Repetitive Transcranial Magnetic Stimulation in Depression. Protocols, Mechanisms, and New Developments

This chapter examines the TMS (transcranial magnetic stimulation), which is a non-invasive neuromodulation technique. It has a very direct influence on brain physiology. The basic principle of TMS is the application of short magnetic pulses over the scalp of a subject with the aim of inducing electrical currents in the neurons of the cortex. A typical TMS device consists of a stimulator that can generate a strong electrical current, and a coil in which the fluctuating electrical current generates magnetic pulses. If the magnetic pulses are delivered in the proximity of a conductive medium, e.g. the brain, a secondary current in the conductive material is induced. In the practice of TMS, a subject is seated in a chair and an operator positions the coil above the scalp of the subject, tunes the stimulation parameters of the stimulator, and applies the TMS pulses