Posts tagged psychology
Articles and news from the latest research reports.
After nearly 10 years of follow-up of study participants who experienced migraines and who had brain lesions indentified via magnetic resonance imaging, women with migraines had a higher prevalence and greater increase of deep white matter hyperintensities (brain lesions) than women without migraines, although the number, frequency, and severity of migraines were not associated with lesion progression, according to a study appearing in the November 14 issue of JAMA. Also, increase in deep white matter hyperintensity volume was not significantly associated with poorer cognitive performance at follow-up.
Migraine affects up to 15 percent of the general population. “A previous cross-sectional study showed an association of migraine with a higher prevalence of magnetic resonance imaging (MRI)-measured ischemic lesions in the brain,” according to background information in the article. White matter hyperintensities are associated with atherosclerotic disease risk factors, increased risk of ischemic stroke, and cognitive decline.
Teenagers’ brains affected by preterm birth
New research at the University of Adelaide has demonstrated that teenagers born prematurely may suffer brain development problems that directly affect their memory and learning abilities.
The research, conducted by Dr Julia Pitcher and Dr Michael Ridding from the University of Adelaide’s Robinson Institute, shows reduced ‘plasticity’ in the brains of teenagers who were born preterm (at or before 37 weeks gestation).
The results of the research are published in the Journal of Neuroscience.
"Plasticity in the brain is vital for learning and memory throughout life," Dr Pitcher says. "It enables the brain to reorganise itself, responding to changes in environment, behaviour and stimuli by modifying the number and strength of connections between neurons and different brain areas. Plasticity is also important for recovery from brain damage.
"We know from past research that preterm-born children often experience motor, cognitive and learning difficulties. The growth of the brain is rapid between 20 and 37 weeks gestation, and being born even mildly preterm appears to subtly but significantly alter brain microstructure, neural connectivity and neurochemistry.
"However, the mechanisms that link this altered brain physiology with behavioural outcomes - such as memory and learning problems - have remained unknown," Dr Pitcher says.
Wired for Harmony?
Many creatures, such as human babies, chimpanzees, and chicks, react negatively to dissonance—harsh, unstable, grating sounds. Since the days of the ancient Greeks, scientists have wondered why the ear prefers harmony. Now, scientists suggest that the reason may go deeper than an aversion to the way clashing notes abrade auditory nerves; instead, it may lie in the very structure of the ear and brain, which are designed to respond to the elegantly spaced structure of a harmonious sound.
"Over the past century, researchers have tried to relate the perception of dissonance to the underlying acoustics of the signals," says psychoacoustician Marion Cousineau of the University of Montreal in Canada. In a musical chord, for example, several notes combine to produce a sound wave containing all of the individual frequencies of each tone. Specifically, the wave contains the base, or "fundamental," frequency for each note plus multiples of that frequency known as harmonics. Upon reaching the ear, these frequencies are carried by the auditory nerve to the brain. If the chord is harmonic, or "consonant," the notes are spaced neatly enough so that the individual fibers of the auditory nerve carry specific frequencies to the brain. By perceiving both the parts and the harmonious whole, the brain responds to what scientists call harmonicity.
In a dissonant chord, however, some of the notes and their harmonics are so close together that two notes will stimulate the same set of auditory nerve fibers. This clash gives the sound a rough quality known as beating, in which the almost-equal frequencies interfere to create a warbling sound. Most researchers thought that phenomenon accounted for the unpleasantness of a dissonance.
Babies rely on words to ‘decode’ underlying intentions of others
A new Northwestern University study shows the power of language in infants’ ability to understand the intentions of others.
As the babies watched intently, an experimenter produced an unusual behavior—she used her forehead to turn on a light. But how did babies interpret this behavior? Did they see it as an intentional act, as something worthy of imitating? Or did they see it as a fluke? To answer this question, the experimenter gave 14-month-old infants an opportunity to play with the light themselves.
The results, based on two experiments, show that introducing a novel word for the impending novel event had a powerful effect on the infants’ tendency to imitate the behavior. Infants were more likely to imitate behavior, however unconventional, if it had been named, than if it remained unnamed, the study shows.
When the experimenter announced her unusual behavior (“I’m going to blick the light”), infants imitated her. But when she did not provide a name, they did not follow suit.
This revealed that infants as young as 14 months of age coordinate their insights about human behavior and their intuitions about human language in the service of discovering which behaviors, observed in others, are ones to imitate.
