Category: Intelligence

You can thank your parents for your smarts — or at least some of them. Psychologists have long known that intelligence, like most other traits, is partly genetic. But a new study led by psychological scientist Christopher Chabris of Union College reveals the surprising fact that most of the specific genes long thought to be linked to intelligence probably have no bearing on one's IQ. And it may be some time before researchers can identify intelligence's specific genetic roots.

Chabris and David Laibson, a Harvard economist, led an international team of researchers that analyzed a dozen genes using large data sets that included both intelligence testing and genetic data.

In nearly every case, the researchers found that intelligence could not be linked to the specific genes that were tested. The results are published online in Psychological Science, a journal of the Association for Psychological Science.

"In all of our tests we only found one gene that appeared to be associated with intelligence, and it was a very small effect. This does not mean intelligence does not have a genetic component. It means it's a lot harder to find the particular genes, or the particular genetic variants, that influence the differences in intelligence," said Chabris.

It had long been believed, on the basis of studies of identical and fraternal twins, that intelligence was a heritable trait. The new research affirms that conclusion. But older studies that picked out specific genes had flaws, Chabris said, primarily because of technological limits that prevented researchers from probing more than a few locations in the human genome to find genes that affected intelligence.

"We want to emphasize that we are not saying the people who did earlier research in this area were foolish or wrong," Chabris said. "They were using the best technology and information they had available. At the time, it was believed that individual genes would have a much larger effect — they were expecting to find genes that might each account for several IQ points."

Chabris said additional research is needed to determine the exact role genes play in intelligence.

"As is the case with other traits, like height, there are probably thousands of genes and their variants that are associated with intelligence," he said. "And there may be other genetic effects beyond the single gene effects. There could be interactions among genes, or interactions between genes and the environment. Our results show that the way researchers have been looking for genes that may be related to intelligence — the candidate gene method — is fairly likely to result in false positives, so other methods should be used."

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Journal Reference:

1. C. F. Chabris, B. M. Hebert, D. J. Benjamin, J. Beauchamp, D. Cesarini, M. van der Loos, M. Johannesson, P. K. E. Magnusson, P. Lichtenstein, C. S. Atwood, J. Freese, T. S. Hauser, R. M. Hauser, N. Christakis, D. Laibson. Most Reported Genetic Associations With General Intelligence Are Probably False Positives. Psychological Science, 2012; DOI: 10.1177/0956797611435528

New research suggests that a mother's high blood pressure during pregnancy may have an effect on her child's thinking skills all the way into old age. The study is published in the October 3, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"High blood pressure and related conditions such as preeclampsia complicate about 10 percent of all pregnancies and can affect a baby's environment in the womb," said study author Katri Räikönen, PhD, with the University of Helsinki in Finland. "Our study suggests that even declines in thinking abilities in old age could have originated during the prenatal period when the majority of the development of brain structure and function occurs."

Researchers looked at medical records for the mother's blood pressure in pregnancy for 398 men who were born between 1934 and 1944. The men's thinking abilities were tested at age 20 and then again at an average age of 69. Tests measured language skills, math reasoning and visual and spatial relationships.

The study found that men whose mothers had high blood pressure while pregnant scored 4.36 points lower on thinking ability tests at age 69 compared to men whose mothers did not have high blood pressure. The group also scored lower at the age of 20 and had a greater decline in their scores over the decades than those whose mothers did not have problems with blood pressure. The finding was strongest for math-related reasoning.

The researchers also looked at whether premature birth affected these findings and found no change. Whether the baby's father was a manual laborer or an office worker also did not change the results.

Keeping the lungs healthy could be an important way to retain thinking functions that relate to problem-solving and processing speed in one's later years, new research suggests.

While these two types of "fluid" cognitive functions were influenced by reduced pulmonary function, a drop in lung health did not appear to impair memory or lead to any significant loss of stored knowledge, the study showed.

Researchers used data from a Swedish study of aging that tracked participants' health measures for almost two decades. An analysis of the data with statistical models designed to show the patterns of change over time determined that reduced pulmonary function can lead to cognitive losses, but problems with cognition do not affect lung health.

"The logical conclusion from this is that anything you could do to maintain lung function should be of benefit to fluid cognitive performance as well," said Charles Emery, professor of psychology at Ohio State University and lead author of the study. "Maintaining an exercise routine and stopping smoking would be two primary methods. Nutritional factors and minimizing environmental exposure to pollutants also come into play."

