Language II October 30, 2008 Speech/Language Production I • Common Features of Models – extensive pre-planning – distinct stages of processing – general (intended meaning)-to-specific (utterance) organization – most models use of speech errors as data Spreading Activation Theory (Dell) • four levels of activity – Semantic (meaning) – Syntactic (grammatical structure of words in the planned sentence) – Morphological (basic units of meaning or word forms) – Phonological (sounds) • representation formed at each level • processing occurs simultaneously at all levels • uses speech errors as primary data Spreading Activation (cont’d) • Lexicon: connectionist network containing nodes for concepts, words, morphemes, and phonemes • Insertion rules (which is highest activated?) determine items selected for insertion into sentences • Errors predicted by model: – Errors more likely when speaker has not formed a coherent speech plan – Errors should be from same category – Anticipation errors (because of multiple activations; “The sky is in the sky”) – Exchange errors (because once selected, items’ activation turns to zero (“I hit the bat with my ball”) Speech Production II • Levelt/Bock approach – four stages: message, functional processing, positional processing, and phonological encoding – information about syntax (lemma) available before sound (lexeme) – consistent with TOT phenomenon Bock & Levelt (1984) Intended meaning Selection of word concepts, grammatical construction Ordering parts of sentence, adding inflection Phonological and prosodic elements worked out ERRORS Semantic substitution (“tennis bat”), blending (“sky is shining”), wordexchange errors (“let the bag out of the cat”) Morpheme exchange errors (“trunked two packs”), spoonerisms (“hissed my mystery lectures”) within same clause WEAVER++ (Word-Form Encoding by Activation and Verification) Neuropsychological evidence of staged selection • Content-word retrieval vs. syntactic processing • Distinction between anomia (e.g., word selection difficulties) vs. agrammatism (inability to construct grammatically correct sentences) • Jargon aphasia: can construct grammatically correct sentences but not find correct words Processes in Writing (Hayes & Flower, 1980) • Planning: generating info from LTM, organizing • Translating: producing language conforming in meaning to that retrieved in the planning stage • Reviewing: editing what is written Deep Dysgraphia Phonological Dysgraphia Language Disorders Types of Disorders • Aphasia: acquired disorder of language due to brain damage • Dysarthria: disorder of motor apparatus of speech • Developmental language disturbances • Associated disorders – Alexia – Apraxia – Agraphia Major Historical Landmarks • Broca (1861): Leborgne: loss of speech fluency with good comprehension • Wernicke (1874): Patient with fluent speech but poor comprehension • Lichtheim (1885): classic description of aphasic syndromes C A M Lichtheim’s Model Arcuate fasciculus Contemporary anologues of Lichtheim’s (1885) Aphasic Syndromes Syndrome Symptom Deficit Lesion Broca’s Aphasia speech production; sparse, halting speech, missing function words, bound morphemes Impaired speech planning and production Posterior aspects of 3rd frontal convolution Wernicke’s Aphasia Auditory comprehension, fluent speech, paraphasia, poor repetion and naming Impaired representation of sound structure of words Posterior half of the first temporal gyrus Pure motor speech disorder Disturbance of articulation, apraxia of speech, dysarthria, aphemia Disturbance of articulation Outflow from motor cortex Pure Word Deafness Disturbance of spoken word comprehension, repetition also impaired Failure to access spoken words Input tracks from auditory cortex to Wernicke’s area Transcortical Motor Aphasia Disturbed spontaneous speech similar to BA; relatively preserved repetition, comprehension Disconnection between conceptual word/sentence representations and motor speech production Deep white matter tracks connecting BA to parietal lobe Transcortical Sensory Aphasia Disturbance in single word comprehension with relatively intact repetition Disturbed activation of word meanings despite normal recognition of auditorily presented words White matter tracks connecting parietal and temporal lobe Conduction Aphasia Disturbance of repetition and spontaneous speech, phonemic paraphasia Disconnetion between sound patterns and speech production mechanisms Arcuate fasciculus; connection between BA and WA Additional Aphasia Syndromes Syndrome Symptom Deficit Lesion Anomic Aphasia single-word production, marked for common nouns; repetition and comprehension intact Impaired storage or access to lexical entries Inferior parietal lobe or connections within perisylvian language areas Global Aphasia Performance in all language functions Disruption of all/most language components Multiple perisylvian language components Isolation of the language zone Spontaneous speech, comprehension, some preservation of repetition; echolalia common Disconnection between concepts and both representations of word sounds and speech production Cortex outside perisylvian association cortex Broca’s Aphasia • • • • • Telegraphic, effortful speech Agrammatism Some degree of comprehension deficit Writing and reading deficits Repetition abnormal – drops function words • Buccofacial apraxia, right hemiparesis M.E. Examiner. M.E. Examiner. M.E. Examiner. M.E. Examiner. M.E. Cinderella ... poor ... um 'dopted her ... scrubbed floor, um, tidy ... poor, um ... 