Long Latency Electromyographic Response Induced by Transcranial Magnetic Stimulation over the Cerebellum Preferentially Appears During Continuous Visually Guided Manual Tracking Task

We investigated whether long latency motor response induced by transcranial magnetic stimulation over the cerebellum (C-TMS) preferentially appears during a continuous visually guided manual tracking task, and whether it originates in a concomitantly evoked neck twitch. C-TMS or magnetic stimulation over the neck (N-MS) was delivered during one of four tasks: a continuous or discrete visually guided manual tracking task, or phasic or tonic contraction of the first dorsal interosseous muscle. The probability of long latency fluctuation of index finger movement induced by C-TMS was not significantly different from that induced by N-MS, but the probability of long latency fluctuation induced by C-TMS and that induced by N-MS was significantly higher than that induced by sham TMS during all the tasks. The probability of long latency electromyographic response in the first dorsal interosseous muscle induced by C-TMS was significantly higher than that induced by N-MS and that induced by sham TMS during the continuous visually guided manual tracking task. Such significant differences were not present during the other tasks. Long latency electromyographic response induced by C-TMS preferentially appears during the continuous visually guided manual tracking task and is not explained by a concomitantly evoked neck twitch.