CALT Neurobiology of Reading and Dyslexia 4 — Questions and Answers
Question 1: Which neuroimaging finding is most consistently associated with dyslexia in adults who have received effective intervention?
- Normalization of left hemisphere activation patterns
- Increased right hemisphere compensatory activation (Correct answer)
- Reduced bilateral occipital activation
- Decreased anterior cingulate activity
Correct answer: Increased right hemisphere compensatory activation
Adults with dyslexia who compensate successfully show increased right hemisphere activity, reflecting an alternative neural pathway for reading.
Question 2: The 'visual word form area' (VWFA) is located in which brain region and is critical for what reading process?
- Left inferior frontal gyrus; phonological assembly
- Left occipito-temporal cortex; rapid orthographic recognition (Correct answer)
- Right fusiform gyrus; letter-sound mapping
- Left angular gyrus; semantic access
Correct answer: Left occipito-temporal cortex; rapid orthographic recognition
The VWFA in the left occipito-temporal cortex specializes in rapid, automatic recognition of whole word forms during skilled reading.
Question 3: Which white matter tract connects Broca's area to Wernicke's area and is frequently disrupted in individuals with dyslexia?
- Uncinate fasciculus
- Corpus callosum
- Arcuate fasciculus (Correct answer)
- Inferior longitudinal fasciculus
Correct answer: Arcuate fasciculus
The arcuate fasciculus is the primary white matter pathway linking frontal and temporoparietal language regions, and its microstructural integrity is reduced in dyslexia.
Question 4: Research on the 'magnocellular deficit' hypothesis of dyslexia suggests that affected individuals show impaired processing in which sensory domain?
- Color discrimination
- Rapid temporal processing of visual and auditory stimuli (Correct answer)
- Sustained low-frequency auditory processing
- Fine motor proprioception
Correct answer: Rapid temporal processing of visual and auditory stimuli
The magnocellular deficit hypothesis proposes that dyslexia involves impaired processing of rapidly changing sensory information across both visual and auditory modalities.
Question 5: Studies of identical twins with dyslexia suggest a heritability estimate of approximately what percentage for reading disability?
- 20–30%
- 40–50%
- 60–70% (Correct answer)
- 85–95%
Correct answer: 60–70%
Twin studies consistently estimate the heritability of dyslexia at approximately 60–70%, indicating a strong but not exclusive genetic contribution.
Question 6: The cerebellum has been implicated in dyslexia primarily because of its role in which reading-related function?
- Visual field mapping
- Automatization of skilled procedures including phonological processing (Correct answer)
- Short-term memory storage
- Lexical semantic retrieval
Correct answer: Automatization of skilled procedures including phonological processing
The cerebellar deficit hypothesis proposes that the cerebellum's role in automating skills contributes to the difficulty dyslexic readers have achieving fluent, automatic decoding.
Question 7: In event-related potential (ERP) research, dyslexic readers typically show atypical responses in which component associated with phonological processing?
- N400 semantic mismatch response
- Mismatch negativity (MMN) to phoneme contrasts (Correct answer)
- P300 target detection response
- N170 face recognition component
Correct answer: Mismatch negativity (MMN) to phoneme contrasts
Dyslexic readers frequently show reduced or atypical MMN responses to phoneme contrasts, reflecting imprecise neural encoding of speech sounds.
CALT Neurobiology of Reading and Dyslexia 4
Which neuroimaging finding is most consistently associated with dyslexia in adults who have received effective intervention?