Complete suppression of voluntary motor drive during the silent period after transcranial magnetic stimulation.

摘要: To evaluate changes in the motor system during silent period (SP) induced by transcranial magnetic stimulation (TMS) of cortex, we investigated thresholds as parameters excitability cortico-muscular pathway after a suprathreshold conditioning stimulus abductor digiti minimi muscle (ADM) normal humans. Since unconditioned threshold was lower voluntary tonic contraction than at rest (31.9±5.4% vs. 45.6±7.5%), it is suggested that difference between active and resting indicates magnitude drive on pathway. Therefore, compared conditioned (cRMT cAMT) SP. cRMT showed an intensity-dependent elevation more 200 ms duration approximately 17% maximum stimulator output above threshold, due to decreased stimulus. Some 30–40 stimulus, cAMT approximated cRMT, indicating complete suppression drive. This did not start directly since still significantly within first ms. Threshold longer SP (220±41 151±28 ms). Recovery started late nearly end SP, although were elevated. We conclude largely drive, while different inhibitory phenomenon less importance for generation least its part. It argued fast cortico-spinal fibers activated TMS partially from involved maintenance activation.