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I. Classifications of Aphasia II. Laterality III. Varieties of Anomia

Ling 411 – 06. I. Classifications of Aphasia II. Laterality III. Varieties of Anomia. Classifications. “Classifications are a necessary evil” Antonio Damasio (1998). Problems of classification. Different aphasics almost never share the same set of symptoms (Benson&Ardila 111)

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I. Classifications of Aphasia II. Laterality III. Varieties of Anomia

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  1. Ling 411 – 06 I. Classifications of Aphasia II. Laterality III. Varieties of Anomia

  2. Classifications “Classifications are a necessary evil” Antonio Damasio (1998)

  3. Problems of classification • Different aphasics almost never share the same set of symptoms (Benson&Ardila 111) • Variations “are so plentiful as to be the rule” (B&A 117) • A single type of aphasia may have distinctly different loci of pathology (B&A 117) • Conduction aphasia (117) • Parietal lobe • Arcuate fasciculus • Insula(?) • Transcortical motor aphasia (118) • Differing interpretations of sets of symptoms • Different approaches to classification

  4. Wide variation in classification schemes • Influential ones in history of aphasiology: • Wernicke-Lichtheim 1881, 1885 • Head 1926 • Goldstein 1948 • Luria 1966 • Benson 1979 • Benson & Ardila 1996 • Damasio 1998 • But .. • All recognize just a small number of basic syndromes • Most of the variation in classification schemes is just terminological (Benson&Ardila 120)

  5. Damasio’s Classification (1998:34ff) • Wernicke’s aphasia • Broca’s aphasia • Conduction aphasia • Transcortical sensory aphasia • Transcortical motor aphasia • Global aphasia • Anomic aphasia • Alexia • Pure word deafness • Atypical aphasias

  6. The 1996 Benson & Ardila Classification(B&A: 119) Pre-Rolandic Post-Rolandic Peri- Sylvian Extra- Sylvian Not included in above scheme: (1) Problems with reading & writing (2) Anomic aphasia (3) Global aphasia

  7. Features of the 1996 B&A Classification(B&A: 119) • Based on two anatomical dichotomies: • Pre- vs post-Rolandic • Perisylvian vs. extrasylvian • For every type, two subtypes • But the two subtypes can be just two ends of a continuous scale, not distinct subtypes • Alternatives to usual terms: • “Extrasylvian” instead of “transcortical” • “Broca” instead of “Broca’s” • ‘Wernicke” instead of “Wernicke’s”

  8. A major anatomical-functional dichotomy:Front (anterior) vs. Back (posterior) • Front • Action and planning of action • Process oriented • Back • Perception • Perceptual integration • Object oriented

  9. Damasio Wernicke’s aphasia Broca’s aphasia Conduction aphasia Transcortical sensory aph. Transcortical motor aph. Global aphasia Anomic aphasia Alexia Benson & Ardila Wernicke aphasia Broca aphasia Conduction aphasia Extrasylvian sensory aph. Extrasylvian motor aph. Global aphasia Anomic aphasia Wernicke II or Posterior extrasylvian Damasio vis-à-vis Benson & Ardila

  10. Fluent Receptive* Sensory Posterior Non-fluent Expressive* Motor Anterior Front-Back dichotomy and aphasia: Alternative terms/emphases *But: (1) Very few aphasic patients are completely free of receptive difficulties (2) Virtually no aphasic is entirely without expressive problems (B&A 112)

  11. Broca’s aphasia Transcortical motor aphasia Wernicke’s aphasia Conduction aphasia Transcortical sensory aphasia Alexia Pure word deafness Damasio’s Categories asAnterior vs Posterior Aphasias(Or: Pre-Rolandic vs Post-Rolandic) Anterior Posterior Others: Global Aphasia: Both anterior and posterior Anomic aphasia: Can be either or both Atypical aphasias

  12. Extra-Sylvian Aphasic SyndromesAccording to Benson & Ardila • “Extra-Sylvian” (a.k.a. “Transcortical”) • Extrasylvian motor aphasia • Type I • Type II • Extrasylvian sensory aphasia • Sometimes just called ‘anomic aphasia’ • Type I • Type II

  13. Extra-Sylvian Aphasic Syndromes • In all perisylvian syndromes, repetition is faulty • In all extra-sylvian aphasic syndromes, repetition is intact (why?) • “Aphasia without repetition disturbance almost invariably indicates pathology outside the perisylvian region” (B&A 1996:146)

