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Page 1: Cognitive Neuroscience of Language

Cognitive Neuroscience of Language

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Page 2: Cognitive Neuroscience of Language

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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Page 3: Cognitive Neuroscience of Language

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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Page 4: Cognitive Neuroscience of Language

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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Page 7: Cognitive Neuroscience of Language

PET Study of Naming

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Page 8: Cognitive Neuroscience of Language

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Page 9: Cognitive Neuroscience of Language

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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Page 11: Cognitive Neuroscience of Language

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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