Dyslexia: Encyclopedia II - Dyslexia - Physiology and treatment

Dyslexia - Physiology and treatment

Even a few weeks of intense phonological training (often involving breaking down and rearranging sounds to produce different words) can help noticeably improve reading skills. Unlike in normal adults, phonological training shows an increase in the activity in the right temporoparietal cortex.

This part of the brain works in spatial tasks and may be the main compensatory structure in phonological training. This is the sister region of the left temporoparietal cortex responsible for visual motion processing which is underactive in many dyslexics. The earlier the phonological regimen is taken on, the better the overall result. Advanced brain scans could identify children at risk of dyslexia before they can even read, although it is thought that simple tests of balance could do the same. It has also been shown that early diagnosis and treatment can almost completely eliminate the symptoms of dyslexia.

The most important thing that can be done for the child is to make sure the child is kept active. You can do this by giving them simple jobs to do around the home such as cleaning the house. This helps improve their concentration and their motivational skills.

One hypothesis for some of the symptoms of dyslexia is a lack of overall short-term memory. Typically a dyslexic will not remember your name, and will suffer an undue amount of difficulty in transcribing (for example) a phone number. These problems could be attributed to difficulty in laying down short-term memories.

Researchers studying the brains of dyslexics have found that during reading tasks, dyslexics show reduced activity in the left inferior parietal cortex. It is not that uncommon for dyslexics who have trained themselves to cope with their affliction, to develop uncannily efficient visual memories which aid in reading and comprehending large quantities of information much faster than is typical. Commonly dyslexics show 10 times more brain activity when reading. Sometimes, depending of the type and extent, also writing, listening and speaking. Conversely, some dyslexics may show a natural dislike of reading and, in consequence, compensate by developing unique verbal communication skills, inter-personal expertise, and leadership skills. Different people adopt different strategies for living with the same affliction.

A popular hypothesis for the reading difficulties experienced by dyslexics is strabismus, which is difficulty in bringing both eyes into focus on the same point. Such problems explain why dyslexics often confuse the sequence of written letters or numbers, as the end of the word is literally being seen first by one eye, then the beginning of the word is seen by the other eye. Studies in which young children are taught reading skills while wearing an eyepatch have shown very promising results. This is based upon the theory that, because children benefit more from learning to read than being confocal, the former should take precedence over the latter.

In 1979, anatomical differences in the brain of a young dyslexic were documented. Albert Galaburda of Harvard Medical School noticed that language centers in dyslexic brains showed microscopic flaws known as ectopias and microgyria. Both affect the normal six-layer structure of the cortex. An ectopia is a collection of neurons that have pushed up from lower cortical layers into the outermost one. A microgyrus is an area of cortex that includes only four layers instead of six.

These flaws affect connectivity and functionality of the cortex in critical areas related to sound and visual processing. These and similar structural abnormalities may be the basis of the inevitable and hard to overcome difficulty in reading.

Several genetic regions on chromosomes 1 and 6 have been found that might be linked to dyslexia. In all likelihood, dyslexia is a conglomeration of disorders that all affect similar and associated areas of the cortex. With time, science is likely to identify and classify all individual suborders with benefits to our understanding of how low-level genetic flaws can affect the wiring of the brain and enhance or reduce a particular component of human mental capacity.

Some studies have concluded that speakers of languages whose orthography has a strong correspondence between letter and sound (e.g. Korean and Italian) have a much lower incidence of dyslexia than speakers of languages where the letter is less closely linked to the sound (e.g. English and French). (Source: http://www-tech.mit.edu/V121/N12/shorts2_12.12w.html )

Whether models of dyslexia are correct or not, the main lesson of dyslexia is that minor genetic changes affecting the layering of the cortex in a minor area of the brain may impose limitations on the overall intellectual function. At the same time, dyslexia shows that the brain exhibits a strong ability to compensate for its acquired limitations, and intense training can often result in miraculous turnabouts.

Dyslexia - Characteristics

Most dyslexics will exhibit about 10 of the following traits and behaviors. These characteristics can vary from day-to-day or minute-to-minute. The most consistent thing about dyslexics is their inconsistency. Symptoms increase dramatically with confusion, time pressure, emotional stress, or poor health.

• Appears to be bright, seemingly highly intelligent, and articulate but unable to read, write, or spell at grade level.
• Isn't "behind enough" or "bad enough" to be helped in the school setting.
• Possibly High in IQ or average or below average, yet may not test well academically; tests well orally, but not written. see Functional illiteracy
• Feels dumb; has poor self-esteem; hides or covers up weaknesses with ingenious compensatory strategies; easily frustrated and emotional about school reading or testing.
• Perhaps talented in either art, drama, music, sports, mechanics, story-telling, sales, business, designing, building, or engineering.
• Seems to "Zone out" or daydream often; gets lost easily or loses track of time.
• Difficulty sustaining attention; seems "hyper" or "daydreamer."
• Learns best through hands-on experience, demonstrations, experimentation, observation, and visual aids.

• Complains of dizziness, headaches or stomach aches while reading.
• Confused by letters, numbers, words, sequences, or verbal explanations.
• Reading or writing shows repetitions, additions, transpositions, omissions, substitutions, and reversals in letters, numbers and/or words.
• Complains of feeling or seeing non-existent movement while reading, writing, or copying.
• Seems to have difficulty with vision, yet eye exams don't reveal a problem.
• Extremely keen sighted and observant, or lacks depth perception and peripheral vision.
• Reads and rereads with little comprehension.
• Spells phonetically and inconsistently

• Has extended hearing; hears things not said or apparent to others; easily distracted by sounds.
• Difficulty putting thoughts into words; speaks in halting phrases; leaves sentences incomplete; stutters under stress; mispronounces long words, or transposes phrases, words, and syllables when speaking.

• Trouble with writing or copying; pencil grip is unusual; handwriting varies or is illegible.
• Clumsy, uncoordinated, poor at ball or team sports; difficulties with fine and/or gross motor skills and tasks; prone to motion-sickness.
• Can be ambidextrous, and often confuses left/right, over/under.

• Has difficulty telling time, managing time, learning sequenced information or tasks, or being on time.
• Shows dependence on finger counting and other tricks when doing math; knows answers, but can't do it on paper.
• Can count, but has difficulty counting objects and dealing with money.
• Can do arithmetic, but fails word problems; when doing maths must see the big picture before the detail.

• Excellent long-term memory for experiences, locations, and faces.
• Poor memory for sequences, facts and information that have not been experienced.
• Thinks primarily with images and feeling, not sounds or words (little internal dialogue).

• Extremely disorderly or compulsively orderly.
• Can be class clown, trouble-maker, or too quiet.
• Had unusually early or late developmental stages (talking, crawling, walking, tying shoes).
• Prone to ear infections; sensitive to foods, additives, and chemical products.
• Can be an extra deep or light sleeper; bedwetting beyond appropriate age.
• Unusually high or low tolerance for pain.
• Strong sense of justice; emotionally sensitive; strives for perfection.

Adapted from the Wikipedia article "Physiology and treatment", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki