DCL Task 5. Reading
Learning goals:
1. Individual differences in reading development, especially dyslexia
2. Underlying processes in reading development
3. Normal and abnormal neural correlates
4. ERP and fMRI studies
Shaywitz
Developmental dyslexia is characterized by an unexpected difficulty in reading in children
and adults who otherwise possess the intelligence and motivation considered necessary for
accurate and fluent reading. It has a neurobiological origin and has a genetic component. It is
characterized by difficulties with accurate and/or fluent word recognition and by poor spelling
and decoding abilities. These difficulties typically result from a deficit in the phonological
component of language (processing of speech sounds). Dyslexia is perhaps the most common
neurobehavioral disorder affecting children, 5 to 17.5 percent prevalence. Dyslexia is a
persistent, chronic condition. Over time, poor readers and good readers tend to maintain their
relative positions along the spectrum of reading ability.
Phonological theory: speech is natural and inherent, while reading is acquired and must be
taught. To read, the beginning reader must recognize that the letters and letter strings (the
orthography) represent the sounds of spoken language. In order to read, a child has to develop
the insight that spoken words can be pulled apart into the elemental particles of speech
(phonemes) and that the letters in a written word represent these sounds; such awareness is
largely missing in dyslexic children and adults. in young school-age children and adolescents
a deficit in phonology represents the most robust and specific correlate of reading disability.
Reading comprises two main processes - decoding and comprehension. In dyslexia, a deficit
at the level of the phonologic module impairs the ability to segment the spoken word into its
underlying phonologic elements and then link each letter(s) to its corresponding sound. As a
result, the reader experiences difficulty, first in decoding the word and then in identifying it.
The higher order cognitive and linguistic functions involved in comprehension, such as
general intelligence and reasoning, vocabulary, and syntax are generally intact. According to
the model, a deficit in a lowerorder linguistic function (phonology) blocks access to
higherorder processes and to the ability to draw meaning from text.
Neurobiological studies: fMRI
Use fMRI to examine the functional organization of the brain for reading in nonimpaired (NI)
and dyslexic (DYS) subjects; nonword rhyming.
- Normal: greater activation in
o left hemisphere sites: inferior frontal, superior temporal, parieto-temporal and
middle temporal–middle occipital gyri
o right hemisphere sites: an anterior site around the inferior frontal gyrus and
two posterior sites, in the parietotemporal and occipito-temporal region.
- Dyslexic: disruption in a posterior region involving the superior temporal gyrus and
angular gyrus with a concomitant increase in activation in the inferior frontal gyrus
anteriorly
Many studies show a failure of left hemisphere posterior brain systems to function properly
during reading and nonreading visual processing tasks and indicate that dysfunction in left
hemisphere posterior reading circuits is already present in dyslexic children.
Learning goals:
1. Individual differences in reading development, especially dyslexia
2. Underlying processes in reading development
3. Normal and abnormal neural correlates
4. ERP and fMRI studies
Shaywitz
Developmental dyslexia is characterized by an unexpected difficulty in reading in children
and adults who otherwise possess the intelligence and motivation considered necessary for
accurate and fluent reading. It has a neurobiological origin and has a genetic component. It is
characterized by difficulties with accurate and/or fluent word recognition and by poor spelling
and decoding abilities. These difficulties typically result from a deficit in the phonological
component of language (processing of speech sounds). Dyslexia is perhaps the most common
neurobehavioral disorder affecting children, 5 to 17.5 percent prevalence. Dyslexia is a
persistent, chronic condition. Over time, poor readers and good readers tend to maintain their
relative positions along the spectrum of reading ability.
Phonological theory: speech is natural and inherent, while reading is acquired and must be
taught. To read, the beginning reader must recognize that the letters and letter strings (the
orthography) represent the sounds of spoken language. In order to read, a child has to develop
the insight that spoken words can be pulled apart into the elemental particles of speech
(phonemes) and that the letters in a written word represent these sounds; such awareness is
largely missing in dyslexic children and adults. in young school-age children and adolescents
a deficit in phonology represents the most robust and specific correlate of reading disability.
Reading comprises two main processes - decoding and comprehension. In dyslexia, a deficit
at the level of the phonologic module impairs the ability to segment the spoken word into its
underlying phonologic elements and then link each letter(s) to its corresponding sound. As a
result, the reader experiences difficulty, first in decoding the word and then in identifying it.
The higher order cognitive and linguistic functions involved in comprehension, such as
general intelligence and reasoning, vocabulary, and syntax are generally intact. According to
the model, a deficit in a lowerorder linguistic function (phonology) blocks access to
higherorder processes and to the ability to draw meaning from text.
Neurobiological studies: fMRI
Use fMRI to examine the functional organization of the brain for reading in nonimpaired (NI)
and dyslexic (DYS) subjects; nonword rhyming.
- Normal: greater activation in
o left hemisphere sites: inferior frontal, superior temporal, parieto-temporal and
middle temporal–middle occipital gyri
o right hemisphere sites: an anterior site around the inferior frontal gyrus and
two posterior sites, in the parietotemporal and occipito-temporal region.
- Dyslexic: disruption in a posterior region involving the superior temporal gyrus and
angular gyrus with a concomitant increase in activation in the inferior frontal gyrus
anteriorly
Many studies show a failure of left hemisphere posterior brain systems to function properly
during reading and nonreading visual processing tasks and indicate that dysfunction in left
hemisphere posterior reading circuits is already present in dyslexic children.
