Posts tagged science
Articles and news from the latest research reports.
Positive, negative thinkers’ brains revealed
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.
A Brain Region for Resisting Alcohol’s Allure
As recovering spring breakers are regretting binge drinking escapades, it may be hard for them to appreciate that there is a positive side to the nausea, sleepiness, and stumbling. University of Utah neuroscientists report that when a region of the brain called the lateral habenula is chronically inactivated in rats, they repeatedly drink to excess and are less able to learn from the experience. The study, published online in PLOS ONE on April 2, has implications for understanding behaviors that drive alcohol addiction.
While complex societal pressures contribute to alcoholism, physiological factors are also to blame. Alcohol is a drug of abuse, earning its status because it tickles the reward system in the brain, triggering the release of feel-good neurotransmitters. The dreaded outcomes of overindulging serve the beneficial purpose of countering the pull of temptation, but little is understood about how those mechanisms are controlled.
U of U professor of neurobiology and anatomy Sharif Taha, Ph.D., and colleagues, tipped the balance that reigns in addictive behaviors by inactivating in rats a brain region called the lateral habenula. When the rats were given intermittent access to a solution of 20% alcohol over several weeks, they escalated their alcohol drinking more rapidly, and drank more heavily than control rats.
“In people, escalation of intake is what eventually separates a social drinker from someone who becomes an alcoholic,” said Taha. “These rats drink amounts that are quite substantial. Legally they would be drunk if they were driving.”
The lateral habenula is activated by bad experiences, suggesting that without this region the rats may drink more because they fail to learn from the negative outcomes of overindulging. The investigators tested the idea by giving the rats a desirable, sweet juice then injecting them with a dose of alcohol large enough to cause negative effects.
“It’s the same kind of learning that mediates your response in food poisoning. You taste something and then you get sick, and then of course you avoid that food in future meals,” explained Taha.
Yet rats with an inactivated lateral habenula sought out the juice more than control animals, even though it meant a repeat of the bad experience.
“The way I look at it is the rewarding effects of drinking alcohol compete with the aversive effects,” explained Andrew Haack, who is co-first author on the study with Chandni Sheth, both neuroscience graduate students. “When you take the aversive effects away, which is what we did when we inactivated the lateral habenula, the rewarding effects gain more purchase, and so it drives up drinking behavior.”
The group’s findings may help explain results from previous clinical investigations demonstrating that men who were less sensitive to the negative effects of alcohol drank more heavily, and were more likely to become problem drinkers later in life.
The researches think the lateral habenula likely works in one of two ways. The region may regulate how badly an individual feels after over-drinking. Alternatively, it may control how well an individual learns from their bad experience. Future work will resolve between the two.
“If we can understand the brain circuits that control sensitivity to alcohol’s aversive effects, then we can start to get a handle on who may become a problem drinker,” said Taha.
New Ways to Prevent Relapse in Cocaine-Addicted Patients
Relapse is the most painful and expensive feature of drug addiction—even after addicted individuals have been drug-free for months or years, the likelihood of sliding back into the habit remains high. The National Institute on Drug Abuse estimates that 40 to 60 percent of addicted individuals will relapse, and in some studies the rates are as high as 80 percent at six months after treatment. Though some relapse triggers can be consciously avoided, such as people, places and things related to drug use, other subconscious triggers related to the brain’s reward system may be impossible to avoid— they can gain entry to the unconscious brain, setting the stage for relapse.
Researchers at Penn Medicine’s Center for Studies of Addiction have now found that the drug baclofen, commonly used to prevent spasms in patients with spinal cord injuries and neurological disorders, can help block the impact of the brain’s response to “unconscious” drug triggers well before conscious craving occurs. They suggest that this mechanism has the potential to prevent cocaine relapse. The new findings are reported in the Journal of Neuroscience.
Noisy brain signals: How the schizophrenic brain misinterprets the world
People with schizophrenia often misinterpret what they see and experience in the world. New research provides insight into the brain mechanisms that might be responsible for this misinterpretation. The study from the Montreal Neurological Institute and Hospital – The Neuro - at McGill University and McGill University Health Centre, reveals that certain errors in visual perception in people with schizophrenia are consistent with interference or ‘noise’ in a brain signal known as a corollary discharge. Corollary discharges are found throughout the animal kingdom, from bugs to fish to humans, and they are thought to be crucial for monitoring one’s own actions. The study, published in the April 2 issue of the Journal of Neuroscience, identifies a corollary discharge dysfunction in schizophrenia, which could aid with diagnosis and treatment of this difficult disorder. It was carried out in collaboration with researchers Veronica Whitford, Gillian O’Driscoll, and Debra Titone in the Department of Psychology, McGill University.
