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Scientists have traced vulnerability to depression-like behaviors in mice to out-of-balance electrical activity inside neurons of the brain’s reward circuit and experimentally reversed it – but there’s a twist. Instead of suppressing it, researchers funded by the National Institutes of Health boosted runaway neuronal activity even further, eventually triggering a compensatory self-stabilizing response. Once electrical balance was restored, previously susceptible animals were no longer prone to becoming withdrawn, anxious, and listless following socially stressful experiences. “To our surprise, neurons in this circuit harbor their own self-tuning, homeostatic mechanism of natural resilience,” explained Ming-Hu Han, Ph.D External Web Site Policy., of the Icahn School of Medicine at Mount Sinai, New York City, a grantee of the NIH’s National Institute of Mental Health (NIMH) and leader of the research team. Han and colleagues report on their discovery April 18, 2014 in the journal Science. Prior to the new study, the researchers had turned resilience to social stress on and off by using pulses of light to manipulate reward circuit neuronal firing rates in genetically engineered mice – optogenetics. But they didn’t know how resilience worked at the cellular level. To find out, they focused on electrical events in reward circuit neurons of mice exposed to a social stressor. Some mice that experience repeated encounters with a dominant animal emerge behaviorally unscathed, while others develop depression-like behaviors.
By Bill Briggs A Vietnam veteran swoops his hand through a row of baby vegetables, caressing the peppers on down to the kale. The plants are aligned in tidy, military order atop his backyard fence. He could spend hours describing his first garden. But he cannot utter a word. He can’t even eat his eventual harvest. So, Bob Hoaglan, 71, simply stands and grins at the spouts behind his Oxnard, Calif., home. Then, he grabs his primary communication tool, an LCD tablet, scribbling a stylus across the screen. He displays his words with a silent chuckle: “I don’t have a green thumb.” With a button click, he erases that sentence before composing another. His daily aim is to throw his body and brain into new pursuits. The crops — fresh life for a man facing mortality — help shove his disease to the back of his mind. He admits, though, he can’t keep it there: “I try,” he writes, “Sometimes it creeps up on me.” As he shows that message, the smile vanishes. Hoaglan was diagnosed with amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, nearly a year ago. Inside a malady that offers no cure or explanation, he embodies two intriguing clues that, a top researcher says, may whisper answers: Hoaglan served in the military, and he is a nice man. U.S. veterans carry a nearly 60 percent greater risk of contracting ALS than civilians, according to a white paper published in 2013 by the ALS Association, citing Harvard University research that tracked ex-service members back to 1910.
Keyword: ALS-Lou Gehrig's Disease
Link ID: 19509 - Posted: 04.19.2014
By David Z. Hambrick and Christopher Chabris The College Board—the standardized testing behemoth that develops and administers the SAT and other tests—has redesigned its flagship product again. Beginning in spring 2016, the writing section will be optional, the reading section will no longer test “obscure” vocabulary words, and the math section will put more emphasis on solving problems with real-world relevance. Overall, as the College Board explains on its website, “The redesigned SAT will more closely reflect the real work of college and career, where a flexible command of evidence—whether found in text or graphic [sic]—is more important than ever.” A number of pressures may be behind this redesign. Perhaps it’s competition from the ACT, or fear that unless the SAT is made to seem more relevant, more colleges will go the way of Wake Forest, Brandeis, and Sarah Lawrence and join the “test optional admissions movement,” which already boasts several hundred members. Or maybe it’s the wave of bad press that standardized testing, in general, has received over the past few years. Critics of standardized testing are grabbing this opportunity to take their best shot at the SAT. They make two main arguments. The first is simply that a person’s SAT score is essentially meaningless—that it says nothing about whether that person will go on to succeed in college. Leon Botstein, president of Bard College and longtime standardized testing critic, wrote in Time that the SAT “needs to be abandoned and replaced,” © 2014 The Slate Group LLC.
