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Neural networks for contextual word learning in children with reading and language difficulties
Poster Session E, Friday, October 2, 11:00 am - 1:00 pm, Wangari Maathai
Ziyun Zhang1, Sana Chughtai1, Suruthi Esaichelvan1, Meghana Rajeev1, Hannah Jones1, Kyle Jasmin2, Pablo Ripollés3, Saloni Krishnan1; 1University College London, 2Royal Holloway, University of London, 3New York University
Vocabulary knowledge is central to children’s academic success and frequently a target for intervention in children with reading and language difficulties. Yet the neural mechanisms that support word learning, particularly in children with reading and language difficulties, remain poorly understood. During the school years, children acquire much of their vocabulary by inferring meaning from context. In adults, this form of learning engages semantic control networks and is reinforced by reward-related signals in the striatum. Whether this neurocognitive system supports learning in children, and how it is disrupted in those with reading and language difficulties, remains unknown. Using fMRI, we examined how children aged 8–11 (N=60) infer the meaning of novel words across three exposures. We manipulated contextual constraint: high-cloze contexts supported meaning inference, whereas low-cloze contexts did not. Children showed robust benefits of contextual support, with higher accuracy in high-cloze trials. Children with reading and language difficulties (N=26) were less accurate even in supportive contexts and reported lower confidence, despite successful learning. Neurally, contextual learning in high-cloze constraints, relative to low-cloze, engaged bilateral inferior frontal gyri, supramarginal gyri, insulae, anterior cingulate cortex, as well as the left amygdala and the putamen and the thalamus bilaterally. This pattern is consistent with the integration and evaluation of semantic information during contextual word learning. In contrast, low-cloze contexts were associated with greater activity in the left posterior parahippocampal gyrus. With increasing exposure in the high-cloze contexts, which allowed for learning, activity decreases were seen in bilateral superior temporal gyri, inferior frontal gyri, hippocampi, caudate nuclei, and dorsolateral prefrontal cortex. Increases in activity were seen in the precuneus bilaterally. Critically, children with reading and language difficulties showed attenuated engagement of the left ventral occipitotemporal cortex, right middle frontal gyrus, and bilateral insulae and caudate nuclei. Together, these findings identify a neurocognitive system in which contextual word learning is supported by interactions between semantic and learning processes. Crucially, they reveal how differences in corticostriatal function can translate into differences in learning. Disruption to this system may limit children’s ability to capitalise on context, providing a mechanistic account of vocabulary learning difficulties.
Topic Areas: Disorders: Developmental, Language Development/Acquisition