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Aphasia

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Title: Aphasia


1
Aphasia
  • Loss or impairment of language comprehension or
    production

2
Language Impairments
COMPREHENSION Auditory Single words Phrases
Commands (Token Test) Syntax Visual (Reading -
alexia) Single words Phrases
  • PRODUCTION
  • Spontaneous Speech
  • Fluent versus nonfluent
  • Unintended or off words (paraphasias)
  • Word finding difficulties (anomia)
  • Poor articulation
  • Prosody (aprosodia)
  • Repetition
  • Single words
  • Phrases
  • Writing (agraphia)

3
Brocas Aphasia
  • Bouillaud (1825) large series of speech loss
    with frontal lesions
  • Marc Dax (1836) LH damage, right hemiplegia,
    aphasia linked
  • Paul Broca (1861) convincing evidence of speech
    laterality Tan Nous parlons avez
    lhemispheregauche

Paul Broca (1824-1880)
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Wernickes Aphasia
  • Carl Wernicke (1874) reports that temporal lobe
    lesion disturbs comprehension.
  • Developed connectionism model of language and
    predicated conduction aphasia

6
Aphasias
  • Conduction
  • Fluent speech
  • Good comprehension
  • Poor repetition
  • Poor naming
  • Possibly lesion in arcuate fasciculus or its
    connections in inferior parietal lobule
  • Wernickes
  • Fluent speech
  • Poor comprehension
  • Poor repetition
  • Poor naming
  • Posterior superior temporal lobe lesion (first
    temporal gyrus)

7
Aphasias
  • Transcortical Sensory
  • Fluent speech
  • Poor comprehension
  • Good repetition
  • Poor naming
  • Lesion in posterior temporo-parietooccipital
    junction while sparing Wernickes area
  • Anomic
  • Fluent speech
  • Good comprehension
  • Good repetition
  • Poor naming
  • Temporal or temporo-parietal lesion

8
Wernicke TCS Aphasia
9
Aphasias
  • Brocas
  • Non-fluent speech
  • Good comprehension
  • Poor repetition
  • Poor naming
  • Posterior inferior frontal lesion
  • Global
  • Non-fluent speech
  • Poor comprehension
  • Poor repetition
  • Poor naming
  • Lesion involves frontal, temporal and parietal
    lobes, Including Brocas and Wernickes area

10
Aphasias
  • Mixed Transcortical
  • Non-fluent speech
  • Poor comprehension
  • Good repetition
  • Poor naming
  • Anterior and posterior association cortex lesions
    while sparing perisylvian language region
  • Transcortical Motor
  • Non-fluent speech
  • Good comprehension
  • Good repetition
  • Poor naming
  • Lesion involves frontal lobe but spares Brocas
    area

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Linguistic processes
15
Turn of the century models for Reading and
Speaking
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Reading Aloud (Grapheme to Phoneme conversion
GPC)
19
Linguistic Competence of the Disconnected RH
Vocabulary vs syntactical competence
TOKEN TEST Point to the large yellow circle
20
Lexical Language in the disconnected RH
Token test assesses auditory comprehension but
more so syntactical competence
21
GPC but may index visual familiarity)
Auditory comprehension
Reading
GPC (via Rhyme)
22
Lexical Language in the disconnected RH
Token test assesses auditory comprehension but
more so syntactical competence
23
LH
RH
24
Syntactical incompetence of the RH (poor
prepositions) but competence for nouns and
adjectives, with control for word frequency
(i.e., visual familiarity)
25
Not all nouns are alikeRH competence for
concrete and imageable
  • Concrete but not imageable
  • Encephalon
  • Matter
  • Welt
  • Imprint
  • Morass
  • plaza
  • Not Concrete but imageable
  • Alone
  • Affectionate
  • Wise
  • Joy
  • Fun
  • blessing

26
Right Hemisphere Ability
27
Lexical Language in the disconnected RH
28
Isolation of grapho-motor module
  • In VJ, writing dissociates from other language
    abilities.
  • Writing in RH
  • All others LH
  • In JW VP all language abilities are localized
    in LH.