'dopted ... Si-sisters and mother ... ball. Ball, prince um, shoe ... Keep going. Scrubbed and uh washed and un...tidy, uh, sisters and mother, prince, no, prince, yes. Cinderella hooked prince. (Laughs.) Um, um, shoes, um, twelve o'clock ball, finished. So what happened in the end? Married. How does he find her? Um, Prince, um, happen to, um ... Prince, and Cinderalla meet, um met um met. What happened at the ball? They didn't get married at the ball. No, um, no ... I don't know. Shoe, um found shoe ... Wernicke’s Aphasia • • • • • • Fluent, nonsensical speech Impaired comprehension Grammar better preserved than in BA Reading impairment often present May be aware or unaware of deficit Finger agnosia, acalculia, alexia without agraphia Wernicke description of “Cookie Theft Picture” C.B. Uh, well this is the ... the /dødøü/ of this. This and this and this and this. These things going in there like that. This is /sen/ things here. This one here, these two things here. And the other one here, back in this one, this one /gø/ look at this one. Examiner. Yeah, what's happening there? C.B. I can't tell you what that is, but I know what it is, but I don't now where it is. But I don't know what's under. I know it's you couldn't say it's ... I couldn't say what it is. I couldn't say what that is. This shu-- that should be right in here. That's very bad in there. Anyway, this one here, and that, and that's it. This is the getting in here and that's the getting around here, and that, and that's it. This is getting in here and that's the getting around here, this one and one with this one. And this one, and that's it, isn't it? I don't know what else you'd want. Conduction Aphasia • • • • • Fluent language Naming and repetition impaired May be able to correct speech off-line Hesitations and word-finding pauses May have good reading skills Global Aphasia • Deficits in repetition, naming, fluency and comprehension • Gradations of severity exist • May communicate prosodically • Involve (typically) large lesions • Outcome poorest; anomic Transcortical Aphasias Transcortical Motor • Good repetition • Impairment in producing spontaneous speech • Good comprehension • Poor naming • • • • • Transcortical Sensory Good repetition Fluent speech Impaired comprehension Poor naming Semantic associations poor Associated Deficits • Alexia without Agraphia – Impairment in reading with spared writing • Apraxia – Loss of skilled movement not due to weakness or paralysis Fundamental Lessons • Language processors are localized • Different language symptoms can be due to an underlying deficit in a single language processor • Language processors are regionally associated with different parts of the brain in proximity to sensory or motor functions What Language Disorders Reveal about Underlying Processes • Pure Word Deafness: selective processing of speech sounds implies a specific speechrelevant phonological processor • Transcortical Sensory Aphasia: repetition is spared relative to comprehension; selective loss of word meaning; some cases suggest disproportionate loss of one or more categories What Language Disorders Reveal about Underlying Processes • Aphasic errors in word production: reveal complex nature of lexical access – Phonological vs. semantic errors: independent vs. interactive relationship? – Grammatical class: nouns vs. verbs (category specificity) • Broca’s aphasia: syntax comprehension and production – Central syntactic deficit; loss of grammatic knowledge – Problems in “closed-class” vocabulary (preposition, tense markers) – Limited capacity account – Mapping account (inability to map from parsing to thematic roles) • Jargon Aphasia: can construct gramatically “better” sentences than agrammatics, but can’t find words, producing neologisms; reinforces distinction between content and grammatical struture Prosody • Linguistic vs. nonlinguistic prosody • Evidence for hemispheric differences • Clinical syndromes – Disturbances of comprehension • Auditory affective agnosia • Phonagnosia – Disturbances of prosodic output • Aprosodias Spontaneous Prosody Good Poor Ross & Monnot (2007) Brain and Language Ross & Monnot (2007) Brain and Language Aphasia and the Semantic System • Meaning stored separately from form • Models of representation in semantics – Feature-based models (see categorization) – Nondecompositional meaning • Modality-specific semantic deficits: optic aphasia as an example Two Example Models of Semantic Organization One Semantic System Multiple Semantic Systems
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