Scientists zap healthy scalps to find the least painful brain stimulation settings

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Adults ages 18 years and older. 2. Capable to give informed written consent, ability to understand study procedures, and ability to comply with procedures for the entire length of the study. 3. Individuals with and without prior exposure to TMS are eligible (including individuals who have received TMS to treat depression). Exclusion Criteria: 1. Medical contraindication for neuromodulation (e.g., ferrous metal in head, seizure disorder, brain tumor, stroke, aneurysm, multiple sclerosis, etc.). 2. Contraindication for scalp sensitivity and tolerability testing (e.g., sunburn, active headache, history of frequent and severe headaches). 3. Contraindication for knee sensitivity and tolerability testing (e.g., current knee injury or ongoing complications from prior history of knee surgery), unless knee testing skipped at the investigators' discretion. 4. Contraindication for participants with metal in both knees, unless knee testing skipped at the investigators' discretion. 5. Active substance use disorder in last 3 months or any current substance use that puts the participant at increased risk or significant impairment 6. Dementia or other cognitive disorder making unable to engage in study. 7. Any history or diagnosis of Schizophrenia, Schizoaffective Disorder, Delusional Disorder or other psychotic illness. 8. Taking any medication that significantly lowers the seizure threshold (e.g., tricyclic antidepressants, clozapine, etc.). 9. Any medication or substance use that significantly impacts sensory and tolerability measures based on the investigators' review of dosing and effect (e.g., topical anesthetics, botulinum toxin injections, ketamine, NSAIDS, opioids, anticonvulsants used in pain management, etc.). 10. Current, planned, or suspected pregnancy. 11. Unstable medical conditions or any current medical condition that could preclude being able to safely participate in TMS treatment (e.g., unstable metabolic abnormality, unstable angina, etc.). 12. Significant ongoing litigation or claims that impact research activities, as determined by the research study team. (Research may especially be impacted when mental health or pain is being evaluated for litigation or claims, such as civil and criminal cases, disability claims and worker's compensation). The investigators will exclude the following individuals: * Adults unable to consent * Individuals who are not yet adults (infants, children, teenagers) * Pregnant women * Prisoners