Speech/Language Function BCS 242 Neuropsychology Fall 2004.

Speech/Language Function

BCS 242 NeuropsychologyFall 2004

Brief Anatomy

In >96% of right-handers and 70% of left-handers, left hemisphere is “dominant” for speech and language

Different areas implicated in different functions 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 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: Substitution of a word by a sound, an incorrect word,

or an unintended word Neologism:

Paraphasia with a completely novel word Nonfluent speech:

Talking with considerable effort Agraphia:

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

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

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

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

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

poor repetition

Major Aphasia SyndromesType 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 intact impaired circumlocutory

Mixed/ impaired limited limited limitednonfluent

Conduction fluent/ intact impaired limitedcircumlocutory

Right Hemisphere Contribution to Language Functions Good comprehension for gestural

language Prosody (inflection, timbre,

melody) Semantic language (word

recognition, verbal meaning, concepts, and especially visual meaning)

Assessment of Language 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)