Posts tagged brain
Articles and news from the latest research reports.
Angry? Sad? Ashamed? Depressed people can’t tell difference
Clinically depressed people have a hard time telling the difference between negative emotions such as anger and guilt, a new University of Michigan study found.
The ability to distinguish between various emotional experiences affects how individuals deal with life stressors, said Emre Demiralp, a researcher in the U-M Department of Psychology and the lead author of the study recently published in Psychological Science.
Being unable to differentiate certain emotions from each other might lead to a person choosing an action that is not appropriate, thus exacerbating the problem, she said.
"It is difficult to improve your life without knowing whether you are sad or angry about some aspect of it," Demiralp said. "For example, imagine not having a gauge independently indicating the gasoline level of your car. It would be challenging to know when to stop for gas.
"We wanted to investigate whether people with clinical depression had emotional gauges that were informative and whether they experienced emotions with the same level of specificity and differentiation as healthy people."
Sleep loss links to illness studied
Insomniacs know the pattern all too well. You toss and turn at night, kept awake by the rave down the street, stress from work, the snores of a significant other.
After a stretch of restless evenings, you wake up with a sore throat or a fever. You’re no longer just tired - you’re also sick.
Physicians know this pattern, too. Constant lack of sleep has long been linked with a laundry list of unpleasant conditions: cardiovascular disease, diabetes, weight gain, infectious illnesses and even death.
While it’s common knowledge that a full night of rest helps ward off ailments, what largely remains a mystery is exactly how sleep loss triggers the biological mechanisms that in turn bring about illness - like the common cold.
A 2009 study of 153 men and women, for example, showed that those who slept fewer than seven hours on average per night were about three times more likely to develop a cold than those with at least eight hours of sleep daily.
Even a small difference in sleep quality made a big difference in health, the Carnegie Mellon University study showed. Participants who actually slept less than 92 percent of the time between the time they laid down to sleep and when they woke up were 5.5 times more likely to develop a cold than those who stayed asleep 98 percent or more of the time, according to the researchers.
The Dementia and Music Project - Chloe Meineck
This project is a culmination of two years research highlighting the advantages of listening to familiar music for dementia sufferers. This coupled with the fact that when many people move into a home they feel lost in their unfamiliar surroundings. The music box, which is all hand made, combines an interactive music player, with a memory box of co-designed special objects.
The film is Barbara talking about her life, her most important objects, music, events and her most treasured people.
Is this the most unpleasant sound in the world?
The ear-splitting screech of a knife on a glass bottle has been identified as the worst sound to the human ear by scientists who studied the brain’s response to unpleasant noises.
People who listened to a series of 74 recordings while having their brain activity measured by an MRI scanner rated the sound of a fork on a glass as the second worst noise, followed by chalk on a blackboard.
The scans revealed that unpleasant sounds provoked a stronger response in the brain than pleasant ones such as the noise of blubbing water. While sounds are processed in the brain’s auditory cortex, uncomfortable noises activate the amygdala, a separate brain region which processes emotions.
The researchers studied a group of 13 volunteers and found that sounds with a frequency of between 2,000 and 5,000 Hz, the range at which our ears are the most sensitive, were the hardest to bear.
Although it remains unclear why our ears are most sensitive to this type of sound, researchers noted that screams, which we naturally find uncomfortable, fall within the same range.
Dr Sukhbinder Kumar of Newcastle University, author of the study, which was published in the Journal of Neuroscience, said: “It appears there is something very primitive kicking in. It’s a possible distress signal from the amygdala to the auditory cortex.”
His colleague Prof Tim Griffiths added: “This might be a new inroad into emotional disorders and disorders like tinnitus and migraine, in which there seems to be heightened perception of the unpleasant aspects of sounds.”
McGill researchers link genetic mutation to psychiatric disease and obesity
McGill researchers link genetic mutation to psychiatric disease and obesity
Deletion of brain-derived neurotrophic factor leads to major depression, anxiety, and obesity
McGill researchers have identified a small region in the genome that conclusively plays a role in the development of psychiatric disease and obesity. The key lies in the genomic deletion of brain-derived neurotrophic factor, or BDNF, a nervous system growth factor that plays a critical role in brain development.
To determine the role of BDNF in humans, Prof. Carl Ernst, from McGill’s Department of Psychiatry, Faculty of Medicine, screened over 35,000 people referred for genetic screening at clinics and over 30,000 control subjects in Canada, the U.S., and Europe. Overall, five individuals were identified with BDNF deletions, all of whom were obese, had a mild-moderate intellectual impairment, and had a mood disorder. Children had anxiety disorders, aggressive disorders, or attention deficit-hyperactivity disorder (ADHD), while post-pubescent subjects had anxiety and major depressive disorders. Subjects gradually gained weight as they aged, suggesting that obesity is a long-term process when BDNF is deleted.
