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.

Brain bases of morphological awareness and longitudinal word reading outcomes.

Children's spoken language skills are essential to the development of the "reading brain," or the neurocognitive systems that underlie successful literacy. Morphological awareness, or sensitivity to the smallest units of meaning, is a language skill that facilitates fluent recognition of meaning in print. Yet despite the growing evidence that morphology is integral to literacy success, associations among morphological awareness, literacy acquisition, and brain development remain largely unexplored. To address this gap, we conducted a longitudinal investigation with 75 elementary school children (5-11 years of age) who completed an auditory morphological awareness neuroimaging task at Time 1 as well as literacy assessments at both Time 1 and Time 2 (1.5 years later). Findings reveal longitudinal brain-behavior associations between morphological processing at Time 1 and reading outcomes at Time 2. First, activation in superior temporal brain regions involved in word segmentation was associated with both future reading skill and steeper reading gains over time. Second, a wider array of brain regions across the language network were associated with polymorphemic word reading as compared with broader word reading skill (reading both simple and complex words). Together, these findings reinforce the importance of word segmentation skills in learning to read and highlight the importance of considering complex word reading skills in building comprehensive neurocognitive models of literacy. This study fills a gap in our knowledge of how processing meaningful units in speech may help to explain differences in children's reading development over time and informs ongoing theoretical questions about the role of morphology in learning to read.

Phonological and morphological literacy skills in English and Chinese: A cross-linguistic neuroimaging comparison of Chinese-English bilingual and monolingual English children.

Over the course of literacy development, children learn to recognize word sounds and meanings in print. Yet, they do so differently across alphabetic and character-based orthographies such as English and Chinese. To uncover cross-linguistic influences on children's literacy, we asked young Chinese-English simultaneous bilinguals and English monolinguals (N = 119, ages 5-10) to complete phonological and morphological awareness (MA) literacy tasks. Children completed the tasks in the auditory modality in each of their languages during functional near-infrared spectroscopy neuroimaging. Cross-linguistically, comparisons between bilinguals' two languages revealed that the task that was more central to reading in a given orthography, such as phonological awareness (PA) in English and MA in Chinese, elicited less activation in the left inferior frontal and parietal regions. Group comparisons between bilinguals and monolinguals in English, their shared language of academic instruction, revealed that the left inferior frontal was less active during phonology but more active during morphology in bilinguals relative to monolinguals. MA skills are generally considered to have greater language specificity than PA skills. Bilingual literacy training in a skill that is maximally similar across languages, such as PA, may therefore yield greater automaticity for this skill, as reflected in the lower activation in bilinguals relative to monolinguals. This interpretation is supported by negative correlations between proficiency and brain activation. Together, these findings suggest that both the structural characteristics and literacy experiences with a given language can exert specific influences on bilingual and monolingual children's emerging brain networks for learning to read.

Brain bases of English morphological processing: A comparison between Chinese-English, Spanish-English bilingual, and English monolingual children.

How do early bilingual experiences influence children's neural architecture for word processing? Dual language acquisition can yield common influences that may be shared across different bilingual groups, as well as language-specific influences stemming from a given language pairing. To investigate these effects, we examined bilingual English speakers of Chinese or Spanish, and English monolinguals, all raised in the US (N = 152, ages 5-10). Children completed an English morphological word processing task during fNIRS neuroimaging. The findings revealed both language-specific and shared bilingual effects. The language-specific effects were that Chinese and Spanish bilinguals showed principled differences in their neural organization for English lexical morphology. The common bilingual effects shared by the two groups were that in both bilingual groups, increased home language proficiency was associated with stronger left superior temporal gyrus (STG) activation when processing the English word structures that are most dissimilar from the home language. The findings inform theories of language and brain development during the key periods of neural reorganization for learning to read by illuminating experience-based plasticity in linguistically diverse learners.

Contributions of bilingual home environment and language proficiency on children's Spanish-English reading outcomes.

