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Development of the dorsal striatum in children with dyslexia
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Maya Yablonski1, Lily C. Gebhart1, Jamie L. Mitchell1, Howard Chiu1, Mia Jimenez1, Zihan Zhou2, Kawin Setsompop1, Jason D. Yeatman1; 1Stanford University, 2GE Healthcare, MR Research
The striatum is a complex subcortical structure that has been implicated in a variety of types of skill learning. It was thus suggested that the striatum is central in learning disorders like dyslexia (Ullman et al., 2020), yet empirical evidence has been sparse. Recent findings highlighted the heterogeneous nature of the striatum by demonstrating structural spatial gradients across the dorsal striatum. These gradients were associated with aging-related changes in water content and iron concentration, and correlated with clinical symptoms in a spatially specific manner (Drori et al., 2022). However, how these gradients emerge in childhood, and whether they change with learning remains unexplored. Within the striatum, recent work suggests that the caudate nucleus is involved in goal-based learning and the putamen in habit-based learning. As learning to read starts as a goal-directed behavior and transitions to an automated process as proficiency improves, we expect learning to read to result in structural changes across the striatum. In the current study, we combine diffusion and quantitative magnetic resonance imaging (dMRI and qMRI) to investigate the microstructure of the striatum in children with dyslexia. We leverage a longitudinal study with up to 5 timepoints of multimodal MRI per child over the course of a year. This dense longitudinal sampling allows us to tackle several questions at different timescales: (1) Do microstructural gradients of the striatum emerge over childhood and do they change over the course of the year? (2) Do these gradients differ in children with dyslexia compared with typical readers? And (3), given the role of the striatum in skill learning, do these patterns change as children learn to read? To address these questions, we followed children with dyslexia who completed an intensive reading intervention program. All children (N=44 intervention; N=42 controls; ages 7-13 years) completed qMRI and dMRI scans before the intervention and up to twelve months later. qMRI data were collected using magnetic resonance fingerprinting (MRF), a novel rapid approach which shows remarkable test-retest reliability. MRF data were used to generate quantitative R1 maps, a proxy for myelin content and tissue iron concentration. Next, striatal spatial gradients will be generated from R1 and dMRI maps using mrGrad, a novel software package for segmenting the striatum (Drori et al., 2022). Preliminary analyses suggest that structural gradients can be observed in children, in both the putamen and caudate nucleus. These data will be analyzed with Generalized Additive Mixed Models (GAMMS) to examine the developmental trajectories of the striatum spatial gradients, whether they differ in children with dyslexia, and whether they change differentially with learning to read following intervention. Findings from this study will provide the first exploration of microstructural gradients of the striatum in children. Further, they will highlight potential structural differences in children with dyslexia, as well as short- and long- term structural changes driven by a reading intervention. This will promote our understanding of the role of the striatum in supporting learning to read in dyslexia and in typical development.
Topic Areas: Disorders: Developmental, Reading