Universal brain signature of proficient reading: Evidence from four contrasting languages

Abstract

We propose and test a theoretical perspective in which a universal hallmark of successful literacy acquisition is the convergence of the speech and orthographic processing systems onto a common network of neural structures, regardless of how spoken words are represented orthographically in a writing system. During functional MRI, skilled adult readers of four distinct and highly contrasting languages, Spanish, English, Hebrew, and Chinese, performed an identical semantic categorization task to spoken and written words. Results from three complementary analytic approaches demonstrate limited language variation, with speech-print convergence emerging as a common brain signature of reading proficiency across the wide spectrum of selected languages, whether their writing system is alphabetic or logographic, whether it is opaque or transparent, and regardless of the phonological and morphological structure it represents.

Keywords: cross-language invariance; functional MRI; word recognition.

Fig. 1.

Intersect maps showing brain regions that are active for print only (cyan), speech only (green), or both print and speech (violet) (threshold for each modality q < 0.001, FDR-corrected) for each language. (A) Spanish. (B) English. (C) Hebrew. (D) Chinese.

Fig. 2.

Intersect maps showing brain regions that are active for print only (cyan), speech only (green), or both print and speech (violet) across all four languages (threshold for each modality q < 0.001, FDR-corrected; conjoint probability of activation for both speech and print across all languages is q < 0.001^8).

Fig. 3.

Print and speech convergence common across all languages. (A) Areas in which print (Pr) and speech (Sp) activation were correlated in the four languages. (Values indicate the minimum r value across all languages.) (B) Scatter plot of the correlation between print and speech activation in a representative area for each language (posterior superior temporal gyrus; MNI coordinates X −47, Y −62, Z 21).

Fig. 4.

Print and speech convergence as a factor of orthographic depth. (A) Areas in yellow show the reading circuit identified by published meta-analyses. Speech–print correlations were higher for transparent (Spanish) than opaque orthographies (English and Hebrew compared independently, P < 0.05 for each comparison) in areas shown in pink. Areas shown in light blue show higher correlations for the opaque orthographies compared with the transparent orthography, P < 0.05. (B) Scatter plots of the correlation between print and speech activation in representative areas showing greater convergence for more transparent languages in left inferior parietal lobule, supramarginal gyrus (Left), and left angular gyrus for opaque languages (Right). Fisher’s R-to-Z transform was performed to calculate statistical significance.

Fig. 5.

Areas in which speech–print convergence differed for alphabetic orthographies (Spanish, English, Hebrew) compared independently with the logographic orthography (Chinese), each comparison P < 0.05, corrected. Areas shown in blue showed greater convergence for the logographic than the alphabetic orthographies; areas in red showed the opposite pattern. Areas in yellow provide a reference to the reading circuit identified by published meta-analyses.

Fig. 6.

Overlap in print, speech, and speech–print convergence regions in relation to reading-related regions. Brain regions in olive represent speech–print convergence regions, namely areas common across speech-related activation (speech), print-related activation (print), and correlated activation between speech and print (correlation). Brain regions in violet represent reading-related regions with speech–print convergence, namely areas common across print, speech, and correlation, and also the known reading circuit defined by prior meta-analyses of fMRI studies (reading). The brain region in cyan represents reading-related regions with print specificity, namely an area common across print and reading but not speech or correlation. Brain regions in green represent reading-related regions with speech specificity, namely areas common across speech and reading but not print or correlation. L, left; R, right.