  14. Extrasylvian motor aphasia • Nonfluent output • Delayed initiation • Terse, poorly elaborated utterances • Incomplete sentences • Verbal paraphasia • Good comprehension • Good repetition

  15. Extrasylvian motor aphasia, Type I • Left dorsolateral prefrontal damage • Anterior and superior to Broca’s area • Non-fluent output, but repetition good • Articulation is normal • Difficulty following commands • Understand command but do not respond • Damage anterior and superior to Broca’s area (Brodmann areas 45, 46, and/or part of area 9) (B&A 1996:152)

  16. Extrasylvian motor aphasia, Type II • Damage to supplementary motor area • Occlusion of left anterior cerebral artery • Non-fluent output, but good repetition • Difficulty initiating speech • Perhaps a purely motor disorder that does not involve basic language functions • (in which case it isn’t really a type of aphasia)

  17. Supplementary motor area Supplementary motor area Important in initiating action (not just speech) Superior parietal lobule

  18. Extrasylvian sensory aphasia • Speech is fluent • Good repetition • Comprehension is impaired • Naming is impaired • Paraphasia is frequent, even verbose • Semantic substitutions • Neologisms • Echolalia (patients repeat words of examiner) • Pointing is impaired • Two subtypes

  19. Extrasylvian sensory aphasia, Type I • Damage to temporal-parietal-occipital junction area • I.e., lower angular gyrus and upper area 37 • Fluent spontaneous output • Poor comprehension • Naming strongly impaired • Semantic paraphasia

  20. Extrasylvian sensory aphasia, Type II • Damage to upper angular gyrus • Fluent output • Variable ability to comprehend speech • Naming strongly impaired • Few semantic paraphasias • Repetition excellent • Many circumlocutions

  21. Comparing Extra-Sensory Aphasia, Types 1 and 2 • Damage to TPO junction area • Fluent spontaneous output • Poor comprehension • Naming strongly impaired • Semantic paraphasia • Repetition good • Damage to upper angular gyrus • Fluent output • Variable ability to comprehend speech • Naming strongly impaired • Few semantic paraphasias • Repetition excellent • Many circumlocutions Type 1 Type 2

  22. Laterality

  23. Cerebral dominance for language • Linguistic abilities are subserved by the left hemisphere in about 97% of people • 99% of right-handed people • A majority of left-handers • But this is just a first approximation

  24. More refined look • Some information is bilaterally represented • Highly entrenched items • Initial consonants of high-frequency words (?) • Some people have more bilateral representation than others • Women and left-handers tend to have more bilateral representation than men and righties • Pitch, intonation, and other prosodic features subserved by RH • Semantic information is in both LH and RH • But different aspects of semantic information • Metaphor, irony, sarcasm, pragmatic features, inferencing, subserved by RH

  25. The Role of RH in semantics • Conceptual information, even for a single item, is complex • Therefore, widely distributed • A network • Occupies both hemispheres • RH information is more connotative • LH information more exact

  26. Left dominance for language in left-handers • Wada test (Milner 1975), on left-handers • 69% aphasic after injection of left brain • 18% aphasic after injection of right brain • 13% aphasic after injection on each side Goodglass 1993:57

  27. Right dominance for language in right-handers • Crossed aphasia: Term for right-handers who suffer aphasia after RH injury • Incidence of crossed aphasia is estimated at 1% Goodglass 1993:58

  28. The genetics of laterality • Matings of left-handed parents produce no more than about 50% left-handed offspring • Annett’s theory (1985) • A single right-shift gene (rs+) • If rs++, right-handed (LH dominant) • If rs+-, right handed (LH dominant) • If rs-- (right-shift gene absent).. • Can go either way • Depends on environment, experience • 50% probability of becoming left-handed

  29. Left hemisphere Analytical thinking Digital Heightened contrast Proof Right Hemisphere Holistic thinking Analog Fuzzy boundaries Hunches, intuition Left hemisphere vs. right hemisphere Question: What anatomical differences are responsible?