This study examines the influence of language environment on language and reading skills and the cross-linguistic contributions to reading outcomes in 132 Spanish-English bilingual children ages 7-12 (52% female; 98% Hispanic). We present three major findings: children's language knowledge is separable into general (e.g., phonological awareness) and language-specific (e.g., meaning, grammar) skills; regular Spanish use positively relates to children's Spanish language and reading skills and does not limit English skills; and Spanish reading comprehension is positively associated with English reading comprehension. The model explains a significant percentage of the variance in English (R2  = .89) and Spanish (R2  = .87) reading comprehension outcomes. Findings shed light on the interdependence of Spanish and English as they relate to bilingual reading acquisition.

What's in a word? Cross-linguistic influences on Spanish-English and Chinese-English bilingual children's word reading development.

This study investigates the cross-linguistic transfer of literacy skills in Spanish-English, Chinese-English bilingual, and English monolingual children (N = 283, 5-10 years). Research question 1 examines English literacy and asks how phonological and morpho-semantic skills contribute to word reading as a function of children's language background. Structural equation modeling revealed contrasting bilingual effects: compared to English monolinguals, Spanish-English bilinguals relied more on phonological awareness in word reading, whereas Chinese-English bilinguals relied more on lexical knowledge. Research question 2 examines relations between bilinguals' heritage language proficiency and English literacy. Results revealed direct and indirect effects of heritage language meta-linguistic skills on English word reading. The study yields implications for reading theories and instructional practices in optimizing literacy in linguistically diverse children.

Cross-linguistic differences in the associations between morphological awareness and reading in Spanish and English in young simultaneous bilinguals.

This study aimed to clarify the relations between morphological awareness and literacy skills in Spanish and English in young simultaneous bilingual learners. Guided by theoretical perspectives on the associations between morphological awareness and word- versus sentence-level literacy skills, and their transfer between bilinguals' two languages, we asked bilingual children (N = 90; M = 8.07 years old) to complete dual-language literacy assessments. First, we observed cross-linguistic differences in the associations between morphology and reading. In English, morphological awareness was directly related to word reading and reading comprehension, whereas in Spanish, the association with reading comprehension was fully mediated by vocabulary and single word reading. Second, we observed cross-linguistic associations from English word reading to Spanish reading comprehension, and from Spanish reading comprehension to English reading comprehension. Our findings inform bilingual literacy theory by revealing both cross-linguistic differences and bidirectional associations between literacy skills across typologically-distinct orthographies. In particular, children's word-level skills transferred from the language of schooling (English) into their heritage language (Spanish), and their broader reading comprehension skills transferred from the heritage language to support English. Taken together, these findings support the value of bilingual heritage language maintenance for reading achievement in children's dominant language of literacy instruction.

Spoken language proficiency predicts print-speech convergence in beginning readers.

Learning to read transforms the brain, building on children's existing capacities for language and visuospatial processing. In particular, the development of print-speech convergence, or the spatial overlap of neural regions necessary for both auditory and visual language processing, is critical for literacy acquisition. Print-speech convergence is a universal signature of proficient reading, yet the antecedents of this convergence remain unknown. Here we examine the relationship between spoken language proficiency and the emergence of the print-speech network in beginning readers (ages 5-6). Results demonstrate that children's language proficiency, but not their early literacy skill, explains variance in their print-speech neural convergence in kindergarten. Furthermore, print-speech convergence in kindergarten predicts reading abilities one year later. These findings suggest that children's language ability is a core mechanism guiding the neural plasticity for learning to read, and extend theoretical perspectives on language and literacy acquisition across the lifespan.

Tracking Qualitative Changes in Cognition and Brain Development Through Bilingualism.

In response to Hernandez and colleagues (2018), we provide commentary on the scientific reasoning that underlies Neuroemergentism. We argue that bilingual language and reading acquisition provide a means for examining and refining the neuroemergentist framework.

Simultaneous acquisition of English and Chinese impacts children's reliance on vocabulary, morphological and phonological awareness for reading in English.

