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A dyslexia research team at Yale University's Center for Learning and
Attention lead by Dr. Sally Shaywitz has found a window on the brain through a
new imaging technique called functional MRI. These medical scientists have
identified parts of the brain used in reading. By observing the flow of
oxygen-rich blood to working brain cells, they have found that people who know
how to sound out words can rapidly process what they see. This information has
shed new light on dyslexia and how to help dyslexics.
When readers are asked to imagine "cat" without the "kah"
sound, they readily summon "at." The MRI photographs show their brains
lighting up like pinball machines. When the brain gets it, the light bulbs
really do go on. However, the brains of people who can't sound out words often
look different on MRI pictures. There is less blood flow to the language centers
of the brain and, in some cases, not much activity evident at all. Scientist's
are not sure why this is or what it means. But simply put, without the ability
to sound out words, the brain is stumped.
Basically this research seems to be saying that the brain learns to read the
same way it learns to talk, one sound at a time. When babies first learn to talk
they may slowly say one sound at a time. Once they get the hang of it, they
speed up. Our brain becomes adept at processing and our experience is that of
hearing words but actually our brain is processing sounds (phonemes) and putting
them together so we hear words. When we read the same process is in operation.
Our brain is processing one sound at a time but we perceive it as a whole word.
In good readers, the process is so fast it appears that they are reading whole
words but in fact they are converting the letters on the written page into
sounds. The brain then recognizes groups of sounds as words.
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Reading is not automatic but must be learned.
The reader must develop a conscious awareness that the letters on the page
represent the sounds of the spoken word. To read the word "cat,"
the reader must parse, or segment, the word into its underlying
phonological elements. Once the word is in its phonological form, it can
be identified and understood. In dyslexia, an inefficient phonological
module produces representations that are less clear and hence more
difficult to bring to awareness. (Scientific American,
November 1996, page 100) |
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In READING the word (for example, "cat") is first decoded into
its phonological form ("kuh, aah, tuh") and identified. Once it
is identified, higher-level cognitive functions such as intelligence and
vocabulary are applied to understand the word's meaning ("small furry
mammal that purrs"). In people who have dyslexia, a phonological
deficit impairs decoding, thus preventing the reader from using his or her
intelligence and vocabulary to get to the word's meaning. (Scientific
American, November 1996, page 101) |
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Neural Architecture for reading has been suggested by
functional magnetic resonance imaging. letter identification activates the
extrastriate cortex in the occipital lobe; phonological processing
activates the inferior frontal gyrus (Broca's area); and accessing meaning
activates primarily the superior temporal gyrus and parts of the middle
temporal and supramarginal gyri. |
According to Dr. Shaywitz, "Over the past two decades, a coherent model
of dyslexia has emerged that is based on phonological processing. The
phonological model is consistent both with the clinical symptoms of dyslexia and
with what neuroscientists know about brain organization and function.
Investigators from many laboratories, including my colleagues and I at the Yale
Center, have had the opportunity through 10 years of cognitive, and more
recently, neurobiological studies."
Dyslexics (or poor readers) are very frustrated by the fact that they can
understand what they hear but not what they read. Dyslexics have average or
above average intelligence. Once they can properly decode words they can
understand the concept. Decoding skills are the key to learning from written
material.
Years of educational research has shown that the use of intensive phonics is
the only way to teach dyslexics and learning disabled individuals how to
read. The new brain research shows why intensive phonics is also the best way
for everyone to learn to read.
Unfortunately, 80% of our nation's schools do not teach reading by intensive
phonics. Most school use either the whole word method or a mix of whole word and
phonics. The pictures above illustrate why the brain is confused by this
approach.
For More Reading on This Subject:
Reiben Laurence & Perfetti, Charles, Learning To Read,
Lawrence Erlbaum Associates: Hillsdale, NJ 1991
Lyon, G Reid, Toward A Definition of Dyslexia, Annals of
Dyslexia, Vol 45 pp3-27
Shaywitz, Sally, Dyslexia, Scientific American,
November 1996 pp98-104
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