"Scientists have been trying to find a region of the genome which plays a role in human psychopathology, searching for answers anywhere in our DNA that may give us a clue to the genetic causes of these types of disorders," says Prof. Ernst, who is also a researcher at the Douglas Mental Health University Institute. "Our study conclusively links a single region of the genome to mood and anxiety."
The findings, published in the Archives of General Psychiatry, reveal for the first time the link between BDNF deletion, cognition, and weight gain in humans. BDNF has been suspected to have many functions in the brain based on animal studies, but no study had shown what happens when BDNF is missing from the human genome. This research provides a step toward better understanding human behaviour and mood by clearly identifying genes that may be involved in mental disorders.
"Mood and anxiety can be seen like a house of cards. In this case, the walls of the house represent the myriad of biological interactions that maintain the structure," says Ernst, "Studying these moving parts can be tricky, so teasing apart even a single event is important. Linking a deletion in BDNF conclusively to mood and anxiety really tells us that it is possible to dissect the biological pathways involved in determining how we feel and act.
We now have a molecular pathway we are confident is involved in psychopathology,” adds Ernst, “Because thousands of genes are involved in mood, anxiety, or obesity, it allows us to root our studies on a solid foundation. All of the participants in our study had mild-moderate intellectual disability, but most people with these cognitive problems do not have psychiatric problems – so what is it about deletion of BDNF that affects mood? My hope now is to test the hypothesis that boosting BDNF in people with anxiety or depression might improve brain health.”
(Source: fiercebiotechresearch.com)
Dual spotlights in the brain
How we manage to attend to multiple objects without being distracted by irrelevant information
The “tiki-taka”-style of the Spanish national football team is amazing to watch: Xavi passes to Andrès Iniesta, he just rebounds the ball once and it’s right at Xabi Alonso’s foot. The Spanish midfielders cross the field as if they run on rails, always maintaining attention on the ball and the teammates, the opponents chasing after them without a chance. An international team of scientists from the German Primate Center and McGill University in Canada, including Stefan Treue, head of the Cognitive Neuroscience Laboratory, has now uncovered how the human brain makes such excellence possible by dividing visual attention: The brain is capable of splitting its ‘attentional spotlight’ for an enhanced processing of multiple visual objects. (Neuron, doi: 10.1016/j.neuron.2011.10.013)
When we pay attention to an object, neurons responsible for this location in our field of view are more active then when they process unattended objects. But quite often we want to pay attention to multiple objects in different spatial positions, with interspersed irrelevant objects. Different theories have been proposed to account for this ability. One is, that the attentive focus is split spatially, excluding objects between the attentional spotlights. Another possibility is, that the attentional focus is zoomed out to cover all relevant objects, but including the interspersed irrelevant ones. A third possibility would be a single focus rapidly switching between the attended objects.
Studying rhesus macaques
In order to explain how such a complex ability is achieved, the neuroscientists measured the activity of individual neurons in areas of the brain involved in vision. They studied two rhesus macaques, which were trained in a visual attention task. The monkeys had learned to pay attention to two relevant objects on a screen, with an irrelevant object between them. The experiment showed, that the macaques’ neurons responded strongly to the two attended objects with only a weak response to the irrelevant stimulus in the middle. So the brain is able to spatially split visual attention and ignore the areas in between. “Our results show the enormous adaptiveness of the brain, which enables us to deal effectively with many different situations.
This multi-tasking allows us to simultaneously attend multiple objects”, Stefan Treue says. Such a powerful ability of our attentive system is one precondition for humans to become perfect football-artists but also to safely navigate in everyday traffic.
(Source: alphagalileo.org)
Neuroscientists Launch 5 Year Study of Music Education and Child Brain Development
Researchers at USC Brain and Creativity Institute will explore the effects of intense music training on cognitive development in LA Phil’s YOLA at HOLA program.
The Los Angeles Philharmonic Association, the USC Brain and Creativity Institute and Heart of Los Angeles (HOLA) are delighted to announce a longitudinal research collaboration to investigate the emotional, social and cognitive effects of musical training on childhood brain development.
The five-year research project, Effects of Early Childhood Musical Training on Brain and Cognitive Development, will offer USC researchers an important opportunity to provide new insights and add rigorous data to an emerging discussion about the role of early music engagement in learning and brain function.
