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Relative language proficiency modulates BOLD signal change when bilinguals perform semantic judgements
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Relative language proficiency modulates BOLD signal change when bilinguals perform semantic judgements Michael Chee, Nicholas Hon, Hwee Ling Lee, Chun Siong Soon Cognitive Neuroscience Lab, Singapore General Hospital ‘unctional imaging studies have shown that blood flow changes occur in spatially congruent regions when proficient or relatively mroficient bilinguals perform linguistic tasks in different languages [l]. There is less agreement when less fluent bilinguals are ompared [Z] We previously observed that Singaporeans (SGP) showed higher BOLD signal change when they performed a semantic judgment isk in Mandarin, compared to when they did the same task in English [3]. This finding differed from an earlier study that drew :om the same population but which did not show cross-language differences in activation [lb]. In the earlier study, performance ras closely matched across languages whereas in the associative semantics experiment, volunteers’ performance was slower and :ss accurate in Mandarin. A plausible explanation for the contrasting observations is to attribute the differences in activation (and erformance) to relative proficiency in Ll and L2. An alternative explanation is that Mandarin inherently requires more resources r process but that somehow this effect was not detected with another paradigm. We studied 16 English-Mandarin bilingurds: 10 Singaporean Chinese who are more proficient in English (SGP) and 6 Chinese om in the People’s Republic of China, exposed to English after the age of 12 years and who are more proficient in Mandarin ‘RC). While undergoing fMRI, subjects performed semantic judgements on triplets of words or Chinese characters. Blocks of tese stimuli were alternated with a size judgement of words or characters [3]. SGP were slower and less accurate in the Chinese ersion of the task (mean RT English: 1.58 set; Chinese: 1.89 sec.; mean accuracy English 84.8% Chinese 71.1%). The converse ‘as observed for PRC (mean RT English: 1.99 set; Chiese: 1.73 sec.; mean accuracy English 63.3% Chinese 4.7%). When the experiment was repeated without time wstmints outside the scanner, all subjects achieved accucy of at least 85% in both languages (SGP English 97%; hinese 86%; PRC English 85%, Chinese 88%). From each E ldividual and for semantic judgement in each language, srcent BOLD signal change in left hemisphere ROI’s was :terrnined. Within left prefrontal and parietal regions, the iange in BOLD signal was smaller and less extensive in a M nticipant’s more proficient language. The least proficient nformance was associated with right, in addition to left, ferior frontal activation. The results indicate that greater nguage proficiency is accompanied by less effortful perlrmance of semantic judgements and lower regional blood flow change in the left prefrontal and parietal regions. These findings iderscore the importance of taking into consideration the nature of task and relative language proficiency when drawing inferences mceming brain activation in bilinguals processing tasks in different languages. eferences Chee MWL (1999) J Neuroscience 19,3050-3056; Chee MWL Illes J (1999) Brain Lang. 70, 347-363 Dahene S.(1997) Neuroreport. 8, 3809-3815; Perani (1996) 421-31 Chee MWL Neuroimage. 12, 392-403.
(1999)
Neuron.
Neuroreport.
S516
23, 127-37; 7, 2439-2444;
Klein
1999 Neuroreport.
Hemandez
(2000)Brain
10.2841-6; Lang.
73,
Relative language proficiency modulates BOLD signal change when bilinguals perform semantic judgements Michael Chee, Nicholas Hon, Hwee Ling Lee, Chun Siong Soon Cognitive Neuroscience Lab, Singapore General Hospital ‘unctional imaging studies have shown that blood flow changes occur in spatially congruent regions when proficient or relatively mroficient bilinguals perform linguistic tasks in different languages [l]. There is less agreement when less fluent bilinguals are ompared [Z] We previously observed that Singaporeans (SGP) showed higher BOLD signal change when they performed a semantic judgment isk in Mandarin, compared to when they did the same task in English [3]. This finding differed from an earlier study that drew :om the same population but which did not show cross-language differences in activation [lb]. In the earlier study, performance ras closely matched across languages whereas in the associative semantics experiment, volunteers’ performance was slower and :ss accurate in Mandarin. A plausible explanation for the contrasting observations is to attribute the differences in activation (and erformance) to relative proficiency in Ll and L2. An alternative explanation is that Mandarin inherently requires more resources r process but that somehow this effect was not detected with another paradigm. We studied 16 English-Mandarin bilingurds: 10 Singaporean Chinese who are more proficient in English (SGP) and 6 Chinese om in the People’s Republic of China, exposed to English after the age of 12 years and who are more proficient in Mandarin ‘RC). While undergoing fMRI, subjects performed semantic judgements on triplets of words or Chinese characters. Blocks of tese stimuli were alternated with a size judgement of words or characters [3]. SGP were slower and less accurate in the Chinese ersion of the task (mean RT English: 1.58 set; Chinese: 1.89 sec.; mean accuracy English 84.8% Chinese 71.1%). The converse ‘as observed for PRC (mean RT English: 1.99 set; Chiese: 1.73 sec.; mean accuracy English 63.3% Chinese 4.7%). When the experiment was repeated without time wstmints outside the scanner, all subjects achieved accucy of at least 85% in both languages (SGP English 97%; hinese 86%; PRC English 85%, Chinese 88%). From each E ldividual and for semantic judgement in each language, srcent BOLD signal change in left hemisphere ROI’s was :terrnined. Within left prefrontal and parietal regions, the iange in BOLD signal was smaller and less extensive in a M nticipant’s more proficient language. The least proficient nformance was associated with right, in addition to left, ferior frontal activation. The results indicate that greater nguage proficiency is accompanied by less effortful perlrmance of semantic judgements and lower regional blood flow change in the left prefrontal and parietal regions. These findings iderscore the importance of taking into consideration the nature of task and relative language proficiency when drawing inferences mceming brain activation in bilinguals processing tasks in different languages. eferences Chee MWL (1999) J Neuroscience 19,3050-3056; Chee MWL Illes J (1999) Brain Lang. 70, 347-363 Dahene S.(1997) Neuroreport. 8, 3809-3815; Perani (1996) 421-31 Chee MWL Neuroimage. 12, 392-403.
(1999)
Neuron.
Neuroreport.
S516
23, 127-37; 7, 2439-2444;
Klein
1999 Neuroreport.
Hemandez
(2000)Brain
10.2841-6; Lang.
73,