The effects of environment change on third languages: the case of returnees.

This chapter discusses the development of the language competence of returnee bilingual speakers, (i.e., heritage speakers who return to their (parents’) country of origin and, as a consequence of the return, are affected by changes of their language dominance). We discuss three scenarios in which an environmental shift may affect the status of a L3: (1) L3 attrition, when the L3 acquired in a foreign setting undergoes attrition due to reduction in input after returning to the homeland; (2) theoretical discussions of whether the relearning of an attrited L2 can be considered L3 acquisition; (3) the source of crosslinguistic influence on the L3 and how studying the returnee population can open an exciting opportunity to tease apart internal and external factors that are otherwise confounded in the traditional bilingual population. We combine the interpretation of the limited existing literature on language development in returnees with theoretical considerations, and propose research hypotheses to be tested in future research

Losing access to the second language and its effect on executive function development in childhood:The case of 'returnees'

This study examined how relative language proficiency and exposure influence the development of executive function (EF) in 7–12 year-old bilingual ‘returnee’ children. Returnees are children of immigrant families who were immersed in an environment where their second language (L2; English) was the majority societal language and returned to their native language (L1; Japanese) environment after the period of prolonged, naturalistic L2 exposure. Targeting this population allows us to address the question of how the loss of opportunities to engage in bilingual activities may longitudinally affect EF development. We administered EF inhibition and monitoring/updating skills tasks shortly after the children's return to their L1 environment and again one year later. The results showed that the amount of reduction in L2 exposure (i.e., the difference in L2 exposure when they lived in an L2 majority language environment vs. back in the L1 environment) affected children's monitoring and updating abilities. The greater reduction the children experienced in L2 exposure, the smaller their improvement was on the updating task in the second interval. The finding suggests that losing access to one's L2, that is, less active bilingualism is associated with attenuated effects in EF development

Language change in bilingual returnee children: mutual effects of bilingual experience and cognition

In this thesis, I focus on the linguistic changes that occur within bilingual returnee children; that is, children who were immersed in a second language (L2) dominant environment and returned to their first language (L1) environment. Tracking the development of such a specific population allows us to disentangle the effects of age from those of the bilingual experience. Longitudinally, these returnee children (ages 7-13) experience an increase in age but decrease in L2 exposure. In other situations that have been studied, age and bilingual experience are variables that are often difficult to tease apart because they are positively correlated. As this is not the case for the population I study, longitudinal data from bilingual returnee children offer opportunities to separate the relative influence of these factors on children’s language and cognitive development. Linguistic changes that occur due to detachment from the L2 environment are typically defined as ‘L2 attrition’. However, these linguistic changes do not necessarily entail a loss of the second language and can be manifested through various linguistic phenomena. Thus, the first aim of the thesis is to examine what aspects of the language undergo changes over time. Various structures of the language, both in L1 and L2 are examined—from genitive structures (Chapter 6) to lexical access (Chapter 7) and language control (Chapter 8). The results of these studies demonstrate that not all changes in L2 are recessive (Chapter 7 and 8) and not all linguistic structures are vulnerable to change (Chapter 6). Specifically, the results of Chapter 6 show that cross-linguistic transfer alone cannot explain the change in preference for linguistic expressions, and instead suggest that processing difficulties (i.e., effects of bilingualism per se) are also at play in the selectivity of language change. The second aim of the thesis is to examine what factors contribute to the process of language change in returnee children. Chapter 7 specifically examines the role of individual variables such as age of L2 onset, length of residence, language exposure, and proficiency on the changes in lexical access. The finding is that length of residence plays a crucial role in L2 maintenance, supporting the maturational account that children require some time to stabilize their language knowledge so that it becomes resistant to change. In addition to individual variables, Chapter 8 explores the influence of cognitive factors on language control. Given the intricate relationship between bilingualism and cognition, I hypothesized that children who are better ‘developers’ in general cognition may also be better ‘retainers’ of the language. The findings offer support for this hypothesis—children who improved their cognitive performance (measured by the Simon task) also better developed their language control (measured by the language-switching paradigm), especially in their L2. Chapter 9 then focuses on the change in general cognition rather than in language, by demonstrating that proficiency is a significant determinant for development in executive control— children who had higher L2 proficiency showed a more significant enhancement in their cognitive performance over time. Through these studies, this thesis contributes to an understanding of attrition and cognition in the development of children. Although much more work is required to fully explore the interplay of factors, this thesis provides evidence that executive control, in addition to bilingual experience, may affect (and even offset) the effects of language attrition in bilingual children

