1 U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD, 21224, USA.
2 U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD, 21224, USA. ahoffman@intra.nida.nih.gov.