The bilingual brain: A theoretical review of the relationship between bilingualism, cognitive control and aphasia
Dafne Palú (Catholic University of Portugal, Portugal)
Language is not an isolated system. Indeed, our linguistic skills rely on our overall cognitive abilities, including executive control. This relationship is made more apparent in cases of language disorder: thus, verbal perseveration (common in transcortical motor aphasia) and logorrhea (typical of receptive aphasia, but also observable in thalamic aphasia) have been linked to impaired inhibition (Allison, 1966; Papagno & Basso, 1996); the inability to grasp figurative meaning to impaired cognitive flexibility (Bertuletti, 2012); and phonemic and verbal paraphasia to a deficit of the phonological loop (a part of our working memory) (Quertaimont, 2012). It is also revealing that aphasic patients perform worse on non-linguistic cognitive tasks than healthy subjects (Purdy, 2002).
Meanwhile, bi- and multilingual individuals usually perform better than monolinguals in non-verbal executive functioning tasks (Carlson & Meltzoff, 2008; Bialystok, 2015). This advantage is often thought to emerge from the constant need to “resolve conflict from jointly-activated languages” (Bialystok, 2015). But does the so-called bilingual advantage hold up in aphasia? While it appears that poststroke aphasia in bilingual speakers is likely to be less severe than in monolingual speakers (Paplikar, et al., 2019) and that aphasic bilinguals have higher inhibition and monitoring skills than their monolingual counterparts (Arantzeta, et al., 2019), aphasic bilinguals do not necessarily outperform aphasic monolinguals in comprehension accuracy (Arantzeta, et al., 2019).
We would like to present a theoretical overview and a critical assessment of several studies exploring the relationship between bilingualism and aphasia. We believe that a better understanding of their joint impact on our cognitive functions may improve rehabilitation guidelines and offer valuable insights into the linguistic brain.
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