Table 2. Comparisons of mean (sd) amplitudes and latencies of crude and standardized ERN waves between patients and controls.
| region of the brain | heroin- dependent patients (n=17) | controls (n=15) | t-test | p | |
| Amplitude (µV) | |||||
| Crude ERN wave | Fz | -2.4 (1.5) | -3.9 (1.5) | 2.73 | 0.011 |
| FCz | -3.4 (2.6) | -4.6 (2.4) | 1.38 | 0.178 | |
| Cz | -2.3 (2.7) | -2.0 (2.9) | 0.23 | 0.816 | |
| Standardized ERN wave | Fz | -2.3 (2.1) | -3.4 (2.4) | 1.42 | 0.167 |
| FCz | -3.7 (3.0) | -6.1 (1.9) | 2.62 | 0.014 | |
| Cz | -3.8 (3.2) | -5.7 (2.2) | 1.95 | 0.061 | |
| Latency (ms) | |||||
| Crude ERN wave | Fz | 31.4 (15.2) | 64.0 (26.0) | 4.39 | <0.001 |
| FCz | 37.5 (21.7) | 65.2 (18.8) | 3.84 | 0.001 | |
| Cz | 43.9 (29.4) | 64.5 (28.7) | 2.00 | 0.054 | |
| Standardized ERN wave | Fz | 49.7 (31.1) | 64.7 (28.8) | 1.42 | 0.166 |
| FCz | 47.3 (27.6) | 71.1 (20.9) | 2.81 | 0.009 | |
| Cza | 44.6 (30.4) | 73.3 (15.7) | 3.41 | 0.002 |
a This value was not normally distributed. Median (IQR) for patient and control groups were 40.0ms (23.0-65.0) and 72.0ms (59.0-88.0), respectively; Z-value for Mann-Whitney test is 2.91, (p=0.004).