Link ID: 19508 - Posted: 04.19.2014
by Ashley Yeager A nerve cell's long, slender tentacle isn’t evenly coated with an insulating sheath as scientists had thought. Instead, many nerve cells in the brains of mice have stretches of these tentacles, called axons, that are naked, researchers report April 18 in Science. The unsheathed feeler can be as long as 80 micrometers. Nerve cells can also have specific patterns in the gaps of the insulating layer, called myelin. The differences in the thickness of that coating may control how fast signals travel between nerve cells, the scientists suggest. The finding could have implications for understanding nerve-based diseases, such as multiple sclerosis, and improve scientists’ understanding of how signals are transmitted in the brain. © Society for Science & the Public 2000 - 2013.
By David Brown, At the very least, the new experiment reported in Science is going to make people think differently about what it means to be a “rat.” Eventually, though, it may tell us interesting things about what it means to be a human being. In a simple experiment, researchers at the University of Chicago sought to find out whether a rat would release a fellow rat from an unpleasantly restrictive cage if it could. The answer was yes. The free rat, occasionally hearing distress calls from its compatriot, learned to open the cage and did so with greater efficiency over time. It would release the other animal even if there wasn’t the payoff of a reunion with it. Astonishingly, if given access to a small hoard of chocolate chips, the free rat would usually save at least one treat for the captive — which is a lot to expect of a rat. The researchers came to the unavoidable conclusion that what they were seeing was empathy — and apparently selfless behavior driven by that mental state. “There is nothing in it for them except for whatever feeling they get from helping another individual,” said Peggy Mason, the neurobiologist who conducted the experiment along with graduate student Inbal Ben-Ami Bartal and fellow researcher Jean Decety. “There is a common misconception that sharing and helping is a cultural occurrence. But this is not a cultural event. It is part of our biological inheritance,” she added. The idea that animals have emotional lives and are capable of detecting emotions in others has been gaining ground for decades. Empathic behavior has been observed in apes and monkeys, and described by many pet owners (especially dog owners). Recently, scientists demonstrated “emotional contagion” in mice, a situation in which one animal’s stress worsens another’s. © 1996-2014 The Washington Post
Everything we do — all of our movements, thoughts and feelings – are the result of neurons talking with one another, and recent studies have suggested that some of the conversations might not be all that private. Brain cells known as astrocytes may be listening in on, or even participating in, some of those discussions. But a new mouse study suggests that astrocytes might only be tuning in part of the time — specifically, when the neurons get really excited about something. This research, published in Neuron, was supported by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health. For a long time, researchers thought that the star-shaped astrocytes (the name comes from the Greek word for star) were simply support cells for the neurons. It turns out that these cells have a number of important jobs, including providing nutrients and signaling molecules to neurons, regulating blood flow, and removing brain chemicals called neurotransmitters from the synapse. The synapse is the point of information transfer between two neurons. At this connection point, neurotransmitters are released from one neuron to affect the electrical properties of the other. Long arms of astrocytes are located next to synapses, where they can keep tabs on the conversations going on between neurons. In recent years, it has been shown that astrocytes may also play a role in neuronal communication. When neurons release neurotransmitters, levels of calcium change within astrocytes. Calcium is critical for many processes, including release of molecules from the cell, and activation of a host of proteins within the cell. The role of this astrocytic calcium signaling for brain function remains a mystery.
