Muscle vibration and prefrontal repetitive transcranial magnetic stimulation

We previously demonstrated that prefrontal subthreshold repetitive transcra nial magnetic stimulation (rTMS) may reduce motor cortex excitability. We h ave now examined whether muscle vibration (MV) can compensate for this depr ession. We enrolled 25 healthy Volunteers (aged 22 to 37 years) who receive d 5 Hr, 10% subthreshold prefrontal rTMS for 12 s. The extensor carpi radia lis muscle was vibrated with an electromagnetic mechanical stimulator with a stimulation frequency of 120 Hz and 0.5 mm amplitude. Motor evoked potent ials (MEPs) from the flexor carpi radialis muscle (FCR) following single-pu lse transcranial magnetic stimulation (TMS) were recorded at baseline, and after 4, 8, and 12 s. During prefrontal rTMS, MEPs of the FCR exhibited a s erial depression (P = 0.001). This effect did not occur during MV. We concl ude that rTMS of the prefrontal cortex may inhibit the corticospinal system . This depression may be compensated by MV, suggesting that vibration chang es motor cortex excitability. The underlying mechanism might be an input fr om la sensory afferents to the motor and prefrontal cortex. (C) 2001 John W iley & Sons, Inc.