Please enable JavaScript.
Coggle requires JavaScript to display documents.
SENTENCE PROCESSING :PENCIL2: D+L2 LECTURE 8 - Coggle Diagram
SENTENCE PROCESSING
:PENCIL2:
D+L2 LECTURE 8
Semantic memory and semantic processing
Multiple convergence zones and distributed meaning.
Hubs, convergence zones or control regions receive features from neighbouring areas and carry out semantic processing in contexts.
Which processing routes are involved in semantic processing then?
Brain regions
Fusiform gyrus = shape representation.
Fusiform Face Area (FFA)
Posterior temporal gyrus - near V5 → motion
‘Hub’ = where lots of different connections converge into one space.
Arcuate fasciculus, superior longitudinal fasciculus.
Uncinate fasciculus → links inferior frontal gyrus (Broca’s area) with the anterior temporal lobe.
Broca’s area gets input from the temporal lobe as well as from the dorsal route.
Semantic processing system is engaging both the ventral and the dorsal route at the same time because it has to work harder to do all of the work required to obtain semantic understanding for sentences.
Combining words into sentences
Selection of relevant features in context of other words is involved in sentence comprehension.
Need to decide what the right interpretation of the sentence is.
Sentence processing
LIFG plus posterior temporal gyrus in comprehension, just as in semantic processing.
Production involves more areas of the dorsal pathways
Because one needs to...
Find the words
Put them together in a motor plan
Pronounce them.
Imaging
Humphreys & Gennari (2014)
Production task (sentence completion)
Easy
: ‘the movie that the director…’
Hard
: ‘the director the the movie…’
Comprehension task:
Easy
: ‘the move that the director watched was good.’
Hard
: ‘the director that the movie impressed was good.’
In the
production
task participants were given a visual prompt (a phrase) that they had to complete into a full, plausible sentence.
In the
comprehension
task, participants simply read the sentence, and later answered comprehension questions.
In each task, the easy and hard conditions were compared, so one can see which regions are working harder in either production and comprehension.
Results...
Core shared network: LIFG, posterior middle temporal lobe (PMTG) showed stronger response to hard cases than easy ones.
Visual cortex is activated (red) as people are reading off of the screen in the scanner.
Temporal lobe activated (red)
Overlapping with the premotor cortex too.
Overlap between the language network when reading and the language network when producing, overlap occurs between posterior middle temporal gyrus (PMTG), parts of the temporal lobe, most of Broca’s area, and a bit of motor cortex.
Production (blue) involves activation of a lot of motoric areas, subcortical regions.
Production additionally recruits other regions in dorsal route, but both routes are involved.
Disorders of sentence processing
Telegraphic Speech:
Simplified formation of sentences where function words are omitted.
Common errors include errors in: tense, number and gender.
Sentence production: Agrammatism...
Agrammatism in Broca’s Area damage.
AKA …
‘Broca’s Aphasia’
, ‘Non-fluent Aphasia’
Results from damage to left inferior frontal gyrus.
Deficit in fluent sentence production.
Affects the ability to convert thoughts into full sentences.
Particularly affects the ability to construct a sentence around the action/verb.
E.g. Who is doing what to whom?
Patients with agrammatism have problems with...
Relationships between words & verb retrieval
Function words like “is”, “by”, “the”, “of”
Inflectional endings like “-ed”, “-ing” and “-s”.
Agrammatic patients base their understanding on...
The meanings of individual words
General knowledge
Simple word order assumptions
Sentence comprehension
Bishop (1982)
Test for the Reception of Grammar (TROG)
E.g. “The girl is chasing the horse.” (active sentence)
In an active sentence (the most commonly used in English), the subject is ‘the girl’, which is the first noun, and this refers to the agent of the action.
So the one doing the action of chasing is the girl.
Patients with damage to Broca’s area have little problems understanding these sentences, and can correctly identify the picture that goes with the sentence.
Most of the time, Broca’s aphasics have little problems with comprehension.
E.g. “The girl is being chased by the horse.” (passive sentence)
In a passive sentence, the subject of the sentence is ‘the girl’, but the agent doing the action ‘the horse’ – this time, the girl is having something done to her, as in ‘the child was raised by her mother’.
Broca’s area supports the processes involved in understanding who is doing what to whom using information in the sentence, like the words “is being chased” or “by”.
In these cases patients cannot guess the correct meaning from the order of the constituents.
It is not the case that the first noun is the agent, so you have to do more serious processing to understand passive sentences.
More subtle comprehension impairments are observed when small function words are required for understanding.
Broca's Area = Speech production and Grammar
Wernicke's Area = Formation of speech and Comprehension
Sentence Comprehension
Semantic knowledge may help interpretation, so the most difficult cases are those where interpretation cannot be inferred but from word order or general knowledge (reversible sentences).
“The football was kicked out by the referee.”
The ball cannot kick the referee → the patient may guess the word order to understand.
“The leopard was killed by the lion.” (
REVERSIBLE SENTENCE
)
Interpretation of who is doing what to whom cannot be inferred from semantic knowledge, and one needs to rely on the relationship between words in the sentence.
Reversible sentences (those in which the two nouns are equally likely to be agents or patients of the action) are difficult for patients, but also for typical adults, because the reading times of these sentences are much higher than in the non-reversible cases.
Patients would misinterpret prepositions like “of” or “under” which indicate grammatical regions.
Patients also show poor comprehension of other grammatical relations…
The language network in sign language
Congenitally deaf individuals: LH regions assume different roles depending on the nature of the input
Auditory cortex activity seen in sign comprehension and production.
But LIFGs role resembles that of hearing individuals.
Changes are mainly around the
posterior cortex.
Sentence comprehension in ASL/BSL
Similar networks but SL recruits auditory cortex and more visual areas when signing.
Sentence production in ASL/BSL
More posterior temporal and parietal engagement.
Producing signs requires different coordinated motor plans than speaking.
‘Hand area’ is more activated in BSL signers.
Innate constraints and experience
Reorganisation of language network, but not entirely.
Left lateralisation remains.
LIFG plays a similar role:
Damage to the LIFG results in similar problems.
Network changes resulting from sensory experience are more posterior.
Basic skeleton of dorsal and ventral pathways remain
But the auditory cortex is redeployed, and different specialised regions emerge along dorsal pathways.
-
Interplay of genes and experience.