“A corollary discharge is a copy of a nervous system message that is sent to other parts of the brain, in order to make us aware that we are doing something,” said Dr. Christopher Pack, neuroscientist at The Neuro and lead investigator on the study. “For example, if we want to move our arm, the motor area of the brain sends a signal to the muscles to produce a movement. A copy of this command, which is the corollary discharge, is sent to other regions of the brain, to inform them of the impending movement. If you were moving your arm, and you didn’t have the corollary discharge signal, you might assume that someone else was moving your arm. Similarly, if you generated a thought, and you had an impaired corollary discharge, then you might assume that someone else placed the thought in your mind. Corollary discharges ensure that different areas of the brain are communicating with each other, so that we are aware that we are moving our own arm, talking, or thinking our own thoughts.”
Schizophrenia is a disorder that interferes with the ability to think clearly and to manage emotions. People with schizophrenia often attribute their own thoughts and actions to external sources, as in the case of auditory hallucinations. Other common symptoms include delusions and disorganized thinking and speech.
Recent research has suggested that an impaired corollary discharge can account for some of these symptoms. However, the nature of the impairment was unknown. In their study, Dr. Pack and his colleagues (including Dr. Alby Richard, neurology resident at The Neuro) used a test called a perisaccadic localization task, to investigate corollary discharge activity. In this test, subjects are asked to make quick eye movements to follow a dot on a computer screen. At the same time they are also asked to localize visual stimuli that appear briefly on the screen from time to time. In order to perform this task accurately, subjects need to know where on the screen they are looking – in other words they use corollary discharges signals that arise from the brain structures that control the eye muscles.
The results showed that people with schizophrenia were less accurate in figuring out where they were looking. Consequently they made more mistakes in estimating the position of the stimuli that were flashed on the screen. “What is interesting and potentially clinically important is that the pattern of mistakes made by the patients correlated with the extent of their symptoms,” said Dr. Pack. “This is particularly interesting because the circuits that control eye movements include the best-understood structures in the brain. So we are optimistic that we can work backward from the behavioral data to the biological basis of the corollary discharge effects. We have already started to do this with computational modeling. Mathematically we can convert the corollary discharge of a healthy control into the corollary discharge of a patient with schizophrenia by adding noise and randomness. It is not that people with schizophrenia have no corollary discharge, or a corollary discharge with delayed or weaker amplitude. Rather the patients appear primarily to have a noisy corollary discharge signal. This visual test is very easy thing to do and quite sensitive to individual differences.“
The study shows that patients with schizophrenia make larger errors in localizing visual stimuli compared to controls. These results could be explained by a corollary discharge signal, which also predicts patient symptom severity, suggesting a possible basis for some of the most common symptoms of schizophrenia. This work was supported by The Natural Sciences and Engineering Research Council of Canada, The Brain & Behavior Research Foundation (NARSAD) and the EJLB Foundation.
New Method Could Improve Ultrasound Imaging
One day while casually reading a review article, Caltech chemical engineer Mikhail Shapiro came across a mention of gas vesicles—tiny gas-filled structures used by some photosynthetic microorganisms to control buoyancy. It was a light-bulb moment. Shapiro is always on the lookout for new ways to enhance imaging techniques such as ultrasound or MRI, and the natural nanostructures seemed to be just the ticket to improve ultrasound imaging agents.
Now Shapiro and his colleagues from UC Berkeley and the University of Toronto have shown that these gas vesicles, isolated from bacteria and from archaea (a separate lineage of single-celled organisms), can indeed be used for ultrasound imaging. The vesicles could one day help track and reveal the growth, migration, and activity of a variety of cell types—from neurons to tumor cells—using noninvasive ultrasound, one of the most widely used imaging modalities in biomedicine.
A paper describing the work appears as an advance online publication in the journal Nature Nanotechnology.
