Figure 1. Cocaine consumption during self-administration.

A) 1^st 10 min of self-administration. Limited-access rats escalated cocaine consumption on day 20 of self-administration. Prolonged-access rats exhibited escalated cocaine consumption on days 12, 14, 15, 18, 19, and 20 of self-administration. Limited + yoked rats escalated cocaine consumption in blocks between days 11 and 20 of self-administration. (* p<0.05) B) 1^st 1 hour of self-administration. Prolonged-access rats exhibited escalated cocaine consumption in time block 5. Limited + yoked rats exhibited escalated cocaine consumption in time blocks 2, 3, 4, and 5. Saline and limited access rats did not escalate cocaine intake in the first hour of cocaine self-administration. (* p<0.05) C) Cocaine consumption recorded every 10 minutes during 1^st hour of self-administration. Limited-access, prolonged-access, and limited + yoked-access rats all displayed increased cocaine consumption during the first 10 minutes of self-administration sessions on both day 6 and day 20 of self-administration. Additionally, prolonged-access and limited + yoked-access rats exhibited increased cocaine consumption within the 1^st 10 minutes of self-administration between day 6 and day 20. (* p<0.05, ψ p <0.05) D) Total daily cocaine infusions for prolonged and limited + yoked access rats. Total cocaine consumption did not differ between prolonged and limited + yoked access rats. Cocaine consumption escalated in both groups beginning on the 10^th day of extended access to cocaine. (* p<0.05)