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Representation of multiple
languages in human brain
Staudacher Veronika
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Presented Paper
Kim, Relkin, Lee, Hirsch. (1997) „Distinct cortical areas
associated with native and second languages“.
Nature ,vol. 338: p. 171
–174.
Research at the Department of Neurology and
Neuroscience, Cornell University Medical College,
New York
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Overview
Methods of investigation
a) Imaging
b) Analysis and subjects (test persons)
c) Task
Results of representation in brain areas of
a) native language
b) second language (early & late bilinguals)
Summary and Conclusions
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Method of investigation
• fMRI: 1.5-tesla magnetic resonance
scanner, with fixed head position
• 16 slices of brain (4.5 - 4.7 mm )
•
Areas of interest:* the inferior frontal gyrus (=anterior
language region; Broca‘s area incl.
Brodmann‘s 44 +46)
* the superior temporal gyrus
(=posterior language region; Wernicke‘s area incl. Brodmann‘s 22)
• 30 images, one every 3 sec., 10 during
baseline period, 10 during a stimulation or task period, 10
baseline again
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Analysis and Subjects
•
2 identical runs with each language, native and a secondlanguage
• Statistical analyses of changing signals between baseline and
stimulation periods
• 12 healthy multilingual volunteers, 9 male, 3 females
• Right-handed or ambidextrous
• Mean age 29.3 years
•
6 early bilinguals (parents speak one language, kids& friendsanother one, or parents spoke 2 languages)
• 6 late bilinguals (L2 in early adulthood, 11.2 years, lived in
country of L2)
•
Alltogether 10 languages represented, equal fluency
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Task
• Persons were prepared before starting
• Describe events of the previous day (morning,
afternoon, nightsignals were taken)
• Sentences had to be generated silently (internal
speech) to avoid head movement
• Briefing before task in which language the person
should be speaking silently, because• Languages were altered during session to avoid
habituation
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Results
• Focus of observations on Broca‘s and Wernicke‘s
areas, axial slice
• Typical late bilingual: anterior language
area (Inferior frontal gyrus, Brodmann‘s 44)
green box:red: significant activity during native
language (Engl.)
yellow: activity during second
language (French)
2 centers of activation(+), separated
7.9 mm
Result: 2 separated areas for each language
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Results
• Late bilinguals: distinct areas of activation in Broca‘s
area (anterior) for different languages
Examples of bilinguals:
red: significant activity during native language
yellow: activity during second language
2 centers of activation(+)
various distances according to language
combinations
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Results
• Late bilingual: posterior language area (superior temporal
gyrus, Brodmann‘s 22)
green box:
red: significant activity during
native language (Engl.)yellow: activity during second
language (French)
orange: common area for native
and second language
2 centers of activation(+),
separated only 1.1 mm
Result: similar or identical
cortical regions serve
both languages
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Results
• Early bilingual (e.g. English, Turkish): : in posterior
language area (superior temporal gyrus, Brodmann‘s 22)
green box
red: significant activity Turkish language task
yellow: activity English language task
orange: common voxels for both languages
2 centers of activation(+), separated only 2.3 mm,
within
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Results
Result: Late acquisition of L2 = tendency of spatially distinction in Broca‘s area,
little or no separation in Wernicke‘s area (be it early or late acquisition)
Late bilinguals Early bilinguals
Broca‘s Area:
Mean distance of
center-of-mass
6.43 mm 1.53 mm
Number of voxels Equal for each
language,separated
multiple common
voxels
Wernicke‘s area:
Mean distance of
center-of-mass
1.95 mm 1.58 mm
Number of voxels Different for each language
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Conclusions
• Age of language acquisiton may be a significant factor for the
functional organization in brain.
• Children can discriminate all phonetical differences at the
beginning of their life, but then may adapt the acoustic space
in brain to their native languages.
• Adjacent cortical areas are used for second language learning
as an adult.
• The younger a child, when learning a second language, the
less distinction in brain (PET study: average age 7.9 years).
• Further questions rise concerning Broca‘s role in processing
the phonetic structure of different languages.
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Thank you!