The investigators will use a Magstim Super Rapid stimulator, which produces a biphasic pulse, and our special customized equipment and coils for deep brain stimulation (Zangen, 2005 ). The TMS coils, which will be used in this study will be specific versions of the H-coil, depending on the region of stimulation. The H-coil versions used in this study, the H-ADD coil, have been tested in healthy volunteers and found to be safe and to induce some short-lasting (1 hour) cognitive alterations (Levkovitz et al., 2007, accepted). The theoretical considerations and design principles of the H-coils are explained in a previous study (Roth, 2002 ). In short, the H-ADD coil is designed to generate summation of the electric field in a specific brain region by locating coil elements at different locations around this region, all of which have a common current component which induce electric field in the desired direction .In addition, since a radial component has a dramatic effect on electric field magnitude and on the rate of decay of the electric field with distance, the overall length of coil elements which are nontangential to the skull should be minimized, and these elements as well as coil elements having current component in the opposite direction should be located as distant as possible from the brain region to be activated.