Transcranial magnetic stimulation (TMS) is a neurophysiological tool for studying cortical functions, and in addition, has an analgesic therapeutic effect whose underlying mechanism is unknown. The proposed research will use TMS in conjunction with brain imaging and electrophysiology to examine cortical plasticity and connectivity modifications induced by repetitive TMS (rTMS) targeted to affect cortical regions associated with endogenous analgesia (EA). This will be carried out in both healthy and chronic pain (fibromyalgia) states. rTMS analgesic intervention, targeted to the motor cortex (M1) will be preceded and followed by structural and functional magnetic resonance imaging (fMRI), and Diffusion Tensor Imaging (DTI). This will be done in order to examine alterations of cortical and brainstem mechanisms involved in EA and to investigate connectivity changes between cortical and sub-cortical regions of the EA networks. The latter as well as EA efficiency and pain-related personality variables will be used to assess individual differences in neuroplasticity within the EA systems in both healthy subjects and chronic pain patients .
