W3.2 and 4.2: Reading and the brain Flashcards
(23 cards)
What is the ‘visual word form’ area? (Cohen)
A region in the left ventral occipitotemporal cortex, also known as the brain letter box. It is activated specifically by letter strings acceptable in the language e.g. the suffix for some words
What is the optic chiasma?
Crossing of optic nerves
What are the differences in function of the inner and outer retina?
Inner retina- sends images across
Outer retina- sends images within, captures info on the opposite side
How are words transformed from initially being seen to at the eye fixation point to the occipital lobes?
Words presented to the left- sent to the opposite hemisphere (contralateral) where processing is restricted to this visual area
Information is then transferred from both occipital poles to a more ventral region of the left occipital lobe aka the visual word form area
What may happen in event of a lesion to the visual word form area at a young age?
It may swap to the right hemisphere in the exact same location
How do the stages of reading translate to brain regions?
Activation starts in both occipital poles- at about 170ms, it shifts to the left occipito temporal region, at about 230ms, it explodes in both regions of both temporal lobes
From 300ms onwards, it extends over prefrontal and other temporal regions, especially in the left hemisphere, before falling back in part to the posterior visual areas (occipital pole)
What is the repetition suppression effect?
If one stimulus is repeated the same, the brain has an easier time the second time around which leads to a reduced neural response- there is less spiking on the part of neurons that do their job, so the amount of activity is not as strong- a neural adaptation which is useful for learning
What did Glezer et al (2015) find about the visual word form area?
Pseudoword pairs showed a graded effect, whereas real words and trained pseudowords showed all or none repetition suppression
When words are coded in that region, pattern of suppression depends on whether they are identical in the trial- if one is different, it falls apart
What claim did Gezer put forward about the VMFA?
Input dictionary (how words look) words as objects and shapes should be stored as neurons. Data showed that when looking at real words, there was a suppression only when the same word was presented a second time round. Novel words were taught to ppts they had been trained on, and some they had not been trained on. For things that are not words in lexicon, there is a graded effect.
What do cognitive models on reading tend to make predictions about?
The functional overlap between brain regions involved in reading- regions most active when you see words that should correspond to your vocab system (dictionary regions of the brain) which are more active for words than they are for pseudowords
What are the distinctions between regular words and irregular words?
Regular- translation rule that can be read by vocab part of the system
Irregular- e.g. have, pint- where the only way to read these is by finding a region that is involved or activated by certain stores or regions, vocab part not as crucial
What did Taylor et al (2012) investigate in a meta analysis of 36 neuroimaging studies on reading and brain regions?
Looked at if the studies pointed at the same regions regarding two contrasting dimensions in DRC: lexical status (words v non words) and regularity (regular v irregular). Distinguished between engagement v effort and how this translates into a BOLD signal, tested whether the distinction between engagement and effort made sense in DRC, checking their relevance. They did this by inserting an electrode and comparing the three strings: pseudowords low frequency words and high frequency words
What does engagement refer to in response to reading?
Whether or not the brain region is able to deal with the capacity of the stimulus and evoke knowledge in that region
What does effort refer to in response to reading?
Refers to the amount of resources/fuel required to code and process the stimulus in that region once it is engaged
What did Taylor et al (2012) find in a meta analysis of 36 neuroimaging studies on reading and brain regions?
Pseudowords take a lot of time to develop a small bit of activity and do not engage the lexicon in comparison to words
Words themselves differ depending on how well practiced they are by the system
Frequent words are recognised faster than rare words
More effort for reaching the same activity for rare words as opposed to frequent words
Confirms that distinction between engagement and effort is a valid one
What is the subtraction logic?
Having to subtract fmRI images from reading words to fMRI images from pseudowords, to isolate brain regions that are involved only in words or pseudowords; this is because it removes the activity common to processing the two kinds of stimuli from the brain map generated by existing words and identify neural activity to lexical processing
What will evoke the lexicon (dictionary) more than symbols or non-orthographic strings and why?
Rare or irregular words
This is because non-orthographics are not represented in lexical memory and will therefore not activate any word neighbour. The mental dictionary should be taxed more by irregular words than regular words, especially for words that occur less often.
What two contrasts point to the lexicon and how does this vary for DRC?
a) irregular words minus non orthographic strings, and
b) low frequency irregular minus high frequency regular words
DRC- specifically excludes the semantic system as the model does not assume more engagements of semantics for irregular words compared to regular words
How can the lexico-semantic pathway be isolated by multiple contrasts?
Engagement- words minus pseudowords
Effort- low frequency minus high frequency words
How can the input lexicon be isolated by multiple contrasts?
Engagement: irregular words minus non orthographic strings
Effort: (low-F) irregular words minus (high-F) regular words
How can the print to sound conversion/phoneme output buffer be isolated by multiple contrasts?
Engagement: pseudowords minus non orthographic strings, irregular words minus non orthographic strings
Effort: pseudowords minus regular words, irregular words minus regular words
How would the following components: lexical decision, visual feature detection, phonological lexical decision, stimulus repetition detection and rhyme judgement, respond to the processing of the word: ‘BRAIN’ ?
Lexical decision- is BRAIN a word?
Visual feature detection- is there an I in BRAIN?
Phonological lexical decision- does BRANE sound like a word?
Stimulus repetition detection- BRAIN, BRAIN
Rhyme judgement- do BRAIN and TRAIN sound the same?
See figure 7
What is the peak of oxygen in the non lexical route predominately used for?
Pseudowords
Speech output system requires stronger effort whereas actual words can be mainly read out by both routes as the system has seen them before
