The anatomo-functional connectivity of language revisited. New insights provided by electrostimulation and tractography.

In addition to the seminal lesion studies of aphasiology, the development of functional neuroimaging has allowed a better understanding of the neural foundations of language. However, despite a substantial improvement in the knowledge of the cortical networks organization, the underlying subcortical association circuits have received less attention. Recent advances in fiber tracking using diffusion tensor imaging, combined with personal studies using intraoperative electrostimulation, which temporarily inactivates restricted regions during brain surgery, have enabled to map language pathways in humans with spatiotemporal resolution unmatched by other techniques. On the basis of these new insights, my purpose is to revisit the anatomo-functional connectivity of language. First, I discuss the role of the white bundles thought to be essential for language, with special emphasis regarding the structure-function relationships pertaining to the distinct subcomponents of language. Second, I propose an integrative view of connectivity, that considers language as the final product of the well-synchronized functioning of parallel distributed cortico-subcortical networks.