■幼児・児童期の＜危険な脳の活性化＞崇拝-3(文責：どんぐり倶楽部)
■＜危険な脳の活性化＞崇拝-1,2を読まれた方でしたら Web翻訳で翻訳しても、ある程度わかると思います。 全訳する気力はありませんので、そのまま引用します。Press ReleaseMay 17th, 2004Contact: Jules AsherNIMH Press Office301-443-4536NIMHpress@nih.govImaging Study Shows Brain Maturing The brain's center of reasoning and problem solving is among the last to mature, a new study graphically reveals. The decade-long magnetic resonance imaging (MRI) study of normal brain development, from ages 4 to 21, by researchers at NIH's National Institute of Mental Health (NIMH) and University of California Los Angeles (UCLA) shows thatsuch "higher-order" brain centers, such as the prefrontal cortex, don't fully develop until young adulthood.A time-lapse 3-D movie that compresses 15 years of human brain maturation, ages 5 to 20, into seconds shows gray matter ― the working tissue of the brain's cortex ― diminishing in a back-to-front wave, likely reflecting the pruning of unused neuronal connections during the teen years. Cortex areas can be seen maturing at ages in which relevant cognitive and functional developmental milestones occur. The sequence of maturation also roughly parallels the evolution of the mammalian brain, suggest Drs. Nitin Gogtay, Judith Rapoport, NIMH, and Paul Thompson, Arthur Toga, UCLA, and colleagues, whose study is published online during the week of May 17, 2004 in The Proceedings of the National Academy of Sciences."To interpret brain changes we were seeing in neurodevelopmental disorders like schizophrenia, we needed a better picture of how the brain normally develops," explained Rapoport.The researchers scanned the same 13 healthy children and teens every two years as they grew up, for 10 years. After co-registering the scans with each other, using an intricate set brain anatomical landmarks, they visualized the ebb and flow of gray matter - neurons and their branch-like extensions - in maps that, together, form the movie showing brain maturation from ages 5 to 20.It was long believed that a spurt of overproduction of gray matter during the first 18 months of life was followed by a steady decline as unused circuitry is discarded. Then, in the late l990s, NIMH's Dr. Jay Giedd, a co-author of the current study, and colleagues, discovered a second wave of overproduction of gray matter just prior to puberty, followed by a second bout of "use-it-or-lose-it" pruning during the teen years.The new study found that the first areas to mature (e.g., extreme front and back of the brain) are those with the most basic functions, such as processing the senses and movement. Areas involved in spatial orientation and language (parietal lobes) follow. Areas with more advanced functions ― integrating information from the senses, reasoning, and other "executive" functions (prefrontal cortex) ― mature last.In a related study published a few years ago, Rapoport and colleagues discovered an exaggerated wave of gray matter loss (PDF file) in teens with early onset schizophrenia. These teens, who became psychotic prior to puberty, lost four times the normal amount of gray matter in their frontal lobes, suggesting that childhood onset schizophrenia "may be an exaggeration of a normal maturation process, perhaps related to excessive synaptic pruning," note the researchers. By contrast, children with autism show an abnormal back-to-front wave of gray matter increases, rather than decreases, suggesting "a specific faulty step in early development."Also participating in the new study were: Leslie Lusk, Cathy Vaituzis, Tom Nugent, David Herman, Drs. Deanna Greenstein, Liv Clasen, NIMH; Kiralee Hayashi, UCLA.NIMH is part of the National Institutes of Health (NIH), the Federal Government's primary agency for biomedical and behavioral research. NIH is a component of the U.S. Department of Health and Human Services.Time-Lapse Imaging Tracks Brain Maturation from ages 5 to 20ﾊConstructed from MRI scans of healthy children and teens, the time-lapse "movie", from which the above images were extracted, compresses 15 years of brain development (ages 5-20) into just a few seconds. Red indicates more gray matter, blue less gray matter. Gray matter wanes in a back-to-front wave as the brain matures and neural connections are pruned. Areas performing more basic functions mature earlier; areas for higher order functions mature later. The prefrontal cortex, which handles reasoning and other "executive" functions, emerged late in evolution and is among the last to mature. Studies in twins are