Biological evidence of positive and negative people in the world

The ability to stay positive when times get tough — and, conversely, of being negative — may be hardwired in the brain, finds new research led by a Michigan State University psychologist.The study, which appears in the Journal of Abnormal Psychology, is the first to provide biological evidence validating the idea that there are, in fact, positive and negative people in the world.”It’s the first time we’ve been able to find a brain marker that really distinguishes negative thinkers from positive thinkers,” said Jason Moser, lead investigator and assistant professor of psychology.For the study, 71 female participants were shown graphic images and asked to put a positive spin on them while their brain activity was recorded. Participants were shown a masked man holding a knife to a woman’s throat, for example, and told one potential outcome was the woman breaking free and escaping.The participants were surveyed beforehand to establish who tended to think positively and who thought negatively or worried. Sure enough, the brain reading of the positive thinkers was much less active than that of the worriers during the experiment.”The worriers actually showed a paradoxical backfiring effect in their brains when asked to decrease their negative emotions,” Moser said. “This suggests they have a really hard time putting a positive spin on difficult situations and actually make their negative emotions worse even when they are asked to think positively.”The study focused on women because they are twice as likely as men to suffer from anxiety related problems and previously reported sex differences in brain structure and function could have obscured the results.Moser said the findings have implications in the way negative thinkers approach difficult situations.”You can’t just tell your friend to think positively or to not worry — that’s probably not going to help them,” he said. “So you need to take another tack and perhaps ask them to think about the problem in a different way, to use different strategies.”Negative thinkers could also practice thinking positively, although Moser suspects it would take a lot of time and effort to even start to make a difference.Story Source:The above story is based on materials provided by Michigan State University. Note: Materials may be edited for content and length.

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MRI reveals genetic activity: Deciphering genes’ roles in learning and memory

Doctors commonly use magnetic resonance imaging (MRI) to diagnose tumors, damage from stroke, and many other medical conditions. Neuroscientists also rely on it as a research tool for identifying parts of the brain that carry out different cognitive functions.Now, a team of biological engineers at MIT is trying to adapt MRI to a much smaller scale, allowing researchers to visualize gene activity inside the brains of living animals. Tracking these genes with MRI would enable scientists to learn more about how the genes control processes such as forming memories and learning new skills, says Alan Jasanoff, an MIT associate professor of biological engineering and leader of the research team.”The dream of molecular imaging is to provide information about the biology of intact organisms, at the molecule level,” says Jasanoff, who is also an associate member of MIT’s McGovern Institute for Brain Research. “The goal is to not have to chop up the brain, but instead to actually see things that are happening inside.”To help reach that goal, Jasanoff and colleagues have developed a new way to image a “reporter gene” — an artificial gene that turns on or off to signal events in the body, much like an indicator light on a car’s dashboard. In the new study, the reporter gene encodes an enzyme that interacts with a magnetic contrast agent injected into the brain, making the agent visible with MRI. This approach, described in a recent issue of the journal Chemical Biology, allows researchers to determine when and where that reporter gene is turned on.An on/off switchMRI uses magnetic fields and radio waves that interact with protons in the body to produce detailed images of the body’s interior. In brain studies, neuroscientists commonly use functional MRI to measure blood flow, which reveals which parts of the brain are active during a particular task. When scanning other organs, doctors sometimes use magnetic “contrast agents” to boost the visibility of certain tissues.The new MIT approach includes a contrast agent called a manganese porphyrin and the new reporter gene, which codes for a genetically engineered enzyme that alters the electric charge on the contrast agent. Jasanoff and colleagues designed the contrast agent so that it is soluble in water and readily eliminated from the body, making it difficult to detect by MRI. However, when the engineered enzyme, known as SEAP, slices phosphate molecules from the manganese porphyrin, the contrast agent becomes insoluble and starts to accumulate in brain tissues, allowing it to be seen.The natural version of SEAP is found in the placenta, but not in other tissues. …

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Nicotine withdrawal weakens brain connections tied to self-control over cigarette cravings

