Posts tagged psychology
Articles and news from the latest research reports.
Genetic analysis reveals insights into the genetic architecture of OCD, Tourette syndrome
An international research consortium led by investigators at Massachusetts General Hospital (MGH) and the University of Chicago has answered several questions about the genetic background of obsessive-compulsive disorder (OCD) and Tourette syndrome (TS), providing the first direct confirmation that both are highly heritable and also revealing major differences between the underlying genetic makeup of the disorders. Their report is being published in the October issue of the open-access journal PLOS Genetics.
"Both TS and OCD appear to have a genetic architecture of many different genes – perhaps hundreds in each person – acting in concert to cause disease,” says Jeremiah Scharf, MD, PhD, of the Psychiatric and Neurodevelopmental Genetics Unit in the MGH Departments of Psychiatry and Neurology, senior corresponding author of the report. “By directly comparing and contrasting both disorders, we found that OCD heritability appears to be concentrated in particular chromosomes – particularly chromosome 15 – while TS heritability is spread across many different chromosomes.”
An anxiety disorder characterized by obsessions and compulsions that disrupt the lives of patients, OCD is the fourth most common psychiatric illness. TS is a chronic disorder characterized by motor and vocal tics that usually begins in childhood and is often accompanied by conditions like OCD or attention-deficit hyperactivity disorder. Both conditions have been considered to be heritable, since they are known to often recur in close relatives of affected individuals, but identifying specific genes that confer risk has been challenging.
Two reports published last year in the journal Molecular Psychiatry (1, 2), with leadership from Scharf and several co-authors of the current study, described genome-wide association studies (GWAS) of thousands of affected individuals and controls. While those studies identified several gene variants that appeared to increase the risk of each disorder, none of the associations were strong enough to meet the strict standards of genome-wide significance. Since the GWAS approach is designed to identify relatively common gene variants and it has been proposed that OCD and TS might be influenced by a number of rare variants, the research team adopted a different method. Called genome-wide complex trait analysis (GCTA), the approach allows simultaneous comparision of genetic variation across the entire genome, rather than the GWAS method of testing sites one at a time, as well as estimating the proportion of disease heritability caused by rare and common variants.
"Trying to find a single causative gene for diseases with a complex genetic background is like looking for the proverbial needle in a haystack,” says Lea Davis, PhD, of the section of Genetic Medicine at the University of Chicago, co-corresponding author of the PLOS Genetics report. “With this approach, we aren’t looking for individual genes. By examining the properties of all genes that could contribute to TS or OCD at once, we’re actually testing the whole haystack and asking where we’re more likely to find the needles.”
Using GCTA, the researchers analyzed the same genetic datasets screened in the Molecular Psychiatry reports – almost 1,500 individuals affected with OCD compared with more than 5,500 controls, and nearly TS 1,500 patients compared with more than 5,200 controls. To minimize variations that might result from slight difference in experimental techniques, all genotyping was done by collaborators at the Broad Institute of Harvard and MIT, who generated the data at the same time using the same equipment. Davis was able to analyze the resulting data on a chromosome-by-chromosome basis, along with the frequency of the identified variants and the function of variants associated with each condition.
The results found that the degree of heritability for both disorders captured by GWAS variants is actually quite close to what previously was predicted based on studies of families impacted by the disorders. “This is a crucial point for genetic researchers, as there has been a lot of controversy in human genetics about what is called ‘missing heritability’,” explains Scharf. “For many diseases, definitive genome-wide significant variants account for only a minute fraction of overall heritability, raising questions about the validity of the approach. Our findings demonstrate that the vast majority of genetic susceptibility to TS and OCD can be discovered using GWAS methods. In fact, the degree of heritability captured by GWAS variants is higher for TS and OCD than for any other complex trait studied to date.”
Nancy Cox, PhD, section chief of Genetic Medicine at the University of Chicago and co-senior author of the PLOS Genetics report, adds, “Despite the fact that we confirm there is shared genetic liability between these two disorders, we also show there are notable differences in the types of genetic variants that contribute to risk. TS appears to derive about 20 percent of genetic susceptibility from rare variants, while OCD appears to derive all of its susceptibility from variants that are quite common, which is something that has not been seen before.”
