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Children's Reading Disability Attributed To Brain Impairment

August 2, 2002  

Children who are poor readers appear to have a disruption in the part of their brain involved in reading phonetically, according to a sophisticated brain imaging study funded by the National Institute of Child Health and Human Development (NICHD). The study also found that children who read poorly but who do not receive any extra help or training eventually compensate for their disability by using other parts of the brain as backup systems for the impaired brain regions. Although most of these children eventually do learn to read, they never do so with the same fluency as do good readers. This is probably because the "backup" brain systems they use when reading apparently cannot process printed information as easily as can the brain systems primarily involved in reading.  

The researchers, led by Bennett Shaywitz, M.D., of the Yale University School of Medicine, published their results in the July Biological Psychiatry. "This study shows us the physical basis of why some children have difficulty reading," said Duane Alexander, M.D., Director of the NICHD. "We are now in a position to observe the brain changes that take place when poor readers receive the training that allows them to become proficient readers. In turn, this knowledge may allow us to design even more effective therapies to help poor readers overcome their disability."

In the study, the researchers used a technology known as functional magnetic resonance imaging (fMRI), which produced computer-generated images of the brain while the children were reading. With fMRI, the team demonstrated differences in brain images between children with dyslexia and non-reading impaired control children. The disruption in the brain systems for reading was evident when the children performed phonologic tasks, that is, tasks that required knowing the sound structure of words. Written English is a kind of code-letters or combinations of letters stand for the individual sounds within words. The reading impaired children had difficulty with tasks that required
interpretation of this code. Dr. Shaywitz noted that the current study with children confirmed the researchers' earlier finding with adults that people with dyslexia have an impairment in the brain regions involved with reading words phonetically. And like adults with dyslexia, they use an alternate brain region as a backup system when reading. [The earlier study is described at: http://www.nichd.nih.gov/new/releases/dyslexianews.cfm.] "The study shows some very important findings," Dr. Shaywitz said. "First it identifies neural pathways for reading in good readers while showing a disruption of these pathways in children who are dyslexic (Fig 1). " Second, Dr. Shaywitz explained, the study identifies a region for skilled reading in the the brain area known as the left occipito-temporal region (Fig. 2). Better readers are more likely to activate this region than are poor readers. Third, the study shows areas of compensatory systems in the front and the right side of the brain in dyslexic children who are older (Fig.3).  These three images can be found at http://www.nichd.nih.gov. The researchers tested the ability of children to
rhyme nonsense words, for example, asking them: "Do [LEAT] and [JETE] rhyme?" The children were also asked to determine the category of real words-- "Are [CORN] and [RICE] in the same category?" These tasks require children to use phonology, that is, their knowledge of the sound structure of words, which is very difficult for dyslexic readers. Shaywitz and his collaborators used fMRI to study 144 children ranging in age from 7 to 18 years, 70 dyslexic readers (21 girls, 49 boys) and 74 nonimpaired readers (31 girls, 43 boys ).  "Our findings show that the impairment in the brains of children with reading disability persists into adulthood," said another author of the study, G. Reid Lyon, Chief of NICHD's Child Development and Behavior Branch. "The findings provide compelling evidence that children with reading disabilities need to receive educational services to help them overcome their disabilities." Dr. Lyon added that NICHD-funded research has shown that such services should have a firm foundation in phonological awareness. Before most poor readers can learn to read successfully, he said, they need to learn that spoken words can be broken apart into smaller segments called phonemes. Next, they usually require training in phonics-"mapping"  phonemes to the printed words on a page. Once children have mastered these steps, they can then receive training to help them read fluently, and to comprehend what they read. ### The NICHD is part of the National Institutes of Health, the biomedical research arm of the federal government. The Institute sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. NICHD publications, as well as information about the Institute, are available from the NICHD Web site, http://www.nichd.nih.gov, or from the NICHD Clearinghouse, 1-800-370-2943; E-mail NICHDClearinghouse@mail.nih.gov.

