[1] Univ S Carolina, Program Behav Neurosci, Dept Psychol, Columbia, SC 29208 USA
[2] Univ S Carolina, Program Behav Neurosci, Dept Physiol & Pharmacol, Columbia, SC 29208 USA
[3] Johns Hopkins Univ, Dept Neurol, Baltimore, MD 21218 USA
[4] Univ Kentucky, Dept Anat & Neurobiol, Lexington, KY USA