Emery said the analysis also offers insights into the process of human aging. While one theory of aging holds that all functions that slow down do so at the same rate, this study suggests that some aspects of functional decline contribute to a change in the rate of other areas of decline.

"In this case, pulmonary functioning may be contributing to other aspects of functioning," he said. "It starts to speak to the bigger question: What are the processes involved in aging?"

The study is published in the current issue of the journal Psychological Science.

The study sample consisted of 832 participants between ages 50 and 85 who were assessed in up to seven waves of testing across 19 years as part of the Swedish Adoption/Twin Study of Aging. Emery and colleagues used data from pulmonary and cognitive tests conducted in the Swedish study.

Lung function was measured in two ways: forced expiratory volume, or how much air a person can push out of the lungs in one second, and forced vital capacity, the volume of air that is blown out after a deep inhalation.

The Swedish participants also were tested in four cognitive domains that measured verbal abilities associated with stored knowledge, memory, spatial abilities related to problem-solving and processing speed — which included the ability to write correct responses quickly.

The researchers entered the data into structural equation models that allow for interaction between the components being compared — in this case, lung function and cognitive function — as well as the trajectory of the changes over time. These dual-change-score models can be likened to a horse race, Emery said.

"We were looking for effects in both directions. We had previously looked in simpler models and found that pulmonary function did predict cognitive function, but there are some studies that show the opposite direction. It was important for us to go into this with an open mind and use this modeling to test both directions," he said.

This kind of statistical analysis did not quantify the effects, but showed clear trends between a decline in lung function and steeper losses in the two types of "fluid" cognitive function. A small effect was seen on verbal tasks, as well. Pulmonary function change had no influence on memory performance.

The study also showed that changes in cognitive function did not predict lung outcomes.

"In these models the relationship is consistently moving from pulmonary function to cognitive function and not the other way," said Emery, also a professor of internal medicine and an investigator in Ohio State's Institute for Behavioral Medicine Research.

The declines seen in this study are expected with age, he noted. And the elements of cognitive function that were not influenced by lung function — memory and retrieval of stored knowledge — are not typically associated with normal aging.

"We know, for example, that the speed at which people can perform the processing task does decline with age. But now we have data that suggests pulmonary function actually predicts that decline," he said.

Though this study does not explain what a loss of pulmonary function does to the brain, the researchers speculated that reduced lung health could lower the availability of oxygen in the blood that could in turn affect chemicals that transmit signals between brain cells.

Emery conducted the study with co-authors Deborah Finkel of Indiana University Southeast and Nancy Pedersen of the Karolinska Institute and the University of Southern California.

Study reenactment: Evelyn Rose, 4, of Brighton, N.Y. participates in a reenactment of the marshmallow experiment. The study found that children's decisions to delay gratification is influenced as much by the environment as by their innate capacity for self-control. The study was conducted at the University of Rochester Baby Lab. (Credit: J. Adam Fenster / University of Rochester)

 

— For the past four decades, the "marshmallow test" has served as a classic experimental measure of children's self-control: will a preschooler eat one of the fluffy white confections now or hold out for two later?

Now a new study demonstrates that being able to delay gratification is influenced as much by the environment as by innate ability. Children who experienced reliable interactions immediately before the marshmallow task waited on average four times longer — 12 versus three minutes — than youngsters in similar but unreliable situations.

"Our results definitely temper the popular perception that marshmallow-like tasks are very powerful diagnostics for self-control capacity," says Celeste Kidd, a doctoral candidate in brain and cognitive sciences at the University of Rochester and lead author on the study to be published online October 11 in the journal Cognition.

"Being able to delay gratification — in this case to wait 15 difficult minutes to earn a second marshmallow — not only reflects a child's capacity for self-control, it also reflects their belief about the practicality of waiting," says Kidd. "Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay."

The findings provide an important reminder about the complexity of human behavior, adds coauthor Richard Aslin, the William R. Kenan Professor of brain and cognitive sciences at the University. "This study is an example of both nature and nurture playing a role," he says. "We know that to some extent, temperament is clearly inherited, because infants differ in their behaviors from birth. But this experiment provides robust evidence that young children's action are also based on rational decisions about their environment."

