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

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) 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

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)

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

The 1996 Benson & Ardila Classification (B&A: 119) Broca AphasiaWernicke Aphasia Conduction Aphasia Extrasylvian Motor Aphasia Extrasylvian Sensory Aphasia Pre-Rolandic Post-Rolandic Peri- Sylvian Extra- Sylvian Not included in above scheme: (1) Problems with reading & writing (2) Anomic aphasia (3) Global aphasia

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”

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

Damasio vis-à-vis Benson & Ardila 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

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

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

Extra-Sylvian Aphasic Syndromes According 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

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)

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

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)Brodmann areas

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)

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

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

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

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

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

Laterality

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

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

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

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

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

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

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

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

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

Varieties of anomia: Semantic categories

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

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)

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?

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)

Warning: Proceed with caution  The assumption of Rapp&Caramazza is easy to make I.e., that meaning (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

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

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

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

(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

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)

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 …”

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?

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

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