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In
today's selection - the nature and mechanics of reading. Recent
research using magnetic resonance imaging has provided neuroscientists
with a clearer picture of which parts of the brain are responsible for
reading and how the brain develops over time into a sophisticated reading
machine.
"Imaging
studies have identified at least two neural pathways for reading, one for
beginning reading, for slowly sounding out words, and another that is a
speedier pathway for skilled reading. ... As they read, good
readers activate highly-interconnected neural systems that encompass regions
in the back and front of the left side of the brain. Not surprisingly, the
reading circuitry includes brain regions dedicated to processing the visual
features, that is, the lines and curves that make up letters, and to
transforming the letters into the sounds of language and to getting to the
meaning of words.
"Most
of the reading part of the brain is in the back. Called the posterior reading
system ... it is made up of two different pathways for reading words, one
sitting somewhat higher in the brain than the other. The upper pathway is
located primarily in the middle of the brain (technically, the
parieto-temporal region), just above and slightly behind the ear. The
lower path runs closer to the bottom of the brain; it is the site where two
lobes of the brain -- the occipital and the temporal -- converge (referred to
as the occipita-temporal area). This hectic region serves as a hub
where incoming information from different sensory systems comes together and
where, for example, all the relevant information about a word -- how it
looks, how it sounds, and what it means -- is tightly bound together and
stored. ...
"The
parieto-temporal system works for the novice reader. Slow and analytic, its
function seems to be in the early stages of learning to read, that is in
initially analyzing a word, pulling it apart, and linking its letters to
their sounds. In contrast to the step-by-step parieto-temporal system, the
occipito-temporal region is the express pathway to reading and is the one
used by skilled readers. The more skilled the reader, the more she activates
this region. It responds very rapidly -- in less than 150 milliseconds (less
than a heartbeat) -- to seeing a word; instead of analyzing a word, the
occipito-temporal area reacts almost instantly to the whole word as a
pattern. One brief glance and the word is automatically identified on sight.
Not surprisingly, the occipita-temporal region is referred to as the word
form area or system.
"Here's
how we think the word form system works. After a child has analyzed and correctly read
a word several times, he forms an exact neural model of that specific word;
the model (word form), reflecting the word's spelling, its pronunciation, and
its meaning, is now permanently stored in the occipito-temporal system.
Subsequently, just seeing the word in print immediately activates the word
form and all the relevant information about that word. It all happens
automatically, without conscious thought or effort. As skilled readers speed
through the text, the word form area is in full gear, instantly
recognizing one word after another. Not surprisingly, the best readers,
those with the highest scores on tests of reading, are the ones who show the
most activation of the word form region during imaging. ... There are therefore
three neural pathways for reading: two slower, analytic ones, the
parieto-temporal and frontal, that are used mainly by beginning readers, and
an express route, the occipita-temporal, relied on by experienced, skilled
readers. ..."
Author:
Sally Shaywitz, M.D.
Title: Overcoming
Dyslexia
Publisher:
First Vintage Books Edition
Date:
Copyright 2003 by Sally Shaywitz, M.D
Pages:
77-79, 81
Overcoming Dyslexia: A New
and Complete Science-Based Program for Reading Problems at Any Level
by Sally Shaywitz M.D. by
Vintage
Paperback ~ Release Date: 2005-01-04
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