Link ID: 19505 - Posted: 04.17.2014
By Melissa Hogenboom Artists have structurally different brains compared with non-artists, a study has found. Participants' brain scans revealed that artists had increased neural matter in areas relating to fine motor movements and visual imagery. The research, published in NeuroImage, suggests that an artist's talent could be innate. But training and environmental upbringing also play crucial roles in their ability, the authors report. As in many areas of science, the exact interplay of nature and nurture remains unclear. Lead author Rebecca Chamberlain from KU Leuven University, Belgium, said she was interested in finding out how artists saw the world differently. "The people who are better at drawing really seem to have more developed structures in regions of the brain that control for fine motor performance and what we call procedural memory," she explained. In their small study, researchers peered into the brains of 21 art students and compared them to 23 non-artists using a scanning method called voxel-based morphometry. Detail of 'Giant Lobster' from NHM specimen collection One artist who has practised for many years is Alice Shirley - here is a detail of her Giant Lobster These detailed scans revealed that the artist group had significantly more grey matter in an area of the brain called the precuneus in the parietal lobe. "This region is involved in a range of functions but potentially in things that could be linked to creativity, like visual imagery - being able to manipulate visual images in your brain, combine them and deconstruct them," Dr Chamberlain told the BBC's Inside Science programme. BBC © 2014
BY Ellen Rolfes Rebecca Kamen’s sculptures appear as delicate as the brain itself. Thin, green branches stretch from a colorful mass of vein-like filaments. The branches, made from pieces of translucent mylar and stained with diluted acrylic paint, are so delicate that they sway slightly when mounted to the wall. Perched on various parts of the sculpture are mylar butterflies, whose wings also move, as if fluttering. One of Kamen's influences is the writing of Santiago Ramon y Cajal, who is called the "father of modern neuroscience." Cajal once said: “Like the entomologist in search of colorful butterflies, my attention has chased in the gardens of the grey matter cells with delicate and elegant shapes, the mysterious butterflies of the soul, whose beating of wings may one day reveal to us the secrets of the mind." One of Kamen’s artistic influences is the writing of Santiago Ramon y Cajal, who is called the “father of modern neuroscience.” The work, called “Butterflies of the Soul” was inspired by neuroscientist Santiago Ramon y Cajal, who won the 1906 Nobel Prize, for his groundbreaking work on the human nervous system. Kamen’s sculpture is a nod to his work and the development of modern neuroscience. Cajal’s observation of the cells under the microscope radically changed how scientists study the brain and its functions, Kamen said. And the butterflies in her sculpture represent Cajal’s drawings of Purkinje cells, which are found in the cerebellar cortex at the base of the brain. Purkinje cells play an important role in motor control and in certain cognitive functions, such as attention and language. And attention and language are skills of great interest to Kamen, who has dyslexia. Her fascination with the brain and its structure deepened when she discovered that she was dyslexic later in life. © 1996 - 2014 MacNeil / Lehrer Productions.
Link ID: 19503 - Posted: 04.17.2014
By DORIS IAROVICI, M.D. “I think our experiment failed,” the young graduate student told me, referring to our attempt to take her off the antidepressant she’d been on for seven years. She was back in my campus office after a difficult summer break, and as she talked about feeling unsettled and upset, I wondered about the broader experiment playing out on college campuses across the country. Antidepressants are an excellent treatment for depression and anxiety. I’ve seen them improve — and sometimes save — many young lives. But a growing number of young adults are taking psychiatric medicines for longer and longer periods, at the very age when they are also consolidating their identities, making plans for the future and navigating adult relationships. Are we using good scientific evidence to make decisions about keeping these young people on antidepressants? Or are we inadvertently teaching future generations to view themselves as too fragile to cope with the adversity that life invariably brings? My patient had started medication as a college freshman, after she’d become depressed and spent much of her time in bed. She was forced to take a medical leave but improved quickly, returned to school and graduated. She married soon after and worked for a few years, feeling well all the while. Professional guidelines recommend six to nine months of medicine for first episodes of depression. But my patient had never been advised to stop taking it. She reluctantly agreed to my recommendation to taper off her antidepressant. © 2014 The New York Times Company
Link ID: 19502 - Posted: 04.17.2014
