Brain's own opioids may power placebo effect for heartbreak and pain

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

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