Fig 1.

Reinforcers earned during 10 sessions of acquisition (fixed ratio [FR] 1) and 10 sessions of responding under a FR5 schedule of reinforcement in adult, female Sprague Dawley rats responding for 0.032 mg/kg/infusion MDPV (circles; n=10), 0.32 mg/kg/infusion cocaine (squares; n=9), or 1 grain-based pellet (triangles; n=10). Left panels represent mean (± 1 S.E.M.) number of reinforcers earned (circle, square or triangle) and responses on the inactive lever (x) across 20 sessions of self-administration. Abscissa: session number (day) where sessions 1-10 were responding under FR1 and sessions 11-20 were responding under FR5. Ordinates: mean number of reinforcers earned or responses per session. Right panels represent the correlation between mean percent timeout (TO) responding and the number of reinforcers earned during the final 3 sessions on FR5:TO 5-sec. Abscissa: percent responses made on the active lever during TOs versus total active lever responses. Ordinates: mean number of reinforcers earned