Symposium on the Biological

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Symposium on the Biological Experiential
Aspects of Reading-Related Disorders Neurology,
Physiology, Genetics and Environment
IDA Denver, November 2005

• Summary, Implications Conclusions
• Angela Fawcett
• University of Sheffield UK

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Objectives - Jeff Gilger

• To understand
• The basis of atypical brain development
• Diverse factors impacting on the development of
  the child
• Overlap between disorders
• Issues The time course or ontogenetic chain for
  the development of learning disabilities

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Neuropsychology of Dyslexia Bruce Pennington

• Results of a longitudinal study examining genetic
  and cognitive overlaps between dyslexia and
  speech sound disorder
• Finds common genetic links for RD and SSD on
  chromosome 6 and 15

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Neuroanatomy (DTI) Robert Dougherty

• Examines the skills underlying skilled reading,
  based on the co-ordination of cognitive, sensory
  and motor systems
• Anatomical substrate
• Variations in brain and effects on reading

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The brain and dyslexiaGuinevere Eden

• Examines the joint influence of the brain, genes
  and the environment on learning to read
• Considers biology, cognition and behaviour
• Tries to account for individual variability in
  dyslexia

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Levels of Analysis
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Twin Studies Quantitative Genetics - Brian Byrne

• The role of genes and the environment
• Preschool precursors of literacy
• Early development of reading and spelling in
  school years
• Dual role for genes in phonology and rapid naming
  - smaller role for environment

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Molecular Genetics
Shelley Smith

• 6 (?) genes that influence dyslexia localized
• Other candidate genes identified
• Functions of these genes as explanation of
  underlying deficits

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Risk factors/Early Infant Studies - Heikki
Lyytinen

• Jyvaskyla Longitudinal study of dyslexia
• Emphases
• i) Early identification
• ii) Preventative training
• For children from at risk families
• See also Maggie Snowling, Saturday 10.45 on risk
  and protective factors

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Experiential/Environmental Risks - Susan Koger

• Examines the vulnerability of the developing
  nervous system
• Impaired brain function based on pre/perinatal
  insult
• Effects of substances such as lead, mercury,
  pesticides, solvents
• Implications for LD

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Ontogeny of LD
Gilger
Other LDs, Diagnoses
Smith, Pennington
Reading
Dougherty Eden
Pre-Cursors Primary Secondary Individual
Differences
Brain development
Genes
Primary symptoms
Environment
Secondary symptoms
Koger Byrne Lyytinen
Interventions
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Dyslexia Paradoxes

• The Diagnosis Paradox
• The Support Paradox
• The Phonology Paradox
• The Comorbidity Paradox
• The Learning Paradox
• Our approach to resolving these paradoxes is to
  consider learning - but this is only one approach!

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Neural Systems

• Cerebellar deficit
• Differences in brain scans and anatomy
• Automaticity deficit
• Difficulty in becoming expert in any task
• More effort
• Even in simple tasks
• Rod Nicolson Friday 10.45

Neural Systems
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The Challenge for Dyslexia research!

• We need to work in a consensual fashion to set up
  several competing frameworks
• Join up these findings into an ideal system.
• Address both theory and practice
• Consider both primary and secondary symptoms
• Begin to resolve the paradoxes

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Conclusions

• This symposium generates clearer understanding of
  protective and risk factors in dyslexia
• Role of genetic endowment, the environment, and
  plasticity in the developing brain
• Importance of co-morbidity and secondary as well
  as primary symptoms
• These are exciting times for dyslexia research -
  but there is still much to be done!