Dataset Information

A cross-linguistic evaluation of script-specific effects on fMRI lateralization in late second language readers.

ABSTRACT: Behavioral and neuroimaging studies have provided evidence that reading is strongly left lateralized, and the degree of this pattern of functional lateralization can be indicative of reading competence. However, it remains unclear whether functional lateralization differs between the first (L1) and second (L2) languages in bilingual L2 readers. This question is particularly important when the particular script, or orthography, learned by the L2 readers is markedly different from their L1 script. In this study, we quantified functional lateralization in brain regions involved in visual word recognition for participants' L1 and L2 scripts, with a particular focus on the effects of L1-L2 script differences in the visual complexity and orthographic depth of the script. Two different groups of late L2 learners participated in an fMRI experiment using a visual one-back matching task: L1 readers of Japanese who learnt to read alphabetic English and L1 readers of English who learnt to read both Japanese syllabic Kana and logographic Kanji. The results showed weaker leftward lateralization in the posterior lateral occipital complex (pLOC) for logographic Kanji compared with syllabic and alphabetic scripts in both L1 and L2 readers of Kanji. When both L1 and L2 scripts were non-logographic, where symbols are mapped onto sounds, functional lateralization did not significantly differ between L1 and L2 scripts in any region, in any group. Our findings indicate that weaker leftward lateralization for logographic reading reflects greater requirement of the right hemisphere for processing visually complex logographic Kanji symbols, irrespective of whether Kanji is the readers' L1 or L2, rather than characterizing additional cognitive efforts of L2 readers. Finally, brain-behavior analysis revealed that functional lateralization for L2 visual word processing predicted L2 reading competency.

SUBMITTER: Koyama MS

PROVIDER: S-EPMC4006067 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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A cross-linguistic evaluation of script-specific effects on fMRI lateralization in late second language readers.

Koyama Maki S MS Stein John F JF Stoodley Catherine J CJ Hansen Peter C PC

Frontiers in human neuroscience 20140424

Behavioral and neuroimaging studies have provided evidence that reading is strongly left lateralized, and the degree of this pattern of functional lateralization can be indicative of reading competence. However, it remains unclear whether functional lateralization differs between the first (L1) and second (L2) languages in bilingual L2 readers. This question is particularly important when the particular script, or orthography, learned by the L2 readers is markedly different from their L1 script. ...[more]

PMID: 24795604

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Project description:The neurobiology of sentence comprehension is well-studied but the properties and characteristics of sentence processing networks remain unclear and highly debated. Sign languages (i.e., visual-manual languages), like spoken languages, have complex grammatical structures and thus can provide valuable insights into the specificity and function of brain regions supporting sentence comprehension. The present study aims to characterize how these well-studied spoken language networks can adapt in adults to be responsive to sign language sentences, which contain combinatorial semantic and syntactic visual-spatial linguistic information. Twenty native English-speaking undergraduates who had completed introductory American Sign Language (ASL) courses viewed videos of the following conditions during fMRI acquisition: signed sentences, signed word lists, English sentences and English word lists. Overall our results indicate that native language (L1) sentence processing resources are responsive to ASL sentence structures in late L2 learners, but that certain L1 sentence processing regions respond differently to L2 ASL sentences, likely due to the nature of their contribution to language comprehension. For example, L1 sentence regions in Broca's area were significantly more responsive to L2 than L1 sentences, supporting the hypothesis that Broca's area contributes to sentence comprehension as a cognitive resource when increased processing is required. Anterior temporal L1 sentence regions were sensitive to L2 ASL sentence structure, but demonstrated no significant differences in activation to L1 than L2, suggesting its contribution to sentence processing is modality-independent. Posterior superior temporal L1 sentence regions also responded to ASL sentence structure but were more activated by English than ASL sentences. An exploratory analysis of the neural correlates of L2 ASL proficiency indicates that ASL proficiency is positively correlated with increased activations in response to ASL sentences in L1 sentence processing regions. Overall these results suggest that well-established fronto-temporal spoken language networks involved in sentence processing exhibit functional plasticity with late L2 ASL exposure, and thus are adaptable to syntactic structures widely different than those in an individual's native language. Our findings also provide valuable insights into the unique contributions of the inferior frontal and superior temporal regions that are frequently implicated in sentence comprehension but whose exact roles remain highly debated.

Project description:Late bilinguals who spend (part of) their adult lives in an environment where a language other than the one they learned in childhood is spoken typically experience a range of language development phenomena. Most obviously, they will acquire some level of receptive and/or productive knowledge of the new, or second, language (L2). How basic or advanced that level will be is determined by a range of environmental, experiential, attitudinal and individual factors. Secondly, they will most likely find the knowledge of their native language (L1) beginning to diverge from that of monolingual speakers in their country of origin, a process known as language attrition. In the course of this developmental process, some L2 skills may eventually match or even overtake the corresponding skill in the L1. This shift in the balance between L1 and L2 is the focus of investigations of language dominance. The present study explores language dominance in four migrant populations (Germans in the Netherlands and Canada, Turks and Moroccans in the Netherlands). Investigating both the development of formal/controlled skills and more automatic aspects of lexical access and fluency, we aim to attain an understanding of how extralinguistic factors contribute to the development of both languages. We argue that an integrated perspective can contribute more profound insights into the predictors of this complex process of bilingual development. In particular, our findings show that statistical models based on linear relationships fall short of capturing the full picture. We propose an alternative method of analysing data, namely discriminant function analysis, based on a categorisation of the populations, and demonstrate how this can enhance our understanding. Our findings suggest that different aspects of the bilingual experience contribute differently to language development, regardless of language combination and type of skill measured. Contrary to what previous research suggests, measures relating to the intensity of informal use of both the L1 and the L2 in daily life are important in determining whether someone is a good or a poor L1 maintainer, while high vs. low success in acquisition appears to be predominantly associated with personal factors such as educational level.

Dataset Information

A cross-linguistic evaluation of script-specific effects on fMRI lateralization in late second language readers.

Publications

A cross-linguistic evaluation of script-specific effects on fMRI lateralization in late second language readers.

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