Ioulia Kovelman

Age of first bilingual language exposure as a new window into bilingual reading development

How does age of first bilingual language exposure affect reading development in children learning to read in both of their languages? Is there a reading advantage for monolingual English children who are educated in bilingual schools? We studied children (grades 2-3, ages 7-9) in bilingual Spanish-English schools who were either from Spanish-speaking homes (new to English) or English-speaking homes (new to Spanish), as compared with English-speaking children in monolingual English schools. An early age of first bilingual language exposure had a positive effect on reading, phonological awareness, and language competence in both languages: early bilinguals (age of first exposure 0-3 years) outperformed other bilingual groups (age of first exposure 3-6 years). Remarkably, schooling in two languages afforded children from monolingual English homes an advantage in phoneme awareness skills. Early bilingual exposure is best for dual language reading development, and it may afford such a powerful positive impact on reading and language development that it may possibly ameliorate the negative effect of low SES on literacy. Further, age of first bilingual exposure provides a new tool for evaluating whether a young bilingual has a reading problem versus whether he or she is a typically-developing dual-language learner.

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.

Should bilingual children learn reading in two languages at the same time or in sequence

Is it best to learn reading in two languages simultaneously or sequentially? We observed second- and third-grade children in two-way dual-language learning contexts: (a) 50:50 or Simultaneous dual-language (two languages within same developmental period) and (b) 90:10 or Sequential dual-language (one language, followed gradually by the other). They were compared to matched monolingual English-only children in single-language English schools. Bilinguals (home language was Spanish only, English-only, or Spanish and English in dual-language schools), were tested in both languages, and monolingual children were tested in English using standardized reading and language tasks. Bilinguals in 50:50 programs performed better than bilinguals in 90:10 programs on English Irregular Words and Passage Comprehension tasks, suggesting language and reading facilitation for underlying grammatical class and linguistic structure analyses. By contrast, bilinguals in 90:10 programs performed better than bilinguals in the 50:50 programs on English Phonological Awareness and Reading Decoding tasks, suggesting language and reading facilitation for surface phonological regularity analysis. Notably, children from English-only homes in dual-language learning contexts performed equally well, or better than, children from monolingual English-only homes in single-language learning contexts. Overall, the findings provide tantalizing evidence that dual-language learning during the same developmental period may provide bilingual reading advantages.

Cortical systems that process language, as revealed by non-native speech sound perception

Over the course of language acquisition, the brain becomes specialized in the perception of native language speech sounds or phonemes. As a result, adult speakers are highly efficient at processing their native language, but may struggle to perceive some non-native phonemes. This specialization is thought to arise from changes that occur in a person’s brain as a result of maturation and language experience. In this study, adult native speakers of English were asked to discriminate between phonemes of varying degrees of difference from English (similar to English: Tagalog /na/-/ŋa/; different from English: Ndebele /k||i/-/k!i/), as their brain activity was measured using functional near infrared spectroscopy imaging. The left inferior frontal region showed activation only during the native condition; this finding is discussed in the context of developmental and adult neuroimaging work and suggests that the left inferior frontal region is critical for perceiving native phoneme contrasts during development and in adulthood.

Comparison of motion correction techniques applied to functional near-infrared spectroscopy data from children.

Abstract. Motion artifacts are the most significant sources of noise in the context of pediatric brain imaging designs and data analyses, especially in applications of functional near-infrared spectroscopy (fNIRS), in which it can completely affect the quality of the data acquired. Different methods have been developed to correct motion artifacts in fNIRS data, but the relative effectiveness of these methods for data from child and infant subjects (which is often found to be significantly noisier than adult data) remains largely unexplored. The issue is further complicated by the heterogeneity of fNIRS data artifacts. We compared the efficacy of the six most prevalent motion artifact correction techniques with fNIRS data acquired from children participating in a language acquisition task, including wavelet, spline interpolation, principal component analysis, moving average (MA), correlation-based signal improvement, and combination of wavelet and MA. The evaluation of five predefined metrics suggests that the MA and wavelet methods yield the best outcomes. These findings elucidate the varied nature of fNIRS data artifacts and the efficacy of artifact correction methods with pediatric populations, as well as help inform both the theory and practice of optical brain imaging analysis.

