Dyslexia

Question 1

Symptoms in Preschool Children

Answer 1

• delayed speech development
• speech problems - mispronunciations e.g. ‘beddy tear’ instead of ‘teddy bear’
• problems with rhyming words and nursery words
• problems learning letters of the alphabet

Question 2

Symptoms in School Children

Answer 2

• problems learning sounds and names of letters
• reversing letters and figures ‘6’ instead of ‘9’
• visual disturbances - words and letters appear blurry or to move around
• problems with sequences e.g. days of the week

Question 3

Symptoms in Teenagers/Adults

Answer 3

• poor organised written work
• difficulty planning/writing essays
• poor spelling
• poor reading fluency

Question 4

Developmental Dyslexia

Answer 4

• significant deficit between reading ability and that expected from child of that age and IQ despite education, family support etc

Question 5

DSM-V Specific Learning Disorder - Reading Disorder

Answer 5

• neurodevelopmental disorder that impedes the ability to learn or use specific academic skills
• criteria a: 6 months of persistent learning difficulty despite extra help or instruction
• criteria b: cause impairment in academic, occupational, everyday activities
  …

Question 6

What is Dyslexic?

Answer 6

• impairment at the word processing level, impairment in grapheme-phoneme conversion
• specific and significant disorder of reading development
• difficulty learning to read accurately and with adequate speed
• impaired decoding skills
• 5-17% of children have dyslexia (Shaywitz, 1998)

Question 7

The Phonological Theory of Dyslexia

Answer 7

• most influential theory
• suggests cognitive deficits specific to the representation and processing of phonological info causes dyslexia
• difficulty associating letters with correct speech sounds (Snowling, 1995)

Question 8

Phonological Processing

Answer 8

• the process of breaking a word down into constituent sounds
• involves detecting and discriminating differences in phonemes or speech sounds
• if unable to break down the word it causes problems with sound segmentation and word blending. Both of which are critical for development of reading and spelling

Question 9

Strengths of The Phonological Theory

Answer 9

Lots of evidence:

• phonological skills are crucial for accurate and fluent reading
• phonological awareness in young children can predict future reading ability (Bradley & Bryant, 1983)
• intervention studies providing phonological training show improvement in word identification , spelling and reading ability (Bryant &Bradley, 1985)

Question 10

Weaknesses of The Phonological Theory

Answer 10

• provides a circular argument
• a singular phonological deficit isn’t capable of explaining the entire phenotype of dyslexia
• not everyone with dyslexia shows a phonological deficit (Valdios et al, 2011)
• not everyone with phonological deficit has dyslexia (Snowling, 2008)

Question 11

The Phonological Deficit Theory Can Explain:

Answer 11

• slower reading speed and poor reading accuracy
• difficulties acquiring phonological skills
• difficulties retrieving spoken language

Question 12

Attention Theories of Dyslexia (The Sluggish Attentional Shifting Hypothesis (Hari & Renvall, 2001))

Answer 12

• key theory
• suggests those with dyslexia struggle to disengage with visual and/or auditory stimuli
• also may explain phonological problems:
  
  • SAS could distort perceptions of speech and hamper the development of phonological representations
  • SAS has been suggested to cause problems with orthographic-phonological binding

Question 13

Strengths of Attentional Theories (SAS)

Answer 13

Evidence:

• research has found impaired serial visual identification (Ruffino et al, 2010) and slower spatial cueing (Facoetti et al, 2010) for dyslexic children
• studies find sluggish attention deficits across auditory and visual domains

Question 14

Weaknesses of Attentional Theories (SAS)

Answer 14

• less dominant theory
• SAS is often found alongside phonological deficits but debates about causality
• deficits in visual spatial skills do not predict reading difficulties in all children and some children without reading difficulties show visual problems

Question 15

Visual Attention Theories (Visual Attention Span Deficit Hypothesis, Bosse, Tinturier & Valdois, 2007))

Answer 15

• suggests visual attention is the ability to rapidly select the most relevant visual info
• those with dyslexia limited to how many letters they can process at once - deficit in the allocation of attention across letter strings

Question 16

Strengths of Visual Attention Theories (Visual Attention Span Deficit Hypothesis, Bosse, Tinturier & Valdois, 2007))

Answer 16

Evidence:

• several studies found visual attention span difficulties in a significant number of poor readers (Bosse et al, 2007)
• visual attention span deficits can be dissociated from phonological deficits, magnocellular dysfunction and SAS

Question 17

Weaknesses of Visual Attention Theories (Visual Attention Span Deficit Hypothesis, Bosse, Tinturier & Valdois, 2007))

Answer 17

• less dominant theory
• inconsistencies within research argue that phonological deficits CAUSE the differences found in visual attention span (Hawelka & Wimmer, 2008)

Question 18

Subtypes of Dyslexia

Answer 18

• current research suggests a majority subtype characterised by a phonological deficit and one or more minority subtypes characterised by a visual deficit (Bosse et al, 2007)

Question 19

Auditory Processing

Answer 19

• how the brain recognises and interprets sounds in the environment

Question 20

Auditory Processing Deficit

Answer 20

• leads to an inadequate understanding/representation of speech sounds which is suggested to impact on a child’s inability to learn to read

Question 21

Is there One Specific Brain Area for Reading?

Answer 21

• rather than one brain area specifically for reading, areas for spoken language and object recognition are redirected for reading (Dahaene & Cohen, 2007)

Question 22

Cognitive Processes Involved in Reading

Answer 22

1) grapheme-phoneme mapping: combos of letters (graphemes) are mapped onto their corresponding sounds (phonemes) - decoding
2) visual word form recognition for mapping of familiar words and their mental representations

Question 23

Brain Areas Involved in Reading

Answer 23

• reading is achieved via a network of regions in the LH (Price, 2012)
• occipito-temporal cortex holds ‘visual word form area’
• temporo-parietal & inferior frontal cortices play a role in phonological and semantic processing of words
• inferior frontal cortex involved in speech and sound formation

-this is altered in people with dyslexia (Richlan et al, 2011)

Question 24

Brain Structure in Dyslexia

Answer 24

Connection between brain structure and dyslexia discovered by examining brains of deceased adults who had dyslexia

Findings:

• asymmetry typically seen in LH temporal lobe not found in these brains (Galaburda & Kemper, 1977)
• ectopias: small displacements of brain tissue on the surface of the frontal regions and left language areas
• dysplasia: loss of characteristic architectural organisation of cortical neurons. Located beneath ectopias.
• vascular micro-malformations

Proposed?

• cause of dyslexia is microscopic changes in brain physiology
• neuronal base cells divide and migrate in dyslexia which leads to cortical malformations

Question 25

Neurological Bases for Dyslexia

Answer 25

• Paulesu et al (2001): dyslexia is Italy < France < England

is there a universal biological origin?

Question 26

Disconnection Hypothesis

Answer 26

• suggests connections between the different components of the language system are weak
• Pugh et al (2000) used fMRI to show dyslexic readers have a disruption in connectivity in the language dominant LH which disrupts tasks that require assembly
• supports idea that neurobiological anomalies are largely confined to phonological processing

Question 27

Changes in Reading, Changes in The Brain

Answer 27

• anatomical and functional changes found in dyslexic readers brains following effective reading instruction (Eden at al, 2004)