In terms of the potential impact of the risk-associated variants, about half the risk for both disorders appears to be accounted for by variants already known to influence the expression of genes in the brain. Further investigation of those findings could lead to identification of the affected genes and how the expression changes contribute to the development of TS and OCD. Additional studies in even larger patient populations, some of which are in the planning stages, could identify the biologic pathways disrupted in the disorder, potentially leading to new therapeutic approaches.
(Source: medicalxpress.com)
![Theatre offers promise for youth with autism
A novel autism intervention program using theatre to teach reciprocal communication skills is improving social deficits in adolescents with the disorder that now affects an estimated one in 88 children, Vanderbilt University researchers released today in the journal Autism Research.
The newly released study assessed the effectiveness of a two-week theatre camp on children with autism spectrum disorder and found significant improvements were made in social perception, social cognition and home living skills by the end of the camp. There were also positive changes in the participants’ physiological stress and reductions in self-reported parental stress.
Called SENSE Theatre, the Social Emotional Neuroscience & Endocrinology (SENSE) program evaluates the social functioning of children with autism and related neurodevelopmental disorders.
Camp participants ages 8 to 17 years join with typically developing peers who are specially trained to serve as models for social interaction and communication, skills that are difficult for children with autism. The camp uses techniques such as role-play and improvisation and culminates in public performances of a play.
“The findings show that treatment can be delivered in an unconventional setting, and children with autism can learn from unconventional ‘interventionists’ – their typically developing peer,” said lead author Blythe Corbett, Ph.D., associate professor of Psychiatry.
Social perception and interaction skills were measured before and after the camp using neuropsychological measures, play with peers and parental reporting. Significant differences were found in face processing, social awareness and social cognition, and duration of interaction with familiar peers increased significantly over the course of the camp.
Additionally, the stress hormone cortisol was measured through saliva samples taken both at home and throughout the camp to compare the stress level of participants at home, at the beginning of the camp and at the end of the camp. Cortisol levels rose on the first day of camp when compared to home values but declined by the end of treatment and during post-treatment play with peers.
“Our findings show that the SENSE Theatre program contributes to improvement in core social deficits when engaging with peers both on and off the stage,” Corbett said. “This research also shows it’s never too late to make a significant difference in the lives of children and youth with autism spectrum disorder, as [this program] targets children who are much older than kids who are participating in early intervention, yet we are still seeing significant gains in the core deficits of autism, and in a rather brief intervention.”
This research was supported by the Martin McCoy-Jesperson Discovery Grant in Positive Psychology and a grant from the National Institute of Mental Health (Grant No. R01 MH085717).
Corbett will continue using theatre techniques to study areas of social functioning among children with autism through a newly awarded grant from the National Institute of Mental Health (Grant No. R34 MH097793). This forthcoming study will explore treatment length and peer familiarity as factors in optimizing and generalizing gains and will enroll more than 30 youth with autism ages 8 to 16 in a 10-week program model beginning January 2014.](http://40.media.tumblr.com/e2806bc80e70035b0238e7cff1782340/tumblr_mv4dx03Ixr1rog5d1o1_500.jpg)
Theatre offers promise for youth with autism
A novel autism intervention program using theatre to teach reciprocal communication skills is improving social deficits in adolescents with the disorder that now affects an estimated one in 88 children, Vanderbilt University researchers released today in the journal Autism Research.
The newly released study assessed the effectiveness of a two-week theatre camp on children with autism spectrum disorder and found significant improvements were made in social perception, social cognition and home living skills by the end of the camp. There were also positive changes in the participants’ physiological stress and reductions in self-reported parental stress.
Called SENSE Theatre, the Social Emotional Neuroscience & Endocrinology (SENSE) program evaluates the social functioning of children with autism and related neurodevelopmental disorders.
Camp participants ages 8 to 17 years join with typically developing peers who are specially trained to serve as models for social interaction and communication, skills that are difficult for children with autism. The camp uses techniques such as role-play and improvisation and culminates in public performances of a play.
“The findings show that treatment can be delivered in an unconventional setting, and children with autism can learn from unconventional ‘interventionists’ – their typically developing peer,” said lead author Blythe Corbett, Ph.D., associate professor of Psychiatry.
Social perception and interaction skills were measured before and after the camp using neuropsychological measures, play with peers and parental reporting. Significant differences were found in face processing, social awareness and social cognition, and duration of interaction with familiar peers increased significantly over the course of the camp.
