Figure 1.

1-CSRTT assessed prior to drug self-administration. Premature responses (top row), pellets earned (middle row), and omissions (bottom row) were recorded twice (i.e., ITI Triad Sets #1 and #2) and averaged for each drug-naive rat at ITI values of 5, 7.5, and 10 seconds. A subject’s baseline (BL) was considered to be the average of premature responses over a 5-day period after reaching stability criteria and immediately before starting ITI Triad Set #1. Rats were subdivided by sex (left column) and impulsivity (right column). Abscissa: ITI value (seconds). Ordinate: Specific variables measured during the 1-CSRTT. &P < 0.01 between female and male points. *P < 0.05 between high impulsive and low impulsive points. #P < 0.05 between mid impulsive and low impulsive points. @P < 0.05 between high impulsive and mid impulsive points.