By Abigail Marshall; © 2003 DDAI. (used with permission)
Scientists studying the brain have found that dyslexic adults who become
capable readers use different neural pathways than nondyslexics. This research
shows that there are two independent systems for reading: one that is typical
for the majority of readers, and another that is more effective for the dyslexic
thinker.
NIMH Study of Dyslexic Adults
Researchers Judith Rumsey and Barry Horwitz at the National Institute of
Mental Health used positron emission tomography (PET) to compare regional
cerebral blood flow (rCBF) among dyslexic and nondyslexic men. The dyslexic
subjects had childhood histories of dyslexia and continued to show some symptoms
related to reading, but their overall reading ability varied. For some word
recognition and comprehension tasks, the dyslexic men scored as well as or
better than controls.
Research correlating brain activity with reading ability showed an intriguing
inverse relationship between reading ability and cerebral blood flow patterns.
For nondyslexic controls, stronger activation of left hemispheric reading
systems, including the left angular gyrus, corresponded to better reading skill.
For dyslexic subjects, the opposite was true: the stronger the left-hemispheric
pattern, the poorer the reader. In contrast, increased reading skill for
dyslexics was correlated with greater reliance on the right hemispheric systems.
The researchers explained:
"The rCBF–reading test correlations identified a region in/near the left
angular gyrus as significantly related to level of reading skill within both
groups. These correlations were uniformly positive for the control group and
uniformly negative for the dyslexic group, indicating diametrically opposed
relationships in the two groups....within the control group higher rCBF was
associated with better reading skill and that within the dyslexic group
higher rCBF was associated with worse reading skill, or more severe
dyslexia."
The researchers observed a similar pattern in the right hemisphere, in an
area near the right angular gyrus. In the right brain area, the dyslexic men had
higher activation levels than controls during the word reading tasks, which
correlated positively to improved reading ability. For the nondyslexic control
group, such activation pattern was negatively correlated to reading ability.
Comparison of Reading Outcomes among children followed since
kindergarten
A team of researchers led by
Sally Shaywitz at
Yale University has confirmed that dyslexic individuals who become good
readers have a different pattern of brain use than either nondyslexic readers,
or dyslexics who still read poorly. The researchers used functional magnetic
resonance imaging (fMRI) to evaluate brain activity among 20-year-old dyslexic
men and women selected from a group that had been followed since kindergarten.
All the dyslexic subjects had a history of severe reading impairment in early
childhood. However, while some of the students continued to struggle with
reading throughout their school years ("persistently poor readers"), others
improved by their high school years, becoming accurate readers with strong
comprehension skills ("accuracy improved readers").
Dyslexic subjects from both groups as well as non-dyslexic control subjects
were asked to perform reading tasks involving phonological processing (non-word
rhyming test) and ascertaining meaning (semantic category test). During the
non-word rhyming test ["Do leat and jete rhyme?], both dyslexic
groups showed less activation of the left posterior and temporal areas of the
brain as compared to the control group. However, the dyslexics who were improved
readers also had greater activation of right temporal areas and both right and
left frontal areas.
For the semantic category test ["Are corn and rice in the same
category?"] the persistently poor readers showed brain activity very similar to
the nondyslexic control group, despite the fact that their reading performance
was significantly impaired. Like the control group, the persistently poor
readers activate left posterior and temporal systems. In contrast, the improved
dyslexic readers bypassed this area entirely.
This research suggests that for dyslexic readers, the left brain areas
associated with phonetic decoding are ineffective. While a non-dyslexic reader
finds such pathways an efficient route to reading, the dyslexic reader
essentially becomes entangled in a neural traffic jam. In contrast, dyslexics
who bypass these mental pathways, relying more on areas of the brain involved in
nonverbal thought and in analytic thought, are able to become capable readers.
Impact of Findings for Education
These brain imaging studies show that teaching methods that may work well for
a large majority of schoolchildren may be counterproductive when used with
dyslexic children. Teaching methods based on intensive or systematic drill in
phonemic awareness or phonetic decoding strategies may actually be harmful to
dyslexic children. Such teaching might simply emphasize reliance on mental
strategies that are as likely to diminish reading ability for dyslexic children
as they are to improve it, increasing both the frustration and impairment level
of dyslexic students.
Davis Theory and Methods
Davis Dyslexia Correction® emphasize a creative, meaning-based strategy for
acquisition of basic reading skills. Children (and adults) use clay to model the
concepts that are associated with word meanings at the same time as modeling the
letters of each word in clay. At the primary level, these methods provide a
route to learning to read that seems easier for students with dyslexic
tendencies than traditional instruction. Among older dyslexic children and
adults, these methods routinely lead to very rapid progress in reading ability.
Scientists know from other studies that the right brain hemisphere is where
the mind connects written words to their meanings, and that it is where creative
and imaginative thought takes place. Modeling words in clay can help build the
mental pathways that brain scan evidence shows to be crucial for reading
development among dyslexic students.
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