1,721,193 research outputs found
From the Richness of the Signal to the Poverty of the Stimulus: Mechanisms of Early Language Acquisition
Full text linkSpeakers aren't blank slates (with respect to sign-language phonology)!
Full text linkA large literature has gauged the linguistic knowledge of signers by comparing sign-processing by signers and non-signers. Underlying this approach is the assumption that non-signers are devoid of any relevant linguistic knowledge, and as such, they present appropriate non-linguistic controls-a recent paper by Meade et al. (2022) articulates this view explicitly. Our commentary revisits this position. Informed by recent findings from adults and infants, we argue that the phonological system is partly amodal. We show that hearing infants use a shared brain network to extract phonological rules from speech and sign. Moreover, adult speakers who are sign-naive demonstrably project knowledge of their spoken L1 to signs. So, when it comes to sign-language phonology, speakers are not linguistic blank slates. Disregarding this possibility could systematically underestimate the linguistic knowledge of signers and obscure the nature of the language faculty
Observation of cortical state-based learning in infants in a functional near-infrared spectroscopy paradigm
No full textSignificance: Learning can be context-dependent, with better outcomes under some circumstances than others. Adult functional magnetic resonance imaging studies have shown that learning outcomes vary as a function of participants’ brain states—patterns of intrinsic neural activity—prior to the learning task. Whether this is also the case in young infants is currently unknown. We report the first functional near-infrared spectroscopy (fNIRS) study that shows prior brain state-dependent learning in a language task in 6.5-month-old infants. Babies whose functional connectivity was lower in the right hemisphere, but not in the left, during a 2-min period prior to the task learned better a grammatical regularity in an artificial grammar learning task. Aim: Adult neuroimaging studies have shown that variability in brain states immediately before specific learning tasks is correlated with variability in learning outcomes. Whether the developing infant brain also shows similar state-based learning is currently unknown. Approach: We have explored whether 6.5-month-old infants’ ability to learn artificial grammar was related to their brain state during a 2-min baseline period of rest prior to the grammar task. We have asked if functional connectivity, a global metric of the cortical brain state, as measured by fNIRS, is correlated with learning a non-adjacent regularity in the artificial grammar task. Results: We have found that the overall level of functional connectivity in the 2-min period immediately prior to the learning experience is negatively correlated with the fNIRS measure of learning in the right hemisphere but not in the left. Conclusions: We show for the first time that the cortical state of an infant immediately prior to a learning experience determines how well that infant learns and that this can account for some of the variability in learning outcomes
Word frequency is a cue to word order for adults: Validating an online method with speakers of Italian and Turkish for more inclusive psycholinguistic testing
No full textAcquiring the relative order of function and content words is a fundamental aspect of language development, and previous studies show that infants develop prelexical representations of this word order. As functors are more frequent than content words, they serve as anchors with respect to which the positions of other words can readily be encoded. This frequency-based bootstrapping strategy has been shown to be used both by infants and adults. However, only a handful of languages, mainly spoken in Western countries, have been tested so far. One hurdle to more inclusive testing is the lack of laboratory facilities in some geographical areas of the world. Online testing is a useful tool to overcome this difficulty. The current study, therefore, implements and validates an online version of an artificial grammar learning paradigm originally developed for laboratory use to test the frequency-based anchoring effect on adults in typologically different languages, Italian and Turkish. Italian has functor-initial word order, while Turkish is functor-final. Our study thus has two related goals. We test whether previous lab-based results by Gervain et al. (2013) with Italian adults are replicable using online testing. Additionally, we leverage online testing to assess a hitherto understudied language, Turkish, which has opposite word order properties compared to Italian. Our findings indicate that online testing can efficiently reproduce laboratory-based results: Italian adults in our online study show similar word order preferences to those tested in the laboratory earlier. Further, we found that Turkish participants have opposite word order preferences, as we predicted. These findings pave the way for testing the frequency-based bootstrapping hypothesis on a more inclusive and diverse sample of languages than previously available
Using functional near-infrared spectroscopy to study the early developing brain: future directions and new challenges
Full text linkSignificance: Functional near-infrared spectroscopy (fNIRS) is a frequently used neuroimaging tool to explore the developing brain, particularly in infancy, with studies spanning from birth to toddlerhood (0 to 2 years). We provide an overview of the challenges and opportunities that the developmental fNIRS field faces, after almost 25 years of research.Aim: We discuss the most recent advances in fNIRS brain imaging with infants and outlines the trends and perspectives that will likely influence progress in the field in the near future.Approach: We discuss recent progress and future challenges in various areas and applications of developmental fNIRS from methodological and technological innovations to data processing and statistical approaches.Results and Conclusions: The major trends identified include uses of fNIRS "in the wild," such as global health contexts, home and community testing, and hyperscanning; advances in hardware, such as wearable technology; assessment of individual variation and developmental trajectories particularly while embedded in studies examining other environmental, health, and context specific factors and longitudinal designs; statistical advances including resting-state network and connectivity, machine learning and reproducibility, and collaborative studies. Standardization and larger studies have been, and will likely continue to be, a major goal in the field, and new data analysis techniques, statistical methods, and collaborative cross-site projects are emerging. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI
Comparing different pre-processing routines for infant fNIRS data
