Ashley Yeager Nearly seven years ago, Sheena Josselyn and her husband Paul Frankland were talking with their two-year-old daughter and started to wonder why she could easily remember what happened over the last day or two but couldn’t recall events that had happened a few months before. Josselyn and Frankland, both neuroscientists at the Hospital for Sick Children Research Institute in Toronto, suspected that maybe neurogenesis, the creation of new neurons, could be involved in this sort of forgetfulness. In humans and other mammals, neurogenesis happens in the hippocampus, a region of the brain involved in learning and memory, tying the generation of new neurons to the process of making memories. Josselyn and Frankland knew that in infancy, the brain makes a lot of new neurons, but that neurogenesis slows with age. Yet youngsters have more trouble making long-term memories than adults do, a notion that doesn’t quite jibe with the idea that the principal function of neurogenesis is memory formation. To test the connection between neurogenesis and forgetting, the researchers put mice in a box and shocked their feet with an electric current, then returned the animals to their home cages and either let them stay sedentary or had them run on a wheel, an activity that boosts neurogenesis. Six weeks later, the researchers put the mice back in the box where they had received the shocks. There, the sedentary mice froze in fear, anticipating a shock, but the mice that had run on a wheel didn’t show signs of anxiety. It was as if the wheel-running mice had forgotten they’d been shocked before. © 1986–2020 The Scientist.

Keyword: Learning & Memory; Glia
Link ID: 27245 - Posted: 05.14.2020

Amy Schleunes When Lilian Kloft stumbled across a 2015 study showing a connection between cannabis use and susceptibility to false memories, she found herself wondering about the legal implications of the results. The study had discovered that heavy users of cannabis were more likely than controls to form false memories—recollections of events that never occurred, for example, or warped memories of events that did—even when they were not at the moment “high.” This kind of false remembering can pose difficulties for people gathering reliable testimony in the event of a crime, says Kloft, a PhD student in psychopharmacology and forensic psychology at Maastricht University in the Netherlands. Consequently, the growing acceptance of cannabis worldwide raises questions not only about how the drug affects memory, but also about how law enforcement officials should conduct interviews with suspects, victims, and witnesses who may be under the influence or regular users of the drug. In order to further investigate the connection between cannabis and false memory formation, Kloft and collaborators recruited 64 volunteers for a series of experiments. Participants, who were occasional cannabis users, were given a vaporizer containing either cannabis or a hemp placebo and then told to inhale deeply and hold their breath for 10 seconds. After that, the researchers tested them in three different tasks designed to induce false memories. © 1986–2020 The Scientist.

Keyword: Drug Abuse; Learning & Memory
Link ID: 27244 - Posted: 05.12.2020

by Peter Hess Low levels of the hormone vasopressin in early infancy may presage an autism diagnosis in childhood, according to a new study1. Although preliminary, the results suggest that testing vasopressin levels — particularly in infants with high odds of having autism — could flag the condition in the first few months of life. Early identification would allow autistic children to start therapies far sooner than is currently possible, says co-lead investigator Karen Parker, associate professor of psychiatry and behavioral sciences at Stanford University in California. “By the time a child receives an autism diagnosis, they’re pretty far along the path of having these robust social impairments,” Parker says. Previous work has shown that autistic children have, on average, 66 percent less vasopressin in their cerebrospinal fluid than their neurotypical peers, and that low levels of vasopressin track with poor social skills. The new study found a similar trend in infants aged 3 months and younger. “The surprising thing is that this relationship extends to infancy,” before any observable autism traits have emerged, says Larry Young, chief of behavioral neuroscience and psychiatric disorders at Emory University in Atlanta, Georgia, who was not involved with the study. The results, if confirmed, suggest there is a direct biological connection between vasopressin release and autism, Young says. © 2020 Simons Foundation

