Impact of one HF-rTMS session on fine motor function in right-handed healthy female subjects: a comparison of stimulation over the left versus the right dorsolateral prefrontal cortex.

BACKGROUND Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive tool to investigate neural conduction in motor processes. Most rTMS research has been conducted by targeting the primary motor cortex. Several studies have also found increased psychomotor speed after rTMS of the dorsolateral prefrontal cortex (DLPFC). However, these studies were mainly performed in psychiatric patients, only targeting the left DLPFC, and often without sham control. Moreover, psychomotor speed is mostly measured based on tasks that also require higher executive functions. METHODS Here, we examined the lateralized effect of one sham-controlled high-frequency rTMS session applied to the left or right DLPFC on fine motor function in 36 healthy right-handed females, using the Fitts' paradigm. RESULTS We found a significant improvement in psychomotor speed only after actively stimulating the right DLPFC. CONCLUSION Our results support the assumption of a right prefrontal neural network implicated in visuomotor behavior and performance processes, and that the improvement in psychomotor speed is not a secondary effect of decreased mood.