Additionally, the stress hormone cortisol was measured through saliva samples taken both at home and throughout the camp to compare the stress level of participants at home, at the beginning of the camp and at the end of the camp. Cortisol levels rose on the first day of camp when compared to home values but declined by the end of treatment and during post-treatment play with peers.
“Our findings show that the SENSE Theatre program contributes to improvement in core social deficits when engaging with peers both on and off the stage,” Corbett said. “This research also shows it’s never too late to make a significant difference in the lives of children and youth with autism spectrum disorder, as [this program] targets children who are much older than kids who are participating in early intervention, yet we are still seeing significant gains in the core deficits of autism, and in a rather brief intervention.”
This research was supported by the Martin McCoy-Jesperson Discovery Grant in Positive Psychology and a grant from the National Institute of Mental Health (Grant No. R01 MH085717).
Corbett will continue using theatre techniques to study areas of social functioning among children with autism through a newly awarded grant from the National Institute of Mental Health (Grant No. R34 MH097793). This forthcoming study will explore treatment length and peer familiarity as factors in optimizing and generalizing gains and will enroll more than 30 youth with autism ages 8 to 16 in a 10-week program model beginning January 2014.
Baby’s Innate Number Sense Predicts Future Math Skill
Innate ability to identify quantities previews future mathematics performance
Babies who are good at telling the difference between large and small groups of items even before learning how to count are more likely to do better with numbers in the future, according to new research from the Duke Institute for Brain Sciences.
The use of Arabic numerals to represent different values is a characteristic unique to humans, not seen outside our species. But we aren’t born with this skill. Infants don’t have the words to count to 10. So, scientists have hypothesized that the rudimentary sense of numbers in infants is the foundation for higher-level math understanding.
A new study, appearing online in the Oct. 21 Proceedings of the National Academy of Sciences, suggests that children do, in fact, tap into this innate numerical ability when learning symbolic mathematical systems. The Duke researchers found that the strength of an infant’s inborn number sense can be predictive of the child’s future mathematical abilities.
"When children are acquiring the symbolic system for representing numbers and learning about math in school, they’re tapping into this primitive number sense," said Elizabeth Brannon, Ph.D., a professor of psychology and neuroscience, who led the study. "It’s the conceptual building block upon which mathematical ability is built."
Brannon explained that babies come into the world with a rudimentary understanding referred to as a primitive number sense. When looking at two collections of objects, primitive number sense allows them to identify which set is numerically larger even without verbal counting or using Arabic numerals. For example, a person instinctively knows a group of 15 strawberries is more than six oranges, just by glancing.
Understanding how infants and young children conceptualize and understand number can lead to the development of new mathematics education strategies, said Brannon’s colleague, Duke psychology and neuroscience graduate student Ariel Starr. In particular, this knowledge can be used to design interventions for young children who have trouble learning mathematics symbols and basic methodologies.
To test for primitive number sense, Brannon and Starr analyzed 48 6-month-old infants to see whether they could recognize numerical changes, capitalizing on the interest most babies show in things that change. They placed each baby in front of two screens, one that always showed the same number of dots (e.g., eight), changing in size and position, and another that switched between two different numerical values (e.g., eight and 16 dots). All the arrays of dots changed frequently in size and position. In this task, babies that could tell the difference between the two numerical values (e.g., eight and 16) looked longer at the numerically changing screen.
Brannon and Starr then tested the same children at 3.5 years of age with a non-symbolic number comparison game. The children were shown two different arrays and asked to choose which one had more dots without counting them. In addition, the children took a standardized math test scaled for pre-schoolers, as well as a standardized IQ test. Finally, the researchers gave the children a simple verbal task to identify the largest number word each child could concretely understand.
"We found that infants with higher preference scores for looking at the numerically changing screen had better primitive number sense three years later compared to those infants with lower scores," Starr said. "Likewise, children with higher scores in infancy performed better on standardized math tests."
Brannon said the findings point to a real connection between symbolic math and quantitative abilities that are present in infancy before education takes hold and shapes our mathematical abilities.
"Our study shows that infant number sense is a predictor of symbolic math," Brannon said. "We believe that when children learn the meaning of number words and symbols, they’re likely mapping those meanings onto pre-verbal representations of number that they already have in infancy," she said.
