Neurophysiological and neuropsychiatric aspects of transcranial magnetic stimulation

Objective: The authors review the literature in the field of transcranial magnetic stimulation (TMS). Method: For this purpose a PubMed search was performed. Additional information was gained by cross-referencing from papers found in the data base. Results: Data from controlled studies as well as supplementary information from relevant review articles pertinent to the topic were used. History and the basics of TMS and repetitive transcranial magnetic stimulation (rTMS) are presented. The ability of rTMS to non-invasively modulate higher cognitive functions such as learning and memory has developed a new and exciting field. TMS, in fact, allows one to transiently disrupt ongoing cortical processing, thus helping to enlighten the causal role of a specific brain area in a certain observable behaviour. Finally, rTMS-clinical effectiveness in mood disorders, anxiety disorders, schizophrenic spectrum disorders and Parkinson's disease as well as in pain syndrome is discussed. Conclusions: rTMS in concert with functional neuroimaging methods allows to analyze neuronal networks. Long term potentiation (LTP) and long term depression (LTD) are phenomena seen in preclinical studies after rTMS, and reflect plastic neuromodulation. Changes in brain plasticity are thought to be mechanisms that underlie the pathophysiology of psychiatric diseases like major depression.