Neural basis of reading

Question 1

what is the word superiority effect?

Answer 1

• Visual processing time is not strongly affected by length
  - suggesting letters are not analysed one by one:
  - PSYCHOLOGY vs. SKY
• Letters identification is affected by whether it makes up a word or not
  - Letter identification has top-down influences from word knowledge
  → the brain stores some sort of ‘word forms’
  → When word form is lost, you develop ‘word blindness’

Question 2

what is word blindness?

Answer 2

• neuropsychological cases
• Monsieur C developed ‘Word Blindness’ – incapable of understanding written words
• Autopsy by neurologist Joseph Dejerine shows stroke damage to the left ventral occipitotemporal cortex (vOTC)
• Dejerine thought this was a connection that carries visual information forward to language areas of the brain
• Others think this could be a ‘mental dictionary’ that stores the word forms

Question 3

Is the left vOTC the Visual Word Form
Area (VWFA)?

Answer 3

• Patients with left vOTC damage (dubbed the Visual Word Form Area) shows the word length effect (pink, yellow), compared to visual cortex-lesioned patients without vOTC damage (green, blue)
• L-vOTC is likely more than a mere visual connection, but an area that processes word forms

Question 4

Is the Visual Word Form Area (VWFA)
Located in the Left Brain Only?

Answer 4

• Visual information is processed contralaterally:
  * Left hemifield → Right brain
  * Right hemifield → Left brain
• Words shown in both hemifields activate the VWFA more than consonant strings
• Only the left vOTC seems to be specialised for word form processing

Question 5

Is The Visual Word Form Area (VWFA)
Really on the Left!

Answer 5

• Split-brain Patient A.C. cannot recognise words presented in the left hemifield
• Visual information in the right visual cortex cannot be sent across to the left vOTC for word form processing
• There is no right-brain equivalent of a VWFA

Question 6

Is the Visual Word Form Area (VWFA) a
Legend or a Myth?

Answer 6

• The so-called VWFA responds to a range of non-visual-word stimuli
• The left vOTC may not be a ‘visual lexicon’ as such
• It is probably specialised in processing particular kinds of stimuli that happen to be very important in reading.

Question 7

What is a basic model of reading aloud?

Answer 7

visual word form → access pronunciation → read it aloud

Question 8

What are the two types of acquired dyslexia?

Answer 8

• Reading difficulties developed due to acquired brain damage (injuries, stroke, dementia, etc.)
• Peripheral dyslexia
  
  • Disruption of early visuo-attentional processing (letter & words)
  • Includes: Pure Alexia, Attentional Dyslexia, Neglect Dyslexia
• Central dyslexia
  
  • Disruption of phonological or semantic processing after visual word form processing
  • Includes: Surface Dyslexia, Phonological Dyslexia, Deep Dyslexia

Question 9

What is Pure Alexia?

Answer 9

• Pure Alexia Maps the Left vOTC to Visual Word Form Processing
• Word Blindness (Pure alexia)
• Visual Word Form →← left vOTC
• In pure alexia, reading is letter-by-letter
• They struggle with abstract letter identity

Question 10

What is attentional dyslexia?

Answer 10

• Attentional Dyslexia Reflects Deficits in Attentional Filtering
• Difficulty in separating constituent letters/words
• O vs. BOTTLE vs. I DRANK A BOTTLE OF WATER
• Letter migration errors
  - WIN FED → FIN FED

Question 11

What is neglect dyslexia?

Answer 11

• Letter substitution errors on one side (contralateral lesion)
• CLOCK → BLOCK left-side
• CLOCK → CLOAK right-side

Question 12

what is surface dyslexia?

Answer 12

• Surface dyslexia patients know the rules of regular pronunciation.
• When the pronunciation is irregular, they follow the regular pronunciation:
  
  • PINT → /p-i-nt/
  • DOVE → /d-oo-v/

Question 13

what is phonological dyslexia?

Answer 13

• Phonological dyslexia patients are fine with real words (regular and irregular)
  
  • Phonological lexicon is fine
• tend to read a nonword as a real word
  
  • CHURSE → NURSE
• They tend to show problems in phonological processing (e.g., auditory rhyme judgment)

Question 14

what is deep dyslexia?

Answer 14

• Like phonological dyslexia patients, deep dyslexia patients can read real words
• But real-word reading is error-prone:
  
  • Semantic errors: CAT → DOG
  • Derivational errors: BEG → BEGGAR
  • Concrete words (wine)> Abstract words (truth)
• Phonological retrieval is affected by semantic impairment