On Wednesday morning we woke to the news that a passenger ferry had sunk off the coast of South Korea, with at least four people confirmed dead and 280 unaccounted for. Meanwhile, though the search has continued for the missing Malaysia Airlines plane, relatives' hopes of a safe landing have long since been extinguished. Human tragedies like these are the stuff of daily news, but we rarely hear about the long-term psychological effects on survivors and the bereaved, who may experience the symptoms of post-traumatic stress disorder for years after their experience. Although most people have heard of PTSD, few will have a clear idea of what it entails. The American Psychiatric Association's Diagnostic and Statistical Manual (DSM) defines a traumatic event as one in which a person "experienced, witnessed, or was confronted with an event or events that involved actual or threatened death or serious injury, or a threat to the physical integrity of self or others". PTSD is marked by four types of responses to the trauma. First, patients repeatedly relive the event, either in the form of nightmares or flashbacks. Second, they seek to avoid any reminder of the traumatic event. Third, they feel constantly on edge. Fourth, they are plagued with negative thoughts and low mood. According to one estimate, almost 8% of people will develop PTSD during their lifetime. Clearly trauma (and PTSD) can strike anyone, but the risks of developing the condition are not equally distributed. Rates are higher in socially disadvantaged areas, for instance. Women may be twice as likely to develop PTSD as men. This is partly because women are at greater risk of the kinds of trauma that commonly produce PTSD (rape, for example). Nevertheless – and for unknown reasons – when exposed to the same type of trauma, women are more susceptible to PTSD than men. © 2014 Guardian News and Media Limited
|By Daisy Yuhas Strange as it may sound, some scientists suspect that the humble armpit could be sending all kinds of signals from casual flirtation to sounding the alarm. That’s because the body’s secretions, some stinky and others below the threshold your nose can detect, may be rife with chemical messages called pheromones. Yet despite half a century of research into these subtle cues, we have yet to find direct evidence of their existence in humans. Humans and other animals have an olfactory system designed to detect and discriminate between thousands of chemical compounds. For more than 50 years, scientists have been aware of the fact that certain insects and animals can release chemical compounds—often as oils or sweat—and that other creatures can detect and respond to these compounds, which allows for a form of silent, purely chemical communication. Although the exact definition has been debated and redefined several times, pheromones are generally recognized as single or small sets of compounds that transmit signals between organisms of the same species. They are typically just one part of the larger potpourri of odorants emitted from an insect or animal, and some pheromones do not have a discernable scent. Since pheromones were first defined in 1959, scientists have found many examples of pheromonal communication. The most striking of these signals elicits an immediate behavioral response. For example, the female silk moth releases a trail of the molecule bombykol, which unerringly draws males from the moment they encounter it. Slower-acting pheromones can affect the recipient’s reproductive physiology, as when the alpha-farnesene molecule in male mouse urine accelerates puberty in young female mice. © 2014 Scientific American
Mégevand P et al., Journal of Neuroscience (2014) Close your eyes and imagine home. Sharp details—such as the shape of the front doorknob, the height of the windows, or the paint color—assemble in your mind with a richness that seems touchable. A new study has found where this mental projection lives in the brain by inducing hallucinations in an epilepsy patient. A 22-year-old male was receiving deep brain stimulation to isolate where his daily seizures originated. His disorder appeared after he caught West Nile virus at the age of 10 and subsequently suffered from brain inflammation. His episodes were always preceded by intense déjà vu, suggesting a visual component of his disease, but he had no history of hallucinations. Brain scans revealed a shrunken spot near his hippocampus—the brain’s memory center. Studies had shown that this region—known as the parahippocampal place area (PPA)—was involved with recognizing of scenes and places. Doctors reconfirmed this by showing the patient pictures of a house and seeing the PPA light up on brain scans with functional magnetic resonance imaging (images above show brain activity; yellow indicates stronger activation than red). Thin wire electrodes—less than 2 mm thick—placed in the PPA (yellow dots in right panel) recorded similar brain activity after viewing these pictures. To assess if the PPA was ground zero for seizures, the doctors used a routine procedure that involves shooting soft jolts of electricity into the region and seeing if the patient senses an oncoming seizure. Rather than have déjà vu, the patient’s surroundings suddenly changed as he hallucinated places familiar to him. In one instance, the doctors morphed into the Italians from his local pizza place. Zapping a nearby cluster of neurons produced a vision of his subway station. The findings, published on 16 April in The Journal of Neuroscience, confirm that this small corner of the brain is not only responsible for recognizing places, but is also crucial to recalling a mental vision of that place. © 2014 American Association for the Advancement of Science
