Whole-Brain Functional Networks for Phonological and Orthographic Processing in Chinese Good and Poor Readers.

Jing Yang,Li Hai Tan

doi:10.3389/fpsyg.2019.02945

Abstract

The neural basis of dyslexia in different languages remains unresolved, and it is unclear whether the phonological deficit as the core deficit of dyslexia is language-specific or universal. The current functional magnetic resonance imaging (fMRI) study using whole-brain data-driven network analyses investigated the neural mechanisms for phonological and orthographic processing in Chinese children with good and poor reading ability. Sixteen good readers and 16 poor readers were requested to make homophone judgments (phonological processing) and component judgments (visual-orthographic processing) of presented Chinese characters. Poor readers displayed worse performance than the good readers in phonological processing, but not in orthographic processing. Whole-brain activation analyses showed compensatory activations in the poor readers during phonological processing and automatic phonological production activation in the good readers during orthographic processing. Significant group differences in the topological properties of their brain networks were found only in orthographic processing. Analyses of nodal degree centrality and betweenness centrality revealed significant group differences in both phonological and orthographic processing. The present study supports the phonological core deficit hypothesis of reading difficulty in Chinese. It also suggests that Chinese good and poor readers might recruit different strategies and neural mechanisms for orthographic processing.

Highlights

Developmental dyslexia, or in short, dyslexia, is characterized by a severe reading acquisition disorder that cannot be explained by general intelligence impairment, lack of education opportunities, or any sensory or neurological disorders (American Psychiatric Association, 2013)
Whole-brain activation analyses, revealed the poor readers compared with the good readers had hyperactivity in left middle frontal gyrus (MFG) (BA 10), right inferior frontal gyrus (IFG) (BA 45), and right superior temporal sulcus (STS) (BA 22) during phonological processing, and hypoactivity in the left premotor cortex (BA 6) during visualorthographic processing
Consistent with previous reports on the phonological deficits of Chinese dyslexia, the present study showed that Chinese children with reading difficulties performed worse than the good readers in the homophone judgment task

Summary

Introduction

Developmental dyslexia, or in short, dyslexia, is characterized by a severe reading acquisition disorder that cannot be explained by general intelligence impairment, lack of education opportunities, or any sensory or neurological disorders (American Psychiatric Association, 2013). Phonological deficits, including impaired phonological representation and speech sound processing, are presented in the majority of dyslexics (Ziegler and Goswami, 2005) and the phonological deficit hypothesis has been the most popular hypothesis about the cause of dyslexia (Rack et al, 1992; Pennington and Lefly, 2001; for a recent review, see Paulesu et al, 2014). This hypothesis posits that dyslexics are impaired. They found decreased activation of left ventral temporo-occipital region only in dyslexic adults

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