The left, the better: white-matter brain integrity predicts foreign-language imitation.

The left, the better: white-matter brain integrity predicts foreign-language imitation

Lucía Vaquero1, Antoni Rodríguez-Fornells1,2, and Susanne Reiterer3

1. Universitat de Barcelona, Spain

2. IDIBELL & ICREA

3. University of Vienna

Speech imitation is crucial for language acquisition and second-language learning. Interestingly, great individual differences regarding the ability in imitating foreign-language sounds have been observed. The cause of this inter–individual difference remains unknown, although it might be explained in part by structural predispositions. We correlated white-matter structural properties of the arcuate fasciculus (AF) with the performance of 52 German-speakers in a Hindi sentence- and word-imitation task. First, a deterministic reconstruction was performed, permitting us to extract the mean values along the three branches of the AF. We found that a larger lateralization of the AF volume towards the left hemisphere predicted the performance of our participants in the imitation task. Secondly, an automatic reconstruction was carried out, allowing us to localize the specific region within the AF that exhibited the largest correlation with foreign-language imitation. Results of this reconstruction also showed a left lateralization trend: greater FA values in the anterior half of the left AF correlated with the performance in the Hindi-imitation task. From the best of our knowledge, this is the first time that foreign language imitation aptitude is tested using a more ecological imitation task and correlated with DTI-tractography, using both a manual and an automatic method.