Orthographic differences across languages impose differential weighting on distinct component processes, and consequently on different pathways during word-reading tasks. Readers of transparent orthographies such as Italian and Hindi are thought to rely on spelling-to-sound assembly and show increased activation in phonologically-tuned areas along the dorsal pathway, whereas reading an opaque orthography such as English is thought to rely more on lexically-mediated processing associated with increased activation of semantically-tuned regions along the ventral pathway. To test if biliterate Hindi/English readers exhibit orthography-specific reading pathways, we used behavioural measures and functional neuroimaging. Reaction times and activation patterns of monolingual English and Hindi readers were compared to two groups of adult biliterates; 14 simultaneous readers who learnt to read both languages at age 5 and 10 sequential readers who learnt Hindi at 5 and English at 10. Simultaneous, but not sequential readers demonstrated relative activation differences of dorsal and ventral areas in the two languages. Similar to native counterparts, simultaneous readers preferentially activated the left inferior temporal gyrus for English and left inferior parietal lobule (L-IPL) for Hindi, whereas, sequential readers showed higher activation along the L-IPL for reading both languages. We suggest that early simultaneous exposure to reading distinct orthographies results in orthography-specific plasticity that persists through adulthood.

The aim of the present study was to use functional imaging to compare cortical activations involved in reading Hindi and English that differ markedly in terms of their orthographies by a group of late bilinguals, more fluent in Hindi (L1) than English (L2). English is alphabetic and linear, in that vowels and consonants are arranged sequentially. In contrast, Hindi, written in Devanagari, is an alphasyllabary and non-linear writing system wherein vowels are placed around consonants making it a visually complex script. Additionally, the grapheme to phoneme mapping in English is opaque while Devanagari is transparent. Effects of reading fluency were seen in significantly slower reading times and direct EnglishHindi comparison showed left putamen activation for the less fluent language (English). Direct Hindi-English orthography comparisons revealed activation in the temporal pole and caudate nucleus of the right hemisphere, cortical areas known to be involved in semantic and visual processing. We also find activation in right superior temporal gyrus, which we attribute to the syllabic rhythm of Hindi. Our

Functional imaging studies have established cortical networks for reading alphabetic, syllabic and logographic scripts. There is little information about the different cortical areas that participate in reading an alphasyllabary. We use functional brain imaging to study the reading network for Devanagari, an alphasyllabary. Similar to syllabic scripts, the basic phonological unit that corresponds to a grapheme in Devanagari, called an akshara, is a syllable but the component consonant and vowel within akshara can always be visually analyzed giving it the appearance of an alphabetic system. Unlike an alphabetic system wherein arrangement of consonants and vowels is linear, in Devanagari, vowels can also be placed linearly in a sequential manner or non-linearly, above or below, making it visuospatially complex. In this study we used functional neuroimaging to ascertain the cortical reading network when 10 native speakers of Hindi, read linear words in Devanagari. Akin to other word reading studies, we find activation in the midfusiform gyrus (visual word form area, BA 37). Region of interest analysis shows involvement of left superior temporal gyrus (BA 41), inferior (BA 40) and superior parietal (BA 7) lobules. These findings suggest that the reading network for Devanagari, an alphasyllabary encompasses cortical areas involved in reading both alphabetic and syllabic writing systems.

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