Effects of Transcranial Direct Current Stimulation (tDCS) and Transcranial Ultrasound on Osteoarthritis Pain of the Knee

STUDY ELIGIBILITY CRITERIA Inclusion Criteria: 1. Providing informed consent to participate in the study 2. 18 to 64 years old 3. Having chronic osteoarthritis knee pain in either knee (existing pain for more than 6 months with an average of at least 3 on a 0-10 VAS scale) 4. Pain resistant to common analgesics and medications for chronic pain such as Tylenol, Aspirin, Ibuprofen, Soma, Parafon Forte DCS, Zanaflex, and Codeine. 5. Must have the ability to feel pain as self reported Exclusion Criteria: 1. Subject is pregnant. 2. Contraindications to tDCS: * metal in the head * implanted brain medical devices 3. Contraindications to TUS: * metal in the head * implanted brain medical devices 4. History of alcohol or drug abuse within the past 6 months as self reported 5. Use of carbamazepine within the past 6 months as self reported. 6. Suffering from severe depression (with a score of \>30 in the Beck Depression Inventory) 7. History of neurological disorders as self reported. 8. History of unexplained fainting spells as self reported, 9. History of head injury resulting in more than a momentary loss of consciousness as self reported 10. History of neurosurgery as self reported