Nitrous Oxide Neuroimaging

The purpose of this study is to determine the effects of acute pain on long-term memory and conditioned physiologic responses in the presence and absence of low dose nitrous oxide. Functional magnetic resonance imaging will be used to identify the neural correlates of these phenomena. The study will occur over 2 visits and involves no long-term follow up.

Inclusion Criteria: * have none of the specific exclusion criteria * have a valid email address and valid phone number throughout the study * free from any non-MRI compatible implants Exclusion Criteria: * are pregnant or attempting to conceive * body mass index (BMI) \> 35 * significant memory impairment or hearing loss * sleep apnea * chronic pain or frequently taking pain medication (including tramadol) * any severe or poorly-controlled medical problem (hypertension, diabetes) * neurologic or psychiatric disease, including anxiety, and depression * severe cardiac disease * history of methylenetetrahydrofolate reductase (MTHFR) deficiency or variant mutation, as assessed by personal report * recent ear or eye surgery * being claustrophobic * have metal implants or non-removable metal piercings * having a history of adverse reaction to anesthetics * daily alcohol or heavy alcohol use; history of alcohol abuse * current daily smoker * regular or recent marijuana use (including prescribed/medical marijuana) * illicit drug use, i.e., street drugs * regularly taking: antiepileptics, antidepressants, anti-psychotics, antihistamines, anti-anxiety medication, stimulants, or sleep-aids