Effects of tDCS and tUS on Pain Perception in OA of the Knee

Inclusion Criteria: 1. Able to provide informed consent to participate in the study. 2. Subjects between 18-85 years old. 3. Diagnosis of chronic osteoarthritis with pain of either the knee as self-reported. Prior to beginning baseline procedures this must be confirmed by medical records or a letter from the subject's physician. This document may either be brought in by the subject or retrieved by study staff after a medical release form is signed by the subject. After consent, if the subject fails to provide the necessary documentation or it cannot be retrieved by study staff the subject will be considered a screen fail. 4. Existing knee pain in the past 6 months of at least 3 on a 0-10 VAS scale on average. 5. Pain resistant to common analgesics and medications for chronic pain used as initial pain management such as Tylenol, Aspirin, Ibuprofen, Soma, Parafon Forte DCS, Zanaflex, and Codeine. 6. Having the ability to feel pain as self-reported Exclusion Criteria: 1. Pregnancy or trying to become pregnant in the next 6 months. 2. History of alcohol or drug abuse within the past 6 months as self-reported. 3. Contraindications to transcranial brain stimulation or TUS, i.e. implanted brain medical devices or implanted brain metallic devices. 4. Unstable medical conditions (e.g. uncontrolled diabetes, uncompensated cardiac issues, heart failure or chronic obstructive pulmonary disease). 5. Epilepsy. 6. Use of carbamazepine within the past 6 months as self-reported. 7. Suffering from severe depression (with a score of \>30 in the Beck Depression Inventory) 8. History of unexplained fainting spells as self-reported. 9. Head injury resulting in more than a momentary loss of consciousness 10. History of neurosurgery as self-reported.