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.

Developmental dyslexia is one of the most prevalent learning disabilities, thought to be associated with dysfunction in the neural systems underlying typical reading acquisition. Neuroimaging research has shown that readers with dyslexia exhibit regional hypoactivation in left hemisphere reading nodes, relative to control counterparts. This evidence, however, comes from studies that have focused only on isolated aspects of reading. The present study aims to characterize left hemisphere regional hypoactivation in readers with dyslexia for the main processes involved in successful reading: phonological, orthographic and semantic. Forty-one participants performed a demanding reading task during MRI scanning. Results showed that readers with dyslexia exhibited hypoactivation associated with phonological processing in parietal regions; with orthographic processing in parietal regions, Broca's area, ventral occipitotemporal cortex and thalamus; and with semantic processing in angular gyrus and hippocampus. Stronger functional connectivity was observed for readers with dyslexia than for control readers 1) between the thalamus and the inferior parietal cortex/ventral occipitotemporal cortex during pseudoword reading; and, 2) between the hippocampus and the pars opercularis during word reading. These findings constitute the strongest evidence to date for the interplay between regional hypoactivation and functional connectivity in the main processes supporting reading in dyslexia.

Learning to read transforms the brain, building on children's existing capacities for language and visuospatial processing. In particular, the development of print-speech convergence, or the spatial overlap of neural regions necessary for both auditory and visual language processing, is critical for literacy acquisition. Print-speech convergence is a universal signature of proficient reading, yet the antecedents of this convergence remain unknown. Here we examine the relationship between spoken language proficiency and the emergence of the printspeech network in beginning readers (ages 5-6). Results demonstrate that children's language proficiency, but not their early literacy skill, explains variance in their print-speech neural convergence in kindergarten. Furthermore, print-speech convergence in kindergarten predicts reading abilities one year later. These findings suggest that children's language ability is a core mechanism guiding the neural plasticity for learning to read, and extend theoretical perspectives on language and literacy acquisition across the lifespan.

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Over the last two decades, neuroimaging research has provided extensive knowledge about the neural basis of reading. However, there are still important debates about the functional role of reading-related regions and networks, and unanswered questions that will need to be addressed to further understand how reading is accomplished by the neural systems of monolingual and bilingual individuals. This chapter offers a critical review of (1) the functional specialization of left perisylvian reading regions and their participation in orthographic, phonological, and semantic reading systems; (2) the division of labor between ventral and dorsal reading networks and the factors that modulate them; and (3) the neural correlates supporting bilingual reading and the impact of age of acquisition, language proficiency, language exposure, and language orthography in the modulation of bilingual reading regions and networks. The chapter summarizes relevant current and future directions in the study of the neural mechanisms supporting this phylogenetically relatively new human ability.

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Consequences of multilingualism vary from offering cognitive benefits to poor educational and cognitive outcomes. One aspect of multilingualism that has not been systematically examined is the typology of multilinguals' languages: Do differences and similarities between languages multilinguals are exposed to contribute to the development of their cognition and brain? We investigated n = 162 5–6-year-olds with various language backgrounds on a monolingual-to-quintilingual continuum. Our results show that typological linguistic diversity can be related to expressive vocabulary knowledge in the dominant language. On neural level, it relates to brain activation patterns in (among others) the PGa area in the bilateral IPL, a brain region previously associated with multilingual experience, but never with language typology. We propose an ecologically valid way of describing the continuum of multilingual language experience and provide evidence for both the cognition and the brain of multilingual kindergartners to be related to the typological linguistic diversity of their environment.

The paper aims at establishing whether relative differences and similarities between languages multilingual children are exposed to contribute to the development of their cognition and brain. Our goal was to investigate the effects of typological linguistic diversity on first language (L1) lexical knowledge and processing in kindergartners and establish its behavioral and neural signatures. We analyzed 162 data points collected from 5-6-year-old kinder-gartners with various language backgrounds on a monolingual-to-quintilingual continuum. Detailed parental questionnaires and in-person interviews were used to calculate the length of cumulative exposure to any language each child in the sample came into contact with. We then gathered information on the relative linguistic distances between each child’s languages, based on languages’ lexicons. Two behavioral outcome variables were used in the study: (1) receptive and (2) expressive L1, English vocabulary; the neuroimaging data consisted of fMRI sequences collected during an English Audito-ry Word-Form Match Task. To deal with variable language backgrounds of our participants, we leveraged computational tools from information tech-nology – Shannon’s (1948) entropy, and the study of ecological diversity – Rao’s (1982) quadratic entropy index of diversity, thus offering a novel, multi-dimensional quantification of language exposure in multilinguals. Our results show that typological linguistic diversity can be related to expressive but not receptive L1 vocabulary scores. On neural level, it relates to brain activation patters in (among others) the PGa area in the bilateral IPL, a brain region that previous studies repeatedly associated with multilingual experience, but never with typological linguistic diversity. With this study, we propose an ecologically valid way of describing the continuum of multilingual language experience, an approach rarely followed but highly called for in the multilingual literature. We furthermore provide evidence for both the cognition and the brain of multilingual kindergartners to be related to the typological linguistic diversity of their environment.