The purpose of this study is to determine whether a new medical technology can help reduce post-operative total knee or hip pain when combined with a Cognitive-Behavioral intervention (CBI).

This new medical technology, is called transcranial direct current stimulation (tDCS), it uses a very small amount of electricity to temporarily stimulate specific areas of the brain thought to be involved in pain reduction. The electrical current passes through the skin, scalp, hair, and skull and requires no additional medication, sedation, or needles.

This study will investigate the effects of tDCS, the Cognitive-Behavioral (CB) intervention and their combination on pain among veterans following total knee arthroplasty (TKA) or total hip arthroplasty (THA). You may benefit in the form of decreased pain and opioid requirements following your knee or hip replacement surgery. However, benefit is only likely if you are randomized to one of the 3 (out of 4) groups.

This study hopes to determine the effects of these interventions and their combined effect on post-operative pain, opioid use and functioning during the 48-hour post-operative period following a total knee or hip replacement.

This study aims to evaluate the effects of odor on pain perception. Specifically, this study will determine whether healthy subjects will indicate greater pain tolerance to a heat stimulus while smelling different odors.

The purpose of this study is to develop transcranial magnetic stimulation (TMS) as a novel, non-pharmacologic approach to decreasing pain in individuals with chronic pain. This study will test whether rTMS over the prefrontal cortex can produce a reduction in your perception of pain, your desire to use opiates, and your brain's response to opiate cues. The results of this study will be used to design and develop a large clinical trial of rTMS as an innovative, new treatment option for chronic lower back pain in individuals that may have used chronic opiates.

This study is to evaluate the effects of cognitive behavorial therapy in combination with tDCS (transcranial direct current stimulation) improving chronic pain and functionality, reducing severity of opioid use disorders, improve sleep, and reducing impairment in associated mental health areas (e.g., depression, anxiety, PTSD).