Biology 202
1999 First Web Reports
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Dyslexia


Nicole Stevenson

Dyslexia is a neurological-based, specific learning disability, characterized by language handling deficiencies, impairment in the ability to recognize and translate words into sentences. It is said that a reading disability reflects a continuous deficit as opposed to an arrest in development and can occur in a person of any level of intelligence. Dyslexia can be related to hormonal or hereditary influences, or brain injury. One in five children are thought to have dyslexia and it is found to be more prevalent in males.(1) The difficulties caused by dyslexia do not accurately measure the sufferer's intelligence. Geniuses of our time, such as Einstein, have been affected by the problems of automatic decoding of words and formation of accurate sentences. It is said that many dyslexics "shine in the arts, creativity, design, computing and lateral thinking." (2) The etiological basis suggests that reading disorders stem from difficulties in phonological processing, i.e. the brain's inability to translate images from the eyes completely and correctly to the ears and mouth.(3) Symptoms of dyslexia range from reading and writing difficulties, to speech, direction, time, concentration, coordination, and even self-esteem issues. Other mental disorders are often found to be co-morbid, yet still separate from dyslexia. Common are disorders such as attention deficit and depression, enhanced by the general feelings of helplessness and confusion of dyslexia..(4) Co-morbid problems tend to lessen once the individual seeks successful help with their dyslexia.

There are thought to be various main factors within the brain that contribute to dyslexia. Two of those factors are linked an underutilized left hemisphere and a central bridge of tissue in the corpus callosum. Via brain scanning techniques, such as the fMRI, scientists have proven that dyslectics fail to use the angular gyrus(visual association area) in the left hemisphere of the brain when they read, unlike "normal" readers. The link between the angular gyrus and the occipital and temporal lobes appears to be almost disconnected, causing problems between visual and auditory processing.(5) Problems in the corpus callosum are blamed for poor reading abilities. The right hemisphere of the brain recognizes a word as connected to a definition. The left hemisphere is in charge of putting the sounds of the word together to make it audible.(6) The corpus callosum is the bridge between the two sides of the brain; if this bridge is weak or faulty, then signals will not transfer well. Lack of proper signaling results in a breakdown of communication, which leads to understanding and execution difficulties. Doctor Harold Levinson's major research findings in the early 1970s helped to back this up. His research was able to demonstrate that learning disabilities(i.e. dyslexia) were due to a "simple signal-scrambling disturbance of the inner-ear"(7) Without the ability of a fully functioning inner-ear, signals get crossed and lost, resulting in a general confusion that inhibits learning and comprehension. It is also thought that the language sectors of the brain in a person with dyslexia are smaller than that of a non-dyslectic.

Furthered research on reading difficulties allows for a better understanding not only of the disorders, but also to how "normal" people read. Different approaches designate different subtypes to the general category of dyslexia. There seem to be four main disorder subtypes, surface dyslexia, phonological dyslexia, spelling dyslexia, and direct dyslexia. These different types of dyslexia range from either the loss of the ability to read phonetically, the loss of whole-word reading ability, or a combination of the two. Direct dyslexia refers to the ability of the sufferer to read words aloud yet with an inability to understand what they read. Other dyslexics can understand what they read but are unable to pronounce those same words.(8)

Primary dyslexia is considered to be a dysfunction within the cerebral cortex, which seems to be hereditary. The condition of an individual with primary dyslexia is not thought to change with age. Secondary dyslexia, on the other hand, is thought to be caused during early fetal development and able to disappear gradually as the individual ages. Trauma dyslexia occurs when damage occurs to a sector(s) of the brain.(9)

An alternative explanation for the existence of dyslexia is that the disorder is actually not a downfall, but actually a gift, a special form of thought. This group chooses to portray dyslexia in a very different light then the more conventional medical community. The idea is that reading difficulties are a result of disorientation and that levels understanding has to do with the confusion threshold of each individual. An entire therapy protocol referred to as Davis Orientation Counseling was developed with the idea in mind that the individual possesses the ability to correct their own disorientation through the mastering of the symbols that cause confusion.(10) Unlike the medical model for dyslexia, the Davis model believes that such reading disabilities are caused by outside factors such as poor diet, print styles, certain sounds, scheduling changes, fear, change in the environment, etc. The general idea is to recognize the confusion and figure out how to control it so that it does not cause cognitive difficulties.

An extensive variety of tests are available in order to assess the likelihood of dyslexia and other learning disorders. Treatment is also available in various different forms, all in favor of strengthening the ability of the individual to compensate for their difficulties. Skilled specialist tutoring and committed learning is a must. One common, straightforward plan is an increased, intense study of phonics. Treatment should be focused on the individual and what their specific desires for themselves are, that need to be met. Due to the wide range of strengths and weakness that arise with each individual affected by dyslexia, treatment and results vary.(11) Attitude is also one of the most important aspects to be stressed. Without a positive outlook, the individual is doomed not to improve. Nothing is concrete in the study of dyslexia, much research and education are still in need for a better understanding and treatment of this disorder.

WWW Sources

1)Barkley, Russel A. & Eric J.Mash. Child Psychopathology Guilford Press, NY, NY. 1996 (pg.418)

2) http://www.dyslexia-inst.org.uk/what.htm#top

3) Barkley, Russel A. & Eric J.Mash. Child Psychopathology Guilford Press, NY, NY. 1996 (pg.418)

4) http://dyslexiaonline.com/information.html

5)http://www.nimh.nih.gov/events/prleftdy.htm

6)http://www.dyslexia.org

7)http://www.dyslexiaonline.com/info_whatisdyslexia.html

8)Carlson, Neil R. Physiology of Behavior. Allyn & Bacon, Mass. 1998 (pg. 507)

9) http://www.medicinenet.com

10) http://www.dyslexia.com

11) http://www.nimh.nih.gov/healinfo/disorder/dyslexia/dyslexia.htm




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