I. Classifications of Aphasia
II. Laterality
III. Varieties of Anomia
IV. Reading and Writing
Ling 411 – 06
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
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 Aphasia Wernicke Aphasia
Conduction Aphasia
ExtrasylvianMotor Aphasia
ExtrasylvianSensory 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 asAnterior 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 posteriorAnomic aphasia: Can be either or bothAtypical aphasias
Anterior Posterior
Cerebral dominance for language
Linguistic abilities are subserved by the left hemisphere in about 97% of people•99% of right-handed people
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
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?
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
Corpus Callosum
(revealed by excision of top of right
hemisphere)
Corpus Callosum
Semantic categories:Varieties of anomia
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 processingand 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, conceptual information 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
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
Brain damage and nominal concepts
Access to nominal concepts is impaired in extra-sylvian sensory aphasia
Type I – Damage to temporal-parietal-occipital junction area• I.e., lower angular gyrus and upper area 37•Poor comprehension•Naming strongly impaired•Semantic paraphasia
Type II –Damage to upper angular gyrus •Variable ability to comprehend speech•Naming strongly impaired•Few semantic paraphasias•Many circumlocutions
Conceptual category dissociation I
J.B.R. and S.B.Y. (905b-906a)
Herpes simplex encephalitis Both temporal lobes affected Could not define animate objects
•ostrich, snail, wasp, duck, holly
Much better at defining inanimate objects•tent, briefcase, compass, wheelbarrow,
submarine, umbrella
How to explain?
Conceptual category dissociation II
J.J. and P.S. (Hillis & Caramazza 1991) (906-7)
• J.J. – left temporal, basal ganglia (CVA) Selective preservation of animal concepts
•P.S. – mostly left temporal (injury) Selective impairment of animate category
P.S
J.J.
Reading and Writing
Alexia and Agraphia
Alexia with agraphia•Reading and writing both impaired
•A rare disorder Patients with both impairments usually
also have Wernicke’s aphasia or transcortical sensory aphasia
Alexia without agraphia, a.k.a. pure alexia•Reading impaired, writing okay
•Can write spontaneously or to dictation
•Some can copy writing but with difficulty
Misprint in Antonio Damasio Reading
Antonio Damasio, Signs of Aphasia P. 38: “As the designation implies,
patients presenting alexia with agraphia become unable to read while they continue to be able to write…”
Should be “…alexia without agraphia…”
More on patient J.G.
Damage: Left posterior temporal-parietal
Meaning spared, phonological recognition okay, but couldn’t spell the word correctly•digit:
D-I-D-G-E-T “A number”
•thief: T-H-E-F-E “A person who takes things”
These spellings are not correct, but..
Reading – relating writing to speech
Phonologicalword image
Phonemes Letters
The “Phonics” route
Reading – relating writing to speech
Phonological Graphicword image word image
Letters
The “whole word” route
Two pathways for relating writing to speech
Phonological Graphicword image word image
Phonemes Letters
Redundancy?
Two pathways for relating writing to speech
The “whole word” route is necessary for• caught
• island
• sign
The “phonics” route is needed for long unfamiliar words• commissurectomy
• prosopagnosia
• magnetoencephalography
The spelling attempts of J.G.(one more look)
digit: •D-I-D-G-E-T•“A number”
thief: •T-H-E-F-E•“A person who takes things”
J.G. has damaged “whole word” route but intact “phonics” route
Evidence that the two routes are separately represented in the cortex
More evidence on phonological and graphic forms
Patient P.W. (905)
•Damage: anterior parietal & posterior frontal•Tested on identifying spoken words
[skirt]: “S-O-C-K, skirt•Verbal paraphasia in spelling but not in speech
[brush]: “B-R-U-S-H, comb”•Verbal paraphasia in speech but not in spelling
[knife]: “S-P-O-O-N, fork”•Verbal paraphasia in both modalities
•Paraphasias are semantically related
Patient D.R.B. (902b-903a)
Left middle cerebral artery infarct Able to discriminate words and pseudo-
words•Either visual or auditory input
Test: Two words – synonyms or not?•For written input, 95% accurate
•For spoken input, only 61% accurate
Evidence that representations of written words can have direct connections to semantic information
Graphic representation and meaning
The traditional view: speech is primary, writing secondary•History
•Development
Might suggest that writing has access to meaning only via phonological representation
But evidence from brain damage indicates that (at least some) written forms have direct access to meaning, independently of phonology
Pathway to meaning
Phonological Graphicword image word image
Phonemes Letters
Conceptualinformation
Pathways to meaning
Phonological Graphicword image word image
Phonemes Letters
Conceptualinformation
Does this pathway also exist?
Evidence for direct connections between meaning and graphic form
Patient D.R.B. (above)• Judgments of synonymy better for pairs of
written words than pairs of spoken words Patient H.W. (904)
•Damage: left parietal and occipital
•Tested on identifying written words Interest:
• “bank”
• “You go to the bank and put it in and you get more money … not very much now”
More evidence for direct connections between meaning and graphic form
Patient R.G.B. (904)
•Damage: left frontoparietal
•Tested on identifying written words Records:
• “radio”
• “You play ‘em on a phonograph … can also mean notes you take and keep”
•Understands meaning from written input, but has impaired phonological information or impaired connection to phonological information
Phonological-Graphic Connections:The Angular Gyrus
The angular gyrus and the white matter below it appear to be uniquely important for all aspects of graphic language that involve its linkage to writing, to spoken language, and to word meaning. Injury to this area disrupts not only the ability to understand the written word, but also disrupts related knowledge such as oral spelling and letter-sound correspondence, and therefore disrupts the ability to write.
Harold Goodglass Understanding Aphasia
1993:51
The angular gyrus
Superior parietal lobule
Angular gyrus
Connecting to output
Phonological Graphicword image word image
Phonemes Letters
Phonologicalproduction
Broca’s area
Arcuate fasciculusAngular gyrus
Connecting to Spoken and Written Output
Phonological Graphicword image word image
Phoneme Letter images images
Graphicproduction
Phonologicalproduction
Broca’s area
Exner’s area Superior longitudinal fasciculus
Arcuate fasciculusAngular gyrus
Exner’s Area
Superior parietal lobule
Broca’s area
Wernicke’s area Angular gyrus
Systems for Speech and Writing
Phonological Graphicword image word image
Phoneme Letter images images
Graphicproduction
Phonologicalproduction
Broca’s area
Exner’s area Superior longitudinal fasciculus
Arcuate fasciculusAngular gyrus
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