these experiments we see that the antibiotic-treated mice demonstrate a robust place preference, while the control mice did not form a significant preference (Fig. 3b; p < 0.0001, t = 5.71). In control experiments in which both sides of the apparatus were paired with saline neither group formed a preference and there was no effect of antibiotic treatment (Fig. 3c; p = 0.67, t = 0.44). These data demonstrate a significant shift in the dose-response curve for the rewarding properties of cocaine in mice with reduced intestinal bacteria.