The developmental process of reading acquisition is frequently conceptualized as a self-organizing mental network consisting of lexico-semantic, phonological and orthographical components. The developmental nature of this network varies across languages and is known to impact second language learners of typologically different languages. Yet, it remains largely unknown whether such cross-linguistic differences interact within young bilingual learners of two typologically different languages. In the present study, we compared Chinese-English bilinguals and English monolinguals (ages 6-12, N=134) born and raised in the US on their English language and reading skills including vocabulary, phonological and morphological awareness, and word reading. We conducted whole group and subgroup analyses on younger participants to examine the extent of the effect. In monolinguals, phonological abilities directly predicted English word reading. In contrast, in bilinguals, both phonological and morphological abilities made an indirect contribution to English literacy via vocabulary knowledge, even though bilinguals had monolingual-like language and reading abilities in English. These findings offer new insights into the flexibility of the phonological and lexical pathways for learning to read.

The effects of Spanish heritage language literacy on English reading for Spanish-English bilingual children in the US.

Models of monolingual literacy propose that reading acquisition builds upon children's semantic, phonological, and orthographic knowledge. The relationships between these components vary cross-linguistically, yet it is generally unknown how these differences impact bilingual children's literacy. A comparison between Spanish-English bilingual and English monolingual children (ages 6-13, N=70) from the U.S. revealed that bilinguals had stronger associations between phonological and orthographic representations than monolinguals during English reading. While vocabulary was the strongest predictor of English word reading for both groups, phonology and morpho-syntax were the best predictors of Spanish reading for bilinguals. This comparison reveals distinct developmental processes across learners and languages, and suggests that early and systematic biliteracy exposure at home and through afterschool programs can influence children's sound-to-print associations even in the context of language-specific (monolingual) reading instruction. These findings have important implications for bilingual education as well as theories that aim to explain how learning to read across languages has a positive impact on the acquisition of literacy.

Bilingualism alters children's frontal lobe functioning for attentional control.

Bilingualism is a typical linguistic experience, yet relatively little is known about its impact on children's cognitive and brain development. Theories of bilingualism suggest that early dual-language acquisition can improve children's cognitive abilities, specifically those relying on frontal lobe functioning. While behavioral findings present much conflicting evidence, little is known about its effects on children's frontal lobe development. Using functional near-infrared spectroscopy (fNIRS), the findings suggest that Spanish-English bilingual children (n = 13, ages 7-13) had greater activation in left prefrontal cortex during a non-verbal attentional control task relative to age-matched English monolinguals. In contrast, monolinguals (n = 14) showed greater right prefrontal activation than bilinguals. The present findings suggest that early bilingualism yields significant changes to the functional organization of children's prefrontal cortex for attentional control and carry implications for understanding how early life experiences impact cognition and brain development.

Brain bases of morphological processing in Chinese-English bilingual children.

Can bilingual exposure impact children's neural circuitry for learning to read? To answer this question, we investigated the brain bases of morphological awareness, one of the key spoken language abilities for learning to read in English and Chinese. Bilingual Chinese-English and monolingual English children (N = 22, ages 7-12) completed morphological tasks that best characterize each of their languages: compound morphology in Chinese (e.g. basket + ball = basketball) and derivational morphology in English (e.g. re + do = redo). In contrast to monolinguals, bilinguals showed greater activation in the left middle temporal region, suggesting that bilingual exposure to Chinese impacts the functionality of brain regions supporting semantic abilities. Similar to monolinguals, bilinguals showed greater activation in the left inferior frontal region [BA 45] in English than Chinese, suggesting that young bilinguals form language-specific neural representations. The findings offer new insights to inform bilingual and cross-linguistic models of language and literacy acquisition.

Human Auditory and Adjacent Nonauditory Cerebral Cortices Are Hypermetabolic in Tinnitus as Measured by Functional Near-Infrared Spectroscopy (fNIRS).