Keyword: Autism; Hormones & Behavior
Link ID: 27243 - Posted: 05.12.2020

By Alexandra Jacobs THE SHAPELESS UNEASE A Year of Not Sleeping By Samantha Harvey As if in unwitting aid of the malady they address, books about insomnia tend to be very dull indeed. Many are stuffed with statistics and unhelpful suggestions, like one of those oversize polyester-plumped sham pillows you see on the fancier beds — and just as likely to be flung in frustration to the floor. Samantha Harvey’s memoir of sleeplessness is more like a small and well-worn eiderdown quilt: It might not cover everything, but it both cools and warms, lofts and lulls, settling gradually on its inhabitant with an ethereal solidity. Harvey is a well-regarded novelist in the United Kingdom, and perhaps the only part of this book that feels a little lumpy and uncomfortable is her working out in its pages an O. Henry-like short story about a husband who loses his wedding ring while robbing an A.T.M. More compelled by her predicament, namely stretch after stretch of not only little sleep (or “petite nuit,” as the French more melodiously put it) but no sleep at all, I found it difficult to care about this fictional character, or figure out if his crime and punishment represented anything larger about what disenchanted millennials have taken to describing as “late-stage capitalism.” Not for nothing does the author’s own experience take place in 2016, that epoch of political shock during which a majority of her compatriots voted to leave the European Union, a.k.a. Brexit (“Why isn’t it called Ukexit,” Harvey wonders with the petty irritability of the sleep-deprived), and Donald J. Trump was elected over the pond. That these events have since been outdone by arrival of the coronavirus pandemic, with its attendant sleep disorders, only amplifies this small volume’s relevance and power. © 2020 The New York Times Company

Keyword: Sleep
Link ID: 27242 - Posted: 05.12.2020

By Tina Hesman Saey A loss of smell and taste may be one of the clearest indicators of whether someone has COVID-19, a new study suggests. Researchers gleaned the information from nearly 2.5 million people in the United Kingdom and about 170,000 people in the United States who entered whether they were feeling well or experiencing symptoms into a smartphone app from March 24 to April 21. Some of the app users also reported results of PCR diagnostic tests for the SARS-CoV-2 virus, which causes COVID-19 (SN: 3/6/20). Nearly 65 percent of roughly 6,400 U.K. residents who tested positive for the virus described a loss of taste and smell as a symptom, researchers report May 11 in Nature Medicine. And just over 67 percent of the 726 U.S. participants with a positive test also reported losing those senses. Only about 20 percent of all people who tested negative had diminished smell and taste. Using data from the app, a team of scientists led by clinical researchers Claire Steves and Tim Spector, both of King’s College London, devised a formula for determining which symptoms best predict COVID-19. A combination of loss of taste and smell, extreme fatigue, cough and loss of appetite was the best predictor of having a positive result from the PCR test, the team found. Based on those symptoms, the researchers estimate that more than 140,000 of the more than 800,000 app users who reported symptoms probably have COVID-19. © Society for Science & the Public 2000–2020.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27241 - Posted: 05.12.2020

Sirin Kale Alice,* a 31-year-old director from London, has been breaking the coronavirus lockdown rules. “I almost don’t want to tell you this,” she says, lowering her voice. Her violation? Once a week, Alice, who lives alone, walks to the end of her garden to meet her best friend Lucy.* There, with the furtiveness of a street drug deal, Lucy hugs her tightly. Alice struggles to let her go. “You just get that rush of feeling better,” Alice says. “Like it’s all OK.” Aside from Lucy’s hugs, Alice hasn’t been touched by another person since March 15, which is when she went into a self-imposed lockdown, a week before the official government advice to self-isolate. “I’ve found it really hard,” she says. “I am a huggy person. You start to notice it after a while. I miss it.” She feels guilty about her surreptitious hugs. “I feel like I can’t tell my other friends about it,” Alice says. “There’s a lot of shaming going on. I know we aren’t meant to. But I am so grateful to her for checking in on me. It gives me such a lift.” Alice is experiencing the neurological phenomenon of "skin hunger," supercharged by the coronavirus pandemic. Skin hunger is the biological need for human touch. It’s why babies in neonatal intensive care units are placed on their parent’s naked chests. It’s the reason prisoners in solitary confinement often report craving human contact as ferociously as they desire their liberty. © 2020 Condé Nast.