"People have struggled to make synthetic nanoscale imaging agents for ultrasound for many years," says Shapiro. "To me, it’s quite amazing that we can borrow something that nature has evolved for a completely different purpose and use it for in vivo ultrasound imaging. It shows just how much nature has to offer us as engineers."
Publication in Nature Showcases Most Comprehensive Wiring Diagram of the Mammalian Brain To Date
Researchers from the Allen Institute for Brain Science have published the first comprehensive, large-scale data set on how the brain of a mammal is wired, providing a groundbreaking data resource and fresh insights into how the nervous system processes information. Their landmark paper in this week’s issue of the journal Nature both describes the publicly available Allen Mouse Brain Connectivity Atlas, and demonstrates the exciting knowledge that can be gleaned from this valuable resource.
(Image: Connectivity Dot-o-Gram)
“Understanding how the brain is wired is among the most crucial steps to understanding how the brain encodes information,” explains Hongkui Zeng, Senior Director of Research Science at the Allen Institute for Brain Science. “The Allen Mouse Brain Connectivity Atlas is a standardized, quantitative, and comprehensive resource that will stimulate exciting investigations around the entire neuroscience community, and from which we have already gleaned unprecedented details into how structures are connected inside the brain.”
Using the data, Allen Institute scientists were able to demonstrate that there are highly specific patterns in the connections among different brain regions, and that the strengths of these connections vary with greater than five orders of magnitudes, balancing a small number of strong connections with a large number of weak connections. This publication comes just as the research team wraps up more than four years of work to collect and make publicly available the data behind the Allen Mouse Brain Connectivity Atlas project, with the completion of the Atlas announced in March 2014.
(Source: alleninstitute.org)
A Critical Window into the Developing Human Brain Profiled in Nature
First major report using data from the BrainSpan Atlas of the Developing Human Brain shines a light on where genes are turned on in the brain during mid-pregnancy, what goes wrong in developmental disorders like autism, and what makes human brains unique.
Researchers at the Allen Institute for Brain Science have generated a high-resolution blueprint for how to build a human brain, with a detailed map of where different genes are turned on and off during mid-pregnancy at unprecedented anatomical resolution. This first major report using data from the BrainSpan Atlas of the Developing Human Brain is published in the journal Nature this week. The data provide exceptional insight into diseases like autism that are linked to early brain development, and to the origins of human uniqueness. The rich data set is publicly available to everyone via the Allen Brain Atlas data portal.
“Knowing where a gene is expressed in the brain can provide powerful clues about what its role is,” says Ed Lein, Investigator at the Allen Institute for Brain Science. “This atlas gives a comprehensive view of which genes are on and off in which specific nuclei and cell types while the brain is developing during pregnancy. This means that we have a blueprint for human development: an understanding of the crucial pieces necessary for the brain to form in a normal, healthy way, and a powerful way to investigate what goes wrong in disease.”
This paper represents the first major report to make use of data collected for the BrainSpan Atlas of the Developing Human Brain, a big science consortium initiative which seeks to create a map of the transcriptome across the entire course of human development. “Coming on the first anniversary of the BRAIN Initiative, this is a terrific example of the potential for public-private partnerships to accelerate progress in neuroscience,” says Lein.
Thomas R. Insel, Director of the National Institute of Mental Health, praises the BrainSpan Atlas as an already invaluable tool to researchers. “While we have had previous reports of molecular and cellular changes during human brain growth, the BrainSpan Atlas is the first comprehensive map of the dramatic trajectory of gene expression across prenatal and postnatal development,” he says. “This atlas is already transforming the way scientists approach human brain development and neurodevelopmental disorders like autism and schizophrenia. Although the many genes associated with autism and schizophrenia don’t show a clear relationship to each other in the adult brain, the BrainSpan Atlas reveals how these diverse genes are connected in the prenatal brain.”
(Source: alleninstitute.org)
Study finds link between child’s obesity and cognitive function
A new University of Illinois study finds that obese children are slower than healthy-weight children to recognize when they have made an error and correct it. The research is the first to show that weight status not only affects how quickly children react to stimuli but also impacts the level of activity that occurs in the cerebral cortex during action monitoring.
“I like to explain action monitoring this way: when you’re typing, you don’t have to be looking at your keyboard or your screen to realize that you’ve made a keystroke error. That’s because action monitoring is occurring in your brain’s prefrontal cortex,” said Charles Hillman, a U of I professor of kinesiology and faculty member in the U of I’s Division of Nutritional Sciences.
