An Exploration of the Neuroplasticity of Endogenous Analgesia in Health and Chronic Pain

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 .

Inclusion criteria

• a prior FMS diagnosis by a rheumatologist or pain specialist based on American College of Rheumatology (ACR) preliminary diagnostic criteria for fibromyalgia
• healthy subjects - no pain/psychiatry/neurological diseases

Exclusion criteria

• other chronic pain, psychiatric or neurological diseases. All will be asked to withdraw from any pain-relieving medications for 24h before the testing.