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FOR IMMEDIATE RELEASE Monday, April 19, 2004

Imaging Study Reveals Brain Function of Poor Readers Can Improve

A brain imaging study has shown that, after they overcome their reading disability, the brains of formerly poor readers begin to function like the brains of good readers, showing increased activity in a part of the brain that recognizes words. The study appears in the May 1 Biological Psychiatry and was funded by the National Institute of Child Health and Human Development (NICHD), one of the National Institutes of Health.  "These images show that effective reading instruction not only improves reading ability, but actually changes the brain's functioning so that it can perform reading tasks more efficiently," said Duane Alexander, M.D., Director of the NICHD.  The research team was led by Bennett Shaywitz, M.D., and Sally Shaywitz, M.D, of Yale University, in New Haven, Connecticut. Other authors of the study were from Syracuse University, in Syracuse, New York; Vanderbilt University, in Nashville, Tennessee; and the NICHD. 

According to Dr. Sally Shaywitz, the results show that "Teaching matters and good teaching can change the brain in a way that has the potential to benefit struggling readers." Along with testing the children's reading ability, the researchers used functional magnetic resonance imaging (fMRI), a sophisticated brain imaging technology, to
observe the children's brain functioning as they read.

In all, 77 children between the ages of 6 and about 9 and 1⁄2 took part in the study. Of these, 49 had difficulty reading, and 29 children were good readers. Of the 49 poor readers, 12 received the standard instruction in reading that was available through their school systems. The remaining 37 were enrolled in an intensive reading program based on instruction in phonemic awareness and phonics.

In the study, the 37 poor readers in the intensive reading program outpaced the 12 poor readers in the standard instruction groups, making strong gains in three measures
of reading skill: accuracy, fluency, and comprehension. These gains were still apparent when the children were tested again a year later. Moreover, fMRI scans showed that the brains of the 37 formerly poor readers began functioning like the brains of good readers. Specifically, the poor readers showed increased activity in an area of the brain that recognizes words instantly without first having to decipher them.  The intensive reading program the 37 children took had strong components in phonemic awareness and phonics. Phonemic awareness refers to the ability to identify phonemes, the individual sounds that make up spoken words. The word "bag," for example, is made up of three such elemental units of speech, which can be represented as bbb, aaa, and ggg. The brain strings together the 40 phonemes making up the English language to produce hundreds and thousands of words. In speech, this process is unconscious and automatic. 

Beginning in the 1970s, NICHD-funded researchers learned that developing a conscious awareness of the smaller sounds in words was essential to mastering the next step in learning to read, phonics. Phonics refers to the ability to match spoken phonemes to the individual letters of the alphabet that represent them. Once children master phonics, the NICHD-funded studies showed, they could make sense of words they haven't seen before, without first having to memorize them. Further NICHD-supported research found that instruction in phonemic awareness was an essential part of a comprehensive program in reading instruction that could help most poor readers overcome their disability.

In the 1990s, the Shaywitzes had used fMRI to learn that reading ability resides in the brain's left half, or hemisphere. Within the hemisphere, three brain regions work together to control reading. In the left front of the brain, one area recognizes phonemes. Further back, another brain area "maps" phonemes to the letters that represent them. Still another brain area serves as a kind of long-term storage system. Once a word is learned, this brain region recognizes it automatically, without first having to decipher it phonetically.

Poor readers, the researchers had learned in the earlier studies, have difficulty accessing this automatic recognition center. Instead, they rely almost exclusively on the phoneme center and the mapping center. Each time poor readers see a word, they must puzzle over it, as if they were seeing it for the first time.

In the current study, the researchers discovered that, as the 37 poor readers progressed through their instruction program, their brains began to function more like the brains of good readers. Specifically, the brains of these children showed increased activation in the automatic recognition center.

"This study represents the fruition of decades of NICHD-supported reading research," said G. Reid Lyon, Ph.D, Chief of NICHD's Child Development and Behavior Branch.

"The findings show that the brain systems involved in reading respond to effective reading instruction." The NICHD is part of the National Institutes of Health (NIH), the biomedical research arm of the federal government. NIH is an agency of the U.S. Department of Health and Human Services. The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. NICHD publications, as well as information about the Institute, are available from the NICHD Web site, http://www.nichd.nih.gov, or from the NICHD Information Resource Center, 1-800-370-2943; e-mail NICHDInformationResourceCenter@mail.nih.gov.

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