Poster B52, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall
Effects of orthographic depth on functional connectivity between the posterior visual word form area and dorsal and ventral reading networks in proficient Welsh-English bilinguals
Pauliina Sorvisto1, Paul Mullins1, Marie-Josèphe Tainturier1;1Bangor University
Background: It has been suggested that word reading occurs along two main anatomical pathways: the dorsal stream implicated in phonology and the ventral stream engaged in lexico-semantic processing. There is cross-linguistic evidence that the recruitment of the ventral stream is stronger in languages with a deeper orthography such as English. In contrast, the recruitment of the dorsal pathway is more prominent in more transparent languages with more consistent letter-to-sound correspondence (e.g. Das et al., 2011; Richlan, 2014). An interesting question is what happens in bilingual readers of languages with different orthographic depth. Would the cross-linguistic patterns also apply or would reading bilingually lead to a more unified system for the two languages? Oliver, Carreiras and Paz-Alonso (2017) compared fMRI activation and functional connectivity while reading for meaning in Spanish speakers that had either English or transparent Basque as a second language. They observed that Basque L2 readers showed greater coactivation within the dorsal network while English L2 readers showed greater coactivation within the ventral network. This is consistent with cross-linguistic results. However, reading bilingually from an early age may lead to a higher convergence in written word comprehension processes. Aims: The goal of the current study was to examine the relative involvement of the ventral vs dorsal pathways in proficient early bilingual readers of two languages with highly contrasted orthographic depth: English vs Welsh. In previous GLM analyses, we showed comparable patterns of activation in the two languages. However, MVPA analyses revealed language sensitivity in several language regions. In this study, we examined if English and Welsh are associated with different patterns of functional connectivity in the ventral/dorsal streams. Methods: While being scanned for fMRI, 20 proficient Welsh-English early bilingual adults performed a semantic categorisation task (natural vs man-made) on 192 Welsh and 192 English written, non-cognate translation equivalent nouns presented. We performed psycho-physiological interactions (PPI) analyses for each language using the posterior visual word form area (pVWFA) as the seed region as it is engaged in the earliest stages of written word processing in alphabetic systems (Bouhali et al., 2014). Results: We observed greater connectivity for English compared to Welsh words between the pVWFA and regions along the ventral pathway, mainly the inferior and middle temporal gyri (BA20; BA21) and the fusiform gyrus (BA37), as well as some regions outside this pathway bilaterally. However, the connectivity observed for Welsh compared to English words was only higher in LH frontal regions outside the dorsal pathway, mainly the orbitofrontal area (BA11). Conclusion: Our results suggest greater temporal coherence of the ventral lexical-semantic pathway in the deeper language of early proficient bilingual readers. However, Welsh reading does not show greater connectivity than English between pVWFA and dorsal regions. This contrasts with earlier studies and may reflect a greater convergence of reading processes across languages differing in orthographic depth in early bilinguals. However, it remains possible that stronger dorsal PPI patterns may emerge in reading tasks less explicitly reliant on processing meaning and making conscious meaning-based decisions.
Themes: Multilingualism, Reading
Method: Functional Imaging