in Manhattan. He heard a ruckus, some shouts, then saw a police officer chase a man into the street and shoot him down in the middle of the avenue. Moments later, Mr. O’Grady spoke to a reporter for The New York Times and said the wounded man was in flight when he was shot. “He looked like he was trying to get away from the officers,” Mr. O’Grady said. Another person on Eighth Avenue then, Sunny Khalsa, 41, had been riding her bicycle when she saw police officers and the man. Shaken by the encounter, she contacted the Times newsroom with a shocking detail. “I saw a man who was handcuffed being shot,” Ms. Khalsa said. “And I am sorry, maybe I am crazy, but that is what I saw.” At 3 p.m. on Wednesday, the Police Department released a surveillance videotape that showed that both Mr. O’Grady and Ms. Khalsa were wrong. Contrary to what Mr. O’Grady said, the man who was shot had not been trying to get away from the officers; he was actually chasing an officer from the sidewalk onto Eighth Avenue, swinging a hammer at her head. Behind both was the officer’s partner, who shot the man, David Baril. And Ms. Khalsa did not see Mr. Baril being shot while in handcuffs; he is, as the video and still photographs show, freely swinging the hammer, then lying on the ground with his arms at his side. He was handcuffed a few moments later, well after he had been shot. © 2015 The New York Times Company
Keyword: Learning & Memory
Link ID: 20939 - Posted: 05.16.2015
By Jonathan Webb Science reporter, BBC News A cluster of cells in the brain of a fly can track the animal's orientation like a compass, a study has revealed. Fixed in place on top of a spherical treadmill, a fruit fly walked on the spot while neuroscientists peered into its brain using a microscope. Watching the neurons fire inside a donut-shaped brain region, they saw activity sweep around the ring to match the direction the animal was headed. Mammals have similar "head direction cells" but this is a first for flies. The findings are reported in the journal Nature. Crucially, the compass-like activity took place not only when the animal was negotiating a virtual-reality environment, in which screens gave the illusion of movement, but also when it was left in the dark. "The fly is using a sense of its own motion to pick up which direction it's pointed," said senior author Dr Vivek Jayaraman, from the Howard Hughes Medical Institute's Janelia Research Campus. In some other insects, such as monarch butterflies and locusts, brain cells have been observed firing in a way that reflects the animal's orientation to the pattern of polarised light in the sky - a "sun compass". But the newly discovered compass in the fly brain works more like the "head directions cells" seen in mammals, which rapidly set up a directional system for the animal based on landmarks in the surrounding scene. "A key thing was incorporating the fly's own movement," Dr Jayaraman told the BBC. "To see that its own motion was relevant to the functioning of this compass - that was something we could only see if we did it in a behaving animal." © 2015 BBC
Keyword: Learning & Memory
Link ID: 20933 - Posted: 05.14.2015
Thomas R. Clandinin & Lisa M. Giocomo An analysis reveals that fruit-fly neurons orient flies relative to cues in the insects' environment, providing evidence that the fly's brain contains a key component for drawing a cognitive map of the insect's surroundings. See Article p.186 Animals need accurate navigational skills as they go about their everyday lives. Many species, from ants to rodents, navigate on the basis of visual landmarks, and this is complemented by path integration, in which neuronal cues about the animal's own motion are used to track its location relative to a starting point. In mammals, these different types of navigation are integrated by neurons called head-direction cells1. In this issue, Seelig and Jayaraman2 (page 186) provide the first evidence that certain neurons in fruit flies have similar properties to head-direction cells, encoding information that orients the insects relative to local landmarks. Head-direction cells act as a neuronal compass that generates a cognitive map of an animal's environment. The activity of each head-direction cell increases as the animal faces a particular direction, with different cells preferentially responding to different directions1, 3. Rather than certain cells always responding to north, south and so on, the direction in which the cells fire is set up arbitrarily when the animal encounters new visual landmarks. The signals are then updated by self-motion cues as the animal navigates. Studying head-direction cells in mammals is challenging because of the complexity of the mammalian brain. By contrast, the small fly brain is a good model for studying neuronal activity. © 2015 Macmillan Publishers Limited.