Keyword: Emotions; Pain & Touch
Link ID: 27240 - Posted: 05.08.2020

by Giorgia Guglielmi More than half of the genes expressed in the prefrontal cortex, a brain region that is implicated in autism, begin to change their expression patterns in late fetal development, according to a new study1. Previous studies have looked at how DNA variants can influence gene expression at specific developmental periods. This is the first to map their effects in a specific region over the full span of human brain development, says co-senior investigator Stephan Sanders, associate professor of psychiatry at the University of California, San Francisco. “If we ever really want to understand what autism is, understanding human fetal development of the brain is going to be absolutely critical,” Sanders says. Some of the changes in expression patterns vary depending on individual differences in neighboring DNA sequences, the study found. Some of that variation occurs in stretches of the genome linked to neurodevelopmental outcomes, such as how much schooling a person completes (a proxy for intelligence) or whether she develops schizophrenia. “This study creates a resource for trying to understand neurodevelopment and neuropsychiatric disorders,” Sanders says. Fetal expression: The researchers analyzed the prefrontal cortex of 176 postmortem brains from donors ranging in age from 6 weeks post-conception to 20 years. None had any known neuropsychiatric conditions or large-scale genetic anomalies. The team identified 23,782 genes expressed during brain development in the dorsolateral prefrontal cortex, a region implicated in many developmental conditions, including autism. © 2020 Simons Foundation

Keyword: Autism; Genes & Behavior
Link ID: 27239 - Posted: 05.08.2020

A small study funded by the National Institutes of Health suggests that sleep problems among children who have a sibling with autism spectrum disorder (ASD) may further raise the likelihood of an ASD diagnosis, compared to at-risk children who do not have difficulty sleeping. Previous research has shown that young children who have a sibling with ASD are at a higher risk for also being diagnosed with the condition. The study appears in The American Journal of Psychiatry. If confirmed by other studies, the findings may give clinicians a tool to identify sleep problems early and provide interventions to reduce their effects on the health and development of children with autism. The findings may also provide insights into the potential role of sleep problems in the development of ASD. The study was conducted by Annette M. Estes, Ph.D., of the University of Washington Autism Center in Seattle, and colleagues in the NIH Autism Centers of Excellence Infant Brain Imaging Study Network. NIH funding was provided by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the National Institute of Mental Health. “The results are a promising lead,” said Alice Kau, Ph.D., of NICHD’s Intellectual and Developmental Disabilities Branch. “If confirmed by more in-depth studies, patterns of sleep disturbance in early life might be used to pinpoint increased risk for ASD among young children already at risk because they have a sibling with ASD.” The researchers analyzed data from a long-term study of children who do and do not have siblings with ASD. When the children were 6 and 12 months of age, parents were asked to respond to an infant temperament questionnaire that asks how much difficulty their child has falling asleep at bedtime and falling back to sleep after waking up during the night. At these time intervals, the children also received MRI scans to track their brain development. At 24 months, the children were assessed for ASD.

Keyword: Autism; Sleep
Link ID: 27238 - Posted: 05.08.2020

By Godfrey Pearlson Around the world, about 188 million people use marijuana every year. The drug has been legalized for recreational use in 11 U.S. states, and it may eventually become legal at the federal level. In a Gallup survey conducted last summer, 12 percent of American adults reported that they smoked marijuana, including 22 percent of 18- to 29-year-olds. Those are the stats. The consequences remain a mystery. As access to marijuana increases—and while acceptance of the drug grows and perception of its harmfulness diminishes—it is important to consider the potential for long-term ill effects, especially in users who start young. One of marijuana’s best-documented consequences is short-lived interference with memory. The substance makes it harder to get information into memory and, subsequently, to access it, with larger doses causing progressively more problems. Much less documented, however, is whether the drug has lasting effects on cognitive abilities. Finding the answer to that question is essential. Depending on the severity of any such effects and their persistence, marijuana use could have significant downstream impacts on education, employment, job performance and income. There are plausible reasons why the teenage brain may be especially vulnerable to the effects of marijuana use. Natural cannabinoids play an essential role in brain cell migration and development from fetal life onward. And adolescence is a crucial age for finalizing brain sculpting and white matter proliferation. The hippocampi, paired structures in the temporal lobe that are crucial in the formation of new memories, are studded with cannabinoid receptors. THC, the main ingredient behind marijuana’s “high,” acts on the brain’s cannabinoid receptors to mimic some of the effects of the body’s endogenous cannabinoids, such as anandamide. The compound’s effects are more persistent and nonphysiological, however. It may be throwing important natural processes out of balance. © 2020 Scientific American,

