Poster A44, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall
The impact of language learning experience on phonological working memory: A functional magnetic resonance imaging study
Shanna Kousaie1,2, Shari Baum2,3, Natalie Phillips2,4,5, Vincent Gracco2,3,6, Debra Titone2,7, Jen-Kai Chen1,2, Denise Klein1,2;1Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, 2Centre for Research on Brain, Language and Music, McGill University, 3School of Communication Sciences and Disorders, Faculty of Medicine, McGill University, 4Department of Psychology/Centre for Research in Human Development, Concordia University, 5Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research and Jewish General Hospital/McGill University Memory Clinic, Jewish General Hospital, 6Haskins Laboratories, 7Department of Psychology, McGill University
Phonological working memory (PWM) is a component of executive function that is important for storing and manipulating speech sounds. The processing of speech sounds in PWM facilitates the acquisition of vocabulary and grammar, making PWM an important building block for language learning. A network of fronto-parietal brain regions, including the left inferior frontal cortex and anterior insula, left inferior parietal lobule and bilateral superior temporal gyri, has been implicated in PWM [1]. Furthermore, phonological units differ across languages and the brain becomes fine-tuned to the units of an individual’s native language (L1) early in brain development [e.g., 2]. This raises questions about how bilingualism impacts PWM processes and whether this varies as a function of when the second language (L2) is learned. Previous research finds that left anterior insula recruitment is a marker of L2 attainment [3] and that early exposure to a language shapes the brain for PWM, even if that language is discontinued [4]. The current investigation further examines the implications of the timing of language learning on PWM processes. Participants underwent functional magnetic resonance imaging (fMRI) while they completed an auditory n-back task comprised of three conditions (0back, 1back, 2back) in both English and French. The three conditions varied in terms of PWM demands, with the 0back condition imposing minimal PWM demands (participant required to identify a target stimulus) and the 2back condition imposing increased PWM demands (participant required to decide whether the current stimulus matches the stimulus two previous in the stimulus sequence). Participants were native speakers of English and varied with respect to their age of L2 (French) acquisition (AoA). Simultaneous (n=10; mean AoA=0), early sequential (n=8; mean AoA=4.6), and late sequential (n=7; mean AoA=7.7) bilinguals were included and groups were matched in terms of chronological age, years of education, and proficiency in L1 and L2. Behaviourally, there were no differences in performance across the two languages for any of the groups. In terms of the fMRI results, simultaneous bilinguals showed similar recruitment of brain regions implicated in PWM in both of their languages. In relation to previous research that compared PWM in bilinguals and monolinguals [i.e., 4], the pattern of activation in the insula region in the simultaneous bilinguals in the current study resembles the pattern observed in monolinguals, while the pattern of activation in response to increased cognitive load (i.e., 2back-0back) in cognitive control regions (i.e., bilateral parietal and middle frontal regions) resembles the pattern observed in bilinguals from the previous research. Ongoing analyses including sequential bilinguals that relate activation patterns to AoA point to age of language learning as impacting the networks involved in PWM. Overall, the current findings increase our understanding of how the brain is set up for phonological language processing. [1] Fiez, J.A. (2016). In G. Hickok and S.L. Small (Eds.), Neurobiology of Language, Academic Press: San Diego. [2] Kuhl, P.K., et al. (2005). Lang Learn Dev, 1, 237. [3] Chee, M.W., et al., (2004). PNAS, 101, 15265. [4] Pierce, L.J., et al. (2015). Nat Commun, 6, 10073.
Themes: Multilingualism, Phonology and Phonological Working Memory
Method: Functional Imaging