Keyword: Learning & Memory
Link ID: 20932 - Posted: 05.14.2015
Alexandra Sifferlin Autism, already a mysterious disorder, is even more puzzling when it comes to gender differences. For every girl diagnosed with autism, four boys are diagnosed, a disparity researchers don’t yet fully understand. In a new study published in the journal Molecular Autism, researchers from the UC Davis MIND Institute tried to figure out a reason why. They looked at 112 boys and 27 girls with autism between ages 3 and 5 years old, as well as a control sample of 53 boys and 29 girls without autism. Using a process called diffusion-tensor imaging, the researchers looked at the corpus callosum — the largest neural fiber bundle in the brain — in the young kids. Prior research has shown differences in that area of the brain among people with autism. They found that the organization of these fibers was different in boys compared with girls, especially in the frontal lobes, which play a role in executive functions. “The sample size is still limited, but this work adds to growing body of work suggesting boys and girls with autism have different underlying neuroanatomical differences,” said study author Christine Wu Nordahl, an assistant professor in the UC Davis Department of Psychiatry and Behavioral Sciences, in an email. In other preliminary research presented at the International Meeting for Autism Research, or IMFAR, in Salt Lake City, the study authors showed that when girls and boys with autism are compared with typically developing boys and girls, the behavioral differences between girls with autism and the female controls are greater than the differences among the boys. Nordahl says this suggests that girls can be more severely affected than boys.
By Emily Underwood We’ve all heard how rats will abandon a sinking ship. But will the rodents attempt to save their companions in the process? A new study shows that rats will, indeed, rescue their distressed pals from the drink—even when they’re offered chocolate instead. They’re also more likely to help when they’ve had an unpleasant swimming experience of their own, adding to growing evidence that the rodents feel empathy. Previous studies have shown that rats will lend distressed companions a helping paw, says Peggy Mason, a neurobiologist at the University of Chicago in Illinois who was not involved in the work. In a 2011 study, for example, Mason and colleagues showed that if a rat is trapped in a narrow plastic tube, its unrestrained cagemate will work on the latch until it figures out how to spring the trap. Skeptics, however, have suggested that the rodents help because they crave companionship—not because their fellow rodents were suffering. The new study, by researchers at the Kwansei Gakuin University in Japan, puts those doubts to rest, Mason says. For their test of altruistic behavior, the team devised an experimental box with two compartments divided by a transparent partition. On one side of the box, a rat was forced to swim in a pool of water, which it strongly disliked. Although not at risk of drowning—the animal could cling to a ledge—it did have to tread water for up to 5 minutes. The only way the rodent could escape its watery predicament was if a second rat—sitting safe and dry on a platform—pushed open a small round door separating the two sides, letting it climb onto dry land. © 2015 American Association for the Advancement of Science
By Gareth Cook Much has been written on the wonders of human memory: the astounding feats of recall, the way memories shape our identity and are shaped by them, memory as a literary theme and a historical one. But what of forgetting? This is the topic of a new book by Douwe Draaisma, author of The Nostalgia Factory and a professor of the history of psychology at the University of Groningen. In Forgetting, Draaisma considers dreaming, amnesia, dementia and all of the ways that our minds — and lives — are shaped by memory’s opposite. He answered questions from Mind Matters editor Gareth Cook. What is your earliest memory and why, do you suppose, have you not forgotten it? Quite a few early memories in the Netherlands involve bicycles, and mine is no exception. I was two-and-a-half years old when my aunts walked my mother to the train station. They had taken a bike along to transport her bags. I was sitting on the back of the bike. Suddenly the whole procession came to a halt when my foot got caught between the spokes. I’m pretty sure this memory is accurate, since I had to see a doctor and there is a dated medical record. It’s a brief, snapshot-like memory, black-and-white. I don’t remember any pain, but I do remember the consternation among my mom and her sisters. Looking back on this memory from a professional perspective, I would say that it has the flash-like character typical for first memories from before age 3; ‘later’ first memories are usually a bit longer and more elaborate. It also fits the pattern of being about pain and danger. Roughly three in four first memories are associated with negative emotions. This may have an evolutionary origin: I never again had my foot between the spokes. And neither have any of my children. © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 20918 - Posted: 05.13.2015
By Simon Makin After wandering around an unfamiliar part of town, can you sense which direction to travel to get back to the subway or your car? If so, you can thank your entorhinal cortex, a brain area recently identified as being responsible for our sense of direction. Variation in the signals in this area might even explain why some people are better navigators than others. The new work adds to a growing understanding of how our brain knows where we are. Groundbreaking discoveries in this field won last year's Nobel Prize in Physiology or Medicine for John O'Keefe, a neuroscientist at University College London, who discovered “place cells” in the hippocampus, a brain region most associated with memory. These cells activate when we move into a specific location, so that groups of them form a map of the environment. O'Keefe shared the prize with his former students Edvard Moser and May-Britt Moser, both now at the Kavli Institute for Systems Neuroscience in Norway, who discovered “grid cells” in the entorhinal cortex, a region adjacent to the hippocampus. Grid cells have been called the brain's GPS system. They are thought to tell us where we are relative to where we started. A third type—head-direction cells, also found in the entorhinal region—fires when we face a certain direction (such as “toward the mountain”). Together these specialized neurons appear to enable navigation, but precisely how is still unclear. For instance, in addition to knowing which direction we are facing, we need to know which direction to travel. Little was known about how or where such a goal-direction signal might be generated in the brain until the new study. © 2015 Scientific American
