White Matter Integrity of Specific Dentato-Thalamo-Cortical Pathways is Associated with Learning Gains in Precise Movement Timing.

The dentato-thalamo-cortical tract (DTCT) connects the lateral cerebellum with contralateral motor and nonmotor areas, such as the primary motor cortex (M1), the ventral premotor cortex (PMv), and the dorsolateral prefrontal cortex (DLPFC). As the acquisition of precisely timed finger movements requires the interplay between these brain regions, the structural integrity of the underlying connections might explain variance in behavior. Diffusion tensor imaging was used to 1) reconstruct the DTCT connecting the dentate nucleus with M1, PMv, and DLPFC and 2) examine to which extent their microstructural integrity (tract-related fractional anisotropy) relates to learning gains in a motor-sequence learning paradigm consisting of a synchronization and continuation part. Continuous DTCT were reconstructed from the dentate nucleus to all cortical target areas. We found that the microstructural integrity of the DTCT connecting the left dentate nucleus with the right DLPFC was associated with better early consolidation in rhythm continuation (R = -0.69, P = 0.02). The present data further advances the knowledge about a right-hemispheric timing network in the human brain with the DLPFC as an important node contributing to learning gains in precise movement timing.