Poster D10, Wednesday, August 21, 2019, 5:15 – 7:00 pm, Restaurant Hall
Developmental changes in the neural underpinnings of word learning
Alyson Abel1;1San Diego State University
Introduction: The school years are a critical time for word learning, an area of language development that is strongly tied to academic success. While recent research has expanded our understanding of developmental changes in the neural processes underlying sentence processing (Schneider, Abel, Ogiela, MCord & Maguire, 2018; Schneider, Abel, Ogiela, Middleton & Maguire, 2016), we know less about the development of the neural networks supporting word learning. Additionally, the past developmental literature has focused on differences between children and adults instead of across children of different ages. Here we use ERPs and time frequency analysis of the EEG to examine changes in the engagement of neural processes supporting word learning in school-age children (8-10 years old) and adolescents (13-15 years old). Methods: Twenty-four children, twelve 8-10 years old (younger group) and twelve 13-15 years old (older group), completed a word learning task in which they listened to naturally-paced sentence triplets that ended with a target novel word. In the Meaning condition, the three sentences in each triplet increasingly supported the novel word’s meaning. The No Meaning condition provided a control to the Meaning condition in that each sentence provided little contextual support, making it difficult to derive meaning for the novel word. After each sentence triplet, participants were asked to identify the novel word’s meaning, if possible. EEG was collected during the word learning task and was analyzed in two ways: 1) ERPs, focusing on the N400, and 2) time frequency analysis of the EEG, focusing on the theta, alpha, and beta frequency bands, often related to lexical retrieval, attention/inhibition, and syntactic integration, respectively. For this study, EEG analysis focused on data from the Meaning condition. Results: The younger group learned significantly fewer words compared to the older group, 68.9% and 83.4%, respectively (t(30)=6.08, p<0.001). For the ERP analysis, mean amplitudes in the 300-500ms time window were compared in an Repeated Measures ANOVA with group as a between-subjects factor and sentence (1,2,3), laterality (left, midline, right), and anterior-posterior (frontal, central, posterior) as within-subjects factors. A significant 4-way interaction was found (F(8,23)=2.93, p<0.05). The younger group showed a graduated attenuation of the N400 amplitude across the sentences at parietal sites. The older group showed an amplitude attenuation from sentence 1 to sentence 2 with no change for sentence 3 across central and parietal sites. The time frequency analysis revealed a significant group x sentence interaction within each frequency band. The age groups differed primarily in theta synchrony and beta desynchrony. Namely, across sentences in the triplet, the older children demonstrated sustained theta synchrony and beta desynchrony that was not as robust in younger children. These patterns are similar to those reported in the auditory sentence processing literature (Schneider et al., 2018). Conclusion: Taken together, these findings suggest that the cognitive and linguistic systems engaged by younger children during word learning are less efficient for learning outcomes compared to older children. In particular, data indicate a developing neural system related to semantic processing and retrieval and syntactic integration through the school years.
Themes: Development, Meaning: Lexical Semantics
Method: Electrophysiology (MEG/EEG/ECOG)