Exploring Pain Modulation With TMS and Repeated Pain Conditioning in Healthy Individuals

Conditioned pain modulation (CPM) is the behavioral measure of diffuse noxious inhibitory control (DNIC), an endogenous pain inhibitory pathway in which pain inhibits pain. CPM is less efficient in individuals with chronic pain conditions, and it is a predictor for the development of chronic pain. Continuous stimulation of central/cortical mechanisms through engaging CPM might alter pain processing and improve pain inhibition. Transcranial Magnetic Stimulation (TMS) is a valuable tool for assessing how effectively the brain's central and cortical mechanisms engage in pain inhibition, particularly through pathways like CPM. While alterations in cortical excitability related to analgesic-induced pain inhibition have been documented, the effects of continuous stimulation of central pain pathways, along with the mediating influence of psychosocial factors, remain underexplored. This study aims to investigate the central pain modulatory mechanisms, as assessed by CPM, and cortical excitability, as measured by TMS, in healthy participants. Additionally, the study will evaluate the impact of sociocultural factors, including ethnic identity, optimism, resilience, perceived stress, and marginalization, on the magnitude and efficiency of CPM responses. The successful completion of this research will determine how cortical excitability changes due to training and whether these changes are mediated by psychosocial factors.

Inclusion Criteria: * pain-free * between 18-75 years old. Exclusion Criteria: Participants will not be excluded based on race or gender but will be excluded if they meet any of the following: * non-English speaking * systemic medical condition is known to affect sensation * regular use of prescription pain medication to manage pain * current or history of chronic pain condition * currently using blood thinning medication * any blood clotting disorder such as hemophilia * any contraindication to the application of ice or cold packs, such as uncontrolled hypertension, cold urticaria, cryoglobulinemia, paroxysmal cold hemoglobinuria, and circulatory compromise * involved in vigorous physical activities like heavy lifting, digging, aerobics or fast bicycling * metal in the head or eyes, pacemakers, shunts, or lines, history of craniotomy, history of focal seizures * Migraine and persistent headaches.