Figure 1.

Schematic diagram of the experimental design. The black arrows indicate when CPP conditioning sessions were administered. The white arrows indicate when CPP testing took place. The boxes indicate when the runner/sedentary conditions and valganciclovir/control chow were administered relative to conditioning and CPP testing. The experiment contained 82 animals (20 Sedentary mice receiving Valganciclovir, 18 Runner mice receiving Valganciclovir, 26 Sedentary mice receiving Control Chow, and 18 Runner mice receiving Control Chow). Animals experienced 1 day of habituation to reduce novelty effects and, subsequently, 1 day of CPP pretesting to establish baseline texture preferences over the 2 days immediately preceding the conditioning. Animals experienced 28 days of uninterrupted running or sedentary treatment and a total of 4 days of CPP conditioning. Animals were returned to cages with or without running wheels immediately after conditioning and testing to avoid the potential confound of animals experiencing withdrawal from running during the testing procedures.