Lecture Three Flashcards
(18 cards)
What is peripheral dyslexia?
Impaired identification of letters in words.
e.g. Pure Alexia - Neglect dyslexia - Attentional Dyslexia
What is central dyslexia?
Intact letter identification but patients have problems accessing the sound/meaning of words.
e.g. Surface - Phonological - Deep
Where is the visual word form area?
In the left fusiform gyrus
It responds to words irrespective of their position in space or their appearance.
What do fMRI studies show that the visual word form areas responds to?
Responds more to words than consonant strings.
Responds to words in different formats.
To words in both the left and right visual fields.
What does EEG evidence show the VWFA is active after?
Active after 150-200ms after presentation of a word.
What did Young and Ellis found happened when right handed participants were told to look at central fixation whilst words were presented either briefly to the LVF or the RVF?
Found words in the RVF were identified more quickly and more accurately.
RVF advantage is also seen in languages that are read from right to left e.g. arabic.
What did Barca et al find happened after 100-300 ms of presenting words? And 200-400ms?
Activity begins to pass from one hemisphere across to the other.
After 200-400 theres activity in both hemisphere.
What did Barca et al find when placing an electrode in the visual word form area?
VWFA showed faster and stronger responses to words presented in the RVF than in the LVF. It responds to both RVF and LVF but the RVF has an advantage.
What can damage to the visual word form area cause?
Pure Alexia.
What is pure alexia?
Letter by letter reading and spelling dyslexia.
First reported by Jules Dejerine
Patients have great difficulty recognizing written words. Not aphasic they can spell and write.
Reading is very slow but speed increases with the number of letters in a word.
What are patients with alexia like when indicating whether two letters are identical.
Patients are quick to indicate whether or not two letters are physically identical but slow to match abstract graphemic identity.
Where does damage occur in people suffering from pure alexia?
Occurs from lesions in the vwfa and can also result from lesions which disconnect the vwfa from visual output.
Where is the visual word form area?
Left mid fusiform gyrus.
What did Price and Devlin (2003) find regarding the visual word form area?
fMRI study showed equal activation of thevwfa to visual objects and written words.
What problems do pure alexics have with reading?
Reading is possible but is extremely slow.
What problems do pure alexics have with visual items e.g. pictures?
Identification of line drawing is easier than reading.
There is some evidence of slowed picture naming but most of the effect is for written words.
What is neglect dyslexia?
Its the impact on reading and writing due to visuo-spatial neglect.
Visuo-spatial neglect involves inattention to the left side of the space following right hemisphere damage.
In reading patients tend to miss the left side of the page.
Theres incomplete/faulty information reaching the vwfa.
What kind of mistakes to neglect dyslexics make?
Deletion
Substitution