Tinnitus is the phantom perception of sound in the absence of an acoustic stimulus. To date, the purported neural correlates of tinnitus from animal models have not been adequately characterized with translational technology in the human brain. The aim of the present study was to measure changes in oxy-hemoglobin concentration from regions of interest (ROI; auditory cortex) and non-ROI (adjacent nonauditory cortices) during auditory stimulation and silence in participants with subjective tinnitus appreciated equally in both ears and in nontinnitus controls using functional near-infrared spectroscopy (fNIRS). Control and tinnitus participants with normal/near-normal hearing were tested during a passive auditory task. Hemodynamic activity was monitored over ROI and non-ROI under episodic periods of auditory stimulation with 750 or 8000 Hz tones, broadband noise, and silence. During periods of silence, tinnitus participants maintained increased hemodynamic responses in ROI, while a significant deactivation was seen in controls. Interestingly, non-ROI activity was also increased in the tinnitus group as compared to controls during silence. The present results demonstrate that both auditory and select nonauditory cortices have elevated hemodynamic activity in participants with tinnitus in the absence of an external auditory stimulus, a finding that may reflect basic science neural correlates of tinnitus that ultimately contribute to phantom sound perception.

Brain bases of morphological processing in young children.

How does the developing brain support the transition from spoken language to print? Two spoken language abilities form the initial base of child literacy across languages: knowledge of language sounds (phonology) and knowledge of the smallest units that carry meaning (morphology). While phonology has received much attention from the field, the brain mechanisms that support morphological competence for learning to read remain largely unknown. In the present study, young English-speaking children completed an auditory morphological awareness task behaviorally (n = 69, ages 6-12) and in fMRI (n = 16). The data revealed two findings: First, children with better morphological abilities showed greater activation in left temporoparietal regions previously thought to be important for supporting phonological reading skills, suggesting that this region supports multiple language abilities for successful reading acquisition. Second, children showed activation in left frontal regions previously found active in young Chinese readers, suggesting morphological processes for reading acquisition might be similar across languages. These findings offer new insights for developing a comprehensive model of how spoken language abilities support children's reading acquisition across languages.

Neural specificity for semantic and syntactic processing in Spanish-English bilingual children.

Brain development for language processing is associated with neural specialization of left perisylvian pathways, but this has not been investigated in young bilinguals. We examined specificity for syntax and semantics in early exposed Spanish-English speaking children (N = 65, ages 7-11) using an auditory sentence judgement task in English, their dominant language of use. During functional near infrared spectroscopy (fNIRS), the morphosyntax task elicited activation in left inferior frontal gyrus (IFG) and the semantic task elicited activation in left posterior middle temporal gyrus (MTG). Task comparisons revealed specialization in left superior temporal (STG) for morphosyntax and left MTG and angular gyrus for semantics. Although skills in neither language were uniquely related to specialization, skills in both languages were related to engagement of the left MTG for semantics and left IFG for syntax. These results are consistent with models suggesting a positive cross-linguistic interaction in those with higher language proficiency.

Lexical Morphology as a Source of Risk and Resilience for Learning to Read With Dyslexia: An fNIRS Investigation.

PURPOSE: We examined the neurocognitive bases of lexical morphology in children of varied reading abilities to understand the role of meaning-based skills in learning to read with dyslexia. METHOD: Children completed auditory morphological and phonological awareness tasks during functional near-infrared spectroscopy neuroimaging. We first examined the relation between lexical morphology and phonological processes in typically developing readers (Study 1, N = 66, Mage = 8.39), followed by a more focal inquiry into lexical morphology processes in dyslexia (Study 2, N = 50, Mage = 8.62). RESULTS: Typical readers exhibited stronger engagement of language neurocircuitry during the morphology task relative to the phonology task, suggesting that morphological analyses involve synthesizing multiple components of sublexical processing. This effect was stronger for more analytically complex derivational affixes (like + ly) than more semantically transparent free base morphemes (snow + man). In contrast, children with dyslexia exhibited stronger activation during the free base condition relative to derivational affix condition. Taken together, the findings suggest that although children with dyslexia may struggle with derivational morphology, they may also use free base morphemes' semantic information to boost word recognition. CONCLUSION: This study informs literacy theories by identifying an interaction between reading ability, word structure, and how the developing brain learns to recognize words in speech and print. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.25944949.

