Language and the Newborn Brain: Does Prenatal Language Experience Shape the Neonate Neural Response to Speech?

Previous research has shown that by the time of birth, the neonate brain responds specially to the native language when compared to acoustically similar non-language stimuli. In the current study, we use near-infrared spectroscopy to ask how prenatal language experience might shape the brain response to language in newborn infants. To do so, we examine the neural response of neonates when listening to familiar versus unfamiliar language, as well as to non language stimuli. Twenty monolingual English-exposed neonates aged 0–3 days were tested. Each infant heard low-pass filtered sentences of forward English (familiar language), forward Tagalog (unfamiliar language), and backward English and Tagalog (non-language). During exposure, neural activation was measured across 12 channels on each hemisphere. Our results indicate a bilateral effect of language familiarity on neonates’ brain response to language. Differential brain activation was seen when neonates listened to forward Tagalog (unfamiliar language) as compared to other types of language stimuli. We interpret these results as evidence that the prenatal experience with the native language gained in utero influences how the newborn brain responds to language across brain regions sensitive to speech processing

Monolingual, bilingual, trilingual: Infants’ language experience influences the development of a word-learning heuristic

How infants learn new words is a fundamental puzzle in language acquisition. To guide their word learning, infants exploit systematic word-learning heuristics that allow them to link new words to likely referents. By 17 months, infants show a tendency to associate a novel noun with a novel object rather than a familiar one, a heuristic known as disambiguation. Yet, the developmental origins of this heuristic remain unknown. We compared disambiguation in 17 to 18-month-old infants from different language backgrounds to determine whether language experience influences its development, or whether disambiguation instead emerges as a result of maturation or social experience. Monolinguals showed strong use of disambiguation, bilinguals showed marginal use, and trilinguals showed no disambiguation. The number of languages being learned, but not vocabulary size, predicted performance. The results point to a key role for language experience in the development of disambiguation, and help to distinguish among theoretical accounts of its emergence

Lexicon Structure and the Disambiguation of Novel Words: Evidence from Bilingual Infants

In ambiguous word learning situations, infants can use systematic strategies to determine the referent of a novel word. One such heuristic is disambiguation. By age 16-18 months, monolinguals infer that a novel noun refers to a novel object rather than a familiar one (Halberda, 2003), while at the same age bilinguals and trilinguals do not reliably show disambiguation (Byers-Heinlein & Werker, 2009; Houston-Price, Caloghiris, & Raviglione, 2010). It has been hypothesized that these results reflect a unique aspect of the bilingual lexicon: bilinguals often know many translation equivalents, cross-language synonyms such as English dog and Mandarin gǒu. We studied the role of vocabulary knowledge in the development of disambiguation by relating 17-18 month-old English-Chinese bilingual infants’ performance on a disambiguation task to the percentage of translation equivalents in their comprehension vocabularies. Those bilingual infants who understood translation equivalents for more than half the words in their vocabularies did not show disambiguation, while infants who knew a smaller proportion of translation equivalents showed disambiguation just as same-aged monolinguals do. These results demonstrate that the structure of the developing lexicon plays a key role in infants’ use of disambiguation

Bilingual beginnings as a lens for theory development: PRIMIR in focus

PRIMIR (Processing Rich Information from Multidimensional Interactive Representations; Werker & Curtin, 2005; Curtin & Werker, 2007) is a framework that encompasses the bidirectional relations between infant speech perception and the emergence of the lexicon. Here, we expand its mandate by considering infants growing up bilingual. We argue that, just like monolinguals, bilingual infants have access to rich information in the speech stream and by the end of their first year, they establish not only language-specific phonetic category representations, but also encode and represent both sub-phonetic and indexical detail. Perceptual biases, developmental level, and task demands work together to influence the level of detail used in any particular situation. In considering bilingual acquisition, we more fully elucidate what is meant by task demands, now understood both in terms of external demands imposed by the language situation, and internal demands imposed by the infant (e.g. different approaches to the same apparent task taken by infants from different backgrounds). In addition to the statistical learning mechanism previously described in PRIMIR, the necessity of a comparison-contrast mechanism is discussed. This refocusing of PRIMIR in the light of bilinguals more fully explicates the relationship between speech perception and word learning in all infants

Bilingual beginnings to learning words

At the macrostructure level of language milestones, language acquisition follows a nearly identical course whether children grow up with one or with two languages. However, at the microstructure level, experimental research is revealing that the same proclivities and learning mechanisms that support language acquisition unfold somewhat differently in bilingual versus monolingual environments. This paper synthesizes recent findings in the area of early bilingualism by focusing on the question of how bilingual infants come to apply their phonetic sensitivities to word learning, as they must to learn minimal pair words (e.g. ‘cat’ and ‘mat’). To this end, the paper reviews antecedent achievements by bilinguals throughout infancy and early childhood in the following areas: language discrimination and separation, speech perception, phonetic and phonotactic development, word recognition, word learning and aspects of conceptual development that underlie word learning. Special consideration is given to the role of language dominance, and to the unique challenges to language acquisition posed by a bilingual environment

