TMS&fMRI - A New Neuroimaging Combinational Tool to Study Brain Function

Functional magnetic resonance imaging (fMRI) has been widely used to evaluate the brain's response to an extensive variety and number of different tasks; however, because many of these paradigms are complex, they stimulate a broad neural network encompassing several brain regions. Therefore, it remains unclear which brain region is relevant to the principal cognitive/behavioral function that is being studied, and which areas are activated either due to the additional cognitive function required to complete the task, or as a consequence of brain connectivity. The recent combination of transcranial magnetic stimulation (TMS) with fMRI holds promise for clarifying this dilemma. Using a pulse of magnetic field, TMS can non-invasively stimulate a specific brain region, thereby allowing brain activity to be manipulated as an independent variable, while, based upon the Blood Oxygenation Level Dependence (the BOLD effect), fMRI can evaluate the brain's response to this localized stimulus, highlighting the functional network directly associated with the stimulated site.