"We can’t measure a baby’s number sense ability at 6 months and know how they’ll do on their SATs," Brannon added. "In fact our infant task only explains a small percentage of the variance in young children"s math performance. But our findings suggest that there is cognitive overlap between primitive number sense and symbolic math. These are fundamental building blocks."
(Source: today.duke.edu)
Learning New Skills Keeps an Aging Mind Sharp
Older adults are often encouraged to stay active and engaged to keep their minds sharp, that they have to “use it or lose it.” But new research indicates that only certain activities — learning a mentally demanding skill like photography, for instance — are likely to improve cognitive functioning.
These findings, forthcoming in Psychological Science, a journal of the Association for Psychological Science, reveal that less demanding activities, such as listening to classical music or completing word puzzles, probably won’t bring noticeable benefits to an aging mind.
“It seems it is not enough just to get out and do something—it is important to get out and do something that is unfamiliar and mentally challenging, and that provides broad stimulation mentally and socially,” says psychological scientist and lead researcher Denise Park of the University of Texas at Dallas. “When you are inside your comfort zone you may be outside of the enhancement zone.”
The new findings provide much-needed insight into the components of everyday activities that contribute to cognitive vitality as we age.
“We need, as a society, to learn how to maintain a healthy mind, just like we know how to maintain vascular health with diet and exercise,” says Park. “We know so little right now.”
For their study, Park and colleagues randomly assigned 221 adults, ages 60 to 90, to engage in a particular type of activity for 15 hours a week over the course of three months.
Some participants were assigned to learn a new skill — digital photography, quilting, or both — which required active engagement and tapped working memory, long-term memory and other high-level cognitive processes.
Other participants were instructed to engage in more familiar activities at home, such as listening to classical music and completing word puzzles. And, to account for the possible influence of social contact, some participants were assigned to a social group that included social interactions, field trips, and entertainment.
At the end of three months, Park and colleagues found that the adults who were productively engaged in learning new skills showed improvements in memory compared to those who engaged in social activities or non-demanding mental activities at home.
“The findings suggest that engagement alone is not enough,” says Park. “The three learning groups were pushed very hard to keep learning more and mastering more tasks and skills. Only the groups that were confronted with continuous and prolonged mental challenge improved.”
The study is particularly noteworthy given that the researchers were able to systematically intervene in people’s lives, putting them in new environments and providing them with skills and relationships:
“Our participants essentially agreed to be assigned randomly to different lifestyles for three months so that we could compare how different social and learning environments affected the mind,” says Park. “People built relationships and learned new skills — we hope these are gifts that keep on giving, and continue to be a source of engagement and stimulation even after they finished the study.”
Park and colleagues are planning on following up with the participants one year and five years down the road to see if the effects remain over the long term. They believe that the research has the potential to be profoundly important and relevant, especially as the number of seniors continues to rise:
“This is speculation, but what if challenging mental activity slows the rate at which the brain ages?” asks Park. “Every year that you save could be an added year of high quality life and independence.”
How Subtle Movements and Facial Features Could Predict Your Demise
Princeton study shows that health assessments made by medically untrained interviewers can predict mortality of individuals better than those made by physicians or the individuals themselves
Features like the wrinkles on your forehead and the way you move may reflect your overall health and risk of dying, according to recent health research. But do physicians consider such details when assessing patients’ overall health and functioning?
In a survey of approximately 1,200 Taiwanese participants, Princeton University researchers found that interviewers — who were not health professionals but were trained to administer the survey — provided health assessments that were related to a survey participant’s risk of dying, in part because they were attuned to facial expressions, responsiveness and overall agility.
The researchers report in the journal Epidemiology that these assessments were even more accurate predictors of dying than assessments made by physicians or even the individuals themselves. The findings show that survey interviewers, who typically spend a fair amount of time observing participants, can glean important information regarding participants’ health through thorough observations.
"Your face and body reveal a lot about your life. We speculate that a lot of information about a person’s health is reflected in their face, movements, speech and functioning, as well as in the information explicitly collected during interviews," said Noreen Goldman, Hughes-Rogers Professor of Demography and Public Affairs in the Woodrow Wilson School.