Keyword: Learning & Memory
Link ID: 20915 - Posted: 05.13.2015
Jane Brody With people worldwide living longer, marketers are seizing on every opportunity to sell remedies and devices that they claim can enhance memory and other cognitive functions and perhaps stave off dementia as people age. Among them are “all-natural” herbal supplements like Luminene, with ingredients that include the antioxidant alpha lipoic acid, the purported brain stimulant ginkgo biloba, and huperzine A, said to increase levels of the neurotransmitter acetylcholine; brain-training games on computers and smartphones; and all manner of puzzles, including crosswords, sudoku and jigsaw, that give the brain a workout, albeit a sedentary one. Unfortunately, few such potions and gizmos have been proven to have a meaningful, sustainable benefit beyond lining the pockets of their sellers. Before you invest in them, you’d be wise to look for well-designed, placebo-controlled studies that attest to their ability to promote a youthful memory and other cognitive functions. Even the widely acclaimed value of doing crossword puzzles has been called into question, beyond its unmistakable benefit to one’s font of miscellaneous knowledge. Although there is some evidence that doing crosswords may help to delay memory decline, Molly Wagster, a neuroscientist at the National Institute on Aging, said they are best done for personal pleasure, not brain health. “People who have done puzzles all their lives have no particular cognitive advantage over anyone else,” she said. The institute is one of several scientific organizations sponsoring rigorous trials of ways to cash in on the brain’s lifelong ability to generate new cells and connections. One such trial, Advanced Cognitive Training for Independent and Vital Elderly, or Active, was a 10-year follow-up study of 2,832 cognitively healthy community-dwelling adults 65 and older. © 2015 The New York Times Company
Andrew Griffin Scientists have created an electronic memory cell that mimics the way that human brains work, potentially unlocking the possibility of the making bionic brains. The cell can process and store multiple bits of information, like the human brain. Scientists hope that developing it could make for artificial cells that simulate the brain’s processes, leading to treatments for neurological conditions and for replica brains that scientists can experiment on. The new cells have been likened to the difference between having an on-off light switch and a dimmer, or the difference between black and white pictures or those with full colour, including shade light and texture. While traditional memory cells for computers can only process one binary thing at a time, the new discovery allows for much more complex memory processes like those found in the brain. They are also able to retain previous information, allowing for artificial systems that have the extraordinary memory powers found in human beings. While the new discovery is a long way from leading to a bionic brain, the discovery is an important step towards the dense and fast memory cells that will be needed to imitate the human brain's processes. “This is the closest we have come to creating a brain-like system with memory that learns and stores analog information and is quick at retrieving this stored information,” Sharath Sriram, who led the project, said.
Margaret Wente Child psychiatrist Susan Bradley was a pioneer in treating kids with gender-identity disorders. In the 1970s, she founded the child and adolescent gender identity clinic at the Clarke Institute in Toronto, which eventually became part of the Centre for Addiction and Mental Health (CAMH). Back then, the field was virtually unknown. Today, it is Ground Zero in a fierce battle between oldfangled psychiatry and transgender activists who insist that practitioners like Dr. Bradley are guilty of child abuse. Caught in the middle are confused parents, well-meaning schools, and – most important of all – troubled and bewildered kids. The new rush to turn little Jason into Janey, or Sally into Sam, is generally regarded (in the media, at least) as progress – proof of what a tolerant and progressive society we’ve become. But what if it’s just another fad? What if the radical step of changing genders isn’t always the right answer for a child’s emotional distress – especially when that child is only 10 or 6, or 3? “Some of these kids are quite significantly ill,” says Dr. Bradley. “They often have serious family problems and anxiety disorders. Or they’ve had serious trauma. A girl I saw had been raped, and after that she decided she was going to be a male. If you didn’t pay attention to the trauma you’re not doing that kid a service.” These days, that eminently reasonable view is being challenged by people who believe that children’s sexual confusion should automatically be taken at face value. The clinic that Dr. Bradley helped to found – which does, in fact, support gender transition for a sizable minority of its patients – is being pilloried as transphobic. “Is CAMH trying to turn trans kids straight?” screamed a headline in NOW magazine. Under pressure from activists, CAMH has put its gender clinic under six-month review. And a new bill before the Ontario legislature, which is supported by Premier Kathleen Wynne, would explicitly bar the therapeutic approach taken by the clinic, wrongly equating it to the notorious “conversion” therapy that seeks to turn gay people straight. © Copyright 2015 The Globe and Mail Inc.
