Fig. 4. Effects of laparotomy on conditioned operant responding. The number of sucrose pellets earned ( A ) was determined after sham surgery ( open bar and circles ) or laparotomy ( dark bar and circles ) (mean ± SEM). Data are also presented indicating the amount of time required for these animals to earn the pellets ( B ). BSL =baseline data that was obtained by averaging the data from the five sessions immediately before surgery. * Significantly different from baseline, P ≤ 0.05. # Significantly different from sham, P ≤ 0.05.