Link ID: 19499 - Posted: 04.17.2014
Virginia Hughes Trauma is insidious. It not only increases a person’s risk for psychiatric disorders, but can also spill over into the next generation. People who were traumatized during the Khmer Rouge genocide in Cambodia tended to have children with depression and anxiety, for example, and children of Australian veterans of the Vietnam War have higher rates of suicide than the general population. Trauma’s impact comes partly from social factors, such as its influence on how parents interact with their children. But stress also leaves ‘epigenetic marks’ — chemical changes that affect how DNA is expressed without altering its sequence. A study published this week in Nature Neuroscience finds that stress in early life alters the production of small RNAs, called microRNAs, in the sperm of mice (K. Gapp et al. Nature Neurosci. http://dx.doi.org/10.1038/nn.3695; 2014). The mice show depressive behaviours that persist in their progeny, which also show glitches in metabolism. The study is notable for showing that sperm responds to the environment, says Stephen Krawetz, a geneticist at Wayne State University School of Medicine in Detroit, Michigan, who studies microRNAs in human sperm. (He was not involved in the latest study.) “Dad is having a much larger role in the whole process, rather than just delivering his genome and being done with it,” he says. He adds that this is one of a growing number of studies to show that subtle changes in sperm microRNAs “set the stage for a huge plethora of other effects”. In the new study, Isabelle Mansuy, a neuroscientist at the University of Zurich, Switzerland, and her colleagues periodically separated mother mice from their young pups and exposed the mothers to stressful situations — either by placing them in cold water or physically restraining them. These separations occurred every day but at erratic times, so that the mothers could not comfort their pups (termed the F1 generation) with extra cuddling before separation. © 2014 Nature Publishing Group,
By DENISE GRADY People with severe brain injuries sometimes emerge from a coma awake but unresponsive, leaving families with painful questions. Are they aware? Can they think and feel? Do they have any chance of recovery? A new study has found that PET scans may help answer these wrenching questions. It found that a significant number of people labeled vegetative had received an incorrect diagnosis and actually had some degree of consciousness and the potential to improve. Previous studies using electroencephalogram machines and M.R.I. scanners have also found signs of consciousness in supposedly vegetative patients. “I think these patients are kind of neglected by both medicine and society,” said Dr. Steven Laureys, an author of the new study and the director of the Coma Science Group at the University of Liège in Belgium. “Many of them don’t even see a medical doctor or a specialist for years. So I think it’s very important to ask the question, are they unconscious?” In the United States, 100,000 to 300,000 people are thought to be minimally conscious, and an additional 25,000 are vegetative. In Belgium, the combined incidence of the two conditions is about 150 new cases per year, Dr. Laureys said. An article about the new research was published on Tuesday in The Lancet. Dr. Laureys and his colleagues studied 122 patients with brain injuries, including 41 who had been declared vegetative — awake but with no behavioral signs of awareness. People who are vegetative for a year are thought to have little or no chance of recovering, and the condition can become grounds for withdrawing medical treatment. Terri Schiavo, in a vegetative state for 15 years, died in 2005 in Florida after courts allowed the removal of her feeding tube. © 2014 The New York Times Company
The two marmosets—small, New World monkeys—had been a closely bonded couple for more than 3 years. Then, one fateful day, the female had a terrible accident. She fell out of a tree and hit her head on a ceramic vase that happened to be underneath on the forest floor. Her partner left two of their infants alone in the tree and jumped down to apparently comfort her, until she died an agonizing death a couple of hours later. According to the researchers who recorded the events with a video camera (see video above), this is the first time such compassionate mourning behavior has been observed outside of humans and chimpanzees, and it could indicate that mourning is more widespread among primates than previously thought. Humans mourn their dead, of course, and some recent studies have strongly suggested that chimpanzees do as well. Scientists have recorded cases of adult chimps apparently caring for fellow animals before they die, and chimp mothers have been observed carrying around the bodies of infants for days after their death—although scientists have debated whether the latter behavior represents true grieving or if the mothers didn’t realize their infants were really dead. But there has been little or no evidence that other primates engage in these kinds of behaviors. Indeed, a recent review of the evidence led by anthropologist Peter Fashing of California State University, Fullerton, concluded that there were no convincing observations of “compassionate caretaking” of dying individuals among other nonhuman primates, such as monkeys. © 2014 American Association for the Advancement of Science.
