Functional Neuroimaging of Speech Perception in Infants
ABSTRACT Human infants begin to acquire their native language in the first months of life. To determine which brain regions support language processing at this young age, we measured with functional magnetic resonance imaging the brain activity evoked by normal and reversed speech in awake and sleeping 3-month-old infants. Left-lateralized brain regions similar to those of adults, including the superior temporal and angular gyri, were already active in infants. Additional activation in right prefrontal cortex was seen only in awake infants processing normal speech. Thus, precursors of adult cortical language areas are already active in infants, well before the onset of speech production.
Full-textDOI: · Available from: Ghislaine Dehaene-Lambertz, Sep 04, 2015
- SourceAvailable from: Alfredo Ardila
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- "The results of neuroimaging studies are congruent with the above observation, as they have shown that very early in life human language is predominantly processed by the left hemisphere. Thus, Dehaene-Lambertz et al.  used fMRI to demonstrate that breastfed babies activate restricted perisylvian brain areas in the left hemisphere when listening to their mothers' language. These brain areas are similar to those involved in language in adult brains (e.g., Wernicke's area in the left hemisphere). "
ABSTRACT: Language development has been correlated with specific changes in brain development. The aim of this paper is to analyze the linguistic-brain associations that occur from birth through senescence. Findings from the neuropsychological and neuroimaging literature are reviewed, and the relationship of language changes observable in human development and the corresponding brain maturation processes across age groups are examined. Two major dimensions of language development are highlighted: naming (considered a major measure of lexical knowledge) and verbal fluency (regarded as a major measure of language production ability). Developmental changes in the brain lateralization of language are discussed, emphasizing that in early life there is an increase in functional brain asymmetry for language, but that this asymmetry changes over time, and that changes in the volume of gray and white matter are age-sensitive. The effects of certain specific variables, such as gender, level of education, and bilingualism are also analyzed. General conclusions are presented and directions for future research are suggested.
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- "How this age-varying structural relationship corresponds to cortical and subcortical functional representation of language remains unclear. The development of language representation in babies and toddlers has been probed using functional MRI in both awake [Dehaene-Lambertz et al., 2002] and asleep [Blasi et al., 2011] infants. A leftward asymmetry in response to language is evident as early as 2 months [Dehaene-Lambertz et al., 2010]. "
ABSTRACT: The normal myelination of neuronal axons is essential to neurodevelopment, allowing fast inter-neuronal communication. The most dynamic period of myelination occurs in the first few years of life, in concert with a dramatic increase in cognitive abilities. How these processes relate, however, is still unclear. Here we aimed to use a data-driven technique to parcellate developing white matter into regions with consistent white matter growth trajectories and investigate how these regions related to cognitive development. In a large sample of 183 children aged 3 months to 4 years, we calculated whole brain myelin volume fraction (VFM ) maps using quantitative multicomponent relaxometry. We used spatial independent component analysis (ICA) to blindly segment these quantitative VFM images into anatomically meaningful parcels with distinct developmental trajectories. We further investigated the relationship of these trajectories with standardized cognitive scores in the same children. The resulting components represented a mix of unilateral and bilateral white matter regions (e.g., cortico-spinal tract, genu and splenium of the corpus callosum, white matter underlying the inferior frontal gyrus) as well as structured noise (misregistration, image artifact). The trajectories of these regions were associated with individual differences in cognitive abilities. Specifically, components in white matter underlying frontal and temporal cortices showed significant relationships to expressive and receptive language abilities. Many of these relationships had a significant interaction with age, with VFM becoming more strongly associated with language skills with age. These data provide evidence for a changing coupling between developing myelin and cognitive development. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.Human Brain Mapping 09/2014; 35(9). DOI:10.1002/hbm.22488 · 6.92 Impact Factor
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- "Reading demands the translation of abstract graphemes (letters) into their corresponding spoken language sounds (phonemes) that format meaningful words (semantics). It therefore engages visual (cuneus and fusiform gyrus) (McCandliss et al., 2003), auditory/phonological (angular gyrus, STG) (Dehaene-Lambertz et al., 2002), and semantic brain regions (IFG) (Newman and Joanisse, 2011) mainly in the left hemisphere (Chiarello et al., 2009). An efficient synchronization of these processes is needed for fluent reading, which demands the engagement of the executive system (Breznitz, 2006). "
ABSTRACT: Introduction: Reading is an acquired-developmental ability that relies on intact language and executive function skills. Verbal fluency tasks (such as verb generation) also engage language and executive function skills. Performance of such tasks matures with normal language development, and is independent of reading proficiency. In this longitudinal fMRI study, we aim to examine the association between maturation of neural-circuits supporting both executive functions and language (assessed using verb generation) with reading proficiency achieved in adolescence with a focus on left-lateralization typical for language proficiency. Methods: Normalized fMRI data from the verb generation task was collected from 16 healthy children at ages 7, 11, and 17 years and was correlated with reading scores at 17 years of age. Lateralization indices were calculated in key language, reading, and executive function-related regions in all age groups. Results: Typical development was associated with (i) increasingly left-lateralized patterns in language regions (ii) more profound left-lateralized activation for reading and executive function-related regions when correlating with reading scores, (iii) greater involvement of frontal and parietal regions (in older children), and of the anterior frontal cortex (in younger children). Conclusion: We suggest that reading and verb generation share mutual neural-circuits during development with major reliance on regions related to executive functions and reading. The results are discussed in the context of the dual-networks architecture model.Frontiers in Human Neuroscience 06/2014; 8:447. DOI:10.3389/fnhum.2014.00447 · 2.90 Impact Factor