Tracing language circuitry: reading Flashcards
Where did Dejeurine suggest word forms live?
The ANGULAR GYRUS. This added a visual component to the classic model of reading.
How did Dejeurine’s model go?
Visual cortex –> angular gyrus –> WA –> BA.
Are there any problems with Dejeurine’s model?
Yup! Surface dyslexics are able to read regularly spelt words, but not irregularly spelt words, and phonological dyslexics can read words they know, but struggle with new words.
THESE TWO DYSLEXIAS SUGGEST THAT A SINGLE ROUTE TO READING IS NOT A SUFFICIENT EXPLANATION.
So what do we do about that?
Someone proposed a ‘dual-route model of reading’… which actually has three routes.
Input goes to either spelling to sound rules, -semantics- or [mental lexicon/recognition].
Thus, if you have damage to the lexical route, you become surface dyslexic, and to the spelling-to-sound route, you become phonologically dyslexic.
Does orthography have a specific place in the brain?
Yep. In the LH fusiform gyrus and occipital central sulcus –> the visual word form area.
Evidence found this. Also found that masked priming worked regardless of font, case etc. Suggests the VWF area must not have representations like this.
What does pure alexia have to do with orthography?
E.g. patient AR. Has a strong impairment in word reading. Can write, recognise letters and do naming tasks.
Had damage to LH OL. Evidence suggested ventral occipital temporal cortex = part of VWF area.
Is there good evidence for a visual word form area?
Not really – the deficit doesn’t seem specifically for recognising words, it seems wider. And a lot of the tasks which show activation in the VWF area do not involve reading at all!
Where does phonology live in the brain?
In the super-marginal gyrus, BA and LH inferior frontal gyrus.
SMG = auditory association cortex.
BA –> PMv = tissue is important for selecting, initiating and coordinating motor patterns.
Does semantics have a specific brain region?
Doesn’t look like it – likely angular gyrus, TLs, anterior BA, but doesn’t seem to be localised in same way, so harder to pinpoint where specific functions live.
Semantic dementia suggests that anterior TL especially in LH is important.
Where in the brain does the lexicon live?
We don’t know yet!
