Probing premotor-to-motor interactions in the left hemisphere during movement selection with highly focal TMS and DTI

Introduction: Bifocal transcranial magnetic stimulation (TMS) has been successfully used to examine interhemispheric interactions between motor cortical areas in the human brain. So far, the large size of the transducing coils has precluded bifocal TMS of adjacent motor areas in the same hemisphere. We recently developed highly focal minicoils which enable bifocal TMS of two adjacent cortical areas. Using these minicoils, we studied effective connectivity between left dorsal premotor cortex (PMd) and left primary motor hand area (M1) during movement selection. Methods: Thirteen healthy volunteers had to press a…