Development of Print-Speech Integration in the Brain of Beginning Readers With Varying Reading Skills.

Fang Wang,Silvia Brem,Georgette Pleisch,Iliana I Karipidis,Gorka Fraga-González

doi:10.3389/fnhum.2020.00289

Abstract

Learning print-speech sound correspondences is a crucial step at the beginning of reading acquisition and often impaired in children with developmental dyslexia. Despite increasing insight into audiovisual language processing, it remains largely unclear how integration of print and speech develops at the neural level during initial learning in the first years of schooling. To investigate this development, 32 healthy, German-speaking children at varying risk for developmental dyslexia (17 typical readers and 15 poor readers) participated in a longitudinal study including behavioral and fMRI measurements in first (T1) and second (T2) grade. We used an implicit audiovisual (AV) non-word target detection task aimed at characterizing differential activation to congruent (AVc) and incongruent (AVi) audiovisual non-word pairs. While children’s brain activation did not differ between AVc and AVi pairs in first grade, an incongruency effect (AVi > AVc) emerged in bilateral inferior temporal and superior frontal gyri in second grade. Of note, pseudoword reading performance improvements with time were associated with the development of the congruency effect (AVc > AVi) in the left posterior superior temporal gyrus (STG) from first to second grade. Finally, functional connectivity analyses indicated divergent development and reading expertise dependent coupling from the left occipito-temporal and superior temporal cortex to regions of the default mode (precuneus) and fronto-temporal language networks. Our results suggest that audiovisual integration areas as well as their functional coupling to other language areas and areas of the default mode network show a different development in poor vs. typical readers at varying familial risk for dyslexia.

Highlights

Linking print to corresponding speech sounds plays a crucial role in reading and reading acquisition (Blomert, 2011)
Congruent (AVc) presentations resulted in weaker BOLD responses than incongruent (AVi) ones bilaterally in the middle/inferior temporal gyri, including parts of the fusiform gyrus, bilaterally in the superior frontal gyrus, in the left inferior frontal gyrus, and in the right medial frontal gyrus (Table 2A and Figure 2A)
The interaction effect of congruency by group was significant in the right middle frontal gyrus: poor reading children showed a significant difference in the form of a more negative BOLD signal for AV incongruent (AVi) than activation to congruent (AVc) pairs (Table 2B and Figure 2B), while no significant difference was detected between the negative BOLD signals for AVi and AVc pairs in typical readers

Summary

Introduction

Linking print (graphemes) to corresponding speech sounds (phonemes) plays a crucial role in reading and reading acquisition (Blomert, 2011). AV paradigms in which the congruency of written and spoken information is manipulated have frequently been used to study the integration of visual and auditory language information in the brain (Raij et al, 2000; van Atteveldt et al, 2007; Blau et al, 2010; Kronschnabel et al, 2014; McNorgan et al, 2014; Xu et al, 2018; Ye et al, 2018) In this context, the difference of neural responses to congruent vs incongruent print-speech pairs (congruency effect), is typically used to quantify the extent of AV integration and characterize involved networks (van Atteveldt et al, 2004; Holloway et al, 2015; Richlan, 2019). The supramarginal gyrus (SMG) and the angular gyrus (AG) in the parietal lobe have been shown to be involved in accessing the phonological representations for written words and letter strings in both typical readers (Church et al, 2011) and in children with reading difficulties (Vandermosten et al, 2016; Xu et al, 2018)

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Discussion

Conclusion