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Exploring the use of aperiodic EEG in investigating multilingualism-induced neural plasticity
Poster Session E, Friday, October 2, 11:00 am - 1:00 pm, Wangari Maathai
Katherine Sendek1, Jason Rothman2, Vincent DeLuca1; 1UiT The Arctic University of Norway, 2Lancaster University
Bilinguals offer a unique opportunity to study mechanisms within the brain. As a result of both languages being active across contexts within the brain, bilinguals constantly exercise control over these languages (Green & Abutalebi, 2013; Kroll et al., 2006; Spivey & Marian, 1999). The impact of this constant exercise on the bilingual brain has been a subject of great interest in recent years, with bilinguals often showing resistance to age-related cognitive decline (Anderson et al., 2020; Bialystok, 2021; Rothman & Gallo, 2025). Adaptations to both structure and function are not a given of being bilingual, rather they obtain as function of degree of bilingual language engagement attributable to greater efficiency of neural connections with increased bilingual engagement. Exploration of these changes to neuroarchitecture and functional connectivity are limited by the accessibility of expensive, computationally demanding methods like (f)MRI or invasive clinical work. However, recent developments in EEG research have demonstrated that the previously overlooked aperiodic component of the signal may be highly informative for these same types of measures (Voytek & Knight, 2015). The aperiodic component of the signal refers to the characteristic, 1/f-like shape of the broadband EEG signal, wherein there is higher power at lower frequencies and lower power at higher frequencies. While this aspect of the signal was previously dismissed as noise, recent work has shown that changes to the exponent (tilt) of this signal correspond to degree of signal coherence, likely related to excitation/inhibition balance within the brain (Gao et al., 2017). Specifically, global flattening of the signal was observed within patients with disrupted signaling, such as schizophrenia (Peterson et al., 2023; Ramsey et al., 2021). In non-clinical samples, flattening has also been seen in older adults and predicted poorer performance in younger adults (Dave et al., 2019). Aperiodic exponent has also been shown to track developmental changes in neuronal pruning, that catalogue changes in signaling efficiency across the lifespan (He et la., 2019). While this measure is still in its infancy, it provides a unique opportunity to investigate the increased efficiency of the bilingual brain in a more accessible way. Bridging this gap, we use resting state EEG data from 146 multilinguals in Norway with wide range of ages (M=47.14, range:18-82) and degrees of multilingual engagement (M=.53, range:0-.88). Data replicated previous findings (He et al., 2019), with linear regression showing flattening of the aperiodic exponent with increased age, indicating that aperiodic exponent indexes age-related declines in signal coherence. Additionally, general-additive model analysis showed an inverted-U relationship between aperiodic exponent and degree of multilingual engagement (p<.001). While the pattern differed across age, there was a general increase in aperiodic exponent, followed by a decrease or plateau as degree of multilingual engagement increased. This aligns with efficiency-based models of multilingual brain adaptation found using fMRI (Pliatsikas, 2019), indicating that aperiodic components may serve as a more accessible measure of connectivity changes due to multilingualism. Additionally, this work shows that aperiodic changes are sensitive to lifestyle characteristics, such as multilingualism, that go beyond current clinical applications.
Topic Areas: Multilingualism, Methods