Developmental Dyslexia

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Developmental Dyslexia. Laurie Philbeck. Definition of Dyslexia. Dyslexia or specific reading disability is neurobiological in origin and is characterized by difficulties with accurate and/or fluent word recognition, poor spelling, and decoding abilities. - PowerPoint PPT Presentation

Transcript of Developmental Dyslexia

Dyslexia in Children

Developmental DyslexiaLaurie PhilbeckDyslexia or specific reading disability is neurobiological in origin and is characterized by difficulties with accurate and/or fluent word recognition, poor spelling, and decoding abilities. Difficulties result from a deficit in the phonological component of language that is unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. (Shaywitz, 2008)

Definition of DyslexiaDyslexia is unexpected because it refers to the presence of a reading difficulty despite having all of the factors (intelligence, motivation, exposure to reasonable reading instruction) present to be a good reader, yet continues to struggle 2Children with dyslexia have difficulty hearing the phonemes within words, resulting in difficulty learning to associate the letters with specific sounds within each word. Thus the word bat is composed of three phonemes, b, aaa, and t but the listener hears this as the holistic word bat and not as three separate sounds.Shaywitz (2008)

Phonological Awareness DifficultyPhonemes are the smallest units of speech distinguishing one spoken word from another.

3Like hypertension and obesity, dyslexia occurs in degrees of severity. Dyslexia follows an unremitting course (meaning a child can not outgrow it) causing early intervention to take on a new urgency.

Degree and Course of DyslexiaBetween dyslexia and ADHD ranging from 15% to 50%ComorbidityDyslexia is heritable. The disorder is found in 23% to 65% of the children of parents who are dyslexic 40% of the siblings of a dyslexic child are affected If a child or parent has a sibling who is dyslexic, that child should be considered at risk and observed carefully for signs of a reading difficulty.Shaywitz (2008)Genetic InfluenceIt is important to note that just because a child may be susceptible to dyslexia does not negate early intervention approaches. Once identified a child who has dyslexia will benefit from evidence-based interventions.6Late speaking, mispronunciations, difficulties with word retrieval, needing time to summon an oral response, confusing words that sound alike, such as saying recession for reception. Slow reading, difficulties in spelling, handwriting.Thinking, reasoning, vocabulary, and listening comprehension are intact.

SymptomsBegin to speak at a later age7Sally Shaywitz (2002) had 70 dyslexic children and 74 non-dyslexic children read words and pronounceable non-words while in fMRI. Shaywitz and other neuroscientists have been able to identify and localize several interrelated left hemisphere neural networks in reading. Three systems are evident: Brocas area, Wernickes area, and posterior occipito-temporal regionBrain Imaging Studies

As seen in the non-impaired brain, Brocas Area (inferior frontal gyrus) associated with articulation (speech), the Wernickes Area (parieto-temporal region) associated with word analysis, and the other in the left occipito-temporal region called the word form area, critical for skilled fluent reading.9Neural Signature for DyslexiaSchematic view of left hemisphere brain systems for reading observed during fMRIFigure reprinted from (Shaywitz 2003)

Functional brain imaging studies show that the dyslexic readers indicate a failure of left hemisphere posterior brain systems to function properly during reading. Dr. Feifer described how an impaired brain works while reading print. The frontal lobes derive meaning from print and the back of the brain decodes the print. An impaired brain activates the frontal lobe only while reading preventing automaticity.

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Develop compensatory systems involving areas around the inferior frontal gyrus in both hemispheres as well as the right hemisphere homologue of the left occipito-temporal word form area.Shaywitz (2008)Compensate

Schools have typically relied on the discrepancy model requiring a discrepancy between the childs measured IQ and reading achievement in order for children to receive services. Problem with discrepancy model is because children who are clearly struggling as early as kindergarten or first grade have to wait until the third grade or later when their failure in reading becomes of such a magnitude that they meet discrepancy requirements. (Shaywitz, 2008).