People who try to quit smoking often say that kicking the habit makes the voice inside telling them to light up even louder, but why people succumb to those cravings so often has never been fully understood. Now, a new brain imaging study in this week’s JAMA Psychiatry from scientists in Penn Medicine and the National Institute on Drug Abuse (NIDA) Intramural Research Program shows how smokers suffering from nicotine withdrawal may have more trouble shifting from a key brain network — known as default mode, when people are in a so-called “introspective” or “self-referential” state — and into a control network, the so-called executive control network, that could help exert more conscious, self-control over cravings and to focus on quitting for good.The findings help validate a neurobiological basis behind why so many people trying to quit end up relapsing — up to 80 percent, depending on the type of treatment — and may lead to new ways to identify smokers at high risk for relapse who need more intensive smoking cessation therapy.The brain imaging study was led by researchers at University of Pennsylvania’s new Brain and Behavior Change Program, led by Caryn Lerman, PhD, who is also the deputy director of Penn’s Abramson Cancer Center, and Elliot Stein, PhD, and collaborators at NIDA. They found that smokers who abstained from cigarettes showed weakened interconnectivity between certain large-scale networks in their brains: the default mode network, the executive control network, and the salience network. They posit that this weakened connectivity reduces smokers’ ability to shift into or maintain greater influence from the executive control network, which may ultimately help maintain their quitting attempt.”What we believe this means is that smokers who just quit have a more difficult time shifting gears from inward thoughts about how they feel to an outward focus on the tasks at hand,” said Lerman, who also serves as the Mary W. Calkins professor in the Department of Psychiatry. “It’s very important for people who are trying to quit to be able to maintain activity within the control network — to be able to shift from thinking about yourself and your inner state to focus on your more immediate goals and plan.”Prior studies have looked at the effects of nicotine on brain interconnectivity in the resting state, that is, in the absence of any specific goal directed activity. This is the first study, however, to compare resting brain connectivity in an abstinent state and when people are smoking as usual, and then relate those changes to symptoms of craving and mental performance.For the study, researchers conducted brain scans on 37 healthy smokers (those who smoke more than 10 cigarettes a day) ages 19 to 61 using functional magnetic resonance imaging (fMRI) in two different sessions: 24 hours after biochemically confirmed abstinence and after smoking as usual.Imaging showed a significantly weaker connectivity between the salience network and default mode network during abstinence, compared with their sated state. Also, weakened connectivity during abstinence was linked with increases in smoking urges, negative mood, and withdrawal symptoms, suggesting that this weaker internetwork connectivity may make it more difficult for people to quit.Establishing the strength of the connectivity between these large-scale brain networks will be important in predicting people’s ability to quit and stay quit, the authors write. Also, such connectivity could serve as a clinical biomarker to identify smokers who are most likely to respond to a particular treatment.”Symptoms of withdrawal are related to changes in smokers’ brains, as they adjust to being off of nicotine, and this study validates those experiences as having a biological basis,” said Lerman. “The next step will be to identify in advance those smokers who will have more difficultly quitting and target more intensive treatments, based on brain activity and network connectivity.”Story Source:The above story is based on materials provided by Perelman School of Medicine at the University of Pennsylvania. …

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Hey, Wake Up, It’s Brain Awareness Week

Your brain doesn’t come with an instruction manual.The Dana Foundation’s annual Brain Awareness Week (BAW), March 10-16, seems particularly appropriate and useful this time around, after a year in which brain-based disease models of human behaviors came under fire from social scientists and neuroscientists alike.A recent analysis of the coverage of neuroscience in the popular press showed that the number of news articles using the terms “neuroscience” or “neuroscientist” had increased by a factor of 30 between 1985 and 2009. Moreover, the NIH’s massive Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, designed to speed up our understanding of the neural workings of the human brain in the years ahead, is in progress.Brain Awareness Week, which takes place each year during the third week of March, is …

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Ever-so-slight delay improves decision-making accuracy

Columbia University Medical Center (CUMC) researchers have found that decision-making accuracy can be improved by postponing the onset of a decision by a mere fraction of a second. The results could further our understanding of neuropsychiatric conditions characterized by abnormalities in cognitive function and lead to new training strategies to improve decision-making in high-stake environments. The study was published in the March 5 online issue of the journal PLoS One.”Decision making isn’t always easy, and sometimes we make errors on seemingly trivial tasks, especially if multiple sources of information compete for our attention,” said first author Tobias Teichert, PhD, a postdoctoral research scientist in neuroscience at CUMC at the time of the study and now an assistant professor of psychiatry at the University of Pittsburgh. “We have identified a novel mechanism that is surprisingly effective at improving response accuracy.The mechanism requires that decision-makers do nothing — just briefly. “Postponing the onset of the decision process by as little as 50 to 100 milliseconds enables the brain to focus attention on the most relevant information and block out irrelevant distractors,” said last author Jack Grinband, PhD, associate research scientist in the Taub Institute and assistant professor of clinical radiology (physics). “This way, rather than working longer or harder at making the decision, the brain simply postpones the decision onset to a more beneficial point in time.”In making decisions, the brain integrates many small pieces of potentially contradictory sensory information. “Imagine that you’re coming up to a traffic light — the target — and need to decide whether the light is red or green,” said Dr. Teichert. “There is typically little ambiguity, and you make the correct decision quickly, in a matter of tens of milliseconds.”The decision process itself, however, does not distinguish between relevant and irrelevant information. Hence, a task is made more difficult if irrelevant information — a distractor — interferes with the processing of the target. …

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Prenatal Nicotine Exposure May Lead to ADHD in Future Generations