Full text linkInternational audienceFunctional Near Infrared Spectroscopy (fNIRS) is an important neuroimaging technique in cognitive developmental neuroscience. Nevertheless, there is no general consensus yet about best pre-processing practices. This issue is highly relevant, especially since the development and variability of the infant hemodynamic response (HRF) is not fully known. Systematic comparisons between analysis methods are thus necessary. We investigated the performance of five different pipelines, selected on the basis of a systematic search of the infant NIRS literature, in two experiments. In Experiment 1, we used synthetic data to compare the recovered HRFs with the true HRF and to assess the robustness of each method against increasing levels of noise. In Experiment 2, we analyzed experimental data from a published study, which assessed the neural correlates of artificial grammar processing in newborns. We found that with motion artifact correction (as opposed to rejection) a larger number of trials were retained, but HRF amplitude was often strongly reduced. By contrast, artifact rejection resulted in a high exclusion rate but preserved adequately the characteristics of the HRF. We also found that the performance of all pipelines declined as the noise increased, but significantly less so than if no pre-processing was applied. Finally, we found no difference between running the pre-processing on optical density or concentration change data. These results suggest that pre-processing should thus be optimized as a function of the specific quality issues a give dataset exhibits
Six-month-old infants' perception of structural regularities in speech
Full text linkIn order to acquire grammar, infants need to extract regularities from the linguistic input. From birth, infants can detect regularities in speech based on identity relations, and show strong neural activation to syllable sequences containing adjacent repetitions of identical syllables (e.g. ABB: mubaba). Meanwhile, newborns' neural responses to sequences of different syllables (e.g. ABC: mubage, i.e. diversity-based relations) do not differ from baseline. However, this latter ability needs to emerge during development, as most linguistic units, such as words, are composed of highly variable sequences. As infants begin to learn their first word forms at 6 months, we hypothesize that the ability to represent sequences of different syllables might become important for them at this age. Using near-infrared spectroscopy (NIRS), we measured 6-month-old infants' brain responses to repetitionand diversity-based sequences in the bilateral temporal, parietal and frontal areas. We found that 6-month-olds discriminated the repetition- and diversity-based structures in frontal and parietal regions, and exhibited equally strong activation to both grammars as compared to baseline. These results show that by 6 months of age, infants encode sequences with diversity-based structures. They thus provide the earliest evidence that prelexical infants represent difference in speech stimuli, which behavioral studies first attest at 11 months of age
Neural oscillations and speech processing at birth
Full text link: Are neural oscillations biologically endowed building blocks of the neural architecture for speech processing from birth, or do they require experience to emerge? In adults, delta, theta, and low-gamma oscillations support the simultaneous processing of phrasal, syllabic, and phonemic units in the speech signal, respectively. Using electroencephalography to investigate neural oscillations in the newborn brain we reveal that delta and theta oscillations differ for rhythmically different languages, suggesting that these bands underlie newborns' universal ability to discriminate languages on the basis of rhythm. Additionally, higher theta activity during post-stimulus as compared to pre-stimulus rest suggests that stimulation after-effects are present from birth
8-month-old infants' ability to process word order is shaped by the amount of exposure
No full textInternational audienceIn the majority of languages, the functional distinction between functors and content words correlates with lower-level, perceptually observable properties. Functors are generally more frequent and prosodically more minimal than content words. Previous studies demonstrate that the frequency distribution and the different acoustic realization of frequent and infrequent words guide infants in discovering their native word order. However, whether and if yes, how the exact frequency ratio impacts infants' ability to recognize function and content words and their relative order has never been explored. Here we investigate this by testing whether with a small ratio between functors' and content words' frequency, 1:3 as opposed to the 1:9 ratio in previous studies, French 8-month-olds are able to establish the functor-initial word order typical of their native language (Experiment 1) and whether prosody (Experiment 2) and the amount of exposure (Experiment 3) modulate this ability. We observed that infants exhibited the predicted functor-initial preference only when they were exposed to a short familiarization phase, i.e. reduced exposure. This suggests that different amounts of information selectively trigger different processing mechanisms, and little exposure may favor the extraction of regularities
The neonate brain's sensitivity to repetition-based structure: Specific to speech?
Full text linkNewborns are able to extract and learn repetition-based regularities from the speech input, that is, they show greater brain activation in the bilateral temporal and left inferior frontal regions to trisyllabic pseudowords of the form AAB (e.g., "babamu") than to random ABC sequences (e.g., "bamuge"). Whether this ability is specific to speech or also applies to other auditory stimuli remains unexplored. To investigate this, we tested whether newborns are sensitive to regularities in musical tones. Neonates listened to AAB and ABC tones sequences, while their brain activity was recorded using functional Near-Infrared Spectroscopy (fNIRS). The paradigm, the frequency of occurrence and the distribution of the tones were identical to those of the syllables used in previous studies with speech. We observed a greater inverted (negative) hemodynamic response to AAB than to ABC sequences in the bilateral temporal and fronto-parietal areas. This inverted response was caused by a decrease in response amplitude, attributed to habituation, over the course of the experiment in the left fronto-temporal region for the ABC condition and in the right fronto-temporal region for both conditions. These findings show that newborns' ability to discriminate AAB from ABC sequences is not specific to speech. However, the neural response to musical tones and spoken language is markedly different. Tones gave rise to habituation, whereas speech was shown to trigger increasing responses over the time course of the study. Relatedly, the repetition regularity gave rise to an inverted hemodynamic response when carried by tones, while it was canonical for speech. Thus, newborns' ability to detect repetition is not speech-specific, but it engages distinct brain mechanisms for speech and music. RESEARCH HIGHLIGHTSThe ability of newborns' to detect repetition-based regularities is not specific to speech, but also extends to other auditory modalities.The brain mechanisms underlying speech and music processing are markedly different
- …