Together with lead author of the paper and Princeton Ph.D. candidate Megan Todd, Goldman analyzed data collected by the Social Environment and Biomarkers of Aging Study (SEBAS). This study was designed by Goldman and co-investigator Maxine Weinstein at Georgetown University to evaluate the linkages among the social environment, stress and health. Beginning in 2000, SEBAS conducted extensive home interviews, collected biological specimens and administered medical examinations with middle-aged and older adults in Taiwan. Goldman and Todd used the 2006 wave of this study, which included both interviewer and physician assessments, for their analysis. They also included death registration data through 2011 to ascertain the survival status of those interviewed.
The survey used in the study included detailed questions regarding participants’ health conditions and social environment. Participants’ physical functioning was evaluated through tasks that determined, for example, their walking speed and grip strength. Health assessments were elicited from participants, interviewers and physicians on identical five-point scales by asking “Regarding your/the respondent’s current state of health, do you feel it is excellent (5), good (4), average (3), not so good (2) or poor (1)?”
Participants answered this question near the beginning of the interview, before other health questions were asked. Interviewers assessed the participants’ health at the end of the survey, after administering the questionnaire and evaluating participants’ performance on a set of tasks, such as walking a short distance and getting up and down from a chair. And physicians — who were hired by the study and were not the participants’ primary care physicians — provided their assessments after physical exams and reviews of the participants’ medical histories. (Study investigators did not provide special guidance about how to rate overall health to any group.)
In order to understand the many variables that go into predicting mortality, Goldman and Todd factored into their statistical models such socio-demographic variables as sex, place of residence, education, marital status, and participation in social activities. They also considered chronic conditions, psychological wellbeing (such as depressive symptoms) and physical functioning to account for a fuller picture of health.
"Mortality is easy to measure because we have death records indicating when a person has died," Goldman said. "Overall health, on the other hand, is very complicated to measure but obviously very important for addressing health policy issues."
Two unexpected results emerged from Goldman and Todd’s analysis. The first: physicians’ ratings proved to be weak predictors of survival. “The physicians performed a medical exam equivalent to an annual physical exam, plus an abdominal ultrasound; they have specialized knowledge regarding health conditions,” Goldman explained. “Given access to such information, we anticipated stronger, more accurate predictions of death,” she said. “These results call into question previous studies’ assumptions that physicians’ ‘objective health’ ratings are superior to ‘subjective’ ratings provided by the survey participants themselves.”
In a second surprising finding, the team found that interviewers’ ratings were considerably more powerful for predicting mortality than self-ratings. This is likely, Goldman said, because interviewers considered respondents’ movements, appearance and responsiveness in addition to the detailed health information gathered during the interviews. Also, Goldman posits, interviewer ratings are probably less affected by bias than self-reports.
"The ‘self-rated health’ question is religiously used by health researchers and social scientists, and, although it has been shown to predict mortality, it suffers from many biases. People use it because it’s easy and simple,” Goldman continued. "But the problem with self-rated health is that we have no idea what reference group the respondent is using when evaluating his or her own health. Different ethnic and racial groups respond differently as do varying socioeconomic groups. We need other simple ways to rate individual health instead of relying so heavily on self-rated health."
One way, Goldman suggests, is by including interviewer ratings in surveys along with self-ratings: “This is a straightforward and cost-free addition to a questionnaire that is likely to improve our measurement of health in any population,” Goldman said.
(Source: wws.princeton.edu)
Psychologists report new insights on human brain, consciousness
UCLA psychologists have used brain-imaging techniques to study what happens to the human brain when it slips into unconsciousness. Their research, published Oct. 17 in the online journal PLOS Computational Biology, is an initial step toward developing a scientific definition of consciousness.
"In terms of brain function, the difference between being conscious and unconscious is a bit like the difference between driving from Los Angeles to New York in a straight line versus having to cover the same route hopping on and off several buses that force you to take a ‘zig-zag’ route and stop in several places," said lead study author Martin Monti, an assistant professor of psychology and neurosurgery at UCLA.
Monti and his colleagues used functional magnetic resonance imaging (fMRI) to study how the flow of information in the brains of 12 healthy volunteers changed as they lost consciousness under anesthesia with propofol. The participants ranged in age from 18 to 31 and were evenly divided between men and women.
