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Unveiling the Neural Substrates of Early Language Development through Precision fMRI

Thursday, October 26, 1:30 - 3:30 pm CEST, Auditorium

Organizers: Ola Ozernov-Palchik¹, Ev Fedorenko¹; ¹MIT
Presenters: Halie Olson, Zeynep Saygin, Xi Yu, Ola Ozernov-Palchik, Saloni Krishnan

Linguistic skills develop extremely rapidly early in life: by age 3-4, children can already understand and express complex ideas. Furthermore, formal education, including learning to read, fosters the development of vocabulary and the acquisition of complex structures. Despite comprehensive behavioral characterization, the neural substrates of early language learning and processing remain poorly understood. This symposium focuses on the individual-subject (precision) fMRI approach and tackles several open questions in the field: 1) Is the language network already selective and left-lateralized early in life? 2) What role do non-linguistic capacities play in language learning? 3) How does learning to read (or struggling to do so) affect the language system and the brain in general? Jointly, these talks from an all-female panel from different institutions, countries of origin, ethnic backgrounds, and career stages highlight complementary lines of work at the cutting edge of the neurobiology of language development.

Presentations

Language-evoked activation in the brains of awake toddlers

Halie Olson¹; ¹MIT

Toddlers undergo remarkable changes in their language skills. To study the neural underpinnings of language processing in awake toddlers, we developed an fMRI task using 20-second videos of Sesame Street, in which the audio stream was either played normally (Forward) or reversed by character (Backward), while the characters either spoke to the viewer (Monologue) or to each other (Dialogue). Using the Forward>Backward contrast, we examined (1) group-level activation for the language contrast in the whole brain, (2) individual-level activation within language regions by condition, using individually-defined functional regions of interest for language, iteratively defined and tested in held-out data, and (3) lateralization for language within individual participants. Preliminary results suggest that we can measure language-evoked activation in canonical language regions in this age group, and that this activation may be left lateralized. Though preliminary, these results point to the possibility and promise of studying language network in awake toddlers.

Specificity of the language network in young children

Zeynep Saygin¹; ¹Ohio State University

Is language distinct from other cognition? In adults, language cortex is dissociated from adjacent domain-general cortex supporting more general cognitive functions; language is also distinct from nonverbal skills that are also vital for effective communication like face/body perception and theory of mind (ToM; the ability to infer others' mental states). However these skills may share common neural processors especially early in development when these skills are still developing. Does the neural machinery for language emerge from general-purpose neural mechanisms? We localized and tracked the development of selectivity, laterality, and overlap of language, ToM, and domain-general multiple-demand networks in children 3-9 years of age. We find that young children show adult-like, modular organization in both frontal and temporal cortices, with no evidence of a common neural substrate across domains. Future work will explore how continued development of communicative skills can be explained by this distinct neural architecture.

Characterizing the functional connectivity of the infant language network in relation to school-age reading outcomes

Xi Yu¹; ¹Beijing Normal University

A critical aspect of successful reading acquisition is oral language skills which start developing in utero. The current study investigated the intrinsic properties of the language neural network in infancy (N=70) and related those properties to 2nd-grade reading outcomes (N=39) in a 7-year longitudinal dataset. Using the LanA probabilistic functional atlas, we first characterized the internal structure of the infant language network using module detection techniques. We identified three modules comprising the inferior frontal (IFG), middle frontal, and temporoparietal regions, respectively. Positive prospective associations were observed between the FC of the infancy IFG module, subsequent kindergarten-age phonological skills, and second-grade reading abilities. Moreover, kindergarten-age phonological skills significantly mediated the relationship between infant FC and subsequent reading outcomes. Our findings suggest that the early-emerging language neural network serves as a neurobiological scaffold important for developing core language/preliteracy skills and laying the foundations for subsequent reading acquisition.

Examining Selectivity and Lateralization in the Language Network of Children with Dyslexia.

Ola Ozernov-Palchik¹; ¹MIT

As children learn to read, there is a dynamic interplay between their oral language and reading skills. Using individual-subject fMRI analyses, we investigated differences in selectivity and lateralization of the language network in children with developmental dyslexia (Dys, N=25, ages 7-10 years), age-matched typical readers (Typ; N=47; ages 7-10 years), and reading level-matched younger typical readers (RL, N= 19, 4-7 years). Comparison to RL allows for disentangling causal and experiential influences on brain development in individuals with dyslexia. Reliable selectivity for language was observed in each left-hemisphere language region across the three groups. While both the Typ and RL groups showed significant left-lateralization across the language network, the Dys group exhibited left-lateralization only in the frontal, but not temporal, regions. This suggests that the reduced left-lateralization in the temporal regions associated with phonological processing is not experientially driven but may have a causal relationship with dyslexia.

Finding the joy: investigating reward processing during word learning in neurotypical and dyslexic childre

Saloni Krishnan¹; ¹University of London

While reading, we extract the meaning of words from context, honing our vocabulary in the process. Studies in adults show experiencing reward can fuel memory for words. We are now investigating the link between reward and reading in development. Specifically, what is the contribution of reward-processing systems in the brain to such learning in childhood? How is the experience of reward influenced by reading proficiency? To address this, we have scanned 25 neurotypical children and 25 dyslexic children aged 11-13. In the scanner, children complete a naturalistic reading paradigm involving extracting novel word meanings from sentence context. Our preliminary analyses reveal increased activity in cortical language regions and the ventral striatum during successful learning. Our work sheds light on the link between reading enjoyment and learning, and will show whether boosting enjoyment might be a good strategy to enhance learning in children with dyslexia.