1. Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
2. Vanderbilt Center for Addiction Research, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
3. Northwestern Center for Psychiatric Neuroscience, Department of Psychiatry and Behavioral Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, United States
4. Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
5. Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
6. Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States