Memory & Conditioning Under Anesthesia

Inclusion Criteria: * Adults, age 18-39, who are native English speakers with at least a high school education * have normal hearing and memory * be of normal body-weight * be generally healthy (free from significant chronic disease) * have none of the specific exclusion criteria * have a valid email address and valid phone number throughout the study * anticipate ability to participate in all visits required for the phase of the study in which they are enrolled Exclusion Criteria: * Pregnancy * Body mass index \> 35 (obese) or \< 18 (underweight) * Use of psychotropic medications, including anti-epileptics, anti-psychotics, anxiolytics, anti-depressants, stimulants, sleep-aids, anti-histamines, or analgesics * History of adverse reaction to OR abuse of: dexmedetomidine (Precedex), propofol (Diprivan) or the opioids class of medications (fentanyl, morphine, hydromorphone, etc) * History of clinically significant memory or hearing loss * History of obstructive sleep apnea * History of neurologic or psychiatric disease, including benign tremor * History of significant cardiac disease, including high blood pressure or arrhythmia * History of significant pulmonary disease * History of diabetes or neuropathy * History of chronic pain, or other pain processing disorder * Have an implanted medical electronic device * Have indwelling or implanted metal in their body that is not MRI-compatible * Have claustrophobia * Have a history of drug abuse