Prenatal exposure to nicotine could manifest as attention deficit hyperactivity disorder in children born a generation later, according to a new study by Florida State University College of Medicine researchers.Professors Pradeep G. Bhide and Jinmin Zhu have found evidence that ADHD associated with nicotine can be passed across generations. In other words, your child’s ADHD might be an environmentally induced health condition inherited from your grandmother, who may have smoked cigarettes during pregnancy a long time ago. And the fact that you never smoked may be irrelevant for your child’s ADHD.The researchers’ findings are published in the current issue of The Journal of Neuroscience.”What our research and other people’s research is showing is that some of the changes in your genome — whether induced by drugs or by experience — may be permanent and you will transmit that to your offspring,” said Bhide, chair of developmental neuroscience and director of the Center for Brain Repair at the College of Medicine.Bhide and Zhu, assistant professor of biomedical sciences, used a mouse model to test the hypothesis that hyperactivity induced by prenatal nicotine exposure is transmitted from one generation to the next. Their data demonstrated that there is a transgenerational transmission via the maternal, but not the paternal, line of descent.”Genes are constantly changing. Some are silenced and others are expressed, and that happens not only by hereditary mechanisms, but because of something in the environment or because of what we eat or what we see or what we hear,” Bhide said. “So the genetic information that is transmitted to your offspring is qualitatively different than the information you got from your parents. This is how things change over time in the population.”Building on recent discoveries about how things like stress, fear or hormonal imbalance in one individual can be passed along to the next generation, Bhide and Zhu were curious about a proven link between prenatal nicotine exposure and hyperactivity in mice.Their work at the Center for Brain Repair has included extensive research around ADHD, a neurobehavioral disorder affecting about 10 percent of children and 5 percent of adults in the United States. Researchers have struggled to produce a definitive scientific explanation for a spike in ADHD diagnoses in the last few decades.”Some reports show up to a 40 percent increase in cases of ADHD — in one generation, basically,” Bhide said. “It cannot be because a mutation occurred; it takes several generations for that to happen.”One possible contributing factor, though unproven, is that the current spike in ADHD cases correlates in some manner to an increase in the number of women who smoked during pregnancy as cigarettes became fashionable in the United States around the time of World War II and in the decades that followed.”Other research has shown a very high correlation between heavy smoking during pregnancy and the incidence of kids with ADHD,” Bhide said.”What’s important about our study is that we are seeing that changes occurring in my grandparents’ genome because of smoking during pregnancy are being passed to my child. …

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The musical brain: Novel study of jazz players shows common brain circuitry processes both music, language

The brains of jazz musicians engrossed in spontaneous, improvisational musical conversation showed robust activation of brain areas traditionally associated with spoken language and syntax, which are used to interpret the structure of phrases and sentences. But this musical conversation shut down brain areas linked to semantics — those that process the meaning of spoken language, according to results of a study by Johns Hopkins researchers.The study used functional magnetic resonance imaging (fMRI) to track the brain activity of jazz musicians in the act of “trading fours,” a process in which musicians participate in spontaneous back and forth instrumental exchanges, usually four bars in duration. The musicians introduce new melodies in response to each other’s musical ideas, elaborating and modifying them over the course of a performance.The results of the study suggest that the brain regions that process syntax aren’t limited to spoken language, according to Charles Limb, M.D., an associate professor in the Department of Otolaryngology-Head and Neck Surgery at the Johns Hopkins University School of Medicine. Rather, he says, the brain uses the syntactic areas to process communication in general, whether through language or through music.Limb, who is himself a musician and holds a faculty appointment at the Peabody Conservatory, says the work sheds important new light on the complex relationship between music and language.”Until now, studies of how the brain processes auditory communication between two individuals have been done only in the context of spoken language,” says Limb, the senior author of a report on the work that appears online Feb. 19 in the journal PLOS ONE. “But looking at jazz lets us investigate the neurological basis of interactive, musical communication as it occurs outside of spoken language.”We’ve shown in this study that there is a fundamental difference between how meaning is processed by the brain for music and language. Specifically, it’s syntactic and not semantic processing that is key to this type of musical communication. Meanwhile, conventional notions of semantics may not apply to musical processing by the brain.”To study the response of the brain to improvisational musical conversation between musicians, the Johns Hopkins researchers recruited 11 men aged 25 to 56 who were highly proficient in jazz piano performance. During each 10-minute session of trading fours, one musician lay on his back inside the MRI machine with a plastic piano keyboard resting on his lap while his legs were elevated with a cushion. A pair of mirrors was placed so the musician could look directly up while in the MRI machine and see the placement of his fingers on the keyboard. …

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New blood cells fight brain inflammation

