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Chapter 20: Language (Language (APHASIA: partial or complete loss of…

- - - - DIFFICULTY SPEAKING but CAN understand language heard/read
      - Good comprehension
      - speech is telegraphic, uses a lot of NOUNS
      - NOT DYSARTHRIA: inability to move face and tongue muscles
    - - speech is fluent but DOESN'T MAKE SENSE
      - NO DIFFICULTY SPEAKING but can NOT understand language heard/read
      - poor comprehension
- - - - 3 year olds can produce full sentences
  - - - this is what child faces when learning native language
        
        adults use "motherese" - slower, exaggerated, vowels more articulated
        
        talking to children and pointing to things, interaction is important in learning speech sounds
- - - - Broca's area
        
        In Broca's APHASIA: grammar and syntax (word order) are disrupted
        
        important for articulation of speech
      - Wernicke's area
        
        important for processing speech sounds, recognizing spoken words
    - - Model considers 2 tasks
        
        Repeating a SPOKEN word
        
        sounds are not understood as meaningful until they are processed in Wernicke's area
        
        to repeat words, signals are passed to Broca's area via arcuate fasciculus
        
        In Broca's area, words are converted to code for muscle movements for speech and sent to motor cortex
        
        Reading a WRITTEN word ALOUD
        
        visual signs are sent to angular gyrus
        
        Transformation of signal: output of angular gyrus follow same path as spoken word pathway (Wernicke's area --> Broca's area --> motor cortex)
    - - lesion in path from Wernicke's to Broca's
        
        Usually parietal lobe lesions affecting arcuate fasciculus
        
        disconnects Wernicke's and Broca's areas but leaves the areas themselves intact
        
        comprehension is good, speech is fluent
        
        difficulty in REPEATING words and phrases that are heard/read
    - - words read DON'T HAVE TO go through Wernicke's area
      - most aphasias involve BOTH comprehension and speech deficits
- - - - fMRI tasks
        
        word generation task: generate as many words as possible in particular category
        
        Silent sentence repetition: silently repeat to themselves a sentence they previously heard read aloud
        
        Passive listening: listen to a story
      - PET scans: observe differences between SENSORY RESPONSES to words and PRODUCTION OF SPEECH
        
        PET Scans tasks
        
        viewing words: visual areas
        
        Listening to words: auditory areas
        
        speaking words: listening to words are subtracted out
        
        M1, supplementary motor area, Broca's area
        
        Generate a verb to be used with a noun
        
        example: cake --> "eat"
        
        frontal lobe, temporal cortex (word association), cingulate gyrus (attention)
- - - - demonstrates functional differences between L and R hemispheres (including language processing)
        
        Hemisphere Language Funcitions
        
        left hemisphere language dominance
        
        visual stimuli presented in RIGHT VISUAL FIELD is described easily because LEFT HEMISPHERE is dominant for language
        
        objects manipulated with right hand (out of view) are easily described
        
        images shown in LEFT VISUAL FIELD or objects felt only by LEFT HAND: person has difficulty or is unable to describe it and will say there is nothing there
        
        right hemisphere language functions
        
        show right hemisphere a noun (person sees nothing), but with his left hand can pick the correct noun because -->
        
        right hemisphere DOES HAVE language comprehension