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Speech/Language Function

Speech/Language Function. BCS 242 Neuropsychology Fall 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

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Speech/Language Function

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  1. Speech/Language Function BCS 242 Neuropsychology Fall 2004

  2. 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

  3. Brain areas involved in Language

  4. Basic Language Components • Auditory Comprehension • Visual Comprehension • Articulation • Word Finding • Grammar/Syntax • Repetition • Verbal Fluency • Writing • Prosody

  5. Language Deficits • Aphasia – spoken language • Alexia – reading • Agraphia - writing • Anomia - naming • Dysarthria - articulation

  6. 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

  7. 19th Century Neuropsychology • Broca (1865) described patients who displayed halting, agrammatic speech • Content words were well preserved • Function words (i.e., adjectives, articles) impaired

  8. Broca’s Aphasia • Patient “Tan” • Brain tumor in Left frontal brain region • Broca: Lesion disrupted speech

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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 intact impaired circumlocutory Mixed/ impaired limited limited limited nonfluent Conduction fluent/ intact impaired limited circumlocutory Major Aphasia Syndromes

  18. 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)

  19. 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)

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