Network-Level Effects of Nitrous Oxide in the Human Brain

The objective of this study is to identify the network transformations that account for the
analgesic effects of nitrous oxide. Our hypothesis is that analgesic doses of nitrous oxide
increase network efficiency and disrupt normal pain processingOur approach is to administer
subanesthetic nitrous oxide during the acquisition of fMRI (functional magnetic resonance
imaging) and EEG (electroencephalogram).

Inclusion Criteria:

1. Body mass index <30

2. Must be right-handed

3. Must be capable of giving written informed consent

Exclusion Criteria:

1. History of obstructive sleep apnea;

2. History of a difficult airway with a previous anesthetic

3. Gastroesophageal reflux;

4. Hypertension or other cardiovascular abnormalities;

5. Pulmonary hypertension;

6. History of recreational drug use;

7. History of chronic alcohol abuse

8. Having any chronic medical illness involving pain;

9. History of major depression;

10. History of psychosis or bipolar disorder;

11. History of methylenetetrahydrofolate reductase deficiency;

12. History of a known hypersensitivity to ketamine, midazolam, Zofran, labetalol or
glycopyrrolate

13. History of seizures or other neurologic disorders;

14. Pregnant or nursing mothers;

15. Tattoos on the head or neck region - all other tattoos are subject to determination by
investigators;

16. Contraindications to neuroimaging methods;

17. Any impairment, activity or situation that in the judgment of the Study Coordinator or
Principal Investigators would prevent satisfactory completion of the study protocol.