Brain Stimul
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The cerebellar influence on the motor cortex output is exerted mostly though the cerebellothalamocortical pathway (CTC). One way to explore this pathway is by the means of transcranial magnetic stimulation (TMS). A single-pulse conditioning magnetic stimulation delivered over the lateral cerebellum was shown to diminish the excitability of the contralateral motor cortex 5 milliseconds later (cerebellocortical inhibition [CBI]), most likely through transynaptic activation of cerebellar Purkinje cells, which in turn inhibit the tonic activity of the CTC. Repetitive TMS (rTMS) delivered over the lateral cerebellum was shown to induce a long-lasting change of the cortical excitability, as well, but the mechanism and time course of this effect are still debated. ⋯ Our findings suggest that repetitive cerebellar stimulation operate at a cerebellar level, rather then at a cortical level.