Dual Training Effects of Bilingualism and Music on Auditory-Motor Integration

Musicianship and bilingualism are both demanding sensorimotor processes that require extensive training and expertise to master. Functional changes have been observed in the dorsal pathway comprised of auditory and motor regions of the brain, a network critical for linking sounds to action, a process called auditory-motor integration. Due to this neural overlap, musicianship has been shown to impact aspects of speech processing. The primary goal of our study was to investigate such a “dual training effect” of musicianship and bilingualism. We recruited two groups of bilingual individuals, with one group also being highly trained musicians, controlled on a number of critical demographic factors. We hypothesized that this type of training would result in converging patterns of functional activity at rest within auditory- motor brain networks and impact ability to reproduce non-native language sounds in a more native-like way. In Study 1, we investigated the impact of being both musician and bilingual on resting- state functional connectivity within the dorsal-auditory motor stream. We observed that musician bilinguals possessed significant decreases in rs-FC between the left IFG pars triangularis and three separate brain clusters comprised of the STG/SMG, left insula, and right insula. We also observed a series of correlations between these reductions in rs-FC and performance on cognitive and musical tasks. In Study 2, we investigated this dual training impact on ability to listen to and correctly reproduce non-native language sounds. No group differences were found for NNL reproduction overall. However, we observed a significant correlation between rs-FC reductions observed in Study 1 and these NNL reproduction tasks. When running a series of hierarchical regressions, we observed that musicianship as a grouping variable significantly predicted this performance. Taken together, our results demonstrate that combined musicianship and bilingualism results in significantly decreased resting-state functional activity between brain areas organized within the dorsal-auditory motor network. Furthermore, we observed that participants with the greatest reductions in rs-FC performed best on tasks assessing spatial organization and working memory, musical rhythm reproduction, and non-native language reproduction. Therefore, we hypothesize that possessing this dual experience may result in a more efficient or streamlined circuit, which may also relate to improved performance on other cognitive tasks, including language tasks