Keyword: Drug Abuse; Learning & Memory
Link ID: 27237 - Posted: 05.08.2020

Ashley Yeager In the spring of 2019, neuroscientist Heather Cameron set up a simple experiment. She and her colleagues put an adult rat in the middle of a plastic box with a water bottle at one end. They waited until the rat started drinking and then made a startling noise to see how the animal would respond. The team did this repeatedly with regular rats and with animals that were genetically altered so that they couldn’t make new neurons in their hippocampuses, a brain region involved in learning and memory. When the animals heard the noise, those that could make new hippocampal neurons immediately stopped slurping water and looked around, but the animals lacking hippocampal neurogenesis kept drinking. When the team ran the experiment without the water bottle, both sets of rats looked around right away to figure out where the sound was coming from. Rats that couldn’t make new neurons seemed to have trouble shifting their attention from one task to another, the researchers concluded. “It’s a very surprising result,” says Cameron, who works at the National Institute of Mental Health (NIMH) in Bethesda, Maryland. Researchers studying neurogenesis in the adult hippocampus typically conduct experiments in which animals have had extensive training in a task, such as in a water maze, or have experienced repetitive foot shocks, she explains. In her experiments, the rats were just drinking water. “It seemed like there would be no reason that the hippocampus should have any role,” she says. Yet in animals engineered to lack hippocampal neurogenesis, “the effects are pretty big.” The study joins a growing body of work that challenges the decades-old notion that the primary role of new neurons within the adult hippocampus is in learning and memory. More recently, experiments have tied neurogenesis to forgetting, one possible way to ensure the brain doesn’t become overloaded with information it doesn’t need, and to anxiety, depression, stress, and, as Cameron’s work suggests, attention. Now, neuro-scientists are rethinking the role that new neurons, and the hippocampus as a whole, play in the brain. © 1986–2020 The Scientist.

Keyword: Neurogenesis; Learning & Memory
Link ID: 27236 - Posted: 05.06.2020

Michael Marshall In 2018, psychiatrist Oleguer Plana-Ripoll was wrestling with a puzzling fact about mental disorders. He knew that many individuals have multiple conditions — anxiety and depression, say, or schizophrenia and bipolar disorder. He wanted to know how common it was to have more than one diagnosis, so he got his hands on a database containing the medical details of around 5.9 million Danish citizens. He was taken aback by what he found. Every single mental disorder predisposed the patient to every other mental disorder — no matter how distinct the symptoms1. “We knew that comorbidity was important, but we didn’t expect to find associations for all pairs,” says Plana-Ripoll, who is based at Aarhus University in Denmark. The study tackles a fundamental question that has bothered researchers for more than a century. What are the roots of mental illness? In the hope of finding an answer, scientists have piled up an enormous amount of data over the past decade, through studies of genes, brain activity and neuroanatomy. They have found evidence that many of the same genes underlie seemingly distinct disorders, such as schizophrenia and autism, and that changes in the brain’s decision-making systems could be involved in many conditions. Researchers are also drastically rethinking theories of how our brains go wrong. The idea that mental illness can be classified into distinct, discrete categories such as ‘anxiety’ or ‘psychosis’ has been disproved to a large extent. Instead, disorders shade into each other, and there are no hard dividing lines — as Plana-Ripoll’s study so clearly demonstrated. © 2020 Springer Nature Limited

