Physiological Mechanisms of Modulation of Motor Cortex Excitability by 1Hz Suprathreshold rTMS

Many studies show consistently that repetitive transcranial magnetic stimulation (rTMS) with a frequency of 1Hz and an intensity of 115% of the resting motor threshold (RMT) performed for several minutes over the primary motor cortex (M1) leads to a depression of cortical excitability. Furthermore, most of the available studies concur on a facilitation of the non-stimulated contralateral M1. Little, however, is known about the physiological mechanisms underlying these effects. It is currently unclear whether the changes in the stimulated M1 are produced by increased excitability in cortical inhibitory circuits o…