Hyperactivity of our immune system can cause a state of chronic inflammation. If chronic, the inflammation will affect our body and result in disease. In the devastating disease multiple sclerosis, hyperactivity of immune cells called T-cells induce chronic inflammation and degeneration of the brain. Researchers at BRIC, the University of Copenhagen, have identified a new type of regulatory blood cells that can combat such hyperactive T-cells in blood from patients with multiple sclerosis. By stimulating the regulatory blood cells, the researchers significantly decreased the level of brain inflammation and disease in a biological model. The results are published in the journal Nature Medicine.Molecule activate anti-inflammatory blood cellsThe new blood cells belong to the group of our white blood cells called lymphocytes. The cells express a molecule called FoxA1 that the researchers found is responsible for the cells’ development and suppressive functions.”We knew that some unidentified blood cells were able to inhibit multiple sclerosis-like disease in mice and through gene analysis we found out, that these cells are a subset of our lymphocytes expressing the gene FoxA1. Importantly, when inserting FoxA1 into normal lymphocytes with gene therapy, we could change them to actively regulate inflammation and inhibit multiple sclerosis, explains associated professor Yawei Liu leading the experimental studies.Activating own blood cells for treatment of diseaseFoxA1 expressing lymphocytes were not known until now, and this is the first documentation of their importance in controlling multiple sclerosis. The number of people living with this devastating disease around the world has increased by 10 percent in the past five years to 2.3 million. It affects women twice more than men and no curing treatment exists. …

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New pathway for fear discovered deep within brain

Fear is primal. In the wild, it serves as a protective mechanism, allowing animals to avoid predators or other perceived threats. For humans, fear is much more complex. A normal amount keeps us safe from danger. But in extreme cases, like post-traumatic stress disorder (PTSD), too much fear can prevent people from living healthy, productive lives. Researchers are actively working to understand how the brain translates fear into action. Today, scientists at Cold Spring Harbor Laboratory (CSHL) announce the discovery of a new neural circuit in the brain that directly links the site of fear memory with an area of the brainstem that controls behavior.How does the brain convert an emotion into a behavioral response? For years, researchers have known that fear memories are learned and stored in a small structure in the brain known as the amygdala. Any disturbing event activates neurons in the lateral and then central portions of the amygdala. The signals are then communicated internally, passing from one group of neurons to the next. …

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How our brain networks: White matter ‘scaffold’ of human brain revealed

For the first time, neuroscientists have systematically identified the white matter “scaffold” of the human brain, the critical communications network that supports brain function.Their work, published Feb. 11 in the open-source journal Frontiers in Human Neuroscience, has major implications for understanding brain injury and disease. By detailing the connections that have the greatest influence over all other connections, the researchers offer not only a landmark first map of core white matter pathways, but also show which connections may be most vulnerable to damage.”We coined the term white matter ‘scaffold’ because this network defines the information architecture which supports brain function,” said senior author John Darrell Van Horn of the USC Institute for Neuroimaging and Informatics and the Laboratory of Neuro Imaging at USC.”While all connections in the brain have their importance, there are particular links which are the major players,” Van Horn said.Using MRI data from a large sample of 110 individuals, lead author Andrei Irimia, also of the USC Institute for Neuroimaging and Informatics, and Van Horn systematically simulated the effects of damaging each white matter pathway.They found that the most important areas of white and gray matter don’t always overlap. Gray matter is the outermost portion of the brain containing the neurons where information is processed and stored. Past research has identified the areas of gray matter that are disproportionately affected by injury.But the current study shows that the most vulnerable white matter pathways — the core “scaffolding” — are not necessarily just the connections among the most vulnerable areas of gray matter, helping explain why seemingly small brain injuries may have such devastating effects.”Sometimes people experience a head injury which seems severe but from which they are able to recover. On the other hand, some people have a seemingly small injury which has very serious clinical effects,” says Van Horn, associate professor of neurology at the Keck School of Medicine of USC. “This research helps us to better address clinical challenges such as traumatic brain injury and to determine what makes certain white matter pathways particularly vulnerable and important.”The researchers compare their brain imaging analysis to models used for understanding social networks. To get a sense of how the brain works, Irimia and Van Horn did not focus only on the most prominent gray matter nodes — which are akin to the individuals within a social network. Nor did they merely look at how connected those nodes are.Rather, they also examined the strength of these white matter connections, i.e. which connections seemed to be particularly sensitive or to cause the greatest repercussions across the network when removed. …

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How chronic stress predisposes brain to mental disorders