Keyword: Schizophrenia; Genes & Behavior
Link ID: 27235 - Posted: 05.06.2020

By Rodrigo Pérez Ortega The left and right sides of our brains store different kinds of memories: The left side specializes in verbal information, for example, while the right side specializes in visual information. But it turns out we’re not the only ones. A new study suggests that ants—like humans, songbirds, and zebrafish—also store different memories in different sides of their tiny brains, in a process called lateralization. Honey bees and bumblebees seem to exhibit lateralization when it comes to memories involving scent. But researchers wanted to know whether other insects were also dividing up the labor of their brains. They trained wood ants (Formica rufa) just as Russian physiologist Ivan Pavlov trained his famous dogs—by treating them with food each time they received a certain signal. To find out whether ants stored visual memories in different parts of their brains, the researchers touched the right antenna, the left antenna, or both, of dozens of ants with a sugary droplet each time they looked at a blue object (above). Then, the researchers tested their memories 10 minutes, 1 hour, and 24 hours after the training. They did this by showing them the blue object and observing whether they extended their mouths, a “thirst” response similar to Pavlov’s dogs salivating. Ants trained with the right antenna had strong thirst responses at the 10-minute mark and lingering responses after 1 hour, but not after that. Ants trained with the left antenna had no response at 10 minutes or 1 hour, but appeared thirsty 24 hours after their training. That suggests that one side of the ant brain stores short-term memories, while the other side stores longer-term ones, the researchers write today in Proceedings of the Royal Society B. © 2020 American Association for the Advancement of Science

Keyword: Laterality; Learning & Memory
Link ID: 27234 - Posted: 05.06.2020

By Amanda Heidt Koalas begging firefighters for water have become emblematic of Australia’s recent wildfire woes. But aside from these unusual interactions, scientists have never been quite sure how koalas drink. Now, a new study has documented the first evidence of the clever way they stay hydrated: by licking water from the smooth bark of gum trees as it rains. Past research has suggested that because koalas spend the vast majority of their time in trees, they likely get most of their water from the eucalyptus leaves they eat. But over the course of 13 years—from 2006 to 2019—citizen scientists, ecologists, and land owners reported 46 sightings of tree-licking behavior (above) in wild koalas. Researchers reviewed video and photographic evidence, and they found that even when puddles or lakes were nearby, koalas were more likely to drink the water running down trees, they report this month in Ethology. Koalas face a number of threats, and dwindling access to water is high on the list. Australia is now experiencing its driest period on record, with higher average temperatures and fewer days of rain. If tree licking provides a significant proportion of koalas’ water needs, researchers hope their results can identify areas where water should be supplemented as the rain dries up. © 2020 American Association for the Advancement of Science.

Keyword: Drug Abuse; Evolution
Link ID: 27233 - Posted: 05.06.2020

Catherine Offord No matter how he looked at the data, Albert Tsao couldn’t see a pattern. Over several weeks in 2007 and again in 2008, the 19-year-old undergrad trained rats to explore a small trial arena, chucking them pieces of tasty chocolate cereal by way of encouragement. He then recorded the activity of individual neurons in the animals’ brains as they scampered, one at a time, about that same arena. He hoped that the experiment would offer clues as to how the rats’ brains were forming memories, but “the data that it gave us was confusing,” he says. There wasn’t any obvious pattern to the animals’ neural output at all. Then enrolled at Harvey Mudd College in California, Tsao was doing the project as part of a summer internship at the Kavli Institute for Systems Neuroscience in Norway, in a lab that focused on episodic memory—the type of long-term memory that allows humans and other mammals to recall personal experiences (or episodes), such as going on a first date or spending several minutes searching for chocolate. Neuroscientists suspected that the brain organizes these millions of episodes partly according to where they took place. The Kavli Institute’s Edvard Moser and May-Britt Moser had recently made a breakthrough with the discovery of “grid cells,” neurons that generate a virtual spatial map of an area, firing whenever the animal crosses the part of the map that that cell represents. These cells, the Mosers reported, were situated in a region of rats’ brains called the medial entorhinal cortex (MEC) that projects many of its neurons into the hippocampus, the center of episodic memory formation. Inspired by the findings, Tsao had opted to study a region right next to the MEC called the lateral entorhinal cortex (LEC), which also feeds into the hippocampus. © 1986–2020 The Scientist

Keyword: Learning & Memory
Link ID: 27232 - Posted: 05.05.2020

by Laura Dattaro / Autistic people have atypical activity in a part of the brain that regulates attention, according to a new study1. The researchers measured pupil responses as a proxy for brain activity in a brain region known as the locus ceruleus. Located in the brain stem, the region plays a key role in modulating activity throughout the brain, in part by controlling attention. It can broaden and narrow pupils to adjust how much visual information a person receives, for example. Because of this, researchers can use pupil size to infer activity in the region and gauge a person’s focus on a task; a wider pupil indicates increased focus. The locus ceruleus may also be key to regulating the balance between excitatory and inhibitory brain signals. Some research indicates this equilibrium is disrupted in autism, suggesting the region plays a role in the condition’s underlying biology. In the new study, researchers compared autistic and typical people’s pupil responses when performing a task with and without a distracting sound. Typical people’s pupils grew larger when hearing the sound, suggesting a boost in focus directed by the locus ceruleus. By contrast, the pupils of autistic people did not widen, indicating they do not modulate their attention in the same way. This might have profound consequences for autistic people’s sensory experience, the researchers say. © 2020 Simons Foundation