The psychologists analyzed the “network properties” of the subjects’ brains using a branch of mathematics known as graph theory, which is often used to study air-traffic patterns, information on the Internet and social groups, among other topics.
"It turns out that when we lose consciousness, the communication among areas of the brain becomes extremely inefficient, as if suddenly each area of the brain became very distant from every other, making it difficult for information to travel from one place to another," Monti said.
The finding shows that consciousness does not “live” in a particular place in our brain but rather “arises from the mode in which billions of neurons communicate with one another,” he said.
When patients suffer severe brain damage and enter a coma or a vegetative state, Monti said, it is very possible that the sustained damage impairs their normal brain function and the emergence of consciousness in the same manner as was seen by the life scientists in the healthy volunteers under anesthesia.
"If this were indeed the case, we could imagine in the future using our technique to monitor whether interventions are helping patients recover consciousness," he said.
"It could, however, also be the case that losing consciousness because of brain injury affects brain function through different mechanisms," said Monti, whose research team is currently addressing this question in another study.
"As profoundly defining of our mind as consciousness is, without having a scientific definition of this phenomenon, it is extremely difficult to study," Monti noted. This study, he said, marks an initial step toward conducting neuroscience research on consciousness.
The research was conducted at Belgium’s University Hospital of Liege.
Monti’s expertise includes cognitive neuroscience, the relationship between language and thought, and how consciousness is lost and recovered after severe brain injury. He was part of a team of American and Israeli brain scientists who used fMRI on former Israeli Prime Minister Ariel Sharon in January 2013 to assess his brain responses.
Surprisingly, Sharon, who was presumed to be in a vegetative state since suffering a brain hemorrhage in 2006, showed significant brain activity, Monti and his colleagues reported.
The former prime minister was scanned to assess the extent and quality of his brain processing, using methods recently developed by Monti and his colleagues. The scientists found subtle but encouraging signs of consciousness.
Depression twice as likely in migraine sufferers
The prevalence of depression among those with migraine is approximately twice as high as for those without the disease (men: 8.4% vs. 3.4%; women 12.4% vs. 5.7%), according to a new study published by University of Toronto researchers.
In a paper published online this week in the journal Depression Research and Treatment, investigators reported that younger migraine sufferers were particularly at risk for depression. Women with migraines who were younger than 30 had six times the odds of depression in comparison to sufferers who were aged 65 and over, said lead author, Professor Esme Fuller-Thomson, Sandra Rotman Endowed Chair at the University of Toronto’s Factor-Inwentash Faculty of Social Work. Unmarried individuals and migraine sufferers who had difficulties with daily activities also had high odds of depression.
Data drawn from a representative sample of more than 67,000 Canadians, the 2005 Canadian Community Health Survey, were used to examine gender-specific associations between migraine and depression. More than 6,000 respondents reported that they had been diagnosed by a health professional with migraines. Consistent with prior research, the prevalence of migraines was much higher in women than men, with one in every seven women, compared to one in every 16 men, reporting that they had migraines.
The study also investigated the relationship between migraine and suicidal ideation. For both men and women, those with migraines were much more likely to have “ever seriously considered suicide or taking (their) own life” than were those without migraines (men: 15.6% versus 7.9%; women: 17.6% versus 9.1%). Migraineurs under age 30 had four times the odds of lifetime suicidal ideation in comparison to migraineurs aged 65 and over. Other factors associated with suicidal ideation among those with migraines included unmarried status, lower household income and greater activity limitations.
Co-author and former graduate student Meghan Schrumm commented “We are not sure why younger migraineurs have such a high likelihood of depression and suicidal ideation. It may be that younger people with migraines have not yet managed to find adequate treatment or develop coping mechanisms to minimize pain and the impact of this chronic illness on the rest of their lives. The much lower prevalence of depression and suicidal ideation among older migraineurs suggests a promising area for future research.”
Dr. Fuller-Thomson adds that this study “draws further attention to the need for routine screening and targeted interventions for depression and suicidality, particularly among the most vulnerable migraineurs: Individuals who are young, unmarried and those with activity limitations.”
(Image: Shutterstock)
Researcher Reveals the Brain Connections Underlying Accurate Introspection
The human mind is not only capable of cognition and registering experiences but also of being introspectively aware of these processes. Until now, scientists have not known if such introspection was a single skill or dependent on the object of reflection. Also unclear was whether the brain housed a single system for reflecting on experience or required multiple systems to support different types of introspection.