The research builds on a long series of marshmallow-related studies that began at Stanford University in the late 1960s. Walter Mischel and other researchers famously showed that individual differences in the ability to delay gratification on this simple task correlated strongly with success in later life. Longer wait times as a child were linked years later to higher SAT scores, less substance abuse, and parental reports of better social skills.

Because of the surprising correlation, the landmark marshmallow studies have been cited as evidence that qualities like self-control or emotional intelligence in general may be more important to navigating life successfully than more traditional measures of intelligence, such as IQ.

The Rochester team wanted to explore more closely why some preschoolers are able to resist the marshmallow while others succumb to licking, nibbling, and eventually swallowing the sugary treat. The researchers assigned 28 three- to five-year-olds to two contrasting environments: unreliable and reliable. The study results were so strong that a larger sample group was not required to ensure statistical accuracy and other factors, like the influence of hunger, were accounted for by randomly assigning participants to the two groups, according to the researchers. In both groups the children were given a create-your-own-cup kit and asked to decorate the blank paper that would be inserted in the cup.

In the unreliable condition, the children were provided a container of used crayons and told that if they could wait, the researcher would return shortly with a bigger and better set of new art supplies for their project. After two and a half minutes, the research returned with this explanation: "I'm sorry, but I made a mistake. We don't have any other art supplies after all. But why don't you use these instead?" She then helped to open the crayon container.

Next a quarter-inch sticker was placed on the table and the child was told that if he or she could wait, the researcher would return with a large selection of better stickers to use. After the same wait, the researcher again returned empty handed.

The reliable group experienced the same set up, but the researcher returned with the promised materials: first with a rotating tray full of art supplies and the next time with five to seven large, die-cut stickers.

The marshmallow task followed, with the explanation that the child could have "one marshmallow right now. Or — if you can wait for me to get more marshmallows from the other room — you can have two marshmallows to eat instead." The researcher removed the art supplies and placed a single marshmallow in a small desert dish four inches from the table's edge directly in front of the child. From an adjoining room, the researchers and the parent observed through a computer video camera until the first taste or 15 minutes had lapsed, whichever came first. All children then received three additional marshmallows.

"Watching their strategies for waiting was quite entertaining," says Holly Palmeri, coauthor and coordinator of the Rochester Baby Lab. Kids danced in their seats, sang, and took pretend naps. Several took a bite from the bottom of the marshmallow then placed it back in the desert cup so it looked untouched. A few then nibbled off the top, forgetting they could then longer hide the evidence since both ends were eaten, she said.

"We had one little boy who grabbed the marshmallow immediately and we thought he was going to eat it," recalled Kidd. Instead he sat on it. "Instead of covering his eyes, he covered the marshmallow."

Children who experienced unreliable interactions with an experimenter waited for a mean time of three minutes and two seconds on the subsequent marshmallow task, while youngsters who experienced reliable interactions held out for 12 minutes and two seconds. Only one of the 14 children in the unreliable group waited the full 15 minutes, compared to nine children in the reliable condition.

"I was astounded that the effect was so large," says Aslin. "I thought that we might get a difference of maybe a minute or so… You don't see effects like this very often."

In prior research, children's wait time averaged between 6.08 and 5.71 minutes, the authors report. By comparison, manipulating the environment doubled wait times in the reliable condition and halved the time in the unreliable scenario. Previous studies that explored the effect of teaching children waiting strategies showed smaller effects, the authors report. Hiding the treat from view boosted wait times by 3.75 minutes, while encouraging children to think about the larger reward added 2.53 minutes.

The robust effect of manipulating the environment, conclude the authors, provides strong evidence that children's wait times reflect rational decision making about the probability of reward. The results are consistent with other research showing that children are sensitive to uncertainly in future rewards and with population studies showing children with absent fathers prefer more immediate rewards over larger but delayed ones.

The findings, says Kidd, are reassuring. She recalls reading about the predictive power of these earlier experiments years ago and finding it "depressing." At the time she was volunteering at a homeless shelter for families in Santa Ana, California. "There were lots of kids staying there with their families. Everyone shared one big area, so keeping personal possessions safe was difficult," she says. "When one child got a toy or treat, there was a real risk of a bigger, faster kid taking it away. I read about these studies and I thought, 'All of these kids would eat the marshmallow right away.' "

But as she observed the children week after week, she began to question the task as a marker of innate ability alone. "If you are used to getting things taken away from you, not waiting is the rational choice. Then it occurred to me that the marshmallow task might be correlated with something else that the child already knows — like having a stable environment."

