Figure 3.

Cocaine intake during periods of extended cocaine access. Left panel: diurnal patterns of cocaine during supplemental sessions of cocaine availability with post-injection time-outs of 30, 15, or 7.5 min. Abscissa: Quintiles of the 21-h supplemental session (Quintile 1: 1:00–5:12 p.m.; Quintile 2: 5:12–9:24 p.m.; Quintile 3: 9:24 p.m.–1:36 a.m.; Quintile 4: 1:36–5:48 a.m.; Quintile 5: 5:48–10:00 a.m.). Ordinate: number of cocaine injections (0.1 mg/kg/injection) during each quintile. Each point shows mean±SEM from four monkeys during the last 3 days of exposure to each type of supplemental session. Right panel: daily cocaine intake at baseline and during access to supplemental sessions. Abscissa: duration of the post-injection time-out period during the supplemental sessions. The bar above ‘BL' shows baseline data when there were no supplemental sessions and cocaine was available only during choice sessions. Ordinate: daily cocaine intake in mg/kg. Baseline data show results from the 3 days preceding each 7-day period of extended access. Supplemental session data show results from the last 3 days of each 7-day period of extended access. All bars show mean±SEM in four monkeys. Asterisks indicate a significant difference from baseline. ^**p<0.01. Dashed bar above each supplemental session indicates total possible cocaine intake.