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Cog neuro (y2s2) > Week 9 Lecture 9 - the speaking brain 2 > Flashcards

Week 9 Lecture 9 - the speaking brain 2 Flashcards

1
Q

Where does much of what we know about language in the brain come from?

A
  • lesion studies –> often post-stroke
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2
Q

What is the hub-and-spoke model?

A

Amodal ‘hub’:
* Representation of specific concepts irrespective of modality
* Categorisation of exceptional concepts
* Generalisation to form categories despite high conceptual feature variability

Distributed, grounded ‘spokes’:
* Semantic representations grounded in
sensory and bodily areas (‘spokes’)
* E.g., representations of the word ‘robin’ or the sound of a robin’s bird call, or the
colours of a robin

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3
Q

What does the hub-and-spoke model predict?

A

if there is an amodal hub then focal damage to that region would lead to a global semantic impairment independent of modality of information

  • E.g., struggling to identify a picture of a robin when given either its name (word), colours, sound etc.
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4
Q

What is semantic dementia (SD)?

A

Global semantic impairment which:
* Is cross-modal
* Shows strong typicality effects
* Shows preservation of general relative to specific information

Relative sparing of other language and cognitive abilities

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5
Q

What evidence is there for a hierarchy of representations in the brain?

A
  • Rogers et al., (2006) fMRI study
  • fMRI study of naming and categorisation
  • Processing at specific level activates anterior temporal pole
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6
Q

Global semantic impairment - Patterson et al., (2007)

Task:
* Presented with a category label (e.g.,
“animal”, “dog”, “beagle”), then a colour
photograph.
* Indicate whether the label matches the
photo.

What was the outcome?

A

SD worse at correctly matching specific
category labels (“beagle”)

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7
Q

Global semantic impairment - Patterson et al., (2007)

Task:
* Verbal picture naming responses from one SD patient over time

What was the outcome?

A

SD gradually lose specific concepts and rely on superordinate category labels

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8
Q

Global semantic impairment - Patterson et al., (2007)

Task 1:
* Presented with a 2 drawings of an
object in different colours
* Indicate which version is coloured
correctly

Task 2:
* Presented with a drawing of an animal
with typical or atypical features
* Indicate which drawing is accurate to a
real animal

What was the outcome?

A

SD are worse at correctly identifying features if they are atypical for the category (orange vegetable, larger eared animal)

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9
Q

Global semantic impairment - Patterson et al., (2007)

Task:
* Presented with a line drawing of an animal,
which is then covered
* After a 10s delay, draw the animal from memory

What was the outcome?

A

Atypical features for ‘animals’ (e.g., hump or flippers) are omitted
* Typical features for ‘animals’ (e.g., having 4 limbs or a tail) are added

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10
Q

What is the summary of evidence from SD for global sematic impairment?

A

Some part(s) of the brain is responsible for specific semantic concepts, regardless of whether the task is to recognise the
category, name, draw, or identify feature

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11
Q

According to a fully grounded model, the global deficits in SD could be caused by what?

A

uniform but distributed damage to all the modality-specific, perceptual and motor areas where representations of these objects are grounded

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12
Q

According to the hub and spoke model, the global deficits in SD could be caused by what?

A

damage to just the amodal hub, thus affecting generalisation across categories and representation of atypical exemplars,
regardless of task

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13
Q

What brain areas are affected in SD?

A

Convergent evidence from different imaging modalities shows (bilateral) damage to anterior temporal lobe

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14
Q

If the global deficit in SD is caused by damage to a circumscribed brain region (anterior temporal lobes), can the global deficit be explained any other way?

A

Semantic dementia vs.:
* AD – semantic impairment due to spread of pathology
* HSVE – semantic impairment caused by viral infection
* Transcortical sensory aphasia – semantic impairment caused by stroke

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15
Q

What patient evidence is there for the anterior temporal lobe as an amodal hub?

A
  • Alzheimer’s disease vs Semantic Dementia
  • Herpes Simplex Viral Encephalitis (HSVE) vs SD
  • Transcortical Sensory Aphasia (TSA) caused by stroke
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16
Q

What is HSVE?

A
  • HSVE is the most common viral encephalitis in humans
  • damage is usually widespread
  • characterized by dense anterograde amnesia, and sometimes by impairments of semantic memory and/or executive functions
  • BUT: when semantic deficits are present, damage is focus in the anterior temporal lobes
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17
Q

What are the effects of cumulative cueing on TSA and SD (evidence for the ATL as amodal hub: patient evidence)?

A
  • TSA: a deficit of access to semantic representations
  • SD: a deficit due to degradation of semantic representations themselves
18
Q

What is syntax?

A

the rules that specify how words can be combined into sentences

19
Q

What is parsing?

A

assigning a syntactic structure to words

20
Q

True or false?