"This work shows, for the first time, that even for infants who have only just begun to ‘crack the language code,’ language promotes culturally-shared knowledge and actions – naturally, generatively and apparently effortlessly," said Sandra R. Waxman, co-author of the study and the Louis W. Menk Professor of Psychology at Northwestern.
"This is the first demonstration of how infants’ keen observational skills, when augmented by human language, heighten their acuity for ‘reading’ the underlying intentions of their ‘tutors’ (adults) and foster infants’ imitation of adults’ actions."
Waxman said absent language and its power in conveying meaning, infants don’t imitate these “strange” actions.
"This means that human language provides infants with a powerful key: it unlocks for them a broader world of social intentions," Waxman said. "We know that language, and especially the shared meaning within a linguistic community, is one of the most powerful conduits of the cultural knowledge that we humans transmit across generations."
(Source: eurekalert.org)
Seeing someone yawn or hearing someone laugh makes you likely to follow suit. The same goes for scratching an itch. Now, for the first time, researchers have investigated the neural basis of contagious itch, identifying several brain regions whose activity predicts how susceptible people are to feeling itchy when they see someone else scratch.
Researchers in the United Kingdom showed volunteers video clips of people scratching an arm or a spot on their chest. Sure enough, subjects reported feeling more itchy, and most scratched themselves at least once during the experiment. When a subset of the volunteers watched the videos inside an functional magnetic resonance imaging scanner, the scans revealed activity in several of the same brain regions known to fire up in response to an itch-inducing histamine injection.
Activity in three of these areas correlated with subjects’ self-reported itchiness, the team reports online in the Proceedings of the National Academy of Sciences. Personality tests suggest that the trait that best predicts susceptibility to contagious itch is neuroticism, not empathy, as some researchers have suggested.
Meditation appears to produce enduring changes in emotional processing in the brain
A new study has found that participating in an 8-week meditation training program can have measurable effects on how the brain functions even when someone is not actively meditating. In their report in the November issue of Frontiers in Human Neuroscience, investigators at Massachusetts General Hospital (MGH), Boston University (BU), and several other research centers also found differences in those effects based on the specific type of meditation practiced.
"The two different types of meditation training our study participants completed yielded some differences in the response of the amygdala – a part of the brain known for decades to be important for emotion – to images with emotional content," says Gaëlle Desbordes, PhD, a research fellow at the Athinoula A. Martinos Center for Biomedical Imaging at MGH and at the BU Center for Computational Neuroscience and Neural Technology, corresponding author of the report. "This is the first time that meditation training has been shown to affect emotional processing in the brain outside of a meditative state."
Several previous studies have supported the hypothesis that meditation training improves practitioners’ emotional regulation. While neuroimaging studies have found that meditation training appeared to decrease activation of the amygdala – a structure at the base of the brain that is known to have a role in processing memory and emotion – those changes were only observed while study participants were meditating. The current study was designed to test the hypothesis that meditation training could also produce a generalized reduction in amygdala response to emotional stimuli, measurable by functional magnetic resonance imaging (fMRI).
Your Unconscious Brain Can Do Math, Process Language
The unconscious brain may not be able to ace an SAT test, but new research suggests that it can handle more complex language processing and arithmetic tasks than anyone has previously believed. According to these findings, just published in the Proceedings of the National Academy of Sciences, we may be blithely unaware of all the hard work the unconscious brain is doing.
In their experiments, researchers from Hebrew University in Israel used a cutting-edge “masking” technique to keep their test subjects from consciously perceiving certain stimuli. With this technique, known as continuous flash suppression, the researchers show a rapidly changing series of colorful patterns to just one of the subject’s eyes. The bright patterns dominate the subject’s awareness to such an extent that when researchers show less flashy material to the other eye (like words or equations), it takes several seconds before the brain consciously registers it.
This masking technique is “a game changer in the study of the unconscious,” the scientists write, “because unlike all previous methods, it gives unconscious processes ample time to engage with and operate on subliminal stimuli.”
To study the unconscious brain’s ability to process language, the researchers subliminally showed the subject short phrases that made variable amounts of sense: For example, subjects might see the phrase “I ironed coffee” or “I ironed clothes.” The researchers gradually turned up the contrast between the phrase and its background, and measured how long it took for the phrase to “pop” into the subject’s conscious awareness. As the nonsensical phrases popped sooner, the researchers hypothesize that the unconscious brain processed the sentence, found it surprising and odd, and quickly passed it along to the conscious brain for further examination.