By Lisa Sanders, M.D On Thursday we challenged Well readers to solve the difficult case of twin sisters who, in the prime of youth, developed a weakness that forced them to use their arms to rise from a chair. Nearly 300 of you wrote in with thoughts on this difficult case. Many of you recognized that this was likely to be a genetic disorder, though I greatly admired the “House”-ian thinking that led to a host of possible reasons why two sisters, living in different states, might develop the same symptoms independent of their shared DNA. It took this patient, Katie Buryk, four years to get her answer, which was: Late onset Tay-Sachs disease Although several of you made this difficult diagnosis, the first to do so was George Bonadurer, a second year medical student at Mayo Medical School in Rochester, Minn. He says he recently read about this disease in a book of unusual cases that had come to the Mayo clinic for help. This is actually Mr. Bonadurer’s second win of this contest. Strong work! Tay-Sachs disease was first identified by two physicians, independently, in the 1880s. Dr. Warren Tay was an ophthalmologist in London. Dr. Bernard Sachs was a neurologist in New York City. Each described a disease in infants that caused profound weakness, blindness and, usually by age 4, death. Careful consideration of cases over the following decades showed that the disease was inherited and often seen in children of Ashkenazi descent. Studying the patterns of inheritance, it became clear that both parents had to have the abnormal gene and that each of their children would have a one in four chance of being born with the disease. The terrible manifestations of the disease derive from an inherited inability to make an essential protein in the brain. This protein acts to break down discarded components of the cells. Without this protein, these discarded cell parts accumulate, interrupting normal nerve and brain cell functioning. This mechanism and the missing protein was identified in 1969, allowing for the development of a test for carriers. Since the development of this test, the incidence of Tay-Sachs in the United States has dropped by 90 percent. © 2015 The New York Times Company
Douwe Draaisma When we sleep, wrote English psychiatrist Havelock Ellis over a hundred years ago, we enter a ‘dim and ancient house of shadow’. We wander through its rooms, climb staircases, linger on a landing. Towards morning we leave the house again. In the doorway we look over our shoulders briefly and with the morning light flooding in we can still catch a glimpse of the rooms where we spent the night. Then the door closes behind us and a few hours later even those fragmentary memories we had when we woke have been wiped away. That is how it feels. You wake up and still have access to bits of the dream. But as you try to bring the dream more clearly to mind, you notice that even those few fragments are already starting to fade. Sometimes there is even less. On waking you are unable to shake off the impression that you have been dreaming; the mood of the dream is still there, but you no longer know what it was about. Sometimes you are unable to remember anything at all in the morning, not a dream, not a feeling, but later in the day you experience something that causes a fragment of the apparently forgotten dream to pop into your mind. No matter what we may see as we look back through the doorway, most of our dreams slip away and the obvious question is: why? Why is it so hard to hold on to dreams? Why do we have such a poor memory for them? In 1893, American psychologist Mary Calkins published her ‘Statistics of Dreams’, a numerical analysis of what she and her husband dreamed about over a period of roughly six weeks. They both kept candles, matches, pencil and paper in readiness on the bedside table. But dreams are so fleeting, Calkins wrote, that even reaching out for matches was enough to make them disappear. Still with an arm outstretched, she was forced to conclude that the dream had gone. © 2015 Salon Media Group, Inc
by Laura Sanders On a test of visual perception, children with autism perceive moving dots with more clarity than children without the disorder. The results, published in the May 6 Journal of Neuroscience, reveal a way in which children with autism see the world differently. When asked to determine the overall direction of a mess of dots moving in slightly different directions, children with autism outperformed children without the disorder. Other tests of motion detection didn’t turn up any differences. The results suggest that children with autism may be taking in and combining more motion information than children without autism, says study coauthor Catherine Manning of the University of Oxford. This heightened ability may contribute to feelings of sensory overload, the researchers suggest. © Society for Science & the Public 2000 - 2015