Words in the bilingual brain: an fNIRS brain imaging investigation of lexical processing in sign-speech bimodal bilinguals.

Early bilingual exposure, especially exposure to two languages in different modalities such as speech and sign, can profoundly affect an individuals language, culture, and cognition. Here we explore the hypothesis that bimodal dual language exposure can also affect the brains organization for language. These changes occur across brain regions universally important for language and parietal regions especially critical for sign language (Newman et al., 2002). We investigated three groups of participants (N = 29) that completed a word repetition task in American Sign Language (ASL) during fNIRS brain imaging. Those groups were (1) hearing ASL-English bimodal bilinguals (n = 5), (2) deaf ASL signers (n = 7), and (3) English monolinguals naïve to sign language (n = 17). The key finding of the present study is that bimodal bilinguals showed reduced activation in left parietal regions relative to deaf ASL signers when asked to use only ASL. In contrast, this group of bimodal signers showed greater activation in left temporo-parietal regions relative to English monolinguals when asked to switch between their two languages (Kovelman et al., 2009). Converging evidence now suggest that bimodal bilingual experience changes the brain bases of language, including the left temporo-parietal regions known to be critical for sign language processing (Emmorey et al., 2007). The results provide insight into the resilience and constraints of neural plasticity for language and bilingualism.

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.

Functional Near-Infrared Spectroscopy Brain Imaging Investigation of Phonological Awareness and Passage Comprehension Abilities in Adult Recipients of Cochlear Implants.

PURPOSE The aim of this study was to examine how the brains of individuals with cochlear implants (CIs) respond to spoken language tasks that underlie successful language acquisition and processing. METHOD During functional near-infrared spectroscopy imaging, CI recipients with hearing impairment (n = 10, mean age: 52.7 ± 17.3 years) and controls with normal hearing (n = 10, mean age: 50.6 ± 17.2 years) completed auditory tasks-phonological awareness and passage comprehension-commonly used to investigate neurodevelopmental disorders of language and literacy. RESULTS The 2 groups had similar reaction time and performance on experimental tasks, although participants with CIs had lower accuracy than controls. Overall, both CI recipients and controls exhibited similar patterns of brain activation during the tasks. CONCLUSIONS The results demonstrate that CI recipients show an overall neurotypical pattern of activation during auditory language tasks on which individuals with neurodevelopmental language learning impairments (e.g., dyslexia) tend to show atypical brain activation. These findings suggest that advancements in functional near-infrared spectroscopy neuroimaging with CI recipients may help shed new light on how varying types of difficulties in language processing affect brain organization for language.

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 childrens reading acquisition across languages. Hum Brain Mapp 36:2890–2900, 2015.

“One glove does not fit all” in bilingual reading acquisition: Using the age of first bilingual language exposure to understand optimal contexts for reading success

Abstract In teaching reading, educators strive to find the balance between a code-emphasis approach and a meaning-oriented literacy approach. However, little is known about how different approaches to literacy can benefit bilingual children’s early reading acquisition. To investigate the novel hypothesis that children’s age of first bilingual exposure can interact with different approaches to literacy, we tested 56 Spanish-English bilingual children (ages 7–9), with birth exposure to Spanish and either early (before age 3) or late (3–4) age of first bilingual exposure to English. The children attended reading programs identified with either phonics or whole language emphasis. Consistent with our hypothesis, differential outcomes were linked to different ages of first bilingual exposure. Early bilingual exposure to English was associated with more advanced reading abilities under whole language emphasis, while later (ages 3–4) exposure was associated with better decoding and reading abilities under phonics emphasis. The findings show that knowing the age of a child’s first bilingual language exposure, as it corresponds to different periods in child development, may contribute to an educator’s design of reading instruction that best accommodates young bilingual learners.