The Structural Connectivity Underpinning Language Aptitude, Working Memory, and IQ in the Perisylvian Language Network

Abstract

In this article, we report the results of a study on the relationship between individual differences in language learning aptitude and the structural connectivity of language pathways in the adult brain, the first of its kind. We measured four components of language aptitude (vocabulary learning; sound recognition; sound-symbol correspondence; and grammatical inferencing) using the LLAMA language aptitude test. Spatial working memory, verbal working memory and IQ were also measured as control factors. Diffusion Tensor Imaging was employed to investigate the structural connectivity of language pathways in the perisylvian language network. Regression analysis suggested significant correlations between most of these behavioural measures and the structural connectivity of certain language pathways, that is, grammatical inferencing and the BA45- and BA46-Temporal pathway, sound-symbol correspondence and the interhemispheric BA45 pathway, vocabulary learning and the BA47-Parietal pathway, IQ and the BA44- and BA-47Parietal pathways, the BA47-Temporal pathway and interhemispheric BA45 pathway, spatial working memory and the interhemispheric BA6 pathway and the BA47-Parietal pathway, and verbal working memory and the BA47-Temporal pathway. These findings provide further insights into the neural underpinnings of the variation in language aptitude of human adults and are discussed in relation to relevant findings in the literature.