Neural substrates of L2-L1 transfer effects on phonological awareness in young Chinese-English bilingual children.

The growing trend of bilingual education between Chinese and English has contributed to a rise in the number of early bilingual children, who were exposed to L2 prior to formal language instruction of L1. The L2-L1 transfer effect in an L1-dominant environment has been well established. However, the threshold of L2 proficiency at which such transfer manifests remains unclear. This study investigated the behavioral and neural processes involved when manipulating phonemes in an auditory phonological task to uncover the transfer effect in young bilingual children. Sixty-two first graders from elementary schools in Taiwan were recruited in this study (29 Chinese monolinguals, 33 Chinese-English bilinguals). The brain activity was measured using fNIRS (functional near-infrared spectroscopy). Bilingual children showed right lateralization to process Chinese and left lateralization to process English, which supports more on the accommodation effect within the framework of the assimilation-accommodation hypothesis. Also, compared to monolinguals, bilingual children showed more bilateral frontal activation in Chinese, potentially reflecting a mixed influence from L2-L1 transfer effects and increased cognitive load of bilingual exposure. These results elucidate the developmental adjustments in the neural substrates associated with early bilingual exposure in phonological processing, offering valuable insights into the bilingual learning process.

Auditory memory span in Mandarin-speaking preschoolers with congenital hearing loss: Impact of task structure.

Objective: The current research was conducted to test the prediction that children who have hearing loss and are developing spoken language can perform at the same level as hearing children in an auditory memory span task if actual production of speech is excluded from task requirement.Method: A listen-and-point digit span task and two sub-tests of Wechsler Intelligence Scale for Children-IV (Verbal Digit Span and Matrix Reasoning) were administered to thirty hearing children and thirty-three children with hearing loss. A language assessment instrument for Mandarin-speaking preschool children was also administered to the participants with hearing loss.Results: The listen-and-point task not only correlated with the Verbal Digit Span sub-test, but also correlated with the comprehension sub-test of the language assessment instrument. The size of auditory memory span was similar in both groups of participants in the listen-and-point task. Moreover, the memory span estimated in the listen-and-point task was smaller than that estimated in the Verbal Digit Span task. The correlation coefficients between chronological age and the listen-and-point task were also similar in both groups of children.Conclusions: When speech processes are not required in an auditory working memory task, demand for the phonological loop is reduced and the children with hearing loss are able to perform as well as the hearing children. Moreover, the auditory memory span develops at the same rate for the children with hearing loss as for the hearing children.

Developmental changes of association strength and categorical relatedness on semantic processing in the brain.

Semantic knowledge has thematic relations of contiguity based on association and taxonomic relations of similarity based on shared features to form categories. It is unknown if there are distinct brain networks between thematic and taxonomic organizations in children and if this distinction is related to changes in specialized brain regions with age and/or skill. We orthogonally manipulated association strength (strong, weak) and categorical relatedness (high, low) to examine 10- to 14-year-old children over a two-year interval. Moreover, we examined whether initial behavioral performance predicted brain activation changes. Weak versus strong association strength produced greater activation over time in left middle temporal gyrus and inferior frontal gyrus, and initial accuracy predicted activation changes in the latter. Moreover, high versus low categorical relatedness produced greater activation over time in left occipito-temporal cortex and precuneus, and initial accuracy predicted activation changes in the latter. These developmental findings suggest different organization for thematic and taxonomic relations.

Developmental changes in the inferior frontal cortex for selecting semantic representations.

Functional magnetic resonance imaging (fMRI) was used to examine the neural correlates of semantic judgments to Chinese words in a group of 10-15 year old Chinese children. Two semantic tasks were used: visual-visual versus visual-auditory presentation. The first word was visually presented (i.e. character) and the second word was either visually or auditorily presented, and the participant had to determine if these two words were related in meaning. Different from English, Chinese has many homophones in which each spoken word corresponds to many characters. The visual-auditory task, therefore, required greater engagement of cognitive control for the participants to select a semantically appropriate answer for the second homophonic word. Weaker association pairs produced greater activation in the mid-ventral region of left inferior frontal gyrus (BA 45) for both tasks. However, this effect was stronger for the visual-auditory task than for the visual-visual task and this difference was stronger for older compared to younger children. The findings suggest greater involvement of semantic selection mechanisms in the cross-modal task requiring the access of the appropriate meaning of homophonic spoken words, especially for older children.

Testing for a cultural influence on reading for meaning in the developing brain: the neural basis of semantic processing in chinese children.

Functional magnetic resonance imaging was used to explore the neural correlates of semantic judgments in a group of 8- to 15-year-old Chinese children. Participants were asked to indicate if pairs of Chinese characters presented visually were related in meaning. The related pairs were arranged in a continuous variable according to association strength. Pairs of characters with weaker semantic association elicited greater activation in the mid ventral region (BA 45) of left inferior frontal gyrus, suggesting increased demands on the process of selecting appropriate semantic features. By contrast, characters with stronger semantic association elicited greater activation in left inferior parietal lobule (BA 39), suggesting stronger integration of highly related features. In addition, there was a developmental increase, similar to previously reported findings in English, in left posterior middle temporal gyrus (BA 21), suggesting that older children have more elaborated semantic representations. There were additional age-related increases in the posterior region of left inferior parietal lobule and in the ventral regions of left inferior frontal gyrus, suggesting that reading acquisition relies more on the mapping from orthography to semantics in Chinese children as compared to previously reported findings in English.