CALT Neurobiology of Reading and Dyslexia 2 — Questions and Answers
Question 1: Neuroimaging research on dyslexia consistently identifies reduced activation in which brain region during reading?
- Broca's area
- The left posterior temporal-parietal region (Correct answer)
- The right frontal lobe
- The cerebellum exclusively
Correct answer: The left posterior temporal-parietal region
fMRI studies consistently show underactivation in left posterior brain regions, particularly the temporoparietal and occipito-temporal areas, during reading in individuals with dyslexia.
Neuroimaging research consistently demonstrates that individuals with dyslexia show reduced activation in left posterior brain regions during reading, particularly the left parietotemporal cortex and the left occipitotemporal cortex known as the visual word form area. Many individuals also show overactivation in Broca's area and right hemisphere regions, thought to represent compensatory strategies.
Question 2: The phonological deficit hypothesis in dyslexia research refers to:
- A deficit in visual processing of letters
- A core weakness in processing the sound structure of spoken language (Correct answer)
- A deficit in understanding word meanings
- A problem with working memory for numbers
Correct answer: A core weakness in processing the sound structure of spoken language
The phonological deficit hypothesis proposes that the core neural deficit in dyslexia involves difficulty processing the sound structure of language.
The phonological deficit hypothesis proposes that the central impairment in dyslexia is a weakness in representing, storing, and retrieving the phonological features of language. This deficit manifests as poor phoneme awareness, difficulty with phonological memory, slow naming speed, and weak phoneme-grapheme mapping, all of which impair the ability to learn to read an alphabetic writing system.
Question 3: Research on brain plasticity and dyslexia intervention has demonstrated that:
- The dyslexic brain cannot change with instruction
- Effective structured literacy intervention produces measurable neurological changes (Correct answer)
- Only medication can normalize reading-related brain activity
- Brain activity during reading is unrelated to instructional approach
Correct answer: Effective structured literacy intervention produces measurable neurological changes
Neuroimaging studies show that effective structured literacy intervention produces measurable increases in activation of the left hemisphere reading circuitry, demonstrating brain plasticity.
Studies by researchers including Sally Shaywitz and Jack Fletcher have used fMRI to show that children with dyslexia who receive effective structured literacy intervention show increased activation in left hemisphere reading regions following treatment. This evidence of neuroplasticity underscores the importance of early, intensive, evidence-based intervention.
Question 4: Magnocellular deficit theory proposes that some individuals with dyslexia have difficulty with:
- Color discrimination
- Processing rapid visual and auditory temporal information (Correct answer)
- Long-term memory for facts
- Spatial navigation
Correct answer: Processing rapid visual and auditory temporal information
Magnocellular deficit theory suggests that a subset of individuals with dyslexia have weaknesses in visual and auditory processing pathways that handle rapid temporal processing.
Magnocellular deficit theory proposes that the magnocellular layers of the visual system and analogous auditory pathways are impaired in some individuals with dyslexia, leading to difficulty with rapid temporal processing. While not the dominant theory, magnocellular deficits may co-occur with phonological weaknesses.
Question 5: The heritability of dyslexia suggests that:
- Dyslexia is caused entirely by poor teaching
- Dyslexia has no genetic component
- Genetic factors significantly contribute to the risk of developing dyslexia (Correct answer)
- Dyslexia is contagious
Correct answer: Genetic factors significantly contribute to the risk of developing dyslexia
Twin and family studies indicate that dyslexia is highly heritable at approximately 50 to 70 percent, with multiple genetic loci contributing to the risk.
Behavioral genetic research, particularly twin studies, indicates that dyslexia has a heritability estimate of approximately 50 to 70 percent, meaning genetic factors account for a substantial portion of the variability in reading ability. Multiple genes have been implicated and dyslexia is considered a complex polygenic trait. Effective early instruction can substantially improve outcomes for children with genetic risk.
Question 6: The double deficit hypothesis proposed by Wolf and Bowers identifies which two core deficits?
- Poor memory and low IQ
- Phonological awareness weakness and slow Rapid Automatized Naming (Correct answer)
- Visual processing deficits and auditory processing disorders
- Motor coordination problems and attention deficits
Correct answer: Phonological awareness weakness and slow Rapid Automatized Naming
Wolf and Bowers proposed that phonological awareness and naming speed are two distinct but related deficit pathways in dyslexia, and having both predicts the most severe reading difficulties.
Maryanne Wolf and Patricia Bowers' double deficit hypothesis proposes that phonological awareness and rapid automatized naming represent two separable core deficit pathways in dyslexia. Students with a phonological-only deficit, a naming speed-only deficit, or both form distinct subtypes, with the double deficit group showing the most severe and resistant reading difficulties.
CALT Neurobiology of Reading and Dyslexia 2
Neuroimaging research on dyslexia consistently identifies reduced activation in which brain region during reading?