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Poster E5, Thursday, August 22, 2019, 3:45 – 5:30 pm, Restaurant Hall

Temporal and topographical changes in theta power between middle childhood and adulthood during sentence comprehension

Mandy Maguire1, Julie M. Schneider2, Yvonne Ralph1, Sonali Poudel1, Tina Melamed1;1University of Texas at Dallas, 2University of Delaware

Introduction. Time frequency analysis of the EEG is increasingly used to study the neural correlates of language comprehension. Although this method holds promise for developmental research (Maguire & Abel, 2013), most existing work focuses on adults. Theta power in particular is consistently found to correspond to semantic processing of individual words (Bastiaansen et al., 2008) and in ongoing text (Davidson & Indefrey, 2007). Developmental differences in theta topography have been reported in response to individual words (Spironelli & Angrilli, 2010). It is unclear, however, how these differences in theta engagement manifest during sentence comprehension. Here we study the timing and topography of theta engagement during word-by-word sentence comprehension in middle childhood, adolescence, and adulthood. Participants and procedure. Fifty-seven children ages 8-10 years, 31 children ages 13-15 years, and 25 adults participated in a word learning from context task using EEG. Participants were right-handed, monolinguals with no history of developmental delay or deficit. The task included 50 visually presented sentence triplets, each ending with a nonsense word to be learned. Only the words preceding the unknown target word are included in the analysis. EEG Processing and Analysis. EEG data were analyzed using the EEGlab toolbox of Matlab. Continuous data were cleaned using the Clean Raw Data plug-in and Independent Components Analysis. Missing channels were spherically interpolated and average referenced. Data were epoched from -500 to 4200 msec around the first word in the sentence. A morlet wavelet analysis and hanning-tapered window were applied and was averaged across all trials, then the mean baseline power was subtracted (Delorme & Makeig, 2004). We investigated changes in the theta (4-8 Hz) band over the course of the sentence, focusing on the time period around each word. A monte-carlo cluster correction permutation analysis was used to determine statistically significant differences (p = 0.05). Results. We observed significant topographical and temporal differences in theta engagement between age groups. Topographically, the response became localized with age. Theta power was broadly distributed in 8-10-year-olds, more localized to left central and posterior areas in 13-15-year-olds, and maximal over left central electrodes in adults. Temporally, in adults, theta power increased most clearly between 200-400 msec after each word’s onset. In both groups of children theta engagement peaked between 200-400 msec after each word’s onset but continued throughout the presentation of each word and between words. This response was most temporally prolonged in the youngest age group. Conclusions. These findings support previous studies showing theta localization during word retrieval through early adolescence and adulthood. We expand on past work by showing that theta in adults seems to be specific to word retrieval. In children, the prolonged theta engagement between words may support unification processes necessary to comprehend the sentence either via semantic integration (Maguire et al., 2010) or general task processing demands (Meyer et al., 2019). Such a finding may support theories that in late childhood and early adolescence children rely more heavily on semantics to aid in sentence comprehension than adults (Schneider et al., 2016; 2018; Schneider & Maguire, 2018).

Themes: Development, Meaning: Lexical Semantics
Method: Electrophysiology (MEG/EEG/ECOG)

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