Table 1.
Behavioural performance of HI and LI rats in the delayed reward task during different stages of heroin self-administration
| Session | Delay (s) | |||||
|---|---|---|---|---|---|---|
| 0 | 5 | 10 | 20 | 40 | ||
| Baseline | HI | 96.04±1.12 | 63.53±4.63 | 22.11±3.10 | 10.01±2.68 | 4.73±1.05 |
| LI | 97.89±0.88 | 94.19±1.93 | 72.81±4.12 | 41.74±5.07 | 22.49±2.52 | |
| After surgery | HI | 91.77±4.29 | 60.24±6.57 | 22.17±5.85 | 10.07±2.43 | 6.93±1.62 |
| LI | 96.67±1.30 | 89.14±3.29 | 68.45±4.92 | 37.39±5.17 | 19.10±3.94 | |
| Acquisition FR1 | HI | 89.06±4.60 | 62.16±6.17 | 25.74±6.25 | 7.41±2.64 | 4.53±1.65 |
| LI | 97.87±0.98 | 89.79±3.18 | 64.09±6.20 | 37.01±7.34 | 18.93±3.44 | |
| Acquisition FR2 | HI | 95.13±1.98 | 51.43±8.55 | 14.87±4.11 | 4.87±2.19 | 2.59±1.37 |
| LI | 98.33±1.12 | 86.59±3.60 | 53.75±8.98 | 20.51±5.35 | 9.95±3.45 | |
| Acquisition FR4 | HI | 94.00±2.99 | 60.13±7.94 | 26.73±9.16 | 12.55±6.02 | 2.91±1.58 |
| LI | 99.17±0.83 | 73.31±8.92 | 55.02±13.28 | 32.80±4.36 | 16.82±5.19 | |
| Progressive ratio | HI | 91.88±3.87 | 62.05±6.48 | 12.82±5.13 | 5.92±2.03 | 2.39±1.70 |
| LI | 96.46±1.52 | 83.98±5.63 | 59.27±10.34 | 31.37±6.44 | 5.72±2.63 | |
| Extinction | HI | 96.88±0.91 | 60.72±7.41 | 24.58±6.42 | 7.03±2.56 | 6.09±2.59 |
| LI | 100.00±0.00 | 92.32±2.78 | 67.49±6.79 | 27.92±5.53 | 13.97±3.42 | |
| Abstinence | HI | 93.18±1.95 | 60.91±7.71 | 17.83±6.34 | 5.14±1.64 | 3.29±1.55 |
| LI | 97.35±1.11 | 91.30±3.23 | 61.09±8.00 | 23.10±6.12 | 13.96±4.10 | |
Preference for the large reward, expressed as percentage of total choice for the large reward (±SEM), for every delay in the delayed reward task tested during different time-points of heroin self-administration and during extinction and abstinence for HI and LI rats