Download - Cognitive Neuroscience of Language
Cognitive Neuroscience of Language
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Cognitive Neuroscience of Language
Premise 1: Constituent Cognitive Processes Phonological analysis Syntactic analysis Semantic analysis
Premise 2: Areas of the brain involved in language are not exclusively involved with that function
Premise 3: Brain areas involved with language are small and widely distributed & parts of other functional systems
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Methodolodogy of Cognitive Neuroscience Approach
Wernicke-Geschwind model – analysis of brain-damaged patients
Cog Neuro approach employs a wide array of other techniques
fMRI, PET, TMS
Functional brain imaging studies have revolutionized study of language
Caveat: Correlation ≠ Causation
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Functional Brain Imaging and Localization of Language
Bevalier’s fMRI study of reading – sought to establish cortical involvement in reading
Reading sentences versus control periods (strings of consonants) Areas of activity were tiny and spread out
Active areas varied between subjects and trials
Activity was widespread
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FIGURE 16.16 The areas in which reading-associated increases in activity were observed in the fMRI study of Bavelier and colleagues (1997). These maps were derived by averaging the scores of all participants, each of whom displayed patchy increases of activity in 5–10% of the indicated areas on any particular trial.
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Damasio’s PET Study of Naming
Damasio and colleagues (1996) PET study of naming Images of famous faces, animals, and tools Activity while judging image orientation subtracted
from activity while naming Left temporal lobe areas activated by naming
varied with category Activity seen well beyond Wernicke’s area
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PET Study of Naming
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Cognitive Neuroscience of Dyslexia
Dyslexia – reading difficulties not due to some other deficit (e.g., vision, intelligence)
Developmental dyslexia – apparent when learning to read Heritability estimate = 50% More common in boys than girls
Acquired dyslexia Due to brain damage Relatively rare
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Developmental Dyslexia: Causes and Neural Mechanisms
Brain differences identified, but none seems to play a role in the disorder
Multiple types of developmental dyslexia – possibly multiple causes
Various subtle visual, auditory, and motor deficits are commonly seen
Weight of evidence: deficit of phonological processing rather than sensorimotor processing
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Developmental Dyslexia and Culture
Genetic component – yet the disorder is also influenced by culture
Twice as many English speakers as Italian speakers diagnosed with dyslexia
Sound-symbol correspondence in English is more complex and difficult to learn
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Cognitive Neuroscience of Deep and Surface Dyslexia
Two procedures for reading aloud Lexical – using stored information about words Phonetic – sounding out
Surface dyslexia – lexical procedure lost, can’t recognize words
Deep dyslexia – phonetic procedure lost, can’t sound out unfamiliar words
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Cognitive Neuroscience of Deep and Surface Dyslexia Continued
Surface dyslexia – loss of visual recognition of words (cannot “look and say”)
Deep (or “phonological”) dyslexia – loss of ability to “sound out” unfamiliar words or “nonwords”
Different error patterns for surface and deep Surface – e.g. trouble with the pronunciation exceptions
“have” or “lose”
Deep: - e.g. “quill” for “quail” or “hen” for “chicken”
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Cognitive Neuroscience of Deep and Surface Dyslexia Continued
Deep dyslexia – extensive damage to left-hemisphere language areas
How is it that lexical procedure is spared? May be housed in left language areas that are spared May be mediated by the right hemisphere Evidence for both exists
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