Before the illusion starts (left panel), the participant feels that their right hand, which is hidden from view, belongs to their body (yellow spotlight) and that the prosthetic hand does not belong. della Gatta et al. applied a single pulse of transcranial magnetic stimulation (lightning bolt) to the region of the left primary motor cortex that controls the right hand (red circle). This causes an electrical pulse to travel down the corresponding motor nerves in the right arm (red line) to the target muscle in the right hand, where an electrode (black circle) records a rapid burst of electrical activity called a motor-evoked potential (i.e., muscle twitch). This potential is illustrated in the inset above the hand. After the illusion (right panel), the prosthetic hand has become embodied, meaning that the participant feels like it is now part of their body (yellow spotlight and outline of an arm). The real right hand, conversely, feels less vivid to the participant. Furthermore, the size of the motor-evoked potential has significantly decreased, providing an objective measure of limb disembodiment.