A new study by UC Santa Barbara graduate student Benjamin Baird and colleagues suggest that the ability to accurately reflect on perceptual experience and the ability to accurately reflect on memories were uncorrelated, suggesting that they are distinct introspective skills. The findings appear in the Journal of Neuroscience.
The researchers used classic perceptual decision and memory retrieval tasks in tandem with functional magnetic resonance imaging to determine connectivity to regions in the front tip of the brain, commonly referred to as the anterior prefrontal cortex. The study tested a person’s ability to reflect on his or her perception and memory and then examined how individual variation in each of these capacities was linked to the functional connections of the medial and lateral parts of the anterior prefrontal cortex.
"Our results suggest that metacognitive or introspective ability may not be a single thing," Baird said. "We actually find a behavioral dissociation between the two metacognitive abilities across people, which suggests that you can be good at reflecting on your memory but poor at reflecting on your perception, or vice versa."
The newly published research adds to the literature describing the role of the medial and lateral areas of the anterior prefrontal cortex in metacognition and suggests that specific subdivisions of this area may support specific types of introspection. The findings of Baird’s team demonstrate that the ability to accurately reflect on perception is associated with enhanced connectivity between the lateral region of the anterior prefrontal cortex and the anterior cingulate, a region involved in coding uncertainty and errors of performance.
In contrast, the ability to accurately reflect on memory is linked to enhanced connectivity between the medial anterior prefrontal cortex and two areas of the brain: the precuneus and the lateral parietal cortex, regions prior work has shown to be involved in coding information pertaining to memories.
The experiment assessed the metacognitive abilities of 60 participants at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, where Baird was a visiting researcher. The perceptual decision task consisted of visual displays with six circles of vertical alternating light and dark bars –– called Gabor gratings –– arranged around a focal point. Participants were asked to identify whether the first or second display featured one of the six areas with a slight tilt, not always an easy determination to make.
A classic in psychology literature, the memory retrieval task consisted of two parts. First, participants were shown a list of 145 words. They were then shown a second set of words and asked to distinguish those they had seen previously. After each stimulus in both the perceptual decision and the memory retrieval task, participants rated their confidence in the accuracy of their responses on a scale of 1 (low confidence) to 6 (high confidence).
"Part of the novelty of this study is that it is the first to examine how connections between different regions of the brain support metacognitive processes," Baird said. "Also, prior means of computing metacognitive accuracy have been shown to be confounded by all kinds of things, like how well you do the primary task or your inherent bias toward high or low confidence.
"Using these precise measures, we’re now beginning to drill down and see how different types of introspection are actually housed in the real human brain," Baird concluded. "So it’s pretty fascinating from that perspective."
Schizophrenia linked to abnormal brain waves
Neuroscientists discover neurological hyperactivity that produces disordered thinking
Schizophrenia patients usually suffer from a breakdown of organized thought, often accompanied by delusions or hallucinations. For the first time, MIT neuroscientists have observed the neural activity that appears to produce this disordered thinking.
The researchers found that mice lacking the brain protein calcineurin have hyperactive brain-wave oscillations in the hippocampus while resting, and are unable to mentally replay a route they have just run, as normal mice do.
Mutations in the gene for calcineurin have previously been found in some schizophrenia patients. Ten years ago, MIT researchers led by Susumu Tonegawa, the Picower Professor of Biology and Neuroscience, created mice lacking the gene for calcineurin in the forebrain; these mice displayed several behavioral symptoms of schizophrenia, including impaired short-term memory, attention deficits, and abnormal social behavior.
In the new study, which appears in the Oct. 16 issue of the journal Neuron, Tonegawa and colleagues at the RIKEN-MIT Center for Neural Circuit Genetics at MIT’s Picower Institute for Learning and Memory recorded the electrical activity of individual neurons in the hippocampus of these knockout mice as they ran along a track.
Previous studies have shown that in normal mice, “place cells” in the hippocampus, which are linked to specific locations along the track, fire in sequence when the mice take breaks from running the course. This mental replay also occurs when the mice are sleeping. These replays occur in association with very high frequency brain-wave oscillations known as ripple events.
