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Previous neuroimaging studies have found atypical cerebellar activation in individuals with dyslexia in either motor-related tasks or language tasks. However, studies investigating atypical cerebellar activation in individuals with dyslexia have mostly used tasks tapping phonological processing. A question that is yet unanswered is whether the cerebellum in individuals with dyslexia functions properly during orthographic processing of words, as growing evidence shows that the cerebellum is also involved in visual and spatial processing. Here, we investigated cerebellar activation and cerebro-cerebellar functional connectivity during word processing in dyslexic readers and typically developing readers using tasks that tap orthographic and phonological codes. In children with dyslexia, we observed an abnormally higher engagement of the bilateral cerebellum for the orthographic task, which was negatively correlated with literacy measures. The greater the reading impairment was for young dyslexic readers, the stronger the cerebellar activation was. This suggests a compensatory role of the cerebellum in reading for children with dyslexia. In addition, a tendency for higher cerebellar activation in dyslexic readers was found in the phonological task. Moreover, the functional connectivity was stronger for dyslexic readers relative to typically developing readers between the lobule VI of the right cerebellum and the left fusiform gyrus during the orthographic task and between the lobule VI of the left cerebellum and the left supramarginal gyrus during the phonological task. This pattern of results suggests that the cerebellum compensates for reading impairment through the connections with specific brain regions responsible for the ongoing reading task. These findings enhance our understanding of the cerebellum's involvement in reading and reading impairment.

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Are the brain mechanisms of reading acquisition similar across writing systems? And do similar brain anomalies underlie reading difficulties in alphabetic and ideographic reading systems? In a cross-cultural paradigm, we measured the fMRI responses to words, faces and houses in 96 Chinese and French 10-year-old children, half of whom were struggling with reading. We observed a reading circuit which was strikingly similar across languages and consisting of the left fusiform gyrus, superior temporal gyrus/sulcus, precentral and middle frontal gyri. Activations in some of these areas were modulated either by language or by reading ability, but without interaction between those factors. In various regions previously associated with dyslexia, reading difficulty affected activation similarly in Chinese and French readers, including the middle frontal gyrus, a region previously described as specifically altered in Chinese. Our analyses reveal a large degree of cross-cultural invariance in the neural correlates of reading acquisition and reading impairment.

Bilingual experience can delay cognitive decline during aging. A general hypothesis is that the executive control system of bilinguals faces an increased load due to controlling two languages, and this increased load results in a more ‘tuned brain’ that eventually creates a neural reserve. Here we explored whether such a neuroprotective effect is independent of language modality, i.e., not limited to bilinguals who speak two languages but also occurs for bilinguals who use a spoken and a signed language. We addressed this issue by comparing bimodal bilinguals to monolinguals in order to detect age-induced structural brain changes and to determine whether we can detect the same beneficial effects on brain structure, in terms of preservation of gray matter volume (GMV), for bimodal bilinguals as has been reported for unimodal bilinguals. Our GMV analyses revealed a significant interaction effect of age × group in the bilateral anterior temporal lobes, left hippocampus/amygdala, and left insula where bimodal bilinguals showed slight GMV increases while monolinguals showed significant age-induced GMV decreases. We further found through cortical surface-based measurements that this effect was present for surface area and not for cortical thickness. Moreover, to further explore the hypothesis that overall bilingualism provides neuroprotection, we carried out a direct comparison of GMV, extracted from the brain regions reported above, between bimodal bilinguals, unimodal bilinguals, and monolinguals. Bilinguals, regardless of language modality, exhibited higher GMV compared to monolinguals. This finding highlights the general beneficial effects provided by experience handling two language systems, whether signed or spoken.

32To determine whether the neural anomalies underlying developmental dyslexia are universal 33 across languages or influenced by the writing system, we tested 10-year-old Chinese and French 34 children, with or without dyslexia, in a cross-cultural fMRI paradigm. We compared their brain 35 responses to words written in their known script, faces and houses while they were asked to 36 detect a rarely presented star. We observed that impaired reading scores were correlated with a 37 decreased activation to words in several key regions of the reading circuit, including left 38 fusiform gyrus, superior temporal gyrus/sulcus, precentral and middle frontal gyrus. In ROIs 39 previously reported as sensitive to dyslexia, we observed main effects of dyslexia common to 40Chinese and French readers, without interaction with the children's native language, suggesting 41 a cross-cultural invariance in the neural anomalies underlying dyslexia. Multivariate pattern 42 analyses further confirmed that dyslexics exhibit a reduced activation to written words in the 43 left fusiform gyrus and left posterior superior temporal gyrus, and not merely a greater inter-44 individual variability. The impairments in these regions may reflect the causes as well as the 45 consequences of orthographic and phonological deficits in dyslexia in different languages. The 46 current study highlights the existence of common brain mechanisms for dyslexia even in highly 47 different writing systems. 48 49 Introduction 52 A large proportion of published studies on reading concern English, even though this 53 language may be considered as an outlier within alphabetic writing systems, compared to 54 Finnish or Italian for example, due to its highly opaque grapheme-phoneme correspondences. 55Thus, international efforts are needed to extend the results obtained in English subjects, or more 56 generally in Western languages, to other writing systems and languages notably during 57 childhood. Daniels and Share listed 10 dimensions that might affect reading acquisition and 58 dyslexia phenotypes, and fall into three main classes: the structure of the oral language, the 59 complexity of the visual shapes, and the translation rules between those two domains [1]. With 60 regard to language, the number of phonemes, the syllabic structure and the complexity and 61 regularity of morphological markers can modulate the ease with which children construct 62 explicit representations of speech, which need to be converted in, or deduced from, writing [2]. 63The visual shapes of letters and characters also vary in number, uniformity, and complexity [1]. 64Finally, the sound-character mappings vary on several dimensions across writings, including 65 granularity, complexity, transparency, and consistency. All these factors may influence the 66 speed and effectiveness with which children learn to read, and at least one of these dimensions, 67 orthographic transparency, has been robustly reported to affect reading acquisition in Western 68 languages [3], with a reported impact o...

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