So does that mean that if little ones gobble up desert without waiting, as is typical of preschoolers, parents should worry that they have failed to be role models of reliability every minute?

Not necessarily, say the researchers. "Children do monitor the behavior of parents and adults, but it is unlikely that they are keeping detailed records of every single action," says Aslin. "It's the overall sense of a parent's reliability or unreliability that's going to get through, not every single action."

Adds Kidd: "Don't do the marshmallow test on your kitchen table and conclude something about your child. It especially would not work with a parent, because your child has all sorts of strong expectations about what a person who loves them very much is likely to do."

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Journal Reference:

1. Celeste Kidd, Holly Palmeri, Richard N. Aslin. Rational snacking: Young children’s decision-making on the marshmallow task is moderated by beliefs about environmental reliability. Cognition, 2012; DOI: 10.1016/j.cognition.2012.08.004

If a 7-year-old is breezing through the "Harry Potter" books, studies indicate that he or she will be a strong reader later in life. Conversely, if a 7-year-old is struggling with "The Cat in the Hat," that child will most likely struggle with reading going forward.

The study findings could eventually influence reading lessons for pre-elementary children, tailoring lesson plans to individual needs.

New research from Stanford shows that brain scans can identify the neural differences between these two children, and could one day lead to an early warning system for struggling students.

The researchers scanned the brain anatomy of 39 children once a year for three consecutive years. The students then took standardized tests to gauge their cognitive, language and reading skills.

In each case, the rate of development (measured by fractional anisotropy, or FA) in the white matter regions of the brain, which are associated with reading, accurately predicted their test scores.

Specifically, children with above-average reading skills exhibit an FA value in two types of nerve bundles — the left hemisphere arcuate fasciculus and the left hemisphere inferior longitudinal fasciculus — that is initially low, but increases over time. Children with lower reading skills initially have a high FA, but it declines over time.

The findings could eventually influence reading lessons for pre-elementary children. Previous studies have shown that a child's reading skills at age 7 can accurately predict reading skills 10 years down the road. A child who is struggling at 7 will most likely be a poor reader at age 17.

"By the time kids reach elementary school, we're not great at finding ways of helping them catch up," said Jason D. Yeatman, a doctoral candidate in psychology at Stanford and the lead author on the study.

The good news: Early screening could reveal which students are at risk; at an early age, the brain is plastic, and genes, environment and experiences can affect FA values.

"Once we have an accurate model relating the maturation of the brain's reading circuitry to children's acquisition of reading skills, and once we understand which factors are beneficial, I really think it will be possible to develop early intervention protocols for children who are poor readers, and tailor individualized lesson plans to emphasize good development," Yeatman said. "Over the next five to 10 years, that's what we're really hoping to do."

The research was published in the current issue of the Proceedings of the National Academy of Science.

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Journal Reference:

1. J. D. Yeatman, R. F. Dougherty, M. Ben-Shachar, B. A. Wandell. PNAS Plus: Development of white matter and reading skills. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1206792109

Researchers have found what they believe is the key to understanding why the human brain is larger and more complex than that of other animals.

The human brain, with its unequaled cognitive capacity, evolved rapidly and dramatically.

"We wanted to know why," says James Sikela, PhD, who headed the international research team that included researchers from the University of Colorado School of Medicine, Baylor College of Medicine and the National Institutes of Mental Health. "The size and cognitive capacity of the human brain sets us apart. But how did that happen?"

"This research indicates that what drove the evolutionary expansion of the human brain may well be a specific unit within a protein — called a protein domain — that is far more numerous in humans than other species."

The protein domain at issue is DUF1220. Humans have more than 270 copies of DUF1220 encoded in the genome, far more than other species. The closer a species is to humans, the more copies of DUF1220 show up. Chimpanzees have the next highest number, 125. Gorillas have 99, marmosets 30 and mice just one. "The one over-riding theme that we saw repeatedly was that the more copies of DUF1220 in the genome, the bigger the brain. And this held true whether we looked at different species or within the human population."

Sikela, a professor at the CU medical school, and his team also linked DUF1220 to brain disorders. They associated lower numbers of DUF1220 with microcephaly, when the brain is too small; larger numbers of the protein domain were associated with macrocephaly, when the brain is too large.

