162,130 research outputs found
Brain responses to repetition-based rule-learning do not exhibit sex differences: an aggregated analysis of infant fNIRS studies
No full textAbstract Studies have repeatedly shown sex differences in some areas of language development, typically with an advantage for female over male children. However, the tested samples are typically small and the effects do not always replicate. Here, we used a meta-analytic approach to address this issue in a larger sample, combining seven fNIRS studies on the neural correlates of repetition- and non-repetition-based rule learning in newborns and 6-month-old infants. The ability to extract structural regularities from the speech input is fundamental for language development, it is therefore highly relevant to understand whether this ability shows sex differences. The meta-analysis tested the effect of Sex, as well as of other moderators on infants’ hemodynamic responses to repetition-based (e.g. ABB: “mubaba”) and non-repetition-based (e.g. ABC: “mubage”) sequences in both anatomically and functionally defined regions of interests. Our analyses did not reveal any sex differences at birth or at 6 months, suggesting that the ability to encode these regularities is robust across sexes. Interestingly, the meta-analysis revealed other moderator effects. Thus in newborns, we found a greater involvement of the bilateral temporal areas compared to the frontal areas for both repetition and non-repetition sequences. Further, non-repetition sequences elicited greater responses in 6-month-olds than in newborns, especially in the bilateral frontal areas. When analyzing functional clusters of HbR timetraces, we found that a larger right-left asymmetry for newborn boys in brain responses compared to girls, which may be interpreted in terms of a larger right-left asymmetry in cerebral blood flow in boys than in girls early in life. We conclude that extracting repetition-based regularities from speech is a robust ability with a well-defined neural substrate present from birth and it does not exhibit sex differences
A Within-Subject Multimodal NIRS-EEG Classifier for Infant Data
No full textFunctional Near Infrared Spectroscopy (fNIRS) and Electroencephalography (EEG) are commonly employed neuroimaging methods in developmental neuroscience. Since they offer complementary strengths and their simultaneous recording is relatively easy, combining them is highly desirable. However, to date, very few infant studies have been conducted with NIRS-EEG, partly because analyzing and interpreting multimodal data is challenging. In this work, we propose a framework to carry out a multivariate pattern analysis that uses an NIRS-EEG feature matrix, obtained by selecting EEG trials presented within larger NIRS blocks, and combining the corresponding features. Importantly, this classifier is intended to be sensitive enough to apply to individual-level, and not group-level data. We tested the classifier on NIRS-EEG data acquired from five newborn infants who were listening to human speech and monkey vocalizations. We evaluated how accurately the model classified stimuli when applied to EEG data alone, NIRS data alone, or combined NIRS-EEG data. For three out of five infants, the classifier achieved high and statistically significant accuracy when using features from the NIRS data alone, but even higher accuracy when using combined EEG and NIRS data, particularly from both hemoglobin components. For the other two infants, accuracies were lower overall, but for one of them the highest accuracy was still achieved when using combined EEG and NIRS data with both hemoglobin components. We discuss how classification based on joint NIRS-EEG data could be modified to fit the needs of different experimental paradigms and needs
The impact of generative linguistics on psychology: Language acquisition, a paradigm example
No full textSpeech perception at birth: The brain encodes fast and slow temporal information
No full textSpeech perception is constrained by auditory processing. Although at birth infants have an immature auditory system and limited language experience, they show remarkable speech perception skills. To assess neonates' ability to process the complex acoustic cues of speech, we combined near-infrared spectroscopy (NIRS) and electroencephalography (EEG) to measure brain responses to syllables differing in consonants. The syllables were presented in three conditions preserving (i) original temporal modulations of speech [both amplitude modulation (AM) and frequency modulation (FM)], (ii) both fast and slow AM, but not FM, or (iii) only the slowest AM (<8 Hz). EEG responses indicate that neonates can encode consonants in all conditions, even without the fast temporal modulations, similarly to adults. Yet, the fast and slow AM activate different neural areas, as shown by NIRS. Thus, the immature human brain is already able to decompose the acoustic components of speech, laying the foundations of language learning
Variability of the hemodynamic response in infants: Influence of experimental design and stimulus complexity
