Figure 4.

Cocaine reinforcement is augmented by intermittent access (IntA) and further enhanced by abstinence. Effects of 3-day IntA and 3-day IntA plus 7 days of abstinence on P_max (b–d) and cocaine consumption at a minimally constraining price (Q₀; e–g) as compared with a pre-IntA. (a) Representative demand curves showing pre-IntA threshold assessment (left) and following 3 days of IntA access plus a 7-day abstinence period (right). (b) Three-day IntA produced a significant increase in the maximal price (P_max) paid for cocaine. (c) Three-day IntA followed by a 7-day withdrawal period produced a significant increase in the maximal price (P_max) paid for cocaine. (d) A 7-day withdrawal period produced a significant increase in the maximal price (P_max) paid for cocaine as compared with 3-day IntA alone. (e) Three-day IntA did not change cocaine consumption when minimally constrained by price (Q₀). (f) Three-day IntA followed by a 7-day withdrawal period reduced Q₀. (g) A 7-day withdrawal period produced a significant reduction in the Q₀ for cocaine as compared with 3-day IntA alone. Data are expressed as mean (±SEM) P_max or consumption. ). *p<0.05 vs pre-IntA; **p<0.01 vs pre-IntA.