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Dyslexia

Reading And The Brain

Sigmund Freud, the father of modern psychiatry, wrote in 1900 that painful childhood experiences or hatred of one or both parents caused dyslexia. He reasoned that children who could not openly rebel against a harsh mother or father defied their parents by refusing to learn to read. Freud recommended psychoanalysis to resolve such emotional problems.

Today, experts reject the psychoanalytic explanation of dyslexia. Sophisticated brain imaging technology known as functional magnetic resonance imaging (fMRI) clearly shows inactivity in a large area that links the angular gyrus—the visual cortex and visual association areas where print or writing is interpreted, to areas in the superior temporal gyrus (Wernicke's area) where language and phonetics are interpreted. Also, during phonologic reading tasks, the area associated with spoken language (Broca's area) showed activation in dyslexic readers where it did not in normal readers. Researchers believe this area may attempt to compensate for impairments in Wernicke's area.

Investigators have studied those with brain lesions (abnormal growths such as tumors) in Wernike's area. Although they had no reading difficulties before the lesion was large enough to detect, patients with brain lesions developed reading problems identical to those associated with dyslexia. Those with dyslexia also tend to have rapid, jerky, hard-to-control eye movements when they read—another indication of a misfire in the brain.

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Science EncyclopediaScience & Philosophy: Direct Variation to DysplasiaDyslexia - Reading And The Brain, How We Read, Causes Of Dyslexia, Treating Dyslexia - Future developments