Transcranial magnetic stimulators
Transcranial magnetic stimulators are used for clinical diagnostic and therapeutic applications as well as in support of research. Consequently, a number of stimulator types and design variations have been developed to serve these purposes each having unique design requirements. Key design elements and performance trade-offs are discussed for conventional monophasic and biphasic pulse generators as well as new circuit topologies that allow controllability of the pulse shape. A brief review of rTMS pulse sequences and terminology provides a basis for the pulse timing requirements used in the various designs. Alternative approaches to delivery of subthreshold electromagnetic fields are also summarized. Methods for quantification of the induced electric field and the resultant neural responses are presented and can be utilized in device development, calibration, and output comparisons. Finally, an overview is given of unique requirements for TMS systems used in clinical and research environments, including safety and regulatory considerations.