Wait-to-Fail ModelData strongly indicates that when interventions are provided within the very first years of school a much more positive response is shown 14Window of Time -When the student becomes around 9 to 11 years old the temporal lobe loses its plasticity causing it to become hard wired. We are born with more neurons then we need that are attune to any sound in the world, however as we are exposed the given language of our household those neurons are wired and fired together allowing other unused neurons to discard (brains pruning approach).Dr. Steven Feifer (2010 NASP Conference)

Early InterventionInterventions with older children involve memorization of words since they can no longer make good use of sound symbol linkages15Evidence-based reading intervention at an early age improves reading fluency and facilitates the development of those neural systems that underlie skilled reading.Fluency focused intervention requires significant reading of connected text with scaffolding support by either peers or teachers.Prevention programs focus on phonemic awareness, phonics, and meaning of text in the earliest grades of reading instruction.Early InterventionToo early to detect dyslexia however this will improve core reading skills in the weakest readers at these ages.

16Interventions focus on word decoding and single word identification levels have had the most consistent effectiveness particularly in prevention in early childhood studies. Explicit, intense, systematic, and developmentally appropriate multi-focused, evidence-based interventions are effective.

Early InterventionAccording to National Reading Panel in 2000, they found five essential elements should be incorporated into effective reading instruction: Phonemic Awareness, Phonics, Fluency, Vocabulary and Comprehension. These should be taught systematically and explicitly.Explicit instruction in speech sound awareness and sound symbol association helps to prevent reading failure (Eden and Moats, 2002)

Effective InstructionStudents should be encouraged to read a lot and often to support the development of fluent and automatic reading.

Effective InstructionDyslexia is a clinical diagnosis best made by a experienced clinician who has taken a careful history, observed the child read and administered a battery of tests to assess cognitive, academic including reading accuracy, fluency, comprehension, spelling, and mathematics (often a high skill), language skills particularly phonological processing. Tests of reading fluency of how quickly and accurately individual words and passages are read.

Diagnosis and TestsTests for Phonological Awareness can be given by asking the child to repeat a word after omitting one of its sounds. For example cat without the /k/ or Germany without the /m/Eden and Moats (2002)TestsBrain imaging is used as a tool to examine the influences of reading instruction on the development or reorganization (repair) of these neural systems. Study of second and third grade dyslexic and non-impaired readers, compared with dyslexic readers who received other types of intervention, children who received an experimental evidence-based phonological intervention improved their reading and demonstrated increased activation both in left anterior (inferior frontal gyrus) and left posterior (middle temporal gyrus) brain regions (Shaywitz 2004).

Repairing Neural Systems

To keep up with classmates and increase knowledge: access to recorded materials such as books on tape etc.Extra time for examinations since that extra time is needed for reading since it is not automatic and fluent. Need quiet separate rooms for testing since they are non-automatic readers who need to call upon their attentional resources during reading

AccommodationsIf they are to demonstrate their full range of knowledge provision of additional time is necessary to compensate for the lack of availability of the efficient word form area (posterior occipito-temporal region)they are highly susceptible to noise and other distractions. Need to concentrate and make maximum use of their often strained attentional resources. 23(Reiter, Tucha, and Lange, 2004) tested 42 children with dyslexia and 42 non-dyslexic children using a neuropsychological test battery consisting of standardized tests examining assessment of working memory, concept formation, inhibition, flexibility, problem solving and fluency functions.Children with dyslexia reveled obvious difficulties with tests measuring working memory, inhibition of inappropriate reactions, and verbal and fluency functions.

Executive Functions

Dyslexic readers rely on memory rather than understanding how letters link to sounds, problem is that their memory has a limited capacity. Lack of reading fluently or automatically brings a need to read manually which is a process that consumes great effort.When teachers ask students to read silently, students with dyslexia will appear to be daydreaming or not attending to the assigned reading because they are depleting their attentional resources

For Teachers and StaffThey can read the words relatively accurately but not automatically, so they read very slowly with great effort.25Guinevere, E. F., Moats, L. (2002). The role of neuroscience in the remediation of students with dyslexia. Nature Neuroscience Supplement, 5, 1080-1084.

Reiter, A., Tucha, O., Lange, K., W., (2004). Executive functions in children with dyslexia. Dyslexia, 11, 116-131.

Shaywitz, S. E., Morris, R., S