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Dyslexia is defined by the difficulty in an individual's ability to read given adequate intelligence and normal opportunities. While such a distinction provides a useful advantage to clinicians and diagnosticians alike, it does not carry implications that are of practical significance to scientist and researchers so as to facilitate further development of interventions that would allow dyslexics to learn as normal individuals. Current neurological research has uncovered clear evidence of biophysical and structural anomalies in individuals who are affected by the disorder. FMRI and behavioral experiments have generated significant results so as to suggest the disorder be viewed as having neurological causes. ==Overview== Modern neuroimaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have produced clear evidence of structural differences in the brains of children with reading difficulties. It has been found that people with dyslexia have a deficit in parts of the left hemisphere of the brain involved in reading, which includes the inferior frontal gyrus, inferior parietal lobule, and middle and ventral temporal cortex. That dyslexia is neurobiological in origin is supported by what Lyon et al. proclaimed as "overwhelming and converging data from functional brain imaging investigations" (2003, p. 3). The results of these studies suggest that there are observable differences in how the dyslexic brain functions when compared to the brain of a typical reader. Using fMRI, Shaywitz found that good readers show a consistent pattern of strong activation in the back of the brain with weaker activation in the front of the brain during reading tasks. In contrast, the brain activation pattern in dyslexics is the opposite during reading tasks—the frontal part of the brain becomes overactive with weaker activation in the back. Shaywitz points out ''"It is as if these struggling readers are using the systems in the front of the brain to try to compensate for the disruption in the back of the brain."'' Fluent word identification in reading is related to the amount of activity in the Left hemisphere posterior system. In dyslexia the posterior system is often disrupted.〔 As mentioned above, in order to compensate for lower activity in the posterior system people with dyslexia rely more on the inferior frontal and right hemisphere regions.〔 Brain activation studies using PET to study language have produced a breakthrough in understanding of the neural basis of language over the past decade. A neural basis for the visual lexicon and for auditory verbal short term memory components have been proposed, with some implication that the observed neural manifestation of developmental dyslexia is task-specific (i.e., functional rather than structural). White matter organization and right prefrontal activity can predict future gain in reading ability. Greater right prefrontal activity during reading tasks has been associated with reading improvement later in life.〔 Language training has been shown to improve neural mechanisms of selective auditory attention of children with learning disabilities. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Neurological research into dyslexia」の詳細全文を読む スポンサード リンク
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