To determine the unconscious brain’s mathematical abilities, the researchers presented a simple subtraction or addition equation (for example, “9 − 3 − 4 = “) to a subject, but took it away before it could pop into consciousness. Then they stopped the masking pattern and displayed a single number, asking the viewer to pronounce the number as soon as it registered. When the number was the answer to the subtraction equation (for example, “2”), the subject was quicker to pronounce it. The researchers argue that the viewer was “primed” to respond to that number because the unconscious brain had solved the equation. Oddly, they didn’t find the same clear effect with easier addition equations.
(Source: spectrum.ieee.org)
Brain-damaged man ‘aware’ of scientists’ questions
A crash victim thought to have been in a vegetative state for more than a decade has used the power of thought to tell scientists he is not in pain.
Canadian Scott Routley, from London, Ontario, communicated with researchers via a brain scan, proving that he is conscious and aware. It is the first time such a severely brain-damaged patient has been able to provide clinically relevant information to doctors.
British neuroscientist Professor Adrian Owen, who leads the research team at the Brain and Mind Institute of Western Ontario, said: “Scott has been able to show he has a conscious, thinking mind. We have scanned him several times and his pattern of brain activity shows he is clearly choosing to answer our questions. We believe he knows who and where he is.”
Prof Owen was speaking on a BBC Panorama programme to be broadcast on Tuesday night.
Early stress may sensitize girls’ brains for later anxiety
High levels of family stress in infancy are linked to differences in everyday brain function and anxiety in teenage girls, according to new results of a long-running population study by University of Wisconsin-Madison scientists.
The study highlights evidence for a developmental pathway through which early life stress may drive these changes. Here, babies who lived in homes with stressed mothers were more likely to grow into preschoolers with higher levels of cortisol, a stress hormone. In addition, these girls with higher cortisol also showed less communication between brain areas associated with emotion regulation 14 years later. Last, both high cortisol and differences in brain activity predicted higher levels of adolescent anxiety at age 18.
The young men in the study did not show any of these patterns.
"We wanted to understand how stress early in life impacts patterns of brain development which might lead to anxiety and depression,” says first author Dr. Cory Burghy of the Waisman Laboratory for Brain Imaging and Behavior. "Young girls who, as preschoolers, had heightened cortisol levels, go on to show lower brain connectivity in important neural pathways for emotion regulation — and that predicts symptoms of anxiety during adolescence."
To test this, scans designed by Dr. Rasmus Birn, assistant professor of psychiatry in the UW School of Medicine and Public Health, showed that teenage girls whose mothers reported high levels of family stress when the girls were babies show reduced connections between the amygdala or threat center of the brain and the ventromedial prefrontal cortex, a part of the brain responsible for emotional regulation. Birn used a method called resting-state functional connectivity (fcMRI), which looks at the brain connections while the brain is at a resting state.
The study was published in Nature Neuroscience.
Schizophrenia Genetic Networks Identified; Connection to Autism Found
Although schizophrenia is highly genetic in origin, the genes involved in the disorder have been difficult to identify. In the past few years, researchers have implicated several genes, but it is unclear how they act to produce the disorder. A new study by researchers at Columbia University Medical Center identifies affected gene networks and provides insight into the molecular causes of the disease.
The paper was published in the online edition of the journal Nature Neuroscience.
Using an unbiased collection of hundreds of mutations associated with schizophrenia, the Columbia researchers applied a sophisticated computational approach to uncover hidden relationships among seemingly unrelated genes. The analysis revealed that many of the genes mutated in schizophrenia are organized into two main networks, which take part in a few key processes, including axon guidance, synapse function, neuron mobility, and chromosomal modification.
The study also uncovered an intriguing connection between schizophrenia and autism. “If we hadn’t known that these were two different diseases, and had put all the mutations into a single analysis, it would have come up with very similar networks,” said the study’s senior author, Dennis Vitkup, PhD, associate professor in the Department of Biomedical Informatics, the Center for Computational Biology and Bioinformatics, and the Columbia Initiative in Systems Biology at Columbia University Medical Center. “It shows how closely the autism and schizophrenia genetic networks are intertwined,” he added.