Depending on the frequency of stimulation and the protocol used, it is possible to increase the activity of the cerebral cortex or to reduce its level of excitation, thus modulating the activity of specific brain regions. The depth to which a single electromagnetic impulse reaches depends, among other things, on the thickness of the skull bone and the individual arrangement of furrows in the cerebral cortex and is approximately 3 cm.

Transcranial magnetic stimulation as a method of brain stimulation and potential therapeutic method was first described in 1985 [1]. Since then, it has become the subject of intensive and extensive scientific research. The first TMS protocol was officially approved as a therapeutic modality in 2008 by the U.S. Food and Drug Administration (FDA) for the treatment of depression. Today, TMS is successfully used in the treatment of psychiatric and neurological disorders as an established therapy not only in the USA, but also in Canada, Australia, Israel, and many Western European countries (in some countries the method is reimbursed). TMS is classified as a non-pharmacological biological treatment.

Through its action on nerve cells, TMS enhances the processes of neuroplasticity, i.e. the brain's ability to create new connections between nerve cells and to regenerate. Numerous scientific evidences indicate a number of neurophysiological changes which take place as a result of repetitive stimulation, ranging from changes in local electrical activity through the effects on protein synthesis or gene expression, structural changes in the cerebral cortex and white matter tracts to the change of global brain activity pattern [2]. 

All these processes and phenomena contribute to the therapeutic efficacy of TMS.