showing that development of such late-maturing areas is less influenced by heredity than areas that mature earlier.Source: Paul Thompson, Ph.D.UCLA Laboratory of NeuroimagingPress ReleaseMarch 29, 2006Contact: Jules AsherNIMH Press Office301-443-4536NIMHpress@nih.govCortex Matures Faster in Youth with Highest IQYouth with superior IQ are distinguished by how fast the thinking part of their brains thickens and thins as they grow up, researchers at the National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) have discovered. Magnetic resonance imaging (MRI) scans showed that their brain's outer mantle, or cortex, thickens more rapidly during childhood, reaching its peak later than in their peers ― perhaps reflecting a longer developmental window for high-level thinking circuitry. It also thins faster during the late teens, likely due to the withering of unused neural connections as the brain streamlines its operations. Drs. Philip Shaw, Judith Rapoport, Jay Giedd and colleagues at NIMH and McGill University report on their findings in the March 30, 2006 issue of Nature."Studies of brains have taught us that people with higher IQs do not have larger brains. Thanks to brain imaging technology, we can now see that the difference may be in the way the brain develops," said NIH Director Elias A. Zerhouni, M.D. While most previous MRI studies of brain development compared data from different children at different ages, the NIMH study sought to control for individual variation in brain structure by following the same 307 children and teens, ages 5-19, as they grew up. Most were scanned two or more times, at two-year intervals. The resulting scans were divided into three equal groups and analyzed based on IQ test scores: superior (121-145), high (109-120), and average (83-108).The researchers found that the relationship between cortex thickness and IQ varied with age, particularly in the prefrontal cortex, seat of abstract reasoning, planning, and other "executive" functions. The smartest 7-year-olds tended to start out with a relatively thinner cortex that thickened rapidly, peaking by age 11 or 12 before thinning. In their peers with average IQ, an initially thicker cortex peaked by age 8, with gradual thinning thereafter. Those in the high range showed an intermediate trajectory (see below). While the cortex was thinning in all groups by the teen years, the superior group showed the highest rates of change."Brainy children are not cleverer solely by virtue of having more or less gray matter at any one age," explained Rapoport. "Rather, IQ is related to the dynamics of cortex maturation."The observed differences are consistent with findings from functional magnetic resonance imaging, showing that levels of activation in prefrontal areas correlates with IQ, note the researchers. They suggest that the prolonged thickening of prefrontal cortex in children with superior IQs might reflect an "extended critical period for development of high-level cognitive circuits." Although it's not known for certain what underlies the thinning phase, evidence suggests it likely reflects "use-it-or-lose-it" pruning of brain cells, neurons, and their connections as the brain matures and becomes more efficient during the teen years."People with very agile minds tend to have a very agile cortex," said Shaw. The NIMH researchers are following-up with a search for gene variants that might be linked to the newly discovered trajectories. However, Shaw notes mounting evidence suggesting that the effects of genes often depends on interactions with environmental events, so the determinants of intelligence will likely prove to be a very complex mix of nature and nurture.Also participating in the study were Drs. Dede Greenstein, Liv Clasen, Rhoshel Lenroot, and Nitin Gogtay, Child Psychiatry Branch, NIMH; and Drs. Jason Lerch and Alan Evans, Montreal Neurological Institute, McGill University.The developmental trajectory of waxing and waning in cortex thickness differs as the brain matures in different IQ groups. Thickness of the area at the top/front/center, highlighted in MRI brain maps at left, peaks relatively late, at age 12 (blue arrow), in youth with superior intelligence, perhaps reflecting an extended critical period for development of high-level cognitive circuits.Source: NIMH Child Psychiatry Branch※日本ブログ村に参加してみました。このブログが参考になりましたら、お手数ですが、下記をクリックお願いします。【どんぐり倶楽部の公式サイト】※「頭の健康診断」年長〜小６向け（中学生も可）。
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