Linguistic consequences of toing and froing:Factors that modulate narrative development in bilingual returnee children

This longitudinal study examined the development of narrative micro- and macrostructure in Japanese-English bilingual returnee children. Returnees are children of immigrant families who move to a foreign country, spending a significant portion of their formative developmental years in the foreign majority language context before returning to their native language environment. The returnees did a narrative task in both their L1 (Japanese) and L2 (English) immediately upon their return to their native language environment and a year after. The results showed no aggregate significant changes in L1 or L2 micro- and macrostructure over time. However, at the individual level, the degree of maintenance of L2 microstructure was modulated by L2 exposure. That is, children who continued to receive L2 exposure better maintained their English microstructure (i.e. Type-Token Ratio and Verbs per Utterance) despite being re-immersed in the L1 environment. In terms of their Japanese, the age of return to the L1 environment and relative proficiency predicted the development of their Japanese microstructure (i.e. MLU, Fluency, Type-Token Ratio) and macrostructure. Our study is the first to track both languages of bilingual returnee children over time, revealing that different background variables affect the change in returnee children’s L1 and L2 narrative abilities

Specific gene expression in unmyelinated dorsal root ganglion neurons in nonhuman primates by intra-nerve injection of AAV 6 vector

霊長類においてウイルスベクターを用いた痛覚神経への遺伝子導入に成功 --神経障害性疼痛治療への応用に期待--. 京都大学プレスリリース. 2021-08-12.Adeno-associated virus 6 has been proposed as a potential vector candidate for specific gene expression in pain-related dorsal root ganglion neurons, but this has not been confirmed in nonhuman primates. The aim of our study was to analyze the transduction efficiency and target specificity of this viral vector in the common marmoset by comparing with those in the rat. When green fluorescent protein-expressing serotype-6 vector was injected into the sciatic nerve, the efficiency of gene expression in dorsal root ganglion neurons was comparable in both species. We found that the serotype-6 vector was largely specific to the pain-related ganglion neurons in the marmoset as well as in the rat, whereas the serotype-9 vector resulted in contrasting effects in the two species. Neither AAV6 nor AAV9 resulted in DRG toxicity when administered via the sciatic nerve, suggesting this as a safer route of sensory nerve transduction than the currently used intrathecal or intravenous administrative routes. Furthermore, the adeno-associated virus 6 vector could be an optimal serotype for gene therapy for human chronic pain that has minimal effect on other somatosensory functions of dorsal root ganglion neurons

Morphological transparency and markedness matter in heritage speaker gender processing: an EEG study

The present study investigated the qualitative nature of grammatical gender knowledge and processing in heritage speakers (HSs) of Spanish living in the United States. Forty-four adult Spanish HS bilinguals participated, completing a behavioral grammatical gender assignment task and a grammaticality judgment task (GJT) while their brain activity was recorded using electroencephalography (EEG). The EEG GJT task included grammatical and ungrammatical sentences with grammatical gender violations on inanimate nouns, where transparency of the morpho(phono)logical cue and markedness were manipulated. The results of this study revealed that grammatical gender violations elicited the typical P600 effect across all relevant conditions, indicating that the grammatical representations and processing of grammatical gender in HSs are qualitatively similar to those in Spanish-dominant native speakers. Given the experimental manipulation in this study, these findings also suggest that both morphological transparency and markedness play significant roles in how grammatical gender is processed. However, the results of this study differ from those reported in previous studies with Spanish-dominant native speakers, as the P600 effect found was accompanied by a biphasic N400 effect. This pattern of results is interpreted as further evidence that the bilingual experience of HSs modulates certain aspects of morphosyntactic processing, particularly conferring a greater reliance on morphology. Additionally, the results of this study highlight the importance of incorporating neurolinguistic online processing methods to better understand what underlies HS bilingual competence and processing outcomes

99mTc generator using molybdenum nanoparticles

The version of record of this article, first published in Journal of Radioanalytical and Nuclear Chemistry, is available online at Publisher’s website: https://doi.org/10.1007/s10967-023-09173-