Long latency fluctuation of the finger movement evoked by cerebellar TMS during visually guided manual tracking task

The purpose of this study was to investigate whether right index finger movement during visually guided manual tracking task is fluctuated by transcranial magnetic stimulation (TMS) specifically over the cerebellum and is differently fluctuated by TMS over different sites of the cerebellum. TMS was delivered over the left, middle, or right cerebellum, or Pz. Index finger movement and electromyographic response in the first dorsal interosseous were recorded. Fluctuation of the finger movement appeared approximately 100 ms after cerebellar TMS with a probability of approximately 20%. The probability was significantly higher than that after TMS over the Pz or that after sham TMS. The probability was not significantly different among different TMS sites over the cerebellum. The long latency fluctuation of the finger movement during visually guided manual tracking task is evoked by TMS specifically over the cerebellum, but is not preferentially evoked by a specific site of the cerebellum. Cerebellar TMS induced long latency motor response may be useful to investigate the neural pathways activated by TMS over the cerebellum.