Through a collaboration with the Youth Orchestra Los Angeles at Heart of Los Angeles (YOLA at HOLA) program, a partnership between the LA Phil and HOLA which provides free instruments and musical training to children from the Rampart District of Los Angeles, researchers with the USC Brain and Creativity Institute — led by acclaimed neuroscientists Hanna Damasio and Antonio Damasio – will track how children respond to music from the very onset of their exposure to systematic, high intensity music education.
The Circuitry of Uncertainty
The human brain likes to make predictions about how the world works. Imagine, for example, that you move to a new town. At first, you don’t know where to go for dinner. But after weeks of trying different restaurants, you pick a favorite, a little Thai place that makes the best green curry. Several months later, however, you notice the curry isn’t as spicy and the vegetables seem undercooked. At first you give your favorite place the benefit of the doubt. But after a few more so-so dinners, you suddenly realize that something must have changed—perhaps the owner hired a new chef—and your notion that this is the best place around is no longer valid. So you begin searching for a new favorite restaurant.
Neuroscientists have long been interested in this adaptability, particularly in the moment when an individual discards an old belief and begins to formulate a new one. “You go from being confident in your model of the world to being uncertain and then abandoning the model altogether,” says Alla Karpova, a group leader at the Howard Hughes Medical Institute’s Janelia Farm Research Campus. She and her colleagues wondered what goes on in the brain when this happens. In rats, they found that the rejection of an old belief correlates with abrupt changes in activity in the medial prefrontal cortex, a brain region involved in cognitive functions such as reward anticipation and decision-making. The team’s research is published in the October 5, 2012, issue of Science.
Wasp has hints of a clockwork brain
The greenhouse whitefly parasite (Encarsia formosa) is just half a millimetre in length. It parasitises the larvae of whiteflies and so it has long been used as a natural pest-controller.
To find out how its neurons have adapted to miniaturisation, Reinhold Hustert of the University of Göttingen in Germany examined the insect’s brain with an electron microscope. The axons - fibres that shuttle messages between neurons - were incredibly thin. Of 528 axons measured, a third were less than 0.1 micrometre in diameter, an order of magnitude narrower than human axons. The smallest were just 0.045 μm (Arthropod Structure & Development, doi.org/jfn).
That’s a surprise, because according to calculations by Simon Laughlin of the University of Cambridge and colleagues, axons thinner than 0.1 μm simply shouldn’t work. Axons carry messages in waves of electrical activity called action potentials, which are generated when a chemical signal causes a large number of channels in a cell’s outer membrane to open and allow positively charged ions into the axon. At any given moment some of those channels may open spontaneously, but the number involved isn’t enough to accidentally trigger an action potential, says Laughlin - unless the axon is very thin. An axon thinner than 0.1 μm will generate an action potential if just one channel opens spontaneously (Current Biology, doi.org/frfwpz).
"That makes the axon impossibly noisy," Laughlin says. Any "legitimate" action potentials will be drowned out.
Hustert suggests that a neuron might get around this problem by firing bursts of action potentials to cut through the noise, but Laughlin is sceptical. “They’d be firing furiously all the time,” he says, and every action potential costs energy.
Instead, the neurons might not bother with conventional action potentials at all. “They could be sending signals mechanically,” Laughlin says. The tiny axons might each carry a long rigid rod stretching down the centre. Pulling the rod could create a physical rather than electrical trigger for the release of a chemical that passes the signal on to the neighbouring neuron.
In larger animals this would be far too slow, says Laughlin, but in the tiny body of the greenhouse whitefly parasite, a partly “clockwork” brain might be the best approach.
Alpha Waves Close Your Mind for Distraction, but Not Continuously, Research Suggests
Alpha waves were long ignored, but gained interest of brain researchers recently. Electrical activity of groups of brain cells results in brain waves with different amplitudes. The so-called alpha wave, a slow brain wave with a cycle of 100 milliseconds, seems to play a key role in suppressing irrelevant brain activity. The current hypothesis is that this alpha wave is associated with pulses of inhibition (every 100 ms) in the brain.
Mathilde Bonnefond and Ole Jensen (Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen) discovered that when distracting information can be anticipated in time there is an increase of the power of this alpha wave just before the distracter. Furthermore, the brain is able to precisely control the alpha wave so that the pulse of inhibition is maximal when the distracter appears. Indeed, between pulses of inhibition, there is still a window where the brain is excitable.
'It is like briefly opening a door to look what's happening outside. This enables us to detect an unexpected but important or dangerous event. But to avoid to be distracted by completely irrelevant information, it is better if the inhibition is active when a distracter is presented. It could be seen as a mechanism slamming the door of the brain on intruders'. The results are published by the scientific journal Current Biology at October 4.