Participants in this single-blind study will be randomly assigned to receive either acupuncture or a placebo treatment. The placebo will consist of a simulation of acupuncture. Functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) will be used to assess activity of brain mu-opioid receptors. These receptors are involved in the body's ability to perceive pain. All participants will be scanned twice using the fMRI scanner, once before any treatment sessions and once at the conclusion of all treatment sessions. Both fMRI sessions will involve applying pressure to the thumb to elicit a response in the brain in order to assess the corresponding fMRI blood oxygen level dependent (BOLD) signal and whether this activation changes after treatment intervention. Participants will then receive nine treatments of acupuncture or placebo outside the scanner over a 4-week period. The PET portion of this study is optional, and, if you elect to participate, your first treatment session will be performed in the PET scanner. After this first session, participants will have seven additional treatment sessions outside of the scanner over a 4-week period. The last session will be performed in the PET scanner to assess changes in mu-opioid receptor activity that may have occurred over the 4 weeks. A baseline visit to determine eligibility and a close-out visit at week 8 are also part of the participation schedule. It is very important that participants live within driving distance of Ann Arbor, MI due to the significant number of visits to our Center.