Language and Aphasia

CSE 140 etc.

Outline

• Review the relationships between lesions and linguistic effects

• Review of the traditional picture about Broca’s aphasia, and agrammatism

• Examine how a particular study arrived at a more detailed picture of the deficit in Broca’s aphasia

Cortical Regions

Although we have seen large scale brainstructures (e.g. lobes), Damasio refers tocortical regions by number in the reading.

Pink: FrontalBlue: ParietalGreen: TemporalYellow: Occipital

Brodmann AreasDistinct brain areas identified in terms of anatomical structure

•So e.g. Broca’s area issometimes definedas consisting of 44,45;much of the literatureuses these numbers because of their precisedefinitions.

Traditional Distinction

• Broca’s: Non-fluent speech; function words and morphemes omitted; comprehension ok.

• Wernicke’s: Fluent speech, but filled with non-sense or filler words; comprehension impaired.

From a traditional point of view:

Areas and Connections

Broca

Wernicke

Arcuate Fascisculus

Causes

• Stroke

• Head injury

• Tumors

• Degenerative conditions (e.g. Alzheimer’s)

Types

• Broca’s (more later)

• Wernicke’s: Damage to posterior area

• Conduction: Arcuate + cortex above

• Global: Entire set of language areas

Wernicke’s

Speech: Fluent and well-articulated; butcontains many non-words, or filler words

Comprehension: Poor

Basic Idea: Damage to areas in whichwords are stored, or in which the phono-logical forms of words are associatedwith meanings.

Conduction AphasiaLesion: Affects areas connecting Wernicke’sand Broca’s areas

Supramarginal gyrus

Also arcuate,which is underneath

Conduction Continued

Speech: Relatively unimpaired; but manyspeech errors, or non-words are used. Alsodefective naming ability.

Comprehension: Also good, unlikeWernicke’s, but repetition is not possible

Idea: Network that builds meaningful unitsout of speech sounds is disabled.

Global Aphasia

Lesion: Covers entire system of languageareas in the dominant hemisphere

Abilities: Almost total inability to produce orcomprehend speech.

Idea: Combines features of Broca’s andWernicke’s aphasias

Additional Specific Deficits

The Temporallobe is shown ingreen.

Left temporal poleAreas 20,21

Temporal Lobe Problems

Damage to the temporal pole and areas 20,21 impairs subjects’ ability to retrieve words.Other abilities seem to remain more intact.

• Temporal pole alone: proper nouns (John, Washington, etc.) are affected, not commonnouns like dog, cat, etc.

• Lesion in 20,21: retrieval of both noun types isseverely impaired.

Summary

•Very specific linguistic effects for lesionsin certain areas.

•Primary role of Broca’s and Wernicke’sareas for language, along with the areasand fibers connecting them

•Remaing questions: how the specifics ofa deficit as complicated as e.g. Broca’s aphasia are studied

Grammaticality JudgmentsReviewing a study by Linebarger et al. (1983)that shows a surprising aspect of Broca’s aphasia

Background: Knowledge that Broca’s aphasics have difficulty with word-order, and assigning roles to participants:

He showed her baby the pictures.He showed her the baby pictures.

The cat that the dog is biting is black.The dog that the cat is biting is black.

The theory at the time: Broca’s patients are unable toconstruct syntactic representations.

Idea behind the study

Basic Idea: Test the idea that Broca’s aphasicscannot construct syntactic representations by presenting them with a mixture of grammatical and ungrammatical sentences, and having themmake a judgment.

Procedure: Subjects listened to sentences of tentypes, grammatical and ungrammatical versions,and had to accept or reject them.

Some sentence typesSyntactic frames:

He came to my house at six o’clock.*He came my house at six o’clock.

Auxiliary Inversion:

Is the boy having a good time?*Is the boy is having a good time?

Gapless relative clauses:

Mary ate the bread that I baked.*Mary ate the bread that I baked a cake.

More sentence typesTag Questions:

The little boy fell down, didn’t he?*The little boy fell down, didn’t it?

Reflexive Sentences:

I helped myself to the birthday cake.*I helped themselves to the birthday cake.

Auxiliary verb in tag question:

John is very tall, isn’t he?*John is very tall, didn’t he?

PredictionsThe study is designed to test the theory that Broca’s aphasics cannot construct syntactic structures.

Prediction of that theory: Broca’s aphasicsshould not show knowledge of grammaticalityor ungrammaticality. They are not able to constructsyntactic representations, so they should haveto guess.

Results from one subject

Sentence Good Sentence Bad

Accept 178 13

Reject 52 208

I.e., the subjects could tell for the majority of caseswhich sentences were grammatical and which not.

The behavior of one subject, indicative of the rest:

Interpreting the results

The Broca’s patients showed remarkably goodresults, suggesting that they are capable of performing syntactic analyses. Two further points:

1. They did not perform equally well on allsentence types.

2. What does this result show, given thatthese patients do have difficulty in tasksthat require them to identify Agents, Patients,and so on?

The problematic cases

Tag-questions and reflexives were considerablymore difficult for the subjects:

The little boy fell down, didn’t he?*The little boy fell down, didn’t it?

John is very tall, isn’t he?*John is very tall, didn’t he?

I helped myself to the birthday cake.*I helped themselves to the birthday cake.

One possibilityThese sentences involve storing the gramma-tical features of an element, for use later:

The little boy fell down, didn’t he? (boy = Masculine)John is tall, isn’t he? (Aux = 3rd Person of be)I helped myself to the cake. (Subject = Ist Person I)

Sentence Storage

One idea is that the syntactic analysis is good, butat the cost of a shallow semantic analysis. That is,the patients parse the structure correctly, but do notretain the features noted above, in this type of case.

The larger pattern

•The authors suggest that there is a tradeoff between syntax and semantics. If tasks like picturenaming tax each, then deficits will be more apparent.

•In any case the result is interesting and surprising,because it shows grammatical sensitivity in a population thought to be incapable of syntacticanalysis.

•Once again, the study shows the integration of linguistic and experimental techniques.