Crinion et al. (2006) Amanda Lee PSYC 260. Introduction Method Results Discussion Thoughts:...
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Transcript of Crinion et al. (2006) Amanda Lee PSYC 260. Introduction Method Results Discussion Thoughts:...
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
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
Introduction
Hypothesis: reduced activation in the left anterior temporal region when 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
Method
Group 1: 11 German-English bilinguals PET
Group 2: 14 German-English bilingualsfMRI
Group 3: 10 Japanese-English bilinguals
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
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)
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
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
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
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
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
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?
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
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
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.