  30. Corpus Callosum(revealed by excision of top of right hemisphere) Corpus Callosum

  31. Separated right and left hemispheres • Cutting corpus callosum separates them • Isolated RH: • Limited one-word reading comprehension • Some grasp of meanings • But unable to make judgments about sound • Isolated LH: • Awareness of both sound and meaning

  32. Varieties of anomia:Semantic categories

  33. Anomic aphasia • Perhaps part of a continuum with extrasylvian sensory aphasia • Comprehension is good in many cases • Unlike extrasylvian sensory aphasia • Production and repetition are good • Cannot be reliably localized • Many different areas of damage can result in naming difficulty • But different semantic categories may be impaired with different areas of damage • Maybe not a true syndrome: Benson&Ardila

  34. 2 Cases of Rapp & Caramazza (1995) • E.S.T. (901b) – Left temporal damage • “Meaning spared, couldn’t say the word”: R&C • J.G. (902a) – Left posterior temporal-parietal • Meaning spared, couldn’t spell the word correctly, but phonological recognition okay Cf. Rapp & Caramazza, Disorders of lexical processing and the lexicon (1995)

  35. Patient E.S.T. (Rapp&Caramazza 1995:901b) • Left temporal damage • Shown picture of a snowman • Unable to name it • “It’s cold, it’s a ma… cold … frozen.” • Shown picture of a stool • “stop, step … seat, small seat, round seat, sit on the…” • Shown written form ‘steak’ • “I’m going to eat something … it’s beef … you can have a [së] … different … costs more …” • What can we conclude?

  36. Assessment of E.S.T. by Rapp & Caramazza • Responses of E.S.T. indicate awareness of the meanings (SNOWMAN, STOOL, STEAK) • Therefore, “meaning is spared” (acc. To R&C)

  37. Warning: Proceed with caution • The assumption of Rapp&Caramazza is easy to make • I.e., thatmeaning (conceptual information) is spared • But there’s more to this than meets the eye! • As we have seen, complex functions are not localized • Only simple functions have locations • Conceptual information, even for a single word • Is complex, has many components • Therefore, is widely distributed • We only have evidence that some of the conceptual information is spared

  38. Patient E.S.T. – a closer look • Left temporal damage • Picture of a snowman • “It’s cold, it’s a ma… cold … frozen.” • Picture of a stool • “stop, step … seat, small seat, round seat, sit on the…” • Written form ‘steak’ • “I’m going to eat something … it’s beef … you can have a [së] … different … costs more …” • These are not definitions • This is connotative information • Vague semantic notions about the meanings

  39. Compare patient J.G. (902a) • Damage: Left posterior temporal-parietal • Meaning spared, couldn’t spell the word correctly, but phonological recognition okay • digit: • D-I-D-G-E-T • “A number” • thief: • T-H-E-F-E • “A person who takes things” • These are actual definitions

  40. Don’t forget this – (repeating) • Some information is bilaterally represented • Highly entrenched items • Initial consonants of high-frequency words (?) • Some people have more bilateral representation than others • Women and left-handers tend to have more bilateral representation than men and righties • Pitch, intonation, and other prosodic features subserved by RH • Semantic information is in both LH and RH • But different aspects of semantic information • Metaphor, irony, sarcasm, pragmatic features, inferencing, subserved by RH

  41. (Repeating:) The Role of RH in semantics • Conceptual information, even for a single item, is widely distributed • A network • Occupies both hemispheres • RH information is more connotative • LH information more exact

  42. Connotative information in RH • Tests on patients with isolated RH resulting from callosotomy • RH has information about (many) nouns and verbs • Not as many as in LH • Semantic information differently organized in RH • Zaidel (1990): “… the right hemisphere is characteristically connotative rather than denotative … . The arcs [of the semantic network] connect more distant concepts … and the organizing semantic relationships are more loosely associative and dependent on experience” (125) Baynes & Eliason, The visual lexicon: its access and organization is commissurotomy patients (1998)

  43. Semantic information: E.S.T. and J.G. • Patient J.G. – real definitions • digit: “A number” • thief: “A person who takes things” • Patient E.S.T. – connotative information • snowman: “It’s cold, it’s a ma… cold … frozen.” • stool: “ … seat, small seat, round seat, sit on the…” • steak: “I’m going to eat something … it’s beef … you can have a [së] … different … costs more …”

  44. Conclusion about E.S.T. • RH semantic information is intact • LH semantic information is wiped out • Phonological information is spared in both hemispheres • Question: Why can’t the RH semantic information be conveyed to LH phonology?

  45. Corpus Callosum(revealed by excision of top of right hemisphere) Corpus Callosum

  46. end

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