The roots of bilingualism in newborns

The first steps towards bilingual language acquisition have already begun at birth. When tested on their preference for English versus Tagalog, “monolingual” newborns, whose mothers spoke only English during pregnancy, showed a robust preference for English. In contrast, “bilingual” newborns, whose mothers spoke both English and Tagalog regularly during pregnancy, showed equal preference for both languages. A group of Chinese-English bilinguals showed an intermediate pattern of preference. Preference for two languages does not suggest confusion between them, however. Study 2 showed that both English monolinguals and Tagalog-English bilinguals could discriminate English from Tagalog. The same perceptual and learning mechanisms that support acquisition in a monolingual environment thus also naturally support bilingual acquisition

Dual roles for LUBAC signaling in thymic epithelial cell development and survival

Thymic epithelial cells (TECs) form a unique microenvironment that orchestrates T cell differentiation and immunological tolerance. Despite the importance of TECs for adaptive immunity, there is an incomplete understanding of the signalling networks that support their differentiation and survival. We report that the linear ubiquitin chain assembly complex (LUBAC) is essential for medullary TEC (mTEC) differentiation, cortical TEC survival and prevention of premature thymic atrophy. TEC-specific loss of LUBAC proteins, HOIL-1 or HOIP, severely impaired expansion of the thymic medulla and AIRE-expressing cells. Furthermore, HOIL-1-deficiency caused early thymic atrophy due to Caspase-8/MLKL-dependent apoptosis/necroptosis of cortical TECs. By contrast, deficiency in the LUBAC component, SHARPIN, caused relatively mild defects only in mTECs. These distinct roles for LUBAC components in TECs correlate with their function in linear ubiquitination, NFκB activation and cell survival. Thus, our findings reveal dual roles for LUBAC signaling in TEC differentiation and survival

ManyBabies 3: A multi-lab study of infant algebraic rule learning

The ability to learn and apply rules lies at the heart of cognition. In a seminal study, Marcus, Vijayan, Rao, and Vishton (1999) reported that seven-month-old infants learned abstract rules over syllable sequences and were able to generalize those rules to novel syllable sequences. Dozens of studies have since extended on that research using different rules, modalities, stimuli, participants (human adults and non-human animals) and experimental procedures. Yet questions remain about the robustness of Marcus et al.’s (1999) core findings, as the presence of significant learning effects has been mixed. In the current study, we aimed to address this issue by testing XX infants of a wide age range (5;0-12;0 months) in a multi-laboratory (XX laboratories) replication of the Marcus et al. (1999) study

Experimental Virus Evolution Reveals a Role of Plant Microtubule Dynamics and TORTIFOLIA1/SPIRAL2 in RNA Trafficking

The cytoskeleton is a dynamic network composed of filamentous polymers and regulatory proteins that provide a flexible structural scaffold to the cell and plays a fundamental role in developmental processes. Mutations that alter the spatial orientation of the cortical microtubule (MT) array of plants are known to cause important changes in the pattern of cell wall synthesis and developmental phenotypes; however, the consequences of such alterations on other MT-network-associated functions in the cytoplasm are not known. In vivo observations suggested a role of cortical MTs in the formation and movement of Tobacco mosaic virus (TMV) RNA complexes along the endoplasmic reticulum (ER). Thus, to probe the significance of dynamic MT behavior in the coordination of MT-network-associated functions related to TMV infection and, thus, in the formation and transport of RNA complexes in the cytoplasm, we performed an evolution experiment with TMV in Arabidopsis thaliana tor1/spr2 and tor2 mutants with specific defects in MT dynamics and asked whether TMV is sensitive to these changes. We show that the altered cytoskeleton induced genetic changes in TMV that were correlated with efficient spread of infection in the mutant hosts. These observations demonstrate a role of dynamic MT rearrangements and of the MT-associated protein TORTIFOLIA1/SPIRAL2 in cellular functions related to virus spread and indicate that MT dynamics and MT-associated proteins represent constraints for virus evolution and adaptation. The results highlight the importance of the dynamic plasticity of the MT network in directing cytoplasmic functions in macromolecular assembly and trafficking and illustrate the value of experimental virus evolution for addressing the cellular functions of dynamic, long-range order systems in multicellular organisms.Instituto de Biotecnologia y Biologia Molecula