Print-Speech Convergence Predicts Future Reading Outcomes in Early Readers

Abstract

Becoming a skilled reader requires building a functional neurocircuitry for printed language processing that converges on spoken language processing networks. In this longitudinal study, functional magnetic resonance imaging (fMRI) was used to examine whether convergence for printed and spoken language in beginning readers predicts reading outcomes two years later. Print-speech co-activation across the left hemisphere reading network predicted later reading achievement beyond the effects of brain activity for either modality alone; moreover, co-activation effects accounted for variance in later reading after controlling for initial reading performance. Within the reading network, effects of co-activation were significant in bilateral inferior frontal gyrus (IFG) and left inferior parietal cortex and fusiform. The contribution of left and right IFG differed, with more co-activation in left IFG predicting better achievement but more co-activation in right IFG predicting poorer achievement. Findings point to the centrality of print-speech convergence in building an efficient reading circuitry in children.

Neural Noise Hypothesis of Developmental Dyslexia

“…We integrate these emerging lines of research to propose that excess neural noise (Box 1) within cortical regions implicated in reading may be a distal contributor to RD. We suggest that multifactorial sources of neural noise, for example arising from neural hyperexcitability related to RD risk genes, may disrupt two key processes important for reading— phonological awareness [44] (see glossary) and multisensory integration of visual symbols with their corresponding speech sounds [45,46]—through the impact of excess noise on neural synchrony and sensory representations (Figure 1). The neural noise hypothesis of RD synthesizes a range of neurobiological findings, providing a mechanistic framework for understanding the deficits observed in RD and identifying targets for systems-level intervention.…”

Individual Differences in Subphonemic Sensitivity and Phonological Skills

“…For instance, in Scarborough's (1989) study, preschoolers' 247 phonological awareness, measured and analyzed as a continuous variable, uniquely explained the 248 wide variation in reading outcomes at second grade, ranging from reading disabled, to low-249 achieving, to normal. Also, functional neuroimaging research shows that the amount of overlap 250 between the neural substrates of speech processing and print processing varies continuously with 251 reading skill (Frost et al, 2009;Preston et al, 2016;Shankweiler et al, 2008), implying that 252 better readers tend to engage more phonological processing in reading and supporting the idea 253 that phonological ability may be an important locus on which individuals with different levels of 254 reading competence vary. 255…”

Neural Noise Hypothesis of Developmental Dyslexia

“…Learning Phoneme-Grapheme Mappings Reading relies on the ability to reorganize left hemisphere speech and/or language-sensitive networks to allow print-speech integration [46,[93][94][95], enabling phoneme-grapheme correspondences to be learned. The neural noise hypothesis predicts that multisensory integration, such as between print and speech, should be consistently impacted in RD.…”

“…Several studies have found that individuals with RD have reduced sensitivity to rhythmic patterns in the speech envelope, particularly at the syllabic rate [90,91], which some studies have attributed to impaired neural entrainment to the speech signal at low frequencies relevant to stress and syllabic segmentation [34]. There is also evidence for deficient phase-locking to both the fine structure of speech [92] and speech envelope in RD [81], consistent with the hyperexcitability-related spike timing variability observed in animal models [5,56].Learning Phoneme-Grapheme Mappings Reading relies on the ability to reorganize left hemisphere speech and/or language-sensitive networks to allow print-speech integration [46,[93][94][95], enabling phoneme-grapheme correspondences to be learned. The neural noise hypothesis predicts that multisensory integration, such as between print and speech, should be consistently impacted in RD.…”

“…We integrate these emerging lines of research to propose that excess neural noise (Box 1) within cortical regions implicated in reading may be a distal contributor to RD. We suggest that multifactorial sources of neural noise, for example arising from neural hyperexcitability related to RD risk genes, disrupt two key processes important for reading [phonological awareness [44] (see Glossary) and multisensory integration of visual symbols with their corresponding speech sounds [45,46]] through the impact of excess noise on neural synchrony and sensory representations (Figure 1). The neural noise hypothesis of RD synthesizes a range of neurobiological findings, providing a mechanistic framework for understanding the deficits observed in RD and identifying targets for systems-level intervention.…”