Speech and Language

Speech/Language Function BCS 242 Neuropsychology Fall 2004

Brief Anatomy 

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In >96% of right-handers and 70% of lefthanders, left hemisphere is “dominant” for speech and language Different areas implicated in different functions 

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For example, anterior location for speech production (left frontal lobe); posterior for speech comprehension (left temporal-parietal region) Roles played by subcortical structures (basal ganglia, posterior thalamus) and right hemisphere less well understood

Brain areas involved in Language

Basic Language Components       

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Auditory Comprehension Visual Comprehension Articulation Word Finding Grammar/Syntax Repetition Verbal Fluency Writing Prosody

Language Deficits     

Aphasia – spoken language Alexia – reading Agraphia - writing Anomia - naming Dysarthria - articulation

Types of Language Errors 

Paraphasia: 

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Neologism: 

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Talking with considerable effort

Agraphia: 

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Paraphasia with a completely novel word

Nonfluent speech: 

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Substitution of a word by a sound, an incorrect word, or an unintended word

Impairment in writing

Alexia: 

Disturbances in reading

19th Century Neuropsychology 

Broca (1865) described patients who displayed halting, agrammatic speech  

Content words were well preserved Function words (i.e., adjectives, articles) impaired

Broca’s Aphasia

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Patient “Tan” Brain tumor in Left frontal brain region Broca: Lesion disrupted speech

Broca’s Aphasia 

“Yes… ah… Monday… er… Dad and Peter H… (patient’s name), and Dad… er… hospital… and ah… Wednesday… Wednesday, nine o’clock… and oh… Thursday… ten o’clock, ah doctors… two… an’ doctors… and er… teeth…yah Goodglass & Geschwind, 1976

Broca’s Aphasia

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Broca’s Aphasia – Damage to “motor images” Language comprehension skills relatively preserved Typically observed in patients with damage to left inferior prefrontal cortex

Wernicke’s Aphasia

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Neologisms Speech appears to have no information content “fluent nonsense” Preserved function words, impaired content words Comprehension impaired Even simple sentences not well understood Associated with left temporal lobe damage

Wernicke’s Aphasia 

“Well this is… mother is away here working her work out o’here to get her better, but when she’s looking in the other part. One their small tile into her time here. She’s working another time…” Goodglass & Geschwind, 1976

Broca’s, Wernicke’s Area, and Connections

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Lichtheim’s (1885) and Geschwind’s (1965) model Auditory input mediated by Wernicke’s area Motor output mediated byBroca’s area Regions connected by arcuate fasciculus

Aphasia Syndromes I 

Fluent (receptive) Aphasias: All have FLUENT speech and no articulatory disorder; problems with comprehension and/or repetition 

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Wernicke (aka sensory): neologisms/anomia/ paraphasias, poor comprehension and repetition Transcortical Sensory(aka isolation syndrome): intact repetition; paraphasias/anomia, poor comprehension Conduction: phonemic paraphasias/neologisms, poor repetition, fairly good comprehension Anomic (aka amnesic):anomia and some paraphasias; all else intact

Aphasia Syndromes II 

Nonfluent (expressive) Aphasias: All have articulatory disorder but relatively preserved comprehension 

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Broca (aka motor, expressive, nonfluent): speechlessness with recurring utterances or phonetic disintegration, or phonemic paraphasias with anomia, agrammatism, and dysprosody; poor repetition Transcortical Motor: uncompleted sentences and anomia; naming better than spontaneous speech; repetition fairly intact Global: speechlessness with recurring utterances, poor comprehension, poor repetition

Aphasia Syndromes III 

“Pure” Aphasias – selective impairments with NORMAL speech production 

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Alexia without Agraphia: poor reading Agraphia: poor writing Word Deafness: poor comprehension, poor repetition

Major Aphasia Syndromes Type

Production

Comp.

Repetition

Naming

Global

impaired

impaired

impaired

impaired

Broca’s

not fluent

intact

limited

limited

Wernicke’s

fluent/ impaired

impaired

impaired

impaired

Anomic

fluent/ intact circumlocutory

intact

impaired

Mixed/ nonfluent

impaired

limited

limited

Conduction

fluent/ intact circumlocutory

impaired

limited

limited

Right Hemisphere Contribution to Language Functions 

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Good comprehension for gestural language Prosody (inflection, timbre, melody) Semantic language (word recognition, verbal meaning, concepts, and especially visual meaning)

Assessment of Language 

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Standard Aphasia Batteries (e.g., Western Aphasia Battery, Boston Diagnostic Aphasia Exam, Halstead Aphasia Screening Test) Boston Naming Test Token Test Verbal Fluency Written Expression (e.g., Cookie Theft)