University of California, Berkeley, researchers have shown that chronic stress generates long-term changes in the brain that may explain why people suffering chronic stress are prone to mental problems such as anxiety and mood disorders later in life.Their findings could lead to new therapies to reduce the risk of developing mental illness after stressful events.Doctors know that people with stress-related illnesses, such as post-traumatic stress disorder (PTSD), have abnormalities in the brain, including differences in the amount of gray matter versus white matter. Gray matter consists mostly of cells — neurons, which store and process information, and support cells called glia — while white matter is composed of axons, which create a network of fibers that interconnect neurons. White matter gets its name from the white, fatty myelin sheath that surrounds the axons and speeds the flow of electrical signals from cell to cell.How chronic stress creates these long-lasting changes in brain structure is a mystery that researchers are only now beginning to unravel.In a series of experiments, Daniela Kaufer, UC Berkeley associate professor of integrative biology, and her colleagues, including graduate students Sundari Chetty and Aaron Freidman, discovered that chronic stress generates more myelin-producing cells and fewer neurons than normal. This results in an excess of myelin — and thus, white matter — in some areas of the brain, which disrupts the delicate balance and timing of communication within the brain.”We studied only one part of the brain, the hippocampus, but our findings could provide insight into how white matter is changing in conditions such as schizophrenia, autism, depression, suicide, ADHD and PTSD,” she said.The hippocampus regulates memory and emotions, and plays a role in various emotional disorders.Kaufer and her colleagues published their findings in the Feb. 11 issue of the journal Molecular Psychiatry.Does stress affect brain connectivity?Kaufer’s findings suggest a mechanism that may explain some changes in brain connectivity in people with PTSD, for example. One can imagine, she said, that PTSD patients could develop a stronger connectivity between the hippocampus and the amygdala — the seat of the brain’s fight or flight response — and lower than normal connectivity between the hippocampus and prefrontal cortex, which moderates our responses.”You can imagine that if your amygdala and hippocampus are better connected, that could mean that your fear responses are much quicker, which is something you see in stress survivors,” she said. “On the other hand, if your connections are not so good to the prefrontal cortex, your ability to shut down responses is impaired. So, when you are in a stressful situation, the inhibitory pathways from the prefrontal cortex telling you not to get stressed don’t work as well as the amygdala shouting to the hippocampus, ‘This is terrible!’ You have a much bigger response than you should.”She is involved in a study to test this hypothesis in PTSD patients, and continues to study brain changes in rodents subjected to chronic stress or to adverse environments in early life.Stress tweaks stem cellsKaufer’s lab, which conducts research on the molecular and cellular effects of acute and chronic stress, focused in this study on neural stem cells in the hippocampus of the brains of adult rats. These stem cells were previously thought to mature only into neurons or a type of glial cell called an astrocyte. The researchers found, however, that chronic stress also made stem cells in the hippocampus mature into another type of glial cell called an oligodendrocyte, which produces the myelin that sheaths nerve cells.The finding, which they demonstrated in rats and cultured rat brain cells, suggests a key role for oligodendrocytes in long-term and perhaps permanent changes in the brain that could set the stage for later mental problems. …

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Scientists identify gene linking brain structure to intelligence

For the first time, scientists at King’s College London have identified a gene linking the thickness of the grey matter in the brain to intelligence. The study is published today in Molecular Psychiatry and may help scientists understand biological mechanisms behind some forms of intellectual impairment.The researchers looked at the cerebral cortex, the outermost layer of the human brain. It is known as ‘grey matter’ and plays a key role in memory, attention, perceptual awareness, thought, language and consciousness. Previous studies have shown that the thickness of the cerebral cortex, or ‘cortical thickness’, closely correlates with intellectual ability, however no genes had yet been identified.An international team of scientists, led by King’s, analysed DNA samples and MRI scans from 1,583 healthy 14 year old teenagers, part of the IMAGEN cohort. The teenagers also underwent a series of tests to determine their verbal and non-verbal intelligence.Dr Sylvane Desrivires, from King’s College London’s Institute of Psychiatry and lead author of the study, said: “We wanted to find out how structural differences in the brain relate to differences in intellectual ability. The genetic variation we identified is linked to synaptic plasticity — how neurons communicate. This may help us understand what happens at a neuronal level in certain forms of intellectual impairments, where the ability of the neurons to communicate effectively is somehow compromised.”She adds: “It’s important to point out that intelligence is influenced by many genetic and environmental factors. The gene we identified only explains a tiny proportion of the differences in intellectual ability, so it’s by no means a ‘gene for intelligence’.”The researchers looked at over 54,000 genetic variants possibly involved in brain development. They found that, on average, teenagers carrying a particular gene variant had a thinner cortex in the left cerebral hemisphere, particularly in the frontal and temporal lobes, and performed less well on tests for intellectual ability. The genetic variation affects the expression of the NPTN gene, which encodes a protein acting at neuronal synapses and therefore affects how brain cells communicate.To confirm their findings, the researchers studied the NPTN gene in mouse and human brain cells. …

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False memories: The hidden side of our good memory

