The investigators propose to evaluate the potential effect of sedation on pain perception in two ways, by asking for a participant's pain rating(subjective) and by evaluating a subject's brain activation using fMRI(objective).

We propose to contrast and compare the effect of propofol and midazolam, two GABA-related sedative drugs, and dexmedetomidine, an alpha-2 adrenergic agonist, on pain perception in human volunteers by asking a participant to rate their pain and by evaluating a subject's brain activation using fMRI.

Inclusion Criteria:

Healthy subjects

• 19 years or older able to follow study instructions

Exclusion Criteria:

• Age less than 19 or greater than 40
• Pregnant female
• Obesity (BMI > or =35)
• Non-English speaking/reading participants
• Sleep apnea
• Pulmonary problems such as moderate or severe bronchial asthma
• Cardiovascular problems such as hypertension
• History of claustrophobia
• Presence of a pacemaker, defibrillator, surgically placed metallic object (e.g., hip replacement)or other implanted device
• Presence of an unremoved bullet or shrapnel in the body
• Presence of a prosthetic that is not removable
• Presence of a hearing aid needed for hearing
• Head girth exceeding that of the head coil used in the magnet
• Extensive metalwork on or in teeth, or irremovable false teeth or bridgework
• Epilepsy
• Chronic analgesic medication
• Excessive tattoos (due to local skin heating with tattoos containing ferromagnetic particles)
• History of surgery for which details are unavailable
• Allery due to study drugs
• History of drug abuse