[1] Univ Kentucky, Tobacco & Hlth Res Inst, Dept Pharmacol, Lexington, KY 40546 USA
[2] Univ Kentucky, Tobacco & Hlth Res Inst, Dept Psychol, Lexington, KY 40546 USA
[3] Vanderbilt Univ, Sch Med, Dept Physiol & Mol Biophys, Nashville, TN 37212 USA
[4] Karolinska Inst, Dept Clin Neurosci, Stockholm, Sweden
[5] Univ Texas, Hlth Sci Ctr, Dept Pharmacol, San Antonio, TX 78284 USA
[6] Fukushima Univ, Sch Med, Dept Neuropsychiat, Fukushima, Japan