The number of nose pokes in the active hole during the 15-minute no-drug period, at which time pokes were not reinforced. *P < 0.05, significant effect of phenotype within sex for that day. #
P < 0.05, statistically significantly different from day 1 (#1) or day 2 (#2) for bLR females. Closed squares, bHR males; closed triangles, bHR females; open squares, bLR males; open triangles, bLR females.