Justice blindly trusts human memory. Every year throughout the world hundreds of thousands of court cases are heard based solely on the testimony of somebody who swears that they are reproducing exactly an event that they witnessed in a more or less not too distant past. Nevertheless, various recent studies in cognitive neuroscience indicate both the strengths and weaknesses in this ability of recall of the human brain.Memory is a cognitive process which is intrinsically linked to language. One of the fundamental tasks that the brain carries out when undertaking a linguistic activity — holding a conversation, for example — is the semantic process.On carrying out this task, the brain compares the words it hears with those that it recalls from previous events, in order to recognise them and to unravel their meaning. This semantic process is a fundamental task for enabling the storing of memories in our brain, helping us to recognise words and to memorise names and episodes in our mind. However, as everyone knows, this is not a process that functions 100% perfectly at times; a lack of precision that, on occasions, gives rise to the creation of false memories.Two pieces of research, recently published by Kepa Paz-Alonso at the Basque Center on Cognition, Brain and Language (BCBL) in the Journal of International Neuropsychological Society and Schizophrenia Research scientific journals, have shown that this semantic process linked to the subsequent recognition of such words amongst children as well as amongst adult schizophrenics, is less efficient than that produced in a normal adult brain. Moreover, both studies have shown that children are less prone to producing this type of false memory in their brains, and something similar occurs in patients with schizophrenia.One of the reasons for this phenomenon is that children do not have this semantic process as automated and developed as adults. That is, the adult brain, after making the same connections over and over again between various zones of the brain concerned with memory, has mechanised the process of semantically linking new information for its storage. Nonetheless, according to the results of Mr. Paz-Alonso’s research, this process is more likely to generate false memories in the brain of an adult than in a child’s brain.According to the researcher, “in reality, the same processes that produce these “false memories” amongst healthy adults are also responsible for their having better memory. …

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Pinpointing the brain’s arbitrator: Reliability weighed before brain centers given control

We tend to be creatures of habit. In fact, the human brain has a learning system that is devoted to guiding us through routine, or habitual, behaviors. At the same time, the brain has a separate goal-directed system for the actions we undertake only after careful consideration of the consequences. We switch between the two systems as needed. But how does the brain know which system to give control to at any given moment? Enter The Arbitrator.Researchers at the California Institute of Technology (Caltech) have, for the first time, pinpointed areas of the brain — the inferior lateral prefrontal cortex and frontopolar cortex — that seem to serve as this “arbitrator” between the two decision-making systems, weighing the reliability of the predictions each makes and then allocating control accordingly. The results appear in the current issue of the journal Neuron.According to John O’Doherty, the study’s principal investigator and director of the Caltech Brain Imaging Center, understanding where the arbitrator is located and how it works could eventually lead to better treatments for brain disorders, such as drug addiction, and psychiatric disorders, such as obsessive-compulsive disorder. These disorders, which involve repetitive behaviors, may be driven in part by malfunctions in the degree to which behavior is controlled by the habitual system versus the goal-directed system.”Now that we have worked out where the arbitrator is located, if we can find a way of altering activity in this area, we might be able to push an individual back toward goal-directed control and away from habitual control,” says O’Doherty, who is also a professor of psychology at Caltech. “We’re a long way from developing an actual treatment based on this for disorders that involve over-egging of the habit system, but this finding has opened up a highly promising avenue for further research.”In the study, participants played a decision-making game on a computer while connected to a functional magnetic resonance imaging (fMRI) scanner that monitored their brain activity. Participants were instructed to try to make optimal choices in order to gather coins of a certain color, which were redeemable for money.During a pre-training period, the subjects familiarized themselves with the game — moving through a series of on-screen rooms, each of which held different numbers of red, yellow, or blue coins. …

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What makes us human? Unique brain area linked to higher cognitive powers

Oxford University researchers have identified an area of the human brain that appears unlike anything in the brains of some of our closest relatives.The brain area pinpointed is known to be intimately involved in some of the most advanced planning and decision-making processes that we think of as being especially human.’We tend to think that being able to plan into the future, be flexible in our approach and learn from others are things that are particularly impressive about humans. We’ve identified an area of the brain that appears to be uniquely human and is likely to have something to do with these cognitive powers,’ says senior researcher Professor Matthew Rushworth of Oxford University’s Department of Experimental Psychology.MRI imaging of 25 adult volunteers was used to identify key components in the ventrolateral frontal cortex area of the human brain, and how these components were connected up with other brain areas. The results were then compared to equivalent MRI data from 25 macaque monkeys.This ventrolateral frontal cortex area of the brain is involved in many of the highest aspects of cognition and language, and is only present in humans and other primates. Some parts are implicated in psychiatric conditions like ADHD, drug addiction or compulsive behaviour disorders. Language is affected when other parts are damaged after stroke or neurodegenerative disease. A better understanding of the neural connections and networks involved should help the understanding of changes in the brain that go along with these conditions.The Oxford University researchers report their findings in the science journal Neuron.Professor Rushworth explains: ‘The brain is a mosaic of interlinked areas. We wanted to look at this very important region of the frontal part of the brain and see how many tiles there are and where they are placed.’We also looked at the connections of each tile — how they are wired up to the rest of the brain — as it is these connections that determine the information that can reach that component part and the influence that part can have on other brain regions.’From the MRI data, the researchers were able to divide the human ventrolateral frontal cortex into 12 areas that were consistent across all the individuals.’Each of these 12 areas has its own pattern of connections with the rest of the brain, a sort of “neural fingerprint,” telling us it is doing something unique,’ says Professor Rushworth.The researchers were then able to compare the 12 areas in the human brain region with the organisation of the monkey prefrontal cortex.Overall, they were very similar with 11 of the 12 areas being found in both species and being connected up to other brain areas in very similar ways.However, one area of the human ventrolateral frontal cortex had no equivalent in the macaque — an area called the lateral frontal pole prefrontal cortex.’We have established an area in human frontal cortex which does not seem to have an equivalent in the monkey at all,’ says first author Franz-Xaver Neubert of Oxford University. ‘This area has been identified with strategic planning and decision making as well as “multi-tasking.” ‘The Oxford research group also found that the auditory parts of the brain were very well connected with the human prefrontal cortex, but much less so in the macaque. The researchers suggest this may be critical for our ability to understand and generate speech.The researchers were funded by the UK Medical Research Council.Story Source:The above story is based on materials provided by University of Oxford. Note: Materials may be edited for content and length.