As an executive control task that requires organizing, planning, and inhibiting, action monitoring requires people to be computational and conscious at all times as they process their behavior. Because these higher-order cognitive processes are needed for success in mathematics and reading, they are linked with success in school and positive life outcomes, he said.
“Imagine a child in a math class constantly checking to make sure she’s carrying the digit over when she’s adding. That’s an example,” he added.
In the study, the scientists measured the behavioral and neuroelectric responses of 74 preadolescent children, half of them obese, half at a healthy weight. Children were fitted with caps that recorded electroencephalographic activity and asked to participate in a task that presented left- or right-facing fish, predictably facing in either the same or the opposite direction. Children were asked to press a button based on the direction of the middle (that is, target) fish. The flanking fish either pointed in the same direction (facilitating) or in the opposite direction (hindering) their ability to respond successfully.
“We found that obese children were considerably slower to respond to stimuli when they were involved in this activity,” Hillman said.
The researchers also found that healthy-weight children were better at evaluating their need to change their behavior in order to avoid future errors.
“The healthy-weight kids were more accurate following an error than the obese children were, and when the task required greater amounts of executive control, the difference was even greater,” he reported.
A second evaluation measured electrical activity in the brain “that occurs at the intersection of thought and action,” Hillman said. “We can measure what we call error-related negativity (ERN) in the electrical pattern that the brain generates following errors. When children made an error, we could see a larger negative response. And we found that healthy-weight children are better able to upregulate the neuroelectric processes that underlie error evaluation.”
Scientists in the Hillman lab and elsewhere have seen a connection between healthy weight and academic achievement, “but a study like this helps us understand what’s happening. There are certainly physiological differences in the brain activity of obese and healthy-weight children. It’s exciting to be able to use functional brain imaging to see the way children’s weight affects the aspects of cognition that influence and underlie achievement,” said postdoctoral researcher and co-author Naiman Khan.
(Source: news.aces.illinois.edu)
Sport makes muscles and nerves fit
Endurance sport does not only change the condition and fitness of muscles but also simultaneously improves the neuronal connections to the muscle fibers based on a muscle-induced feedback. This link has been discovered by Christoph Handschin’s research group at the Biozentrum of the University of Basel. The group was also able to induce the same effect through raising the protein concentration of PGC1α in the muscle. Their findings, which are also interesting in regard to muscle and nerve disorders such as muscle wasting and ALS, have been published in the current issue of the journal “Nature Communications”.
It’s springtime – the start signal for all joggers. It is well known that a regular run through the forest makes your muscles fit. Responsible for this effect is the protein PGC1α, which plays a central role in the adaptation of muscles to training. The research team led by Prof. Christoph Handschin has discovered that such endurance training not only affects the condition of the muscles but also the upstream synaptic neuronal connections in a muscle-dependent manner.
PGC1α does not only make muscles fit…
How do muscles change during muscle training or in muscle disease? Christoph Handschin and his team have been addressing this question for some years. In the past, they have already shown that the protein PGC1α plays a key role in the adaptation of the muscle by regulating the genes that cause the muscles to change accordingly to meet the more demanding requirements. When muscle is inactive or ill, only a low concentration of PGC1α is present. However, when the muscle is challenged, the PGC1α level increases. Through artificial elevation of the PGC1α concentration, it is possible to stimulate muscle endurance.
… but also the nerve connections
Now, the scientists have been able to demonstrate that the increase in muscle PGC1α concentration also improves the upstream synaptic nerve connections to the result of this feedback from muscle to the motor neuron: The health of the synapse improves and its activation pattern adapts to meet the requirements of the muscle. Until now, the influence of the muscle on the synaptic connection was primarily recognized in embryonic development. “That in adults, where the nerve and muscular systems are fully developed, not only the muscle changes due to an increase in PGC1α concentration but also a muscle-controlled improvement in the entire nerve and muscular system takes place, was completely unexpected and a great surprise to us”, says Handschin. “Our current aim is to identify the exact signal that leads to this stabilization of the synaptic connections, in order to apply this for treating muscle disorders.”
