Low frequency rTMS: Induction of neuroplastic effects

Objectives: Repetitive Transcranial Magnetic Stimulation receives increasing attention as a non-invasive method for specific stimulation of distinct cortical areas. Based on its quality to reduce cortical excitability low frequency rTMS was proposed as an innovative treatment strategy for so called hyperexcitability disorders. Methods: To elucidate the mechanism of action of low frequency rTMS we investigated the effect of 5 sessions 1 Hz rTMS to the temporal cortex in patients suffering from chronic tinnitus and in healthy subjects. For the assessment of stimulation effects electrophysiological methods (cortical evoked potentials) were combined with Voxel- Based Morphometry (VBM). Results: rTMS delivered to the superior temporal cortex induces macroscopic cortical changes within the auditory cortex which are mirrored by changes in cortical evoked potentials. Conclusions: Our study demonstrates neuroplastic changes, which occur within a time range, characteristic for the onset of behavioural effects in neuropsychiatric diseases induced by a variety of treatment methods including rTMS.