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Language Control in the Bilingual Brain

Crinion et al. (2006). Language Control in the Bilingual Brain. Amanda Lee PSYC 260. Outline. Introduction Method Results Discussion Thoughts: Strengths and Limitations Summary. Introduction. Multilingualism is a valuable asset and becoming more widespread

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Language Control in the Bilingual Brain

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  1. Crinionet al.(2006) Language Control in the Bilingual Brain Amanda Lee PSYC 260

  2. Outline • Introduction • Method • Results • Discussion • Thoughts: Strengths and Limitations • Summary

  3. Introduction • Multilingualism is a valuable asset and becoming more widespread • How does the bilingual brain use and process different languages? • Previous studies: both languages that a bilingual individual speaks activate the same brain areas: • Frontal, temporal and parietal regions

  4. Introduction • No specific areas determined for multilingualism • Left anterior temporal region highlighted in past research • Not confirmed to be responsible • Objective: identify language-dependent neuronal mechanisms to be tested on a semantic level

  5. Introduction • Hypothesis: reduced activation in the left anterior temporal regionwhen two semantically similar words are presented compared to a dissimilar pair. • Eg: trout-SALMON = less activation than trout-HORSE • Semantic priming effect • Both words in the pair also tested in different languages • Language-independent  neuronal responses the same throughout brain • i.e. trout-SALMON = less activation regardless of language • Only semantics affect brain activation • Language-dependent  different neuronal responses based on both semantics and language of target word

  6. Method • Group 1: 11 German-English bilinguals  PET • Group 2: 14 German-English bilinguals fMRI • Group 3: 10 Japanese-English bilinguals

  7. Method • 1750 ms long period • 250 ms to view prime word • Semantic decision based on physical characteristic • Baseline brain activation = deciding whether or not non-literary symbols were the same • Independent variables: congruency of the prime and target words in semantic relation and language • Dependent variables: Response time (s), accuracy (%), brain activation

  8. Results • All 3 groups: brain activation in frontal, temporal, parietal regions and visual cortices • Semantic priming evident in all cases • Response time for semantically related words (S) was 41 ms faster than unrelated words (U)

  9. Results • Reduced activation in left ventral anterior temporal lobe for semantically related word pairs • Same effect for both languages • Neural response only changed with semantic content (A) German-English fMRI. (B) Japanese-English fMRI. (C) German-English PET

  10. Results • Reduced activation in left caudate nucleus for semantically related words • Only if the prime and target words were the same language • Change accompanies language and semantics

  11. Discussion • Anterior temporal lobe  language-independent • Left caudate nucleus language-dependent • Works to extract the same semantic meaning from two different terms and make them equivalent

  12. Discussion • Possible neural mechanism of left caudate: • Same neurons respond to both languages • Increased neuronal firing when language input changes • Helps us modify output and use appropriate language

  13. Discussion • Damaged left caudate nucleus: • Impairs ability to respond to input change • Language production affected  switch languages inappropriately • Support for hypothesis and idea of general language-dependent structure • Not left anterior temporal lobe as thought • Left caudate projects to frontal, temporal, parietal lobes  thalamus  motor sequences for articulation

  14. Discussion: Further studies • Test wider variety of languages that are also more different from English • Tonal languages, different phonetics • Arrive at universal conclusion for language • Other aspects of language • Syntax, pragmatics, etc. • Study the left caudate • How does it connect to other brain structures to create a mechanism responsible for multilingualism?

  15. Thoughts: Strengths & Limitations • Strengths: • Thorough discussion on possible neuronal mechanisms for left caudate nucleus • Pinpointed specific structure and examined entire brain • Limitations • Not well laid out: data all in figure captions • Lack of detail  difficult to replicate experiment • Confusing 2 x 2 x 2 design: hard to track dependent variable • Ability to generalize results is questionable

  16. Summary • Left anterior temporal lobe is language-independent • only responds to semantic meaning • Left caudate nucleus plays a critical role in language control • activates upon change in semantic/language input • is the language-dependent mechanism for monitoring language • Future studies could test the proposed mechanism: left caudate and surrounding areas • broaden scope of languages tested to come to universal conclusion

  17. References • Crinion, J., Turner, R., Grogan, A., Hanakawa, T., Noppeney, U., Devlin, J.T., Aso, T., Urayama, S., Stockton, K., Usui, K., Green, D.W., Price, C.J. (2006). Language control in the bilingual brain. Science, 312 (5779), 1537-1540.

  18. Thank you! Questions?

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