Neuromodulation

While single TMS pulses have short-lived effects on local and distributed physiology, repeated pulses in frequency-specific patterned trains can induce more durable effects on physiology and behavior, well outlasting the stimulation itself. This phenomenon, known as neuromodulation, can be used to study brain function in health and disease, and forms the basis of many clinical treatment applications. Neuromodulation is likely a result of engaging aspects of neuroplasticity. As in pharmacology, where a drug can have different effects depending on its chemical composition, rTMS stimulation parameters critically influence the resulting neuromodulatory effects on the brain. This chapter outlines several key approaches with established protocols and the most used parameters from the literature. These approaches can be used to evaluate the physiological effects of rTMS (often referred to as cortical plasticity) using either a TMS brain target alone or a TMS brain target paired with a precisely timed peripheral nerve stimulation. These same approaches can be adapted for use as behavioral or therapeutic interventions. Scenarios for lab-based investigation and clinical treatment application are discussed.