By Emily Chung, CBC News If you're in your late 20s or older, you're not as sharp as you used to be, suggests a study of gamers playing the popular video game Starcraft 2. The study analyzed the way 3,305 people, aged 16 to 44, played the game against a single random opponent of similar skill, in order to measure the gamers' cognitive motor performance. Cognitive motor performance is how quickly your brain reacts to things happening around you, allowing you to act during tasks such as driving. The analysis revealed exactly when advancing age starts to take its toll on brain performance – at the tender age of 24 years. The results were published late last week in the journal PLOS ONE. Joe Thompson, lead author of the study, said he was surprised by how early the decline started and how big the age effect was, even among those in their 30s. "If you're 39, competing against a 24-year-old and you're both in the otherwise same level of skill," Thompson said, "the effect of age is expected to offset a great deal of your learning." Starcraft 2 is a popular strategy game, similar in concept to Risk, where players compete to build armies and conquer a science fictional world. Unlike Risk, however, players don't take turns. "Starcraft is like high-speed chess," said Thompson, a PhD student who plays the game himself. "You simply can make as many moves as you want, as fast as you can go." Players can't see the whole "world" at once, as they mine resources needed to build up their armies, as they attack their opponents, and as they defend against opponents' attacks, they need to quickly move their screen around from one part of the world to another. © CBC 2014
by Simon Makin Could drama workshops help children with autism-spectrum disorders? Results from a pilot study called Imagining Autism suggests this might be the case. The research involved 22 children aged between 7 and 12 and consisted of one 45-minute session every week for 10 weeks. During this time, groups of four children entered an enclosed themed environment, such as a forest or outer space. These environments were designed to engage all senses simultaneously, using lights, sounds, puppetry and interactive digital elements. Trained performers used improvisation techniques to encourage the children to engage creatively with the environment and each other, both physically and verbally. The hope was that the sessions would help develop the children's communication, social interaction, and imagination skills – the "triad of impairments" seen in autism. Children were assessed before the intervention, and again between two and six weeks after the sessions ended. As well as looking at whether behaviours used to diagnose autism changed after the drama sessions, the researchers also assessed emotion recognition, imitation, IQ and theory of mind – the ability to infer what others are thinking and feeling. Subjective ratings were also gathered from parents and teachers and follow-up assessments were conducted up to a year later. At the early assessments, all children showed some improvement. The most significant change was in the number of facial expressions recognised, a key communication skill. Nine children improved on this. Six children improved on their level of social interaction. The majority of these changes were also seen at the follow-up assessments. © Copyright Reed Business Information Ltd.
