Research ArticleNEUROSCIENCE

Learning to read alters cortico-subcortical cross-talk in the visual system of illiterates

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Science Advances  24 May 2017:
Vol. 3, no. 5, e1602612
DOI: 10.1126/sciadv.1602612

Figures

  • Fig. 1 Learning to read modifies subcortical network centrality.

    Whole-brain degree centrality map thresholded at z = 2.58 (P < 0.005, corrected for cluster size) with corresponding color bar indicating the range of z scores. The effect of literacy instruction is depicted as a group (reading-trained individuals versus untrained illiterates) by time (before versus after intervention) interaction. The significant cluster stretches from the right superior colliculus of the brainstem (MNI coordinates: +6, −30, −3) to the bilateral pulvinar nuclei of the thalamus (MNI coordinates: +6, −18, −3; −6, −21, −3). The box plot resolves the interaction by separately showing the individual mean z values for each factor level. Mean degree centrality values of the untrained group did not differ significantly from zero (time 1: t1,8 = 1.76, P = 0.116; time 2: t1,8 = 1.10, P = 0.302; one-sample t tests).

  • Fig. 2 Learning to read strengthens cortico-subcortical functional connectivity.

    (A) Voxel-wise functional connectivity map derived from seeding in the significant degree centrality cluster. The image is thresholded at z = 2.58 (P < 0.005, corrected for cluster size). The color bar indicates the range of z scores. Becoming literate goes along with increased coupling of BOLD signal time courses between mesencephalic/diencephalic visual nuclei and a single cluster spanning the areas V1, V2, V3, and V4 of the right occipital cortex (MNI coordinates: +24, −81, +15; +24, −93, +12; +33, −90, +3). (B) The group (reading-trained individuals versus untrained illiterates) by time (before versus after intervention) interaction becomes evident from the box plot, indicating that the functional connectivity is strongly and specifically enhanced in the group that underwent reading instruction. (C) Line graphs depicting the coefficients of the correlations between the hemodynamic time series separately for each individual subject, each group, and each time. (D) Mean time series of the BOLD signal for each group and each time.

Tables

  • Table 1 Participant demographic information and behavioral performance.
    Trained groupUntrained groupGroup difference
    n219
    Age (years)31.57 ± 4.90*31.78 ± 5.47*z = 0.21, P = 0.837
    Gender (female/male)20/18/1
    Monthly income (Rupees)2313.50 ± 629.15*2500 ± 433.01*z = 0.96, P = 0.375
    Literate family members2.95 ± 1.54*2.86 ± 1.46*z = 0, P = 1
    Raven test13.29 ± 2.67*11.67 ± 2.60*z = 1.42, P = 0.164
    Letter knowledge pretest10.38 ± 12.50*7.22 ± 10.12*z = 0.98, P = 0.341
    Letter knowledge posttest33.81 ± 7.11*5.44 ± 9.84*z = 4.21, P < 0.001
    Word reading pretest0.57 ± 1.57*1.56 ± 2.65*z = 1.41, P = 0.301
    Word reading posttest7.10 ± 8.53*1.56 ± 2.35*z = 2.61, P = 0.009
    Days between tests189.76 ± 22.74*171.22 ± 63.85*z = 1.31, P = 0.193

    *Mean ± SD.

    †Raven test raw scores (maximum 60 points).

    ‡Raw scores.

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