The Role of the Opioid System in Placebo Effects on Pain and Social Rejection

Inclusion Criteria: * Adults aged 18-55 years * No current psychiatric or major neurological diagnosis * No reported substance abuse within the last six months * Are capable of performing experimental tasks (e.g., are able to read, able to cooperate with fMRI examination) * Are fluent or native speakers of English * No current or recent history of pathological pain or reported neurological disorders. * Having abstained from alcohol and substance use for 48 hours * Passed fMRI safety screener * Experienced a recent unwanted breakup of a romantic relationship Exclusion Criteria: * Current presence of pain * Current or past history of primary psychiatric disorder * Current or past history of psychoactive substance abuse or dependence * Dementias * Movement disorders except familial tremor * CNS infection * CNS vasculitis, inflammatory disease or autoimmune disease * CNS demyelinating disease (e.g. multiple sclerosis) * Space occupying lesions (mass lesions, tumors) * Congenital CNS abnormality (e.g. cerebral palsy) * Seizure disorder * History of closed head trauma with loss of consciousness * History of cerebrovascular disease (stroke, TIAs) * Abnormal MRI (except changes accounted for by technical factors or UBOs) * Neuroendocrine disorder (e.g., Cushings disease) * Uncorrected hypothyroidism or hyperthyroidism * Current or past history of cancer; Recent history (within two years) of myocardial infarction, severe cardiovascular disease, or currently active cardiovascular disease (e.g. angina, cardiomyopathy) * Uncontrolled hypertension or hypotension * Chronic pain syndromes * Chronic fatigue syndromes * Subjects unable to tolerate the scanning procedures (e.g., claustrophobia) * Prior treatment within the last month with any of the following: antidepressants, mood stabilizers, glucocorticoids, opiates * Prior treatment with any of the following: antipsychotics, isoniazid, centrally active antihypertensive drugs (e.g. clonidine, reserpine) * Metal in body or prior history working with metal fragments (e.g., as a machinist) * For women, pregnancy * Any other contraindications for MRI examination (e.g., metallic implants such as pacemakers, surgical aneurysm clips, or known metal fragments embedded in the body) * Claustrophobia