Artikel
Identifying cortical first and second language sites by navigated transcranial magnetic stimulation of the dominant hemisphere in bilinguals
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Autoren
Veröffentlicht: | 8. Juni 2016 |
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Gliederung
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Objective: The cortical areas coding for first (L1) and second language (L2) in bilinguals are still not sufficiently explored. Thus, this study aimed to investigate the left-hemispheric distribution of L1 and L2 using repetitive navigated transcranial magnetic stimulation (rTMS) in combination with an object-naming task.
Method: rTMS was applied to the dominant left hemisphere in ten healthy bilingual right-handers during an object-naming task, and resulting naming errors were categorized into all errors (no responses, performance errors, hesitations, neologisms, semantic and phonological errors together), all errors without hesitation, and no responses. Error rates (ERs, number of errors / number of stimulations) and subject rates (number of subjects with errors / total number of subjects) were calculated and compared.
Results: Higher ERs were observed in L1, and there was a significant difference between ERs of L1 and L2 for no-response errors (L1 mean 11.9 ± 9.0%, L2 mean 6.5 ± 5.2%; p=0.03), but not for all errors (L1 mean 20.8 ± 12.8%, L2 mean 13.6 ± 6.4%; p=0.06) and all errors without hesitation errors (L1 mean 14.0 ± 10.1%, L2 mean 8.5 ± 5.5%; p=0.08), respectively. With respect to the cortical pattern of naming errors, the left hemisphere shows different cortical distributions for L1 and L2. Furthermore, L1 presents a more stable pattern of language distribution compared to L2.
Conclusions: The cortical language distribution of bilinguals is different for L1 and L2. Moreover, a more stable distribution of language areas for L1 and a more variable spatial distribution for L2 was observed.