Speech without syntax is difficult to understand

A

True

21
Q

Demonstrate how there is a history of localising cognitive functions to brain areas

A
  • Paul Broca (1861) – localised ‘speech production’ to a dedicated ‘language centre’ (via autopsy), termed ‘Broca’s area’
22
Q

What is Broca’s aphasia cardinal symptom?

A

cardinal symptom is agrammatism (loss of grammar) in speech production: speech which is characterised by the absence of function words and verbs

23
Q

What is Broca’s aphasia often assessed through?

A

the Cookie Theft test

24
Q

True or false?
Broca’s aphasia involves only deficits in speech production

A

False
Broca’s aphasia involves deficits in both
production and comprehension of syntactically complex sentences

25
Q

When does Broca’s area show greater activity?

A

Broca’s area shows greater activity with increasing syntactic complexity in fMRI

26
Q

What is the current view of the subdivisions of Broca’s area?

A

BA44: processing hierarchical structures and sequencing
* E.g., sentence-level constructions
* Feedforward predictions

BA45: working memory and semantic control
* E.g., judging semantic-ness, such as concreteness or synonym judgements

27
Q

What evidence disputes the current view of the subdivisions of Broca’s area?

A

Posterior temporal lobe structures also active for syntactic vs. semantic processing

28
Q

Parsing: assigning syntactic structure to words

What is the debate around this?

A

Debate as to whether this is:
* Structure-driven (syntax separate from semantics) –> garden path sentences
* Discourse-driven (semantics influences syntax processing) –> High or Low congruence semantic context biases processing of homophones

29
Q

Concerning syntax and semantics, what do the N400 and P600 ERP components show?

A

N400 ERP component:
* Semantic anomalies regardless of sentence context
* “I take coffee with milk and dog”
* “river-bank-money”

  • P600 ERP component:
  • Syntactic anomalies regardless of semantic content
  • “The boiled watering can smokes the telephone in the cat
30
Q

What is lexicalisation?

A

the selection of a word based on the
meaning that one wishes to convey

31
Q

What is Lexeme?

A

the phonological code that drives articulation

32
Q

What is Lemma?

A
  • a modality-independent word-level entry that specifies the syntactic components of the word
  • Syntax is independent of modality of production (e.g., speaking, writing)
33
Q

What is Logopenic progressive aphasia?

A
  • disorder of word retrieval
  • Often associated with Alzheimer’s disease pathology
  • Speech characterised by word-finding pauses
  • Impaired speech processing (repetition or comprehension) for sentences more than words
  • Impaired phonological working memory
  • Atrophy in left posterior temporal cortex
34
Q

What is Levelt’s model of word retrieval?

A

Discrete, sequential stages
Can explain:
- ‘tip-of-the-tongue’ phenomenon
- Activation of lemma without lexeme
- Correctly selecting a word based on its syntactic properties, when it has a homophone with the same phonological properties:
* ‘watch’ (accessory/to watch)
* “I have watched that show”
* Not “I have a watch that show”

35
Q

What is the SLAM model of word retrieval?

A

SLAM: semantic -> lexical -> auditory -> motor
- Speech production involves ventral stream in reverse (temporal lobes
to auditory cortex) followed by dorsal stream (auditory to frontal)
- The auditory stage acts as a forward model (predicts the sensory
consequences of motor actions)

36
Q

What patient evidence is there for the SLAM model?

A

Fridriksson et al. (2018)
* Lesion-symptom mapping of damage to grey and white matter in stroke patients
* Performance on variety of language tasks
* To test the dual steam model of language production and comprehension

37
Q

What is an example of an error in word level representations? (word retrieval errors)

A

Freudian slip: the substitution of one word for another that is sometimes thought to reflect the hidden intentions of the speaker

38
Q

What is an example of an error in phonemelevel representations? (word retrieval errors)

A

Malapropisms, e.g., spoonerism
- A speech error in which initial consonants are swapped between words

39
Q

In articulation, what is syllabification?

A
  • the process of segmenting phonological information into syllables across adjacent morphemes and adjacent words
  • Syllables can occur across morphemes (written words)
  • “He owns it” = “he own zit”
  • Neural correlates:
  • Phoneme-level: basal ganglia
  • Syllable-level: ventral premotor
40
Q

Give 2 examples of disorders of articulation

A
  • apraxia of speech
  • dysarthria
41
Q

What is apraxia of speech?

A
  • Damage to the insula
  • Difficulty shaping the vocal tract

Altered speech production despite intact:
* Semantics, syntax
* Word retrieval
* Muscle tone of articulators

42
Q

What is dysarthria?

A
  • Damage to the cerebellum and basal ganglia
  • Impairment in muscular contractions of articulators

Altered speech production despite intact:
* Semantics, syntax
* Word retrieval

Cog neuro (y2s2) (11 decks)

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