…and helps in the treatment of muscle and nerve disorders
A direct therapeutic application of the research findings in illnesses such as muscle wasting and amyotrophic lateral sclerosis (ALS) is already conceivable for Christoph Handschin. “In patients, whose muscles due to their illness are too weak to move on their own, an increase in PGC1α levels could strengthen muscles and nerves until the patients can move enough to finally do some physical therapy and to further improve their mobility”, he explains. After the pharmacological improvement of the health status of the muscles and nerves, the patient could independently continue their treatment through practicing endurance sports.
Dog watch - How attention changes in the course of a dog’s life
Dogs are known to be Man’s best friend. No other pet has adjusted to Man’s lifestyle as this four-legged animal. Scientists at the Messerli Research Institute at the Vetmeduni Vienna, have been the first to investigate the evolution of dogs’ attentiveness in the course of their lives and to what extent they resemble Man in this regard. The outcome: dogs’ attentional and sensorimotor control developmental trajectories are very similar to those found in humans. The results were published in the journal Frontiers in Psychology.
Dogs are individual personalities, possess awareness, and are particularly known for their learning capabilities, or trainability. To learn successfully, they must display a sufficient quantity of attention and concentration. However, the attentiveness of dogs’ changes in the course of their lives, as it does in humans. The lead author Lisa Wallis and her colleagues investigated 145 Border Collies aged 6 months to 14 years in the Clever Dog Lab at the Vetmeduni Vienna and determined, for the first time, how attentiveness changes in the entire course of a dog’s life using a cross-sectional study design.
Humans are more interesting for dogs than objects
To determine how rapidly dogs of various age groups pay attention to objects or humans, the scientists performed two tests. In the first situation the dogs were confronted with a child’s toy suspended suddenly from the ceiling. The scientists measured how rapidly each dog reacted to this occurrence and how quickly the dogs became accustomed to it. Initially all dogs reacted with similar speed to the stimulus, but older dogs lost interest in the toy more rapidly than younger ones did.
In the second test situation, a person known to the dog entered the room and pretended to paint the wall. All dogs reacted by watching the person and the paint roller in the person’s hands for a longer duration than the toy hanging from the ceiling.
Wallis’ conclusion: “So-called social attentiveness was more pronounced in all dogs than “non-social” attentiveness. The dogs generally tended to react by watching the person with the object for longer than an object on its own. We found that older dogs - like older human beings - demonstrated a certain calmness. They were less affected by new items in the environment and thus showed less interest than younger dogs.”
Selective attention is highest in mid-adulthood
In a further test the scientists investigated so-called selective attention. The dogs participated in an alternating attention task, where they had to perform two tasks consecutively. First, they needed to find a food reward thrown onto the floor by the experimenter, then after eating the food, the experimenter waited for the dog to establish eye contact with her. These tasks were repeated for a further twenty trials. The establishment of eye contact was marked by a clicking sound produced by a “clicker” and small pieces of hot dog were used as a reward. The time spans to find the food and look up into the face were measured. With respect to both time spans, middle-aged dogs (3 to 6 years) reacted most rapidly.
Under these test conditions, sensorimotor abilities were highest among dogs of middle age. Younger dogs fared more poorly probably because of their general lack of experience. Motor abilities in dogs as in humans deteriorate with age. Humans between the age of 20 and 39 years experience a similar peak in sensorimotor abilities,” says Wallis.
Adolescent dogs have the steepest learning curve
Dogs also go through a difficult phase during adolescence (1-2 years) which affects their ability to pay attention. This phase of hormonal change may be compared to puberty in Man. Therefore, young dogs occasionally reacted with some delay to the clicker test. However, Wallis found that adolescent dogs improved their performance more rapidly than other age groups after several repetitions of the clicker test. In other words, the learning curve was found to be steepest in puberty. “Thus, dogs in puberty have great potential for learning and therefore trainability” says Wallis.
Dogs as a model for ADHD and Alzheimer’s disease
As the development of attentiveness in the course of a dog’s life is similar to human development in many respects, dogs make appropriate animal models for various human psychological diseases. For instance, the course of diseases like ADHD (attention deficit/hyperactivity disorder) or Alzheimer’s can be studied by observing the behavior of dogs. In her current project Wallis is investigating the effects of diet on cognition in older dogs together with her colleague Durga Chapagain. The scientists are still looking for dog owners who would like to participate in a long-term study.