Table 2. Linear mixed effects modelling of inter-regional correlation coefficients.
| Group A |
Group B |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Intercept |
Drug effects |
Intercept |
Drug effects |
|||||||
| Regional correlation |
μ (SE) |
P value (corrected) |
Methylphenidate β (SE) |
Sulpiride β (SE) |
P value (corrected) |
μ (SE) |
P value (corrected) |
Diazepam β (SE) |
Scopolamine β (SE) |
P value (corrected) |
| CD/VPT | 0.28 (0.07) | 0.0001 (0.015) | 0.01 (0.07) | 0.22 (0.07) | 0.0017 (0.025) | 0.28 (0.07) | 0.0001 (0.015) | 0.03 (0.06) | 0.13 (0.07) | 0.1015 |
| CD/VMB | 0.3 (0.06) | 0.0001 (0.015) | −0.08 (0.06) | 0.12 (0.06) | 0.0038 (0.057) | 0.3 (0.07) | 0.0001 (0.015) | −0.02 (0.06) | 0.04 (0.06) | 0.6532 |
| CD/LPFC | 0.14 (0.07) | 0.0001 (0.015) | −0.02 (0.07) | 0.09 (0.08) | 0.3253 | 0.24 (0.08) | 0.0001 (0.015) | 0.06 (0.09) | 0.03 (0.09) | 0.7825 |
| CD/RPFC | 0.38 (0.08) | 0.0001 (0.015) | 0.06 (0.1) | 0.05 (0.1) | 0.7702 | 0.43 (0.09) | 0.0001 (0.015) | −0.14 (0.09) | 0.08 (0.09) | 0.0298 (0.447) |
| VPT/VMB | 0.78 (0.08) | 0.0001 (0.015) | 0.06 (0.09) | 0.13 (0.09) | 0.3207 | 0.93 (0.12) | 0.0001 (0.015) | 0.03 (0.08) | 0.21 (0.08) | 0.0189 (0.283) |
| VPT/LPFC | 0.25 (0.06) | 0.0001 (0.015) | 0.04 (0.08) | 0.02 (0.08) | 0.8471 | 0.35 (0.07) | 0.0001 (0.015) | −0.02 (0.07) | −0.05 (0.07) | 0.7713 |
| VPT/RPFC | 0.27 (0.07) | 0.0001 (0.015) | 0.09 (0.08) | 0.07 (0.08) | 0.5117 | 0.35 (0.06) | 0.0001 (0.015) | 0.01 (0.06) | 0.11 (0.6) | 0.1037 |
| VMB/LPFC | 0.21 (0.06) | 0.0001 (0.015) | −0.001 (0.06) | −0.01 (0.06) | 0.9686 | 0.32 (0.07) | 0.0001 (0.015) | 0.03 (0.07) | −0.05 (0.07) | 0.5053 |
| VMB/RPFC | 0.23 (0.06) | 0.0001 (0.015) | 0.04 (0.08) | 0.03 (0.08) | 0.8337 | 0.28 (0.06) | 0.0001 (0.015) | 0.09 (0.05) | 0.13 (0.05) | 0.0601 |
| LPFC/RPFC | 0.36 (0.06) | 0.0001 (0.015) | 0.11 (0.06) | 0.08 (0.07) | 0.1733 | 0.49 (0.09) | 0.0001 (0.015) | 0.17 (0.1) | 0.07 (0.1) | 0.2015 |
A model treating drug and load as fixed effects and subject as a random effect (Eqn 2) was fitted to the individually estimated inter-regional correlation coefficients in each treatment group. The intercept (μ) indicates the mean value of the correlation coefficient under all drug (and load) conditions; the main effect of drug indicates the probability of the observed between drug difference for each correlation in each group; the coefficients (β) for each drug indicate their effect on each correlation compared to placebo. P values <0.05 are also reported (in parentheses after correction for multiple comparisons by a Bonferroni procedure). CD = caudate; LPFC = left dorsolateral prefrontal cortex; RPFC = right dorsolateral prefrontal cortex; VMB = ventral midbrain; VPT = ventro-posterior thalamus; SE = standard error.