Keyword: Autism; Attention
Link ID: 27231 - Posted: 05.05.2020

By Susan Milius An elephant, a narwhal and a guinea pig walk into a bar. From there, things could get ugly. All three might get drunk easily, according to a new survey of a gene involved in metabolizing alcohol. They’re among the creatures affected by 10 independent breakdowns of the ADH7 gene during the history of mammal evolution. Inheriting that dysfunctional gene might make it harder for their bodies to break down ethanol, says molecular anthropologist Mareike Janiak of the University of Calgary in Canada. She and colleagues didn’t look at all the genes needed to metabolize ethanol, but the failure of this important one might allow ethanol to build up more easily in these animals’ bloodstreams, Janiak and colleagues report April 29 in Biology Letters. The carnivorous cetaceans, grain- or leaf-eating guinea pigs and most other animals that the study identified as potentially easy drunks probably don’t binge on sugary fruit and nectar that brews ethanol. Elephants, however, will feast on fruit, and the new study reopens a long-running debate over whether elephants truly get tipsy gorging on marula fruit, a relative of mangoes. Descriptions of elephants behaving oddly after binging on overripe fruit go back at least to 1875, Janiak says. Later, a taste test offering the animals troughs of water spiked with ethanol found that elephants willingly drank. Afterward, they swayed more when moving and seemed more aggressive, observers reported. © Society for Science & the Public 2000–2020.

Keyword: Drug Abuse; Evolution
Link ID: 27230 - Posted: 05.05.2020

By Kim Severson In the 1980s, when marriage and adopting children seemed impossible dreams for gay men, the psychoanalyst Richard C. Friedman became their champion. His 1988 book, “Male Homosexuality: A Contemporary Psychoanalytic Perspective,” showed that sexual orientation was largely biological and presented a case that helped undermine the belief held by most Freudian analysts at the time that homosexuality was a pathology that could somehow be cured. “I felt an ethical obligation to find the reasons for anti-homosexual prejudice,” he once told an interviewer. His wife, Susan Matorin, a clinical social worker at the Weill Medical College of Cornell, put it more plainly: “Straight people had the same personality issues, and they got away with murder, but gay people were stigmatized, and he didn’t think that was right.” Dr. Friedman’s motivation wasn’t political. “He very much felt like you followed the science, and it didn’t matter what the political backdrop was,” his son, Jeremiah, a screenwriter in Los Angeles, said in a phone interview. Although the American Psychiatric Association, the dominant mental health organization in the United States, changed its diagnostic manual in 1973 and stopped classifying homosexuality as an illness, psychoanalysts continued to describe homosexuality as a perversion, and many believed it could be cured. Dr. Friedman, using studies of identical twins and theories of developmental psychology, made a scholarly rather than ideological case that biology rather than upbringing played a significant role in sexual orientation. It was a direct challenge to popular Freudian theories and thrust him into the center of debates among the more established heavyweights of psychoanalysis. It led to a model in which analyst and patient simply assumed that homosexuality was intrinsic, said Jack Drescher, a professor of psychiatry at Columbia University who knew Dr. Friedman and would later offer his own critiques of Dr. Friedman’s theory as new approaches to working with gay and lesbian patients emerged. © 2020 The New York Times Company

