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Language selection, language switching and subcortical links in bilingual aphasia
Poster Session D, Thursday, October 1, 4:30 - 6:30 pm, Wangari Maathai
Amanda Miller Amberber1; 1Postdoctoral researcher, Sydney, Australia
Current psycholinguistic and neurolinguistic models of language selection and switching in bilinguals posit either (i) inhibition of the non-target language is central to language selection and control (e.g. Abutalebi & Green 2007, 2008; Kroll et al. 2006, 2008) or (ii) that language selection and switching is achieved through selection of the most highly activated language items (Blanco-Elorrieta & Caramazza 2021; Zhu et al. 2022, see also Paradis 2004). Impaired language selection and switching in bilinguals with aphasia is argued to result from impaired inhibitory control (Green 2005; Green & Abutalebi 2013) mediated via a fronto-temporo-parietal cortex and subcortical (including basal ganglia) network. This research reports a series of experiments that examined language selection and language switching in early proficient bilinguals with aphasia (n=5) who presented with grammatical impairment of each language subsequent to left fronto-temporal or basal ganglia stroke, and matched bilingual controls (n=5). Participants were tested in each language on a comprehensive language battery, on language selection tasks including naming, narrative, reading and translation, monolingual and bilingual discourse, and a novel language switching experimental paradigm. The results showed intact language selection across all tasks in monolingual and bilingual contexts for bilingual participants with aphasia, and performance that was indistinguishable from controls. Grammatical impairment of language switching on both lexical production and written lexical selection tasks was found for bilingual participants with aphasia, unlike the bilingual controls, with significant differences in performance. Similar findings across diverse language pairs (Maltese-English, Rarotongan-English, French-English) attested to the robustness of the results. These findings of intact language selection despite left basal ganglia and cortical lesions provide evidence supporting the bilingual language activation model, consistent with recent neuroimaging studies, and counter-evidence to the inhibitory control model for bilinguals with aphasia. This research further establishes that grammatical aspects of language switching can be selectively impaired in early bilinguals with aphasia, and that grammatical and discourse-pragmatic aspects of language switching are dissociable, with results consistent across diverse language pairs. Implications for subcortical regions of the brain and the hyperdirect cortico-subthalamic nucleus route increasingly implicated in language and goal-directed learning are discussed in conclusion.
Topic Areas: Multilingualism, Disorders: Acquired