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In the Brain: Number of neurons in a network may not matter

Last spring, President Obama established the federal BRAIN Initiative to give scientists the tools they need to get a dynamic picture of the brain in action.To do so, the initiative’s architects envision simultaneously recording the activity of complete neural networks that consist of thousands or even millions of neurons. However, a new study indicates that it may be possible to accurately characterize these networks by recording the activity of properly selected samples of 50 neurons or less — an alternative that is much easier to realize.The study was performed by a team of cognitive neuroscientists at Vanderbilt University and reported in a paper published the week of Feb. 3 in the online Early Edition of the Proceedings of the National Academy of Sciences.The paper describes the results of an ambitious computer simulation that the team designed to understand the behavior of the networks of hundreds of thousands of neurons that initiate different body movements: specifically, how the neurons are coordinated to trigger a movement at a particular point in time, called the response time.The researchers were surprised to discover that the range of response times produced by the simulated population of neurons did not change with size: A network of 50 simulated neurons responded with the same speed as a network with 1,000 neurons.For decades, response time has been a core measurement in psychology. “Psychologists have developed powerful models of human responses that explain the variation of response time based on the concept of single accumulators,” said Centennial Professor of Psychology Gordon Logan. In this model, the brain acts as an accumulator that integrates incoming information related to a given task and produces a movement when the amount of information reaches a preset threshold. The model explains random variations in response times by how quickly the brain accumulates the information it needs to act.Meanwhile, neuroscientists have related response time to measurements of single neurons. “Twenty years ago we discovered that the activity of particular neurons resembles the accumulators of psychology models. We haven’t understood until now how large numbers of these neurons can act collectively to initiate movements,” said Ingram Professor of Neuroscience Jeffrey Schall.No one really knows the size of the neural networks involved in initiating movements, but researchers estimated that about 100,000 neurons are involved in launching a simple eye movement.”One of the main questions we addressed is how ensembles of 100,000 neuron accumulators can produce behavior that is also explained by a single accumulator,” Schall said.”The way that the response time of these ensembles varies with ensemble size clearly depends on the ‘stopping rules’ that they follow,” explained co-author Thomas Palmeri, associate professor of psychology. For example, if an ensemble doesn’t respond until all of its member neurons have accumulated enough activity, then its response time would be slower for larger networks. On the other hand, if the response time is determined by the first neurons that react, then the response time in larger networks would be shorter than those of smaller networks.Another important factor is the degree to which the ensemble is coordinated. …

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Researchers discover how brain regions work together, or alone

Stanford researchers may have solved a riddle about the inner workings of the brain, which consists of billions of neurons, organized into many different regions, with each region primarily responsible for different tasks.The various regions of the brain often work independently, relying on the neurons inside that region to do their work. At other times, however, two regions must cooperate to accomplish the task at hand.The riddle is this: what mechanism allows two brain regions to communicate when they need to cooperate yet avoid interfering with one another when they must work alone?In a paper published today in Nature Neuroscience, a team led by Stanford electrical engineering professor Krishna Shenoy reveals a previously unknown process that helps two brain regions cooperate when joint action is required to perform a task.”This is among the first mechanisms reported in the literature for letting brain areas process information continuously but only communicate what they need to,” said Matthew T. Kaufman, who was a postdoctoral scholar in the Shenoy lab when he co-authored the paper.Kaufman initially designed his experiments to study how preparation helps the brain make fast and accurate movements — something that is central to the Shenoy lab’s efforts to build prosthetic devices controlled by the brain.But the Stanford researchers used a new approach to examine their data that yielded some findings that were broader than arm movements.The Shenoy lab has been a pioneer in analyzing how large numbers of neurons function as a unit. As they applied these new techniques to study arm movements, the researchers discovered a way that different regions of the brain keep results localized or broadcast signals to recruit other regions as needed.”Our neurons are always firing, and they’re always connected,” explained Kaufman, who is now pursuing brain research at Cold Spring Harbor Laboratory in New York. “So it’s important to control what signals are communicated from one area to the next.”Experimental designThe scientists derived their findings by studying monkeys that had been trained to make precise arm movements. The monkeys were taught to pause briefly before making the reach, thus letting their brain prepare for a moment before moving.Remember, the goal was to help build brain-controlled prostheses. Because the neurons in the brain always send out signals, engineers must be able to differentiate the command to act from the signals that accompany preparation.To understand how this worked with the monkey’s arm, the scientists took electrical readings at three places during the experiments: from the arm muscles, and from each of two motor cortical regions in the brain known to control arm movements.The muscle readings enabled the scientists to ascertain what sorts of signals the arm receives during the preparatory state compared with the action step.The brain readings were more complex. Two regions control arm movements. They are located near the top center of the brain, an inch to the side.Each of the two regions is made up of more than 20 million neurons. The scientists wanted to understand the behavior of both regions, but they couldn’t probe millions of neurons. …

