Subcortical Contributions to Language—What Are the Roles of the Corticostriatal and Corticocerebellar Loops?

The cerebral cortex has long been considered as the main seat of our higher cognition, including language, but the critical roles played by the subcortical regions in linguistic processing are increasingly recognized. The present article aims to give an overview of the fundamental theories about three subcortical regions: thalamus, basal ganglia, and cerebellum. Along the way, the master–slave control circuit (MSCC) hypothesis is proposed to characterize the postulated functional relationships between the corticostriatal and corticocerebellar loops, and how such a framework may allow inferences to be drawn regarding the linguistic functions of these networks. The article will close by raising a series of questions and a corresponding set of experiments currently contemplated by the author. Specifically, through contrasting the basal ganglia and cerebellar involvement in timing and sequencing linguistic and motor events, and tracking the transformation of explicit to implicit procedural memory in language learning with a longitudinal pre–post design, the research will seek to explicate the functional differentiations of these corticostriatal and corticocerebellar loops in linguistic processes. Some potential hemispheric and age-related differences within these subcortical networks will also be discussed.