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Cognition & Emotion II > Acquired Dyslexias > Flashcards

Acquired Dyslexias Flashcards

1
Q

DEJERINE: MONSIEUR C. (1892)

A
  • 68yo; unable to read post stroke
  • oral language/spelling = intact
  • object/face/drawing/number recognition largely preserved
  • tactile/gestural letter/word recognition remains intact
  • post-mortem = pure verbal blindness (aka. pure alexia w/o agraphia) results from disconnection between primary visual areas/other occipital areas dealing specifically w/letters/words
    COHEN ET AL. (2000)
  • now we know this region is located in ventral occipito-temporal region
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2
Q

CLASSIFICATIONS

A

PERIPHERAL DYSLEXIAS
- any reading disorder in which seeing word as stable orthographic object fails (PRE linguistic relevance failure)
CENTRAL DYSLEXIAS
- any reading disorder in which impairment occurs POST stage of visual word form (aka. reading system so psycho/neurolinguistic in nature)

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3
Q

PERIPHERAL DYSLEXIAS

A

DEJERINE (1892)
- pure alexia/alexia w/o agraphia/letter-by-letter reading
SHALLICE & WARRINGTON (1977)
- attentional dyslexia
ELLIS, FLUDE & YOUNG (1987)
- neglect dyslexia

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4
Q

CENTRAL DYSLEXIAS

A

BEAUVOIS & DEROUESNE (1979)
- phonological dyslexia
MARSHALL & NEWCOMBE (1973)
- deep dyslexia
- surface dyslexia
SCHWARTZ ET AL. (1980)
- semantic dyslexia

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5
Q

PURE ALEXIA

A
  • “alexia w/o agraphia” (ie. no concurrent spelling impairment)
  • many cases described
  • substantial length effect/almost linear relation between length in letters/reading time
  • readers = heavily affected by whether the font = ambiguous at first lvl aka. contextual info (ie. “s_ile”) doesn’t help
    MAIN SYMPTOM
  • word identification = impossible except via explicit sequential identification of individual letters (slowly & w/effort)
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6
Q

PURE ALEXIA: THE SAFFRAN EFFECT

A

SAFFRAN & COSLETT (1998)
- pure alexias = well above chance in categorising meaning of word (is it an animal?)/lexial status of letter string (is it a real world?) despite inability to consciously identify word
- cerebral area involved; visual word form area (VMFA; ventral occipito-temporal region) = damaged/disconnected

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7
Q

HEMI-ALEXIA: MOLKO ET AL. (2002)

A
  • info from left visual hemi-field initially processed in right hemisphere needs to cross to left hemisphere to combine w/right hemi-field info in visual word-form area
  • BUT if corpus callosum (which allows communication between hemispheres) = damaged then transfer may no longer be possible
  • result = patient has difficulty reading only words presented in left visual field aka. hemi-alexia
  • NOT hemi-neglect dyslexia
  • patient AC = visual word-form area is NOT activated by strings presented in left visual field
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8
Q

ATTENTIONAL DYSLEXIA: SHALLICE & WARRINGTON (1977)

A
  • v rare; associated w/left parietal lesion
  • difficulty in identifying letters/words when flanked by other items of same category
  • BUT naming of letter/word in isolation = preserved:
    1) “o” is fine BUT error-prone in “word”
    2) “word” is fine BUT error-prone in “when the word is in a sentence”
  • aka. highly sensitive to crowding from same-lvl items (ie. words from words)
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9
Q

ATTENTIONAL DYSLEXIA: WARRINGTON (1993)

A
  • migration of letters to analogous position (info within-word letter position = preserved despite attentional deficit) in other words (ie. left hemisphere > heft hemisphere)
  • disorder of attentional filter = larger window of attention > target part of visual field; lets in other info
  • specific to reading as doesn’t hold for pics
  • flankers’ nature modulates manifestation of disorders; less interference w/dif category than w/same category distractors
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10
Q

NEGLECT DYSLEXIA: KINSBOURNE & WARRINGTON (1962)

A
  • NOT attentional dyslexia
  • oft not necessarily associated w/spatial neglect
  • typically contralateral parietal lesion
  • most common form = initial portion of word is problematic (ie. right lesion)
  • aka. lend > end; wine > mine; oat > boat
    MAIN SYMPTOM
  • failure to identify initial/final letters of word/group of words resulting in omissions/substitutions/additions
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11
Q

NEGLECT DYSLEXIA: ERRONEOUS LETTERS

A
  • many erroneous letters to left/right of neglect point as neglected letters in target
  • ie. car > bar; enigma > stigma (opposed to sigma)
  • aka. some processing of neglected letters occurs; suggests that position = preserved BUT identity = lost
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12
Q

NEGLECT DYSLEXIA: IMPAIRMENT

A
  • disorder of orientation of spatial attention but various lvls possible:
    1) impairment tied to left visual hemi-field
  • ie. end x blend
    2) impairment tied to left stimulus part irrespective of horizontal location in visual field
  • ie. end x end BUT (vertical) blend
    3) impairment tied to onset word part irrespective of orientation (most abstract form of impairment)
  • ie. (vertical) end x (horizontal) end x (opposite vertical) end
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13
Q

PHONOLOGICAL DYSLEXIA

A
  • lesion of temporal lobe of dominant hemisphere
  • BUT reading words/visual letter string processing/immediate nonword repetition = relatively intact/perfect
  • some patients read concrete words better than abstract words/show difficulty w/function (opposed to content) words
    MAIN SYMPTOM
  • impaired ability to read new/made up words/nonwords or to sound out individual graphemes
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14
Q

