Anatomical and functional data were collected before and after the literacy program using a 3.0-T Siemens MAGNETOM Skyra (Siemens AG, Germany) whole-body magnetic resonance scanner using a 64-channel radiofrequency head coil. T1-weighted three-dimensional (3D) magnetization–prepared rapid-acquisition gradient echo images were obtained using a pulse sequence with repetition time (TR) of 1.690 ms, echo time (TE) of 2.60 ms, inversion time (TI) of 1.100 ms, field of view (FOV) of 256 by 256, matrix size of 256 by 256 by 192, and voxel size of 1.0 mm by 1.0 mm by 1.0 mm. Functional images for the visual and localizer runs were acquired as continuous echo-planar imaging (EPI) (TR, 2400 ms; TE, 30 ms; 38 slices; voxel size, 3.5 mm by 3.5 mm by 3 mm; no interslice gap and interleaved slice order). Images in each run were realigned using a two-pass procedure (a mean EPI image was produced after an initial rigid body realignment, and all volumes were then realigned to the mean image). Realigned EPI volumes were coregistered with the T1 images. T1 images were normalized to the single-subject MNI T1 template provided with Statistical Parametric Mapping (SPM). Realignment parameters were applied to the coregistered realigned EPI images, and normalized EPI volumes were output-resliced to 3-mm isotropic voxels. Images were initially smoothed using an 8-mm full width at half maximum 3D Gaussian kernel. However, different analyses required different smoothing parameters, and where relevant, these are specified below.

Each functional imaging session (one for each of the localizer and visual categories) was modeled at the single-subject level using a general linear model in SPM12. The design consisted of one regressor per condition (localizer: sentence reading, sentence listening, horizontal checkerboards, and vertical checkerboards; visual: nonwords, false font strings, faces, houses, tools, and checkerboards).

Six regressors of no interest coding for scan-to-scan movement (x, y, and z translations and rotations) and a constant term were added. Stimulus blocks were modeled as epochs convolved with the canonical hemodynamic response function in SPM12.

For each subject, parameter estimates for conditions were contrasted with the baseline, and contrast images were used for second-level, random-effects analyses. Further analyses examining the relationships between literacy and brain responses to various visual inputs were carried out as described below. Statistical parametric maps of the contrasts for each of the categories of stimuli presented in the visual and localizer runs were generated at the group level and are presented in figs. S1 and S2. All visually presented stimuli evoked substantial bilateral visual cortical activation and significant activation in the ventral visual stream. Auditory stimuli evoked substantial bilateral auditory activation.

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