Figure 4.

Shows the mean ± SEM number of active nose pokes (a; note the log10 scale) and cocaine infusions (b) made by rats receiving 0.4 mg/kg per infusion of cocaine over 5, 45, or 90 s after self-administration sessions were lengthened from 1 to 6 h/d (LgA). LgA session data were analyzed as blocks of two daily sessions, and the average for the ShA sessions is shown for comparison. In a, ^†p < 0.011 for 5 versus 90 s; *p < 0.024 for 45 versus 90 s. In b, ^†p < 0.001 for 5 versus 90 s and p < 0.004 for interaction; *p < 0.001 for 45 versus 90 s.