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Worry on the brain: Researchers find new area linked to anxiety

According to the National Institute of Mental Health, over 18 percent of American adults suffer from anxiety disorders, characterized as excessive worry or tension that often leads to other physical symptoms. Previous studies of anxiety in the brain have focused on the amygdala, an area known to play a role in fear. But a team of researchers led by biologists at the California Institute of Technology (Caltech) had a hunch that understanding a different brain area, the lateral septum (LS), could provide more clues into how the brain processes anxiety. Their instincts paid off — using mouse models, the team has found a neural circuit that connects the LS with other brain structures in a manner that directly influences anxiety.”Our study has identified a new neural circuit that plays a causal role in promoting anxiety states,” says David Anderson, the Seymour Benzer Professor of Biology at Caltech, and corresponding author of the study. “Part of the reason we lack more effective and specific drugs for anxiety is that we don’t know enough about how the brain processes anxiety. This study opens up a new line of investigation into the brain circuitry that controls anxiety.”The team’s findings are described in the January 30 version of the journal Cell.Led by Todd Anthony, a senior research fellow at Caltech, the researchers decided to investigate the so-called septohippocampal axis because previous studies had implicated this circuit in anxiety, and had also shown that neurons in a structure located within this axis — the LS — lit up, or were activated, when anxious behavior was induced by stress in mouse models. But does the fact that the LS is active in response to stressors mean that this structure promotes anxiety, or does it mean that this structure acts to limit anxiety responses following stress? The prevailing view in the field was that the nerve pathways that connect the LS with different brain regions function as a brake on anxiety, to dampen a response to stressors. But the team’s experiments showed that the exact opposite was true in their system.In the new study, the team used optogenetics — a technique that uses light to control neural activity — to artificially activate a set of specific, genetically identified neurons in the LS of mice. During this activation, the mice became more anxious. …

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Brain scans show unusual activity in retired American football players

Oct. 17, 2013 — A new study has discovered profound abnormalities in brain activity in a group of retired American football players.Although the former players in the study were not diagnosed with any neurological condition, brain imaging tests revealed unusual activity that correlated with how many times they had left the field with a head injury during their careers.Previous research has found that former American football players experience higher rates of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. The new findings, published in Scientific Reports, suggest that players also face a risk of subtle neurological deficits that don’t show up on normal clinical tests.The study involved 13 former National Football League (NFL) professionals who believed they were suffering from neurological problems affecting their everyday lives as a consequence of their careers.The former players and 60 healthy volunteers were given a test that involved rearranging coloured balls in a series of tubes in as few steps as possible. Their brain activity was measured using functional magnetic resonance imaging (fMRI) while they did the test.The NFL group performed worse on the test than the healthy volunteers, but the difference was modest. More strikingly, the scans showed unusual patterns of brain activity in the frontal lobe. The difference between the two groups was so marked that a computer programme learned to distinguish NFL alumni and controls at close to 90 per cent accuracy based just on their frontal lobe activation patterns.”The NFL alumni showed some of the most pronounced abnormalities in brain activity that I have ever seen, and I have processed a lot of patient data sets in the past,” said Dr Adam Hampshire, lead author of the study, from the Department of Medicine at Imperial College London.The frontal lobe is responsible for executive functions: higher-order brain activity that regulates other cognitive processes. The researchers think the differences seen in this study reflect deficits in executive function that might affect the person’s ability to plan and organise their everyday lives.”The critical fact is that the level of brain abnormality correlates strongly with the measure of head impacts of great enough severity to warrant being taken out of play. This means that it is highly likely that damage caused by blows to the head accumulate towards an executive impairment in later life.”Dr Hampshire and his colleagues at the University of Western Ontario, Canada suggest that fMRI could be used to reveal potential neurological problems in American football players that aren’t picked up by standard clinical tests. Brain imaging results could be useful to retired players who are negotiating compensation for neurological problems that may be related to their careers. Players could also be scanned each season to detect problems early.The findings also highlight the inadequacy of standard cognitive tests for detecting certain types of behavioural deficit.”Researchers have put a lot of time into developing tests to pick up on executive dysfunction, but none of them work at all well. …

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