Investigation of the transcallosal ventral premotor cortex connection in humans using transcranial magnetic stimulation

Abstract

Background: The premotor cortex plays a role in the planning of movement. Previous tran scranial magnetic stimulation (TMS) studies have shown ipsilateral premotor-to-motor inhibi tion in healthy subjects at rest. Moreover, this premotor-to-motor inhibition has been found to be modulated during preparation for movement, such as precision grip and whole hand grasp. Cooperation between the bilateral ventral premotor cortices may play a functional role. We aimed to investigate the influence of the contralateral on the ipsilateral ventral premotor cortex. Methods: Fourteen right-handed healthy subjects (six women and eight men; mean age, 37 years; standard deviation, 14 years) completed the study. We used a three single-pulse TMS paradigm (preconditioning, conditioning and test pulse) to sequentially stimulate the right ventral premotor cortex, left ventral premotor cortex and left primary motor cortex. Results: We found that in healthy subjects at rest, stimulating the contralateral ventral pre motor cortex resulted in reversal of the resting premotor-to-motor inhibition. Conclusions: Our results suggest that the contralateral ventral premotor cortex exerts an inhibitory influence on the ipsilateral ventral premotor cortex, which may be a component of bi-hemispheric control of manual tasks. This is the first study to evaluate the functional con nectivity between the bilateral ventral premotor cortices.