Neuroimaging of repetitive transcranial magnetic stimulation effects on the brain

Brain imaging can tell us a lot about how transcranial magnetic stimulation (TMS) affects the brain, and it can also help us guide and deliver TMS in more precise ways. For example, one can use structural or functional brain imaging to precisely position the TMS coil over the proper scalp position to interact with the brain. This chapter focuses on studies that have used brain imaging to understand exactly how TMS is influencing and affecting the brain. Researchers have now used the full quiver of imaging methods to address this issue. While there is still much more work to be done, studies to date reveal that TMS acts locally to change brain activity under the coil, with secondary, transynaptic effects. Different frequencies of stimulation divergently affect the brain, with some effects lasting beyond the acute stimulation. The intensity of stimulation matters, with effects following the known physics of TMS. Using brain imaging to better understand the translational neurobiological effects of TMS offers the promise of eventually using TMS in much more sophisticated ways to change brain function and treat illnesses. In this chapter, we overview this rapidly advancing field by posing a series of relatively simple questions, and responding to them informed by TMS and brain imaging studies.