Unusual brain organization - dissociations
29
Gross functions across split brain series
30
Patient O.A.
31
Linguistic Competence that requires intact
interhemispheric language systems
  • Alternative meanings
  • Narrative processing, inference
  • Metaphor
  • Humor
  • Indirect request

Technique suitable for fast, short presentations
only lt180 ms
32
inference
33
How to test sustained visual attention in one
visual field Z-lens
34
Ongoing inference in sentential readingsThe
pizza was too hot to cry
35
Hough (1990) - Narrative Integration
36
Polysemantic Processing
  • Revising interpretations of non-humorous
    discourse
  • Sally became too bored to finish the history
    book.
  • She had already spent five years writing it.
    (or we saw her duck)
  • Same initial inference generated by controls and
    RHD, but RHD failed to abandon dominant inference
    for alternative interpretation consistent with
    both sentences (Brownell 1996)
  • RHD performance normals for integrating across
    sentence boundaries.
  • Johnny missed the wild pitch.
  • The windshield was shattered.
  • Related Findings
  • RH maintains activation over longer prime-target
    intervals.
  • RH primed by weakly associated primes (foot, cry,
    glass for cut) as much as by direct prime
    (scissors for cut).
  • LH shows only priming for direct prime
  • Conclusions
  • RH generates extensive (multiple)
    representational sets for meanings implied or
    novel
  • LH inhibits alternatives and focuses on dominant
    reading.
  • LH excels at selecting processing one
    (dominant) interpretation.

37
Priming for Polysemy
  • Dominant context The dog played with the ball
  • Subordinate context She bought a new dress for
    the ball
  • Associated ROUND (dominant) or DANCE
    (subordinate)

38
  • By 40 ms LH (RVF) has collapsed all subordinate
    (alternative) word meanings or never allowed them
    to emerge
  • (I put my money in the bank)

39
Deep dyslexia
40
Deep dyslexia - Reliance on diffuse
representational system of RH
41
New word learning shifts childs attention from
thematic (RH) to categorical (LH)
42
  • RH vocab 13y, syntax 5y

43
Aphasia with multiple languages
  • Bilingual recovery
  • Parallel recovery
  • Differential or nonparallel recovery
  • L1 recovers faster (Ribots lawold before new)
  • L2 recovers faster (Pitres lawfrequent first)
  • Due to different or overlapping brain areas, or
    what?
  • Recovery implies that actual language centers
    werent destroyed, only cut off or inhibited.

44
Recovery from aphasia
  • L1 and L2 may recover independently
  • implies some differential representation in the
    brain.
  • Case L1 recovery only Dimitrijevic (1940).
  • Woman grew up speaking Bulgarian Yiddish (both
    L1), As adult, she learned Serbian (L2) which she
    spoke daily for 25y. She kept forgetting
    Bulgarian until brain injury at 60y resulted in
    loss of Serbian in speech (however, she still
    could understand L2)

45
Second language recovery
  • 1/3rd of multilinguals do not recover L1, but L2
    or L3
  • Case L2 recovery Minkowski (1928).
  • Acquisition
  • L1Swiss German
  • L2 schooled in standard German
  • L3 became fluent in French, then stroke after 19
    y
  • Recovery
  • spoke French (L3) for 3 weeks, then German (L2),
    but incapable of using Swiss German (L1) for 6
    months.
  • Suddenly L1 returned, to detriment of French
    (L3).

46
Factors involved in L2 recovery
  • Minkowski Languages are not spatially separated,
    but exert mutual inhibition in delicate balance
    (Great Powers of Europe metaphor 19-20th c).
  • Lesion disrupts balance and can suppress any
    language (including L1).
  • In support, lost languages can be recovered
    faster than usually required to learn from
    scratch
  • Little evidence of right hemisphere involvement
    in L2
  • But Brocas area in polyglots is no larger than
    monolinguals (e.g. Sauerwein spoke 54 languages
    with a normal-sized Brocas area, Fabbro 2001)

47
Experimental inhibition(Ojemann Whitaker 1978)
  • Dutch inhibited
  • English inhibited
  • Both inhibited
  • Neither inhibited

48
Recovery of dead languages
  • Case Grasset (1884). Patient knew only French.
    After stroke, he could speak only single words in
    Latin that he learned from Mass.
  • Case Pötzl (1925). Classics professor suffered a
    stroke and was only able to express himself in
    dead languages (Latin ancient Greek), which he
    acquired through reading alone.