The findings were reported today in the online edition of The American Journal of Human Genetics. The researchers drew their conclusions by comparing genome sequences from humans and other animals as well as by looking at the DNA of individuals with microcephaly and macrocephaly and of people from a non-disease population.

"The take home message was that brain size may be to a large degree a matter of protein domain dosage," Sikela says. "This discovery opens many new doors. It provides new tools to diagnose diseases related to brain size. And more broadly, it points to a new way to study the human brain and its dramatic increase in size and ability over what, in evolutionary terms, is a short amount of time."

People who are obese and also have high blood pressure and other risk factors called metabolic abnormalities may experience a faster decline in their cognitive skills over time than others, according to a study published in the August 21, 2012, print issue of Neurology®, the medical journal of the American Academy of Neurology.

Metabolic abnormality was defined as having two or more of the following risk factors: high blood pressure or taking medication for it; low HDL or "good" cholesterol; high blood sugar or taking diabetes medication; and high triglycerides (a type of fat found in the blood) or taking medication to lower cholesterol.

The study involved 6,401 people with an average age 50 at the start of the study. Information on body mass index (BMI) and the risk factors was gathered at the beginning of the study. The participants took tests on memory and other cognitive skills three times over the next 10 years.

A total of 31 percent of the participants had two or more metabolic abnormalities. Nine percent were obese and 38 percent were overweight. Of the 582 obese people, 350, or 60 percent, met the criteria for metabolic abnormality. The metabolically normal obese individuals also experienced more rapid decline.

Over the 10 years of the study, people who were both obese and metabolically abnormal experienced a 22.5 percent faster decline on their cognitive test scores than those who were of normal weight without metabolic abnormalities.

"More research is needed to look at the effects of genetic factors and also to take into account how long people have been obese and how long they have had these metabolic risk factors and also to look at cognitive test scores spanning adulthood to give us a better understanding of the link between obesity and cognitive function, such as thinking, reasoning and memory," said study author Archana Singh-Manoux, PhD, of INSERM, the French research institute in Paris and University College London in England.

Singh-Manoux said the study also provides evidence against the concept of "metabolically healthy obesity" that has suggested that obese people without metabolic risk factors do not show negative cardiac and cognitive results compared to obese people with metabolic risk factors.

The study was supported by the National Institutes of Health, the Academy of Finland, the Bupa Foundation and the British Medical Research Council.

ntensive preparation for the Law School Admission Test (LSAT) actually changes the microscopic structure of the brain, physically bolstering the connections between areas of the brain important for reasoning, according to neuroscientists at the University of California, Berkeley.

The results suggest that training people in reasoning skills — the main focus of LSAT prep courses — can reinforce the brain's circuits involved in thinking and reasoning and could even up people's IQ scores.

"The fact that performance on the LSAT can be improved with practice is not new. People know that they can do better on the LSAT, which is why preparation courses exist," said Allyson Mackey, a graduate student in UC Berkeley's Helen Wills Neuroscience Institute who led the study. "What we were interested in is whether and how the brain changes as a result of LSAT preparation, which we think is, fundamentally, reasoning training. We wanted to show that the ability to reason is malleable in adults."

The new study shows that reasoning training does alter brain connections, which is good news for the test prep industry, but also for people who have poor reasoning skills and would like to improve them. The findings are reported today (Wednesday, Aug. 22) in the open access journal Frontiers in Neuroanatomy.

"A lot of people still believe that you are either smart or you are not, and sure, you can practice for a test, but you are not fundamentally changing your brain," said senior author Silvia Bunge, associate professor in the UC Berkeley Department of Psychology and the Helen Wills Neuroscience Institute. "Our research provides a more positive message. How you perform on one of these tests is not necessarily predictive of your future success, it merely reflects your prior history of cognitive engagement, and potentially how prepared you are at this time to enter a graduate program or a law school, as opposed to how prepared you could ever be."

John D. E. Gabrieli, a professor of cognitive neuroscience at the Massachusetts Institute of Technology, who was not involved in the research, noted that researchers in the past have shown anatomical changes in the brain from simpler tasks, such as juggling or playing a musical instrument, but not for tasks as complex and abstract as thinking or reasoning, which involve many areas of the brain.

"I think this is an exciting discovery," he said. "It shows, with rigorous analysis, that brain pathways important for thinking and reasoning remain plastic in adulthood, and that intensive, real-life educational experience that trains reasoning also alters the brain pathways that support reasoning ability."

