Neurobiological signatures of L2 proficiency: Evidence from a bi-directional cross-linguistic study.

Recent evidence has shown that convergence of print and speech processing across a network of primarily left-hemisphere regions of the brain is a predictor of future reading skills in children, and a marker of fluent reading ability in adults. The present study extends these findings into the domain of second-language (L2) literacy, through brain imaging data of English and Hebrew L2 learners. Participants received an fMRI brain scan, while performing a semantic judgement task on spoken and written words and pseudowords in both their L1 and L2, alongside a battery of L1 and L2 behavioural measures. Imaging results show, overall, show a similar network of activation for reading across the two languages, alongside significant convergence of print and speech processing across a network of left-hemisphere regions in both L1 and L2 and in both cohorts. Importantly, convergence is greater for L1 in occipito-temporal regions tied to automatic skilled reading processes including the visual word-form area, but greater for L2 in frontal regions of the reading network, tied to more effortful, active processing. The main groupwise brain effects tell a similar story, with greater L2 than L1 activation across frontal, temporal and parietal regions, but greater L1 than L2 activation in parieto-occipital regions tied to automatic mapping processes in skilled reading. These results provide evidence for the shifting of the reading networks towards more automatic processing as reading proficiency rises and the mappings and statistics of the new orthography are learned and incorporated into the reading system.

Prereader to beginning reader: changes induced by reading acquisition in print and speech brain networks.

BACKGROUND: Literacy acquisition is a demanding process that induces significant changes in the brain, especially in the spoken and written language networks. Nevertheless, large-scale paediatric fMRI studies are still limited. METHODS: We analyzed fMRI data to show how individual differences in reading performance correlate with brain activation for speech and print in 111 children attending kindergarten or first grade and examined group differences between a matched subset of emergent-readers and prereaders. RESULTS: Across the entire cohort, individual differences analysis revealed that reading skill was positively correlated with the magnitude of activation difference between words and symbol strings in left superior temporal, inferior frontal and fusiform gyri. Group comparisons of the matched subset of pre- and emergent-readers showed higher activity for emergent-readers in left inferior frontal, precentral, and postcentral gyri. Individual differences in activation for natural versus vocoded speech were also positively correlated with reading skill, primarily in the left temporal cortex. However, in contrast to studies on adult illiterates, group comparisons revealed higher activity in prereaders compared to readers in the frontal lobes. Print-speech coactivation was observed only in readers and individual differences analyses revealed a positive correlation between convergence and reading skill in the left superior temporal sulcus. CONCLUSIONS: These results emphasise that a child's brain undergoes several modifications to both visual and oral language systems in the process of learning to read. They also suggest that print-speech convergence is a hallmark of acquiring literacy.

Universal brain signature of proficient reading: Evidence from four contrasting languages.

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.

Early and late talkers: school-age language, literacy and neurolinguistic differences.

Early language development sets the stage for a lifetime of competence in language and literacy. However, the neural mechanisms associated with the relative advantages of early communication success, or the disadvantages of having delayed language development, are not well explored. In this study, 174 elementary school-age children whose parents reported that they started forming sentences 'early', 'on-time' or 'late' were evaluated with standardized measures of language, reading and spelling. All oral and written language measures revealed consistent patterns for 'early' talkers to have the highest level of performance and 'late' talkers to have the lowest level of performance. We report functional magnetic resonance imaging data from a subset of early, on-time and late talkers matched for age, gender and performance intelligence quotient that allows evaluation of neural activation patterns produced while listening to and reading real words and pronounceable non-words. Activation in bilateral thalamus and putamen, and left insula and superior temporal gyrus during these tasks was significantly lower in late talkers, demonstrating that residual effects of being a late talker are found not only in behavioural tests of oral and written language, but also in distributed cortical-subcortical neural circuits underlying speech and print processing. Moreover, these findings suggest that the age of functional language acquisition can have long-reaching effects on reading and language behaviour, and on the corresponding neurocircuitry that supports linguistic function into the school-age years.