Thirty-eight adult male Wistar rats (bred from Charles River Laboratory stock) approximately 70 days old were communally housed (2-3 per cage) in a temperature (21 ± 2oC) controlled vivarium on a 12-hr reverse light cycle (lights off at 6 am) with ad libitum food and water available. Prior to training, animals were handled daily for a one-week period. This work adheres to the National Research Council Guide for the Care and Use of Laboratory Animals (National Research Council, 1996) and was approved by the Washington State University Institutional Animal Care and Use Committee.