No full textMeasuring brain activity in developmental populations remains a major challenge despite great technological advances. Among the numerous available methods, functional near-infrared spectroscopy (fNIRS), an imaging modality that probes the hemodynamic response, is a powerful tool for recording brain activity in a great variety of situations and populations. Neurocognitive studies with infants have often reported inverted hemodynamic responses, i.e. a decrease instead of an increase in regional blood oxygenation, but the exact physiological explanation and cognitive interpretation of this response remain unclear. Here, we first provide an overview of the basic principles of NIRS and its use in cognitive developmental neuroscience. We then review the infant fNIRS literature to show that the hemodynamic response is modulated by experimental design and stimulus complexity, sometimes leading to hemodynamic responses with non-canonical shapes. We also argue that this effect is further modulated by the age of participants, the cortical regions involved, and the developmental stage of the tested cognitive process. We argue that this variability needs to be taken into account when designing and interpreting developmental studies measuring the hemodynamic response. Keywords: fNIRS, Inverted Hemodynamic Response, Experimental complexity, Infants, Developmen
Frequency-based organization of speech sequences in a nonhuman animal
No full textA recurrent question regarding language acquisition is the extent to which the mechanisms human infants use to discover patterns over the linguistic signal are highly specialized and uniquely human, or are the result of more general mechanisms present in other species. Research with very young infants suggests that they are able to use the relative frequency of elements in a linguistic sequence to infer word order. Here we ask if this ability could emerge from grouping biases present in nonhuman mammals. We show that animals discover differences in the frequency of elements in a sequence and can learn the relative order of frequent and infrequent elements. Nevertheless, in animals, relative frequency does not appear to be overridden by other cues that have been shown to be important to human infants, such as prosody. Our results demonstrate that the basic mechanism that allows listeners to extract ordering relations based on frequency is shared across species.The present research has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement no. 269502 (PASCAL) to MN; ERC grant agreement no. 312519 and PSI2013-44992-P to JMT, and from the Agence Nationale de la Recherche (Programme JCJC 21373), the Emergence(s) program of the City of Paris as well as from the French Investissements d’Avenir – Labex EFL Program (ANR-10-LABX-0083) to JG
How 15-month-old infants process morphologically complex forms in an agglutinative language?
No full textWhile phonological development is well-studied in infants, we know less about morphological development. Previous studies suggest that infants around one year of age can process words analytically (i.e., they can decompose complex forms to a word stem and its affixes) in morphologically simpler languages such as English and French. The current study explored whether 15-month-old infants learning Hungarian, a morphologically complex, agglutinative language with vowel harmony, are able to decompose words into a word stem and a suffix. Potential differences between analytical processing of complex forms with back versus front vowels were also studied. The results of Experiment 1 indicate that Hungarian infants process morphologically complex words analytically when they contain a frequent suffix. Analytic processing is present both in the case of complex forms with back and front vowels according to the results of Experiment 2. In light of the results, we argue for the potential relevance of the early development of analytic processing for language development
Word Frequency Is a Cue to Lexical Category for 8-Month-Old Infants
No full textThe linguistic distinction between function words (functors) (e.g., the, he, that, on...), signaling grammatical structure, and content words (e.g., house, blue, carry...), carrying meaning, is universal across the languages of the world. These two lexical categories also differ in their phonological makeup (functors being shorter and more minimal) and frequency of occurrence (individual functors being much more frequent than most content words). The frequency-based discrimination of the two categories could constitute a powerful mechanism for infants to acquire the basic building blocks of language. As functors constitute closed classes and content words come in open classes, we examined whether 8-month-old monolingual infants relied on word frequency to categorize and track functors and content words. In six artificial grammar-learning experiments, we have found that infants process frequent words as belonging to closed classes, and infrequent words as belonging to open classes, and they map the relative order of these categories following the basic word order of their native language. These findings provide the earliest evidence that infants use word frequency as a cue to lexical categories and combine them to build rudimentary representations of grammar
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