reading and the brain Flashcards
The proximity of Ventral occipito-temporal cortex area to other regions coding faces and objects supports what idea
that the brain has evolved to perceive letters and words as complex objects
emergence in reading required….
The emergence of reading in the course of evolution may have required recycling of the some of the neurons initially dedicated to coding just regular visual objects.
what did Cohen et al 2000 say about the brain fixation points
Fixation cross- words presented to the left is processed in the right 168ms after. Same goes for words presented to the right (152ms later in left).
what happens when a retina captures visual field?
the inner retinas send information across, to the opposite hemispheres, whereas the outer retinas send information to the hemisphere on the same side
What happens because of the visual word form area is located in the left hemisphere
information coded in the primary visual areas in the right hemisphere (i.e., the left visual hemi-field) has to cross to the left hemisphere. This transfer from right to left is done via the corpus callosum, which connects the two hemispheres
how can we look at the timecourse of visual word processing
using magneto-encephalography (MEG).
What happens during reading
- During reading, activation starts in both occipital poles.
- At about 170ms it shifts to the left occipito-temporal region.
- At about 230ms activity explodes in regions of both temporal lobes.
- From 300ms onwards it extends over prefrontal and other temporal regions, before falling back in part to the posterior visual areas (occipital pole).
- Marinkovic et al. (2003)
What did Catani et al 2003 find about the brain
Fibres depicted in red convey information from port-to-port, in an omnibus fashion; those depicted in green work like motorways
the reading system, obviously, these two types of fibers are especially important in the left hemisphere (unlike on the picture), to transfer information from the ventro-occipital regions (VWFA) to both posterior areas of the frontal lobe and temporal regions
They (Taylor et al 2012) examined whether 36 neuroimaging studies of reading pointed at the same brain regions regarding two main contrasting dimensions in DRC
1) lexical status (i.e., words vs. nonwords; Is the stimulus part of your long-term memory?)
2) regularity (i.e., regular/irregular; Can the word be read correctly by both routes?)
What does engagement refer to
Engagement refers to whether or not the brain region in question is able to deal with the stimulus. In other words, it refers to the capacity of the stimulus to evoke knowledge in that region
what does effort refer to
Effort refers to the amount of resources/fuel required to code and process the stimulus in that region, once the region is engaged
what is lexical status
words vs. nonwords; Is the stimulus part of your long-term memory
what is regularity
regular/irregular; Can the word be read correctly by both routes?)
what did Taylor et al 2012 do
They examined whether 36 neuroimaging studies of reading pointed at the same brain regions regarding two main contrasting dimensions in DRC:
1) lexical status (i.e., words vs. nonwords; Is the stimulus part of your long-term memory?)
2) regularity (i.e., regular/irregular; Can the word be read correctly by both routes?)
- They distinguished between engagement vs. effort in how these dimensions translate into BOLD (Blood Oxygen Level Dependent) signal (i.e., amount of oxygen needed by a region).
what is the subtraction logic
If interested in retrieving regions involving reading words. Look at the areas activated and subtract areas activated by pseudowords. This gets rid of regions focusing on both types of words
apply subtraction logic to DRC model lexical pathway
The lexical pathway (in red and yellow) engages words, but not or only weakly pseudoword strings. It is also taxed more by low-frequency words compared to high-frequency words. We have therefore here two contrasts that point towards the lexical route: (a) words minus pseudowords, (b) low-frequency words minus high frequency words.
In DRC, the regularity contrast points specifically to the lexicon and excludes the semantic system. This is because the model does not assume more engagement of semantics for irregular words compared to regular words.
what does the lexical pathway engage
words but not pseudowords
what does the lexicon pathway engage
irregular words more than non-orthographic
what does the non-lexical route engage
words and pseudowords over non-orthographic strings
how to do subtraction method in the lexico-semantic pathway
- words minus peudowords
- low-frequency minus high-frequency words
how to do subtraction method in the input lexicon
- Irregular words minus non-orthographic strings
- (Low-frequency) Irregular words minus (high-frequency) regular words
how to do subtraction method in The conversion route and phonemic output buffer
pseudowords and words minus non-orthographic strings
pseudowords minus regular words
irregular words minus regular words
what was taylor et al 2012 study
36 fMRI or PET studies included in the meta-analysis.
Same task on both words and pseudowords, or regular and irregular words.
Tasks
- reading aloud or silently
- lexical decision (Is BRAIN a word?)
- visual feature detection (Is there a | in BRAIN?)
- phonological lexical decision (Does BRANE sound like a word?)
- stimulus repetition detection (e.g., BRAIN BRAIN)
- rhyme judgement (do BRAIN and TRAIN sound the same?)
notes about taylor et al 2012 results
To be included, studies simply had to measure brain activity using functional magnetic resonance imaging (fMRI) or positron emission tomography (PET) during reading words vs. pseudowords, or irregular vs. regular words, in the same task. As you can see, just focusing on lexical status and regularity already provided an impressive and consistent picture of the brain regions sub-serving the main assumed components of the DRC model.
