Non-invasive Brain Stimulation with Multimodal Acquisitions

Non-invasive brain stimulation (NIBS) techniques, including transcranial magnetic stimulation (TMS) and low-intensity transcranial electric current stimulation (tES), offer the unique possibility of directly interfering with local and remote neural network activity in conscious human participants, with a quantifiable impact on behaviour or cognition. This makes brain stimulation in many ways complementary to brain imaging and a combination of both techniques particularly desirable. Brain stimulation can be combined with brain imaging either in two separate experimental sessions or simultaneously by using TMS or tES inside the MR scanner. The simultaneous combination of NIBS with fMRI enables the modulation of brain circuits, while concurrently assessing direct and remote neural network effects across the entire brain and linking these (network) activity changes to the induced behavioural manipulation. This chapter introduces the fundamental workings of NIBS and its application in fundamental brain research, rehabilitation and psychiatry and describes the different possibilities of combining brain stimulation and brain imaging with a focus on the methodological and technical challenges. Concrete research studies are used to exemplify how valuable such combined brain stimulation and brain imaging studies can be for fundamental and clinical brain research.