Durable effect of very low-frequency repetitive transcranial magnetic stimulation for modulating cortico-spinal neuron excitability

摘要

Objective: We studied the durable effects of 0.2 Hz-rTMS on the cortico-spinal neuron excitabilities by recording the motor-evoked potentials (MEPs) or Hoffman-reflex (H-reflex) before and after rTMS. Methods: We employed a figure-of-eight coil for stimulating the primary motor (Ml) or premotor cortex (PMC) or a round coil held over the vertex with subthreshold stimulus intensity (90% resting motor threshold). rTMS consisted of six blocks of 30 pulses (total 180 pulses). Changes in the MEP or H-reflex amplitudes in the forearm muscles following rTMS were expressed as the test/control (tic) ratio. Results: In comparison to sham stimulation, rTMS to PMC induced a significant reduction of tic ratios of MEP amplitudes (P0.05).