Chapter 16 Slides - Part 3

January 9, 2018 | Author: Anonymous | Category: Science, Health Science, Neurology
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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 2

Methodolodogy of Cognitive Neuroscience Approach  

Wernicke-Geschwind model – analysis of braindamaged 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 4

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 6

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 9

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 12

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” 13

Cognitive Neuroscience of Deep and Surface Dyslexia Continued 



Deep dyslexia – extensive damage to lefthemisphere 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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