Harnessing brain's spatial areas improves deductive reasoning

The results also suggest that LSAT training improves students' reasoning ability by strengthening the connections between the left and right hemispheres of the brain. According to Bunge, director of the Building Blocks of Cognition Laboratory, deductive reasoning, such as language comprehension, taxes a predominantly left-hemisphere brain network, whereas spatial cognition taxes a predominantly right-hemisphere network.

"You could argue that, to the extent that you can employ spatial cognition to think through a verbal problem, you would have the edge," she said.

The structural changes were revealed by diffusion tensor imaging (DTI) scans of the brains of 24 college students or recent graduates before and after 100 hours of LSAT training over a three-month period. When compared with brain scans of a matched control group of 23 young adults, the trained students developed increased connectivity between the frontal lobes of the brain, and between frontal and parietal lobes.

"A lot of data on reasoning has suggested that it is left-hemisphere dominant," Mackey said. "But what we thought originally was that this kind of reasoning training would require repeated co-activation of frontal and parietal cortices on both sides of the brain. Our data are consistent with the idea that, while reasoning is left-hemisphere dominant, with training you learn to compensate; if you are not very good at reasoning, you start bringing on the right side."

The study focused on fluid reasoning — that is, the ability to tackle a novel problem, which is central to IQ tests and has been shown to predict academic performance and performance in demanding careers, Bunge said.

"People assume that IQ tests measure some stable characteristic of an individual, but we think this whole assumption is flawed," Bunge said. "We think that the skills measured by an IQ test wax and wane over time depending on the individual's level of cognitive activity." One fascinating question, Gabrieli noted, is whether the brain changes observed in this study persist for months or longer after the training.

For the past decade, Bunge has studied the ability to integrate multiple pieces of information, "which we see as central to all tests of reasoning," she said.

LSAT prep students are highly motivated study group

Mackey and Bunge showed several years ago that children can improve their reasoning skills by regularly playing commercially available games that involve reasoning, though the researchers did not have the opportunity to test for actual physical changes in the brain. In searching for a program that provides adults with intensive reasoning training, they hit upon the idea of recruiting aspiring lawyers preparing for the LSAT. Allyson discovered that the company Blueprint Test Preparation offered 100 hours of class time, including 70 hours of reasoning training. With the company's cooperation, she recruited students as they signed up for a Blueprint LSAT course. This arrangement allowed her to test whether training changes brain structure in a group of highly motivated young adults.

Mackey and Bunge tested for changes in the white matter of the brain, the brain tissue that contains the connections between the brain's neurons. These connections, called axons, are surrounded by a variety of support cells called glia, some of which form myelin that insulates the axons and speeds the passage of signals. In animal studies, increased myelination and glial support cells are associated with learning, and a recent study found that some of these glial cells provide energy to the axons.

Using diffusion tensor imaging (DTI), they followed water movement in the white matter and found differences, on average, between the trained group and the control group. Specifically, the trained group showed a change in the directionality of water diffusion that is consistent with increased myelination. Also, near the boundary between the white matter and gray matter, the trained group showed a reduction in water diffusion, possibly because of more densely packed glial cells. While the real cause of the changes in water diffusion is unclear, the researchers said, it reflects an alteration in the microstructure of the brain associated with a change in cognitive activity.

"One thing that gives us confidence in these data is that a lot of these changes are in the tracts that connect frontal and parietal cortex, or between different hemispheres in those areas, and frontal and parietal regions are absolutely essential for reasoning," Bunge said. "So, we are seeing the changes exactly where we would expect to see them. And we think that they reflect strengthening of the connections between them."

"This work could inspire further research in non-human animals, because there seems to be a resurgence of interest in environmental influences on the brain," Bunge said, noting that, in the 1960s and '70s, UC Berkeley Professors Mark Rosenzweig and Marion Diamond conducted landmark research on the effects of environmental enrichment on behavior and brain anatomy in rats.

The work was funded by the National Institute of Neurological Diseases and Stroke of the National Institutes of Health, with the assistance of Blueprint Test Preparation. Graduate student Kirstie Whitaker also contributed to the research.

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Journal Reference:

1. Allyson P. Mackey, Kirstie J. Whitaker, Silvia A. Bunge. Experience-dependent plasticity in white matter microstructure: reasoning training alters structural connectivity. Frontiers in Neuroanatomy, 2012; 6 DOI: 10.3389/fnana.2012.00032