Link ID: 19494 - Posted: 04.16.2014
by Bethany Brookshire Every hipster knows that something is only cool before it becomes popular. There’s no point in liking a band once it hits the big time. That shirt is no good once it’s no longer ironic. And it’s certainly not enough to go clean shaven or grow a short beard — that’s much too mainstream. Recent years have seen a resurgence of moustaches, mutton chops and Fu Manchus. A style that really stands out sticks it to conformity. It turns out that when people buck the facial hair trend, they may end up making themselves more attractive. A new study published April 16 in Biology Letters shows that either clean-shaven or fully bearded looks become more attractive when they are rare in the population. The study suggests that humans may practice what’s called negative frequency-dependent selection — people rate rare looks as more attractive than they might otherwise. But when we try to figure out why, the interpretations can get pretty hairy. In every population, there is variation, both in genetics and in how individuals look. But at first blush, this variation doesn’t make a lot of sense. If one particular look is the most attractive and best for the population, sexual selection should make a species converge on a single, popular look. For example, if the best male guppies have stripes, soon all male guppies will have stripes, as females will only mate with stripey males. But in nature, this is clearly not the case. Guppies come in a wild variety of patterns, and so do humans. In guppies, this variation is a result of negative frequency-dependent selection: Female guppies prefer male guppies that look unusual compared to others, rather than guppies that share common features. This helps keep looks and genes variable, a distinct advantage for the species. So an individual guppy’s attractiveness doesn’t just depend on his shining character, it depends on how rare his looks are in relation to other guppies. © Society for Science & the Public 2000 - 2013
|By Janali Gustafson Cravings—we all have them. These intense desires can be triggered by a place, a smell, even a picture. For recovering drug addicts, such memory associations can increase vulnerability to relapse. Now researchers at the Florida campus of the Scripps Research Institute have found a chemical that prevents rats from recalling their drug-associated memories. The study, published online in Biological Psychiatry last fall, is also the first of its kind to disrupt memories without requiring active recollection. Over the course of six days the rats in this study alternated between one of two chambers. On days one, three and five, the animals were injected with methamphetamine hydrochloride—the street drug known as meth—and placed in one room. On the even-numbered days they received a saline placebo and entered a different chamber. After two more days, half the rodents were given a choice between the rooms. As expected, they showed a clear preference for the place they visited after receiving meth. The other half of the animals were injected with a solution containing Latrunculin A (LatA). This chemical interferes with actin, a protein known to be involved in memory formation. These animals showed no preference between rooms, even up to a day later: their choices seemed not to be driven by a memory of meth. Previous research has suggested that drugs of abuse alter the way actin functions, causing it to constantly refresh memories associated with these drugs rather than tucking them away into typical memory storage, which is more inert. As a result of their active status, drug memories might remain susceptible to disruption long after their initial formation. © 2014 Scientific American
Associated Press NEW YORK -- A small study of casual marijuana smokers has turned up evidence of changes in the brain, a possible sign of trouble ahead, researchers say. The young adults who volunteered for the study were not dependent on pot, nor did they show any marijuana-related problems. "What we think we are seeing here is a very early indication of what becomes a problem later on with prolonged use," things like lack of focus and impaired judgment, said Dr. Hans Breiter, a study author. Longer-term studies will be needed to see if such brain changes cause any symptoms over time, said Breiter, of the Northwestern University Feinberg School of Medicine and Massachusetts General Hospital. Previous studies have shown mixed results in looking for brain changes from marijuana use, perhaps because of differences in the techniques used, he and others noted in Wednesday's issue of the Journal of Neurosciences. The study is among the first to focus on possible brain effects in recreational pot smokers, said Dr. Nora Volkow, director of the National Institute on Drug Abuse. The federal agency helped pay for the work. She called the work important but preliminary. The 20 pot users in the study, ages 18 to 25, said they smoked marijuana an average of about four days a week, for an average total of about 11 joints. Half of them smoked fewer than six joints a week. Researchers scanned their brains and compared the results with those of 20 nonusers who were matched for age, sex and other traits. The results showed differences in two brain areas associated with emotion and motivation - the amygdala and the nucleus accumbens. Users showed higher density than nonusers, as well as differences in shape of those areas. Both differences were more pronounced in those who reported smoking more marijuana. © 2014 Hearst Communications, Inc.