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. Author manuscript; available in PMC: 2012 Mar 1.
Published in final edited form as: Behav Brain Res. 2010 Nov 9;217(2):354–362. doi: 10.1016/j.bbr.2010.11.005

Figure 1.

Figure 1

(A) Mean distance (km) run each day by adult male Fisher 344 rats allowed voluntary access to running wheels. Rats included in the first experiment (Exp 1) were used for CPP behavioral testing and had voluntary access to running wheels every other night. Rats in experiment 2 (Exp 2) and experiment 3 (Exp 3) were used for immunohistochemistry and in situ hybridization, respectively, and had nightly voluntary access to running wheels. (B) Mean hourly distance run (m) during the first, second, and sixth week of voluntary wheel access. Values represent group means ± standard error of measurement.