49
Bilingual representation
  • Sometimes only one language returns
  • not always L1
  • Production, comprehension and translation
    separable, even within a language.
  • Comprehension often spared in all languages
  • Inconsistent evidence for macroscopic
    localization differences for multiple languages
    (VHS Mind 26)

50
PET vs Lesion data Why is PET data so much more
focal?
51
Individual Differences in Language Lateralization
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Agnosia
  • Greek for lack of knowledge
  • Coined by Sigmund Freud
  • Inability to recognize people or objects even
    when basic sensory modalities, such as vision,
    are intact.
  • Modality-specific impairment

55
What Where Ventral and Dorsal Visual
Pathways
  • Established with electophysiology, lesion,
    neuropsychology and neuroimaging data

56
What-Where Distinction
Object task Same objects? Spatial Task Same
locations?
57
Three Types of Object in the World
  • Words Objects Faces
  • Alexia Agnosias Prosopagnosia
  • Recognition involved three (or four) stages of
    processing
  • Sensory input
  • Perception (able to form percepts)
  • Categorization (able to associate percept to
    meaning)
  • Identification (able to identify specific example)

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Agnosia
  • Apperceptive
  • Object recognition failure due to perceptual
    processing
  • Associative
  • Perceptual processing intact but subject cannot
    use information to recognize objects

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Apperceptive Agnosia
  • Impaired global structure (gestalt) extraction
  • Diffuse brain injury (CO poisoning)
  • Intact acuity, brightness discrimination, color
    vision and other elementary capabilities
  • Real images recognized better than illustrations
    motion better than static (more cues)

62
Gestalt Principles
63
Example of connectedness
64
Gestalt principles
65
Case D.F. (Milner Goodale, 1995)
  • Classic Apperceptive Agnosic
  • Severly impaired FORM perception
  • Damage to V2, V3, V4-- Ventral Stream
  • Intact abilities should reflect operation of
    dorsal stream

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Dissociating What from How
  • Orientation reports IMPAIRED
  • verbal
  • matching
  • Posting behavior SPARED
  • Implication Orientation shape representations
    available for guiding action

68
Associative Agnosia
  • Impaired matching percept to memory
  • Occipitotemporal damage
  • Draw accurately without recognizing
  • Identify objects through other modalities (touch,
    verbal description)
  • Not perceptual except copying is slow and
    sequential

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Prosopagnosia or Face Blindness
74
Prosopagnosia
  • Specific inability to recognize faces
  • Are faces and other objects in the world
    represented in fundamentally different ways in
    memory?
  • Does face-memory depend on fundamentally
    different brain systems?

75
Are Faces Special?
76
Are Faces Special?
  • Objects represented in parts and holistically
  • Faces represented holistically

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Prosopagnosia
  • Impairment of identity of familiar faces
  • Posterior artery (medial OT, right sided usually)
  • Perception and categorization is intact. Patient
    can still determine gender, ethnicity, age,
    emotions, everything but identity
  • Conscious recognition impaired
  • Nonconscious (implicit) recognition intact in
    some GSRs, EPs, forced decision
  • Are faces a unique set of stimuli? Or difficult
    to discriminate highly similar exemplars from
    each other (e.g., prosopagnosic farmer who
    couldnt recognize faces but could recognize his
    cows)

ISSUE Are faces and other objects in the world
represented in fundamentally different ways in
memory?
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Single cell recording in IT
82
Other agnosias
  • Auditory Agnosia
  • inability to recognize specific sounds in the
    context of intact hearing.
  • pure word deafness
  • sound agnosia
  • receptive amusia (agnosia for music).
  • Somatosensory Agnosia (Astereognosis)
  • difficulty perceiving objects through tactile
    stimulation though basic tactile sensation
    intact.
  • Simultanagnosia, Inability to recognize a whole
    image although individual details are recognized.
  • Color anomia can discriminate colors on tasks but
    cannot name colors or point to colors named by
    examiner. (color recognition problem, not color
    perception which is Central Achromatosia)

83
Alexia (with or w/o agraphia
  • Impairment in letter recognition and reading
  • OP damage
  • Word blindness inability to read

84
Patterns of dissociation support this idea
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