Keyword: Sexual Behavior
Link ID: 27229 - Posted: 05.05.2020

Amber Dance A mouse finds itself in a box it’s never seen before. The walls are striped on one side, dotted on the other. The orange-like odor of acetophenone wafts from one end of the box, the spiced smell of carvone from the other. The mouse remembers that the orange smell is associated with something good. Although it may not recall the exact nature of the reward, the mouse heads toward the scent. Except this mouse has never smelled acetophenone in its life. Rather, the animal is responding to a false memory, implanted in its brain by neuroscientists at the Hospital for Sick Children in Toronto. Sheena Josselyn, a coauthor on a 2019 Nature Neuroscience study reporting the results of the project, says the goal was not to confuse the rodent, but for the scientists to confirm their understanding of mouse memory. “If we really understand memory, we should be able to trick the brain into remembering something that never happened at all,” she explains. By simultaneously activating the neurons that sense acetophenone and those associated with reward, the researchers created the “memory” that the orange-y scent heralded good things. Thanks to optogenetics, which uses a pulse of light to activate or deactivate neurons, Josselyn and other scientists are manipulating animal memories in all kinds of ways. Even before the Toronto team implanted false memories into mice, researchers were making rodents forget or recall an event with the flick of a molecular light switch. With every flash of light, they test their hypotheses about how these animals—and by extension, people—collect, store, and access past experiences. Scientists are also examining how memory formation and retrieval change with age, how those processes are altered in animal models of Alzheimer’s disease, and how accessing memories can influence an animal’s emotional state. © 1986–2020 The Scientist.

Keyword: Learning & Memory; Alzheimers
Link ID: 27228 - Posted: 05.02.2020

By Dennis Normile Scientists studying brains and other organs and cancerous tumors have long tried to get detailed 3D views of their insides—down to the level of blood vessel and cell type. But producing such images is time-consuming and difficult. Now, dramatic improvements to a 3D imaging technique can reveal the internal components of entire organs or even animals in a simple procedure, researchers report this week. The new tissue staining protocol allows cellular level analyses in unprecedented detail; it could aid research efforts in neuroscience, developmental and evolutionary biology, and immunology, and it could prove useful in diagnosing some cancers and studying damaged brain tissue after death. To image biological samples in 3D, researchers basically have two main options: They can slice tissues into thin sections and use computer software to reconstruct the whole sample, or they can render biological tissue transparent using special chemicals, which lets researchers view its interior with an optical microscope. To distinguish different cell types, researchers typically stain tissues by soaking them in a cocktail of dyes and chemicals. But getting staining dyes to penetrate organs and large samples has proved difficult. To tackle this problem, researchers at the RIKEN Center for Biosystems Dynamics Research identified a gel that closely mimics the physicochemical properties of organs that have undergone the tissue clearing process. Starting with computer simulations and following up with laboratory tests, the team optimized the soaking solution temperature, dye and antibody concentrations, chemical additives, and electrical properties to produce the best staining and imaging results. They then tested their method with more than two dozen commonly used dyes and antibodies on mouse and marmoset brains. © 2020 American Association for the Advancement of Science.

Keyword: Brain imaging
Link ID: 27227 - Posted: 05.02.2020

Ruth Williams Scientists have created a light-responsive opsin so sensitive that even when engineered into cells deep within tissue it can respond to an external light stimulus, according to a report in Neuron yesterday (April 30). Experiments in mice and macaques showed that shining blue light on the surface of the skull or brain was sufficient to activate opsin-expressing neurons six millimeters deep. “I was pretty blown away that this was even possible,” says Gregory Corder, who studies the neurological basis of pain and addiction at the University of Pennsylvania and who was not involved with the work. At that sort of depth, he continues, “essentially no part of the rodent brain is off-limits now for doing this non-invasive [technique]. . . . It’s pretty impressive.” “This development will help to extend the use of optogenetics in non-human primate models, and bring the techniques closer to clinical application in humans,” adds neurological disease expert Adriana Galvan of Yerkes National Primate Research Center in an email to The Scientist. Galvan was not a member of the research team. Optogenetics is a technique whereby excitable cells, such as neurons, can be controlled at will by light. To do this, cells are genetically engineered to produce ion channels called opsins that sit in the cells’ membranes and open in response to a certain wavelength of light. Switching on the light, then, floods the cells with ions, causing them to fire. Because light doesn’t penetrate tissue easily, to activate opsin-producing neurons deep in the brain of a living animal, researchers insert fiber optic cables. This is “highly invasive,” says Galvan, explaining that “the brain tissue can be damaged.” © 1986–2020 The Scientist.

Keyword: Brain imaging
Link ID: 27226 - Posted: 05.02.2020