In mice lacking calcineurin, the researchers found that brain activity was normal as the mice ran the course, but when they paused, their ripple events were much stronger and more frequent. Furthermore, the firing of the place cells was abnormally augmented and in no particular order, indicating that the mice were not replaying the route they had just run.
This pattern helps to explain some of the symptoms seen in schizophrenia, the researchers say.
“We think that in this mouse model, we may have some kind of indication that there’s a disorganized thinking process going on,” says Junghyup Suh, a research scientist at the Picower Institute and one of the paper’s lead authors. “During ripple events in normal mice we know there is a sequential replay event. This mutant mouse doesn’t seem to have that kind of replay of a previous experience.”
The paper’s other lead author is David Foster, a former MIT postdoc. Other authors are Heydar Davoudi and Matthew Wilson, the Sherman Fairchild Professor of Neuroscience at MIT and a member of the Picower Institute.
The researchers speculate that in normal mice, the role of calcineurin is to suppress the connections between neurons, known as synapses, in the hippocampus. In mice without calcineurin, a phenomenon known as long-term potentiation (LTP) becomes more prevalent, making synapses stronger. Also, the opposite effect, known as long-term depression (LTD), is suppressed.
“It looks like this abnormally high LTP has an impact on activity of these cells specifically during resting periods, or post exploration periods. That’s a very interesting specificity,” Tonegawa says. “We don’t know why it’s so specific.”
The researchers believe the abnormal hyperactivity they found in the hippocampus may represent a disruption of the brain’s “default mode network” — a communication network that connects the hippocampus, prefrontal cortex (where most thought and planning occurs), and other parts of the cortex.
This network is more active when a person (or mouse) is resting between goal-oriented tasks. When the brain is focusing on a specific goal or activity, the default mode network gets turned down. However, this network is hyperactive in schizophrenic patients before and during tasks that require the brain to focus, and patients do not perform well in these tasks.
Further studies of these mice could help reveal more about the role of the default mode network in schizophrenia, Tonegawa says.
Individuals Genetically Predisposed to Anxiousness May Be Less Likely to Volunteer and Help Others
Scientists increasingly are uncovering answers for human behavior through genetic research. Now, a University of Missouri researcher has found that prosocial behavior, such as volunteering and helping others, is related to the same gene that predisposes individuals to anxiety disorders. Helping such individuals cope with their anxiety may increase their prosocial behavior, the researcher said.
“Prosocial behavior is linked closely to strong social skills and is considered a marker of individuals’ health and well-being,” said Gustavo Carlo, Millsap Professor of Diversity in MU’s College of Human Environmental Sciences. “Social people are more likely to be healthier, excel academically, experience career success and develop deeper interpersonal relationships that may help alleviate stress.”
Carlo and his colleagues found that, on average, those individuals who carried the genotype associated with higher social anxiety were less likely to engage in prosocial behavior.
“Previous research has shown that the brain’s serotonin neurotransmitter system plays an important role in regulating emotions,” said study co-author Scott Stoltenberg, an associate professor at the University of Nebraska-Lincoln. “Our findings suggest that individual differences in social anxiety levels are influenced by this serotonin system gene and that these differences help to partially explain why some people are more likely than others to behave prosocially. Studies like this one show that biological factors are critical influences on how people interact with one another.”
Because prosocial behavior is linked to genetically based anxiety, Carlo suggests that helping nervous individuals cope with their social anxiety through targeted efforts, such as encouragement, support, counseling and medication, could help them engage in more prosocial behavior.
“Some forms of anxieties can be very debilitating for individuals,” Carlo said. “When people have severe levels of social anxiety, such as agoraphobia, which is the fear of public places and large crowds, they will avoid social situations altogether and miss the prosocial opportunities.”
Carlo said that it is difficult to distinguish how much of prosocial behavior is based on learned environmental behavior and how much is biologically based.
“The nature-versus-nurture debate is always interesting,” Carlo said. “However, I think that in our contemporary models of human behavior, we are beginning to understand the interplay between biology and the environment.”
Much of Carlo’s previous study on prosocial development has focused on how environmental influences, such as family relationships, influence prosocial behavior. This study brings researchers closer to understanding the effect that individuals’ biological makeup has on their behaviors, Carlo said.