Brain basis of phonological awareness for spoken language in children and its disruption in dyslexia.

Phonological awareness, knowledge that speech is composed of syllables and phonemes, is critical for learning to read. Phonological awareness precedes and predicts successful transition from language to literacy, and weakness in phonological awareness is a leading cause of dyslexia, but the brain basis of phonological awareness for spoken language in children is unknown. We used functional magnetic resonance imaging to identify the neural correlates of phonological awareness using an auditory word-rhyming task in children who were typical readers or who had dyslexia (ages 7-13) and a younger group of kindergarteners (ages 5-6). Typically developing children, but not children with dyslexia, recruited left dorsolateral prefrontal cortex (DLPFC) when making explicit phonological judgments. Kindergarteners, who were matched to the older children with dyslexia on standardized tests of phonological awareness, also recruited left DLPFC. Left DLPFC may play a critical role in the development of phonological awareness for spoken language critical for reading and in the etiology of dyslexia.

Neural Correlates of Morphosyntactic Processing in Spanish-English Bilingual Children: A Functional Near-Infrared Spectroscopy Study.

PURPOSE: The aim of this study was to examine the effects of early bilingual exposure on Spanish-English bilingual children's neural organization of English morphosyntactic structures. This study examines how children's age and language experiences are related to morphosyntactic processing at the neural level. METHOD: Eighty-one children (ages 6-11 years) completed an auditory sentence judgment task during functional near-infrared spectroscopy neuroimaging. The measure tapped into children's processing of early-acquired (present progressive -ing) and later-acquired (past tense -ed and third-person singular -s) English morphosyntactic structures, the primary language of academic instruction. RESULTS: We observed effects of syntactic structure and age. Early-acquired morphemic structures elicited activation in the left inferior frontal gyrus, while the later-acquired structures elicited additional activations in the left middle temporal gyrus and superior temporal gyrus (STG). Younger children had a more distributed neural response, whereas older children had a more focal neural response. Finally, there was a trending association between children's English language use and left STG activation for later-acquired structures. CONCLUSION: The findings inform theories of language and brain development by highlighting the mechanisms by which age and language experiences influence bilingual children's neural architecture for morphosyntactic processing.

The Development of Left Hemisphere Lateralization for Sentence-Level Prosodic Processing.

PURPOSE: The fine-tuning of linguistic prosody in later childhood is poorly understood, and its neurological processing is even less well studied. In particular, it is unknown if grammatical processing of prosody is left- or right-lateralized in childhood versus adulthood and how phonological working memory might modulate such lateralization. Furthermore, it is virtually unknown how prosody develops neurologically among children with cochlear implants (CIs). METHOD: Normal-hearing (NH) children ages 6-12 years and NH adults ages 18-28 years completed a functional near-infrared spectroscopy neuroimaging task, during which they heard sentence pairs and judged whether the sentences did or did not differ in their overall prosody (declarative, question, with or without narrow focus). Children also completed standard measures of expressive and receptive language. RESULTS: Age group differences emerged; children exhibited stronger bilateral temporoparietal activity but reduced left frontal activation. Furthermore, children's performance on a nonword repetition test was significantly associated with activation in the left inferior frontal gyrus-an area that was generally more activated in adults than in children. CONCLUSIONS: The prosody-related findings are generally consistent with prior neurodevelopmental works on sentence comprehension, especially those involving syntax and semantics, which have also noted a developmental shift from bilateral temporal to left inferior frontal regions typically associated with increased sensitivity to sentence structure. The findings thus inform theoretical perspectives on brain and language development and have implications for studying the effects of CIs on neurodevelopmental processes for sentence prosody. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.22255996.