TB7 B&B Lecture 3; Reading and Writing 1

• Writing can be defined as the use of visual systems to represent aspects of spoken lang.
• Types of writing system include;
  • Logographic; One symbol per word
  • Syllabic; One symbol per syllable
  • Alphabetic; One symbol per phoneme
• English orthography has messy rules, but there are some complex ones too. These include;
  • A few logographs (e.g &, %, @)
  • Single phonemes spelt with double letters (sh, ck, oo, ee)
  • Single letters spelling two phonemes (x --> ks)
  • Same phoneme spelt in different ways (fox, pheasent)
  • Complex rules (bath/bathe) 

• There is a distinction between regular, consistent spellings and irregular exception spellings.
  • Regular, consistent spellings are pronounced as you would expect from their spellings.
    • Hint, gore, boat, root
  • Irregular exception spellings are the opposite, their pronounciation is not as expected!
    • could, pint, love, sword...
• Due to these, English CANNOT be read reliably using normal grapheme-conversion rules. These would cause you to mispronounce irregular words = Regularisation errors.
• This complexity does mean however that when studying language disorders, many subsets can be compared, e.g familiar with inverted non-words, regular and irregular spelt words, concrete v.s abstract meanings...

• DYSLEXIA = Disorder of reading
  • Peripheral dyslexia; impaired identification of LETTERS in words. 
    • Pure alexia (letter-by-letter)
    • Neglect dyslexia
    • Attentional dyslexia
  • Central dyslexia; Intact letter identification, impaired ACCESS of the sounds or meanings.
    • Surface dyslexia
    • Phonological dyslexa
    • Deep Dyslexia
• DYSGRAPHIA = Disorders of spelling and/or writing

These disorders can be either acquired (following damage) or developmental (present in childhood in the absence of damage).

• Disorders of semantic and syntactic processing have SIMILAR effects on spoken and written language processing.
• Ths suggests that speaking, listening, reading and writing SHARE common semantic and syntactic processes.
• There is a need for abstract representations of words. This enables us to recognise words in a variety of different formats; it is asked if the different forms a word can take converge upon the same abstract representation? <- a VISUAL WORD FORM.

• Located on the LEFT MIDDLE fusiform gyrus.
• Responds to words irrespective of position in space or appearence.
• fMRI evidence suggests;
  • vwfa responds words > consonant strings (chair v.s chr)
  • vwfa responds to words in different formats (chair and CHAIR > chAIr)
  • vwfa is active within 150-200ms after word presentation (EEG).
  • vwfa responds to words in either visual field BUT!...there is a right visual field advantage.

What is the natural function of the vwfa? We cannot be born with one due to our historically recent addition of complex language. vwfa's expertise must be acquired over reading development!

• fMRI shows equal activation of vwfa to both visual objects and written words...is the vwfa an object recognition area which adapts to recognising written words as well as objects?

• Words presented to the LEFT visual field will be projected into the RIGHT hemisphere. Words presented to the RIGHT visual field will be projected to the LEFT hemisphere.
  • Via the corpus collosum, there can be cross-hemisphere talk between the corresponding regions of cortex.
• In healthy pps, words presented in the RVF are identified quicker and more accurately than those in the left. (Ellis and Young, 1985)
• The RVF advantage is NOT due to habitual reading or scanning directions as it has also been shown in languages read from left to reight such as arabic and hebrew.

There is also the question of does the vwfa respond EQUALLY quickly and strongly to LVF and RVF words? 0-200 ms, there is activity in the L and R cortex for the opposite VF. 100-300ms there is transfer of activity from hemis and 200-40ms there is activity in both hemis.

NO! EEG recordings from vwfa show a bias of strength towards RIGHT compared to left, although it still responds to both.

Also known as 'spelling dyslexia', letter-by-letter reading.

Cause

• Damage to the vwfa, or damage resulting in the vwfa disconnecting from visual input.

Symptoms

• Pps can still spell and write (not aphasic), but have great difficulty recognising written words.
  • Patients are QUICK when discriminating between physical differences
  • Patients are SLOW on matching on abstract graphic identity
• Reading speed is slow but also INCREASES with the number of letters in a word.
• With pictures, identification of LINE drawings is easier than reading. There is also evidence of slowed picture naming.

This disorder highlights the impact of reading+writing on visuo-spatial neglect. Visuo-spatial neglect is characterised by INATTENTION to the left side of space following right hemi damage.

Clinical signs include;

• Bisection of a line towards the RIGHT.
• OMISSION of left sided targets in cancellation tasks.

In reading, patients tend to miss words on the left side of the page, aswell as misreading the beginnings of words.

It seems there is incomplete/defective information reaching the vwfa.