Figure 4.

Decision making during cocaine self-administration as measured by score (a positive score reflects advantageous decision making). A, The score of optimal animals did not change, regardless of whether cocaine or saline was self-administered. B, In contrast, risk-preferring animals exhibited significant decreases in score, reflecting an increase in disadvantageous choice after cocaine exposure. This stabilized from Session 5 onwards (t tests vs Session 1: Session 2: t₍₁₅₎ = 0.498, p = 0.625; Session 3: t₍₁₅₎ = 3.074, p = 0.008; Session 4: t₍₁₅₎ = 0.910, p = 0.377; Session 5: t₍₁₅₎ = 2.604, p = 0.020; Session 6: t₍₁₅₎ = 2.399, p = 0.030; Session 7: t₍₁₅₎ = 2.720, p = 0.016; Session 8: t₍₁₃₎ = 2.314, p = 0.038; Session 9: t₍₁₃₎ = 3.569, p = 0.003; Session 10: t₍₁₃₎ = 2.897, p = 0.012). C–G, Changes in individual rat score from day 1 to day 10 of self-administration in optimal and risk-preferring subgroups. Only cocaine-exposed, risk-preferring animals exhibit decreases in score. A, B, Data are mean ± SEM. C–G, Data represent individual rat scores. The asterisks reflect a significant effect of session p < 0.05.