PHONOLOGICAL DYSLEXIA: BEAUVOIS & DEROUESNE (1979)

A
  • complex correspondences between letters group & 1 individual sound (ie. complex graphemes (“igh” read as “ai”) acquired late in reading development
  • their less secured knowledge is therefore first to go compared to simple graphemes (ie. P read “p”)
  • BUT sound familiarity to existing words improves reading performance on nonwords (ie. “brane”) as whole-word knowledge of existing homophone can compensate for failure to apply correspondence rules
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15
Q

PHONOLOGICAL DYSLEXIA: DRC

A
  • explains poor performance on pseudowords by impairment (slowing down) of grapho-phonological conversion mechanism
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16
Q

DEEP DYSLEXIA: MARSHALL & NEWCOMBE (1973)

A
  • associated w/extensive damage to dominant (left) hemisphere; consists of:
    1) inability to read nonwords
    2) semantically related errors (ill > sick; bush > tree; bad > liar)
    3) visual errors (life > wife; sword > words); could be compensation by lexical knowledge for imprecise grapheme-phoneme conversion
    4) derivational errors (card > cards; fleeing > flee; beg > beggar)
    5) effect of syntactical class (nouns > adjectives > verbs > functors); shared w/phonological dyslexia
    6) effect of imageability (concrete > abstract words); shared w/phonological dyslexia
17
Q

DEEP DYSLEXIA: COMMON EXPLANATION

A
  • reading only by semantic lexical route
  • all other routes (nonsemantic lexical/graphophonological) = impaired
  • interpretation of this symptomatology in DRC would implicate damage to both nonlexical route/direct nonsemantic lexical route
  • the only way to retrieve pronunciation is via semantic system
18
Q

DEEP DYSLEXIA: SEMANTIC ERRORS

A
  • semantic route = by default inaccurate w/selecting words for speech production
  • patient has no info about target word other than meaning
  • would explain imageability effect & low performance on functors
  • NOT sign of damage to semantic system; just sign that this may be only source of knowledge available to achieve pronunciation
19
Q

SURFACE DYSLEXIA: MARSHALLL & NEWCOMBE (1973)

A

MAIN SYMTPOMS
- regularisations (typical pronunciation chosen) esp. for low frequency irregular words (ie. pint rhyming w/mint)
- stress shift (ie. guiTAR > GUItar)
- comprehension based on pronunciation (ie. bear = alcoholic beverage (beer))
- failures to apply contextual rules (ie. insect > insist; guest > just)
- incomplete decoding of diagram vowels (ie. niece > nice)

20
Q

SURFACE DYSLEXIA: ARGUMENT FOR NONLEXICAL ROUTE

A
  • reading regular words/nonwords = spared
  • traditional interpretation = impairment of lexical route; reading primarily reflects reliance on nonlexical route & thus GPC reliance
  • strong sensitivity to regularity = critical variable
  • better performance on frequent > rare irregular words interpreted into -> representations of rare irregular words are more likely to go > frequent irregular words
  • aka. surface dyslexia = argument for nonlexical route existence
21
Q

SURFACE DYSLEXIA: DRC

A
  • at least 3 possible functional loci:
    1) orthographic input lexicon (or access to it)
    2) pathway between orthographic input/phonological output lexica
    3) phonological output lexicon (or its connection w/lower speech lvls)
22
Q

SURFACE DYSLEXIA: LIMITATIONS TO NONLEXICAL ROUTE ARGUMENT

A
  • DRC doesn’t explain lexical errors that aren’t just regulations (ie. incense > increase; barge > bargain)
  • surface dyslexia possibly reflects compensatory strategy given slowness of reading/occasional use of letter names
    LAMBON-RALPH & PATTERSON (2005)
  • damage to lexical route doesn’t explain why surface dyslexia tends to be associated w/semantic dyslexia
23
Q

SEMANTIC DYSLEXIA

A
  • aka. reading w/o meaning
  • disorder associated w/neurological disease (ie. Alzheimer’s/semantic dementia)
  • most patients evolve towards surface dyslexia (itself associated w/semantic disorders)
  • damage to semantic system = most straightforward explanation in DRC
    MAIN SYMPTOM
  • ability of patients to read fast/fluently (even irregular words in some patients) BUT inability to comprehend what they’re reading
24
Q

SEMANTIC DYSLEXIA: SCHWARTZ ET AL. (1980)

A
  • case of WLP (patient w/semantic dementia)
  • can:
    1) read pseudowords
    2) match spoken word (“brain”) w/written pseudohomophone (brane”
    3) read aloud irregular words (pint) which by contrast she cannot define/match w/picture
  • BUT fails at object naming task (1/70) though she can mimic use of certain objects (-> poor conceptual knowledge)
  • aka. DRC w/o semantic system
  • WLP -> drastic revision of dual-route theory; needed to include direct (non-semantic) lexical route to explain good performance on irregular words in absence of semantic access
25
Q

SEMANTIC DYSLEXIA: PRE WLP

A
  • reading was thought to involve only semantic route & grapho-phonological route
  • reading irregular words w/o comprehension was impossible for this concept
  • semantic dyslexia patients forced to distinguish:
    1) within lexical system
    2) between access to meaning
    3) access to pronounciation
  • aka. DRC became TRC (three-route reading theory)

Cognition & Emotion II (15 decks)

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