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Poster D18, Thursday, November 9, 6:15 – 7:30 pm, Harborview and Loch Raven Ballrooms

Early classroom exposure to expository texts predicts developmental trajectory of genre-related neural specialization

Katherine Aboud1,2, Laurie Cutting1,2,3,4;1Vanderbilt Brain Institute, 2Peabody College of Education and Human Development, 3Vanderbilt Kennedy Center, 4Vanderbilt University Institute of Imaging Science

Successful language comprehension in elementary school is a key predictor of long-term educational outcomes, and requires adequate skill in both narrative and expository genres (e.g. stories versus science/history material). Historically, expository text has received lower attention in the classroom, resulting in a critical gap between expository and narrative reading performance in grade school. In response, the Common Core State Standards of education now encourage introduction to expository comprehension as early as first grade (5-7 years old). However, very little is known of the neural substrates of genre, or how/whether the development of genre-specific neural networks are influenced by early exposure. Previous neuroimaging work in our own lab has found that expository texts do indeed require different neural resources than stories in young learners. Specifically, appropriate comprehension of expository texts requires recruitment of restricted regions within the left-lateralized default mode network (DMN) as compared to the bilateral DMN in narratives, and this specialization in exposition is facilitated by the frontoparietal control network. While these findings shed critical light on the disparate neural demands of different types of texts, no studies to date have tracked the development of these systems, or how they are influenced by early classroom experiences. In the current study, we used functional magnetic resonance imaging to identify (1.) the developmental trajectories of expository comprehension, and (2.) whether greater exposure to exposition in the first-grade classroom interacts with these neural trajectories. As part of a larger longitudinal study (n = 140), we examined 20 second and third graders (time 1 age = 8.54 +/- .28, time 2 age = 9.52 +/- .31, 10 females) with typical IQ and word reading ability as they listened to scientific texts in the scanner. We found that during expository comprehension, third graders showed greater recruitment of DMN areas than second graders, potentially suggesting increased engagement in building a situation model of the stimuli with increased age and experience. Interestingly, however, children who had a higher percentage of first grade expository exposure showed significantly decreased reliance on the right angular gyrus in third vs. second grade. Given previous findings that adult patterns of expository comprehension are restricted to left-lateralized DMN, these results indicate that greater early exposure to exposition results in earlier specialization towards ideal expository neural networks in children. These findings have important implications for early classroom practice, and pave the way towards future examinations of how these trends vary among different learner subpopulations.

Topic Area: Language Development

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