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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