Table 3. Linear mixed effects modelling of inter-regional path coefficients.
| Group A |
Group B |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Intercept |
Drug effects |
Intercept |
Drug effects |
|||||||
| Path coefficients |
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) |
| VMB → CD | 0.16 (0.06) | 0.0001 (0.015) | −0.05 (0.06) | 0.15 (0.06) | 0.0021 (0.031) | 0.21 (0.06) | 0.0001 (0.015) | −0.002 (0.06) | −0.07 (0.06) | 0.4698 |
| RPFC → CD | 0.31 (0.07) | 0.0001 (0.015) | 0.03 (0.08) | −0.02 (0.08) | 0.81 | 0.32 (0.08) | 0.0001 (0.015) | −0.15 (0.08) | 0.05 (0.08) | 0.0364 (0.54) |
| CD → VPT | 0.09 (0.05) | 0.0005 (0.075) | 0.02 (0.05) | 0.05 (0.05) | 0.67 | 0.04 (0.04) | 0.0022 (0.033) | 0.07 (0.04) | 0.07 (0.04) | 0.2213 |
| VMB → VPT | 0.34 (0.03) | 0.0001 (0.015) | 0.009 (0.04) | 0.003 (0.04) | 0.97 | 0.35 (0.04) | 0.0001 (0.015) | −0.03 (0.04) | 0.05 (0.04) | 0.1236 |
| CD → VMB | 0.04 (0.05) | 0.9407 | −0.054 (0.06) | −0.16 (0.06) | 0.0234 (0.351) | −0.02 (0.05) | 0.024 (0.36) | −0.01 (0.05) | −0.02 (0.05) | 0.9225 |
| VPT → VMB | 0.38 (0.05) | 0.0001 (0.015) | 0.04 (0.06) | 0.15 (0.06) | 0.0383 (0.574) | 0.45 (0.07) | 0.0001 (0.015) | 0.04 (0.05) | 0.18 (0.05) | 0.0046 (0.07) |
| RPFC → VMB | 0.07 (0.04) | 0.0301 | −0.04 (0.05) | −0.02 (0.04) | 0.6759 | 0.09 (0.05) | 0.1204 | 0.04 (0.08) | −0.12 (0.08) | 0.1016 |
| VPT → LPFC | 0.17 (0.05) | 0.0001 (0.015) | −0.009 (0.06) | −0.005 (0.06) | 0.9892 | 0.25 (0.05) | 0.0001 (0.015) | −0.06 (0.05) | −0.09 (0.05) | 0.1954 |
| RPFC → LPFC | 0.16 (0.03) | 0.0001 (0.015) | 0.07 (0.03) | 0.05 (0.03) | 0.0668 | 0.22 (0.04) | 0.0001 (0.015) | 0.09 (0.05) | 0.02 (0.05) | 0.1605 |
| VPT → RPFC | 0.18 (0.07) | 0.0001 (0.015) | 0.03 (0.08) | 0.09 (0.08) | 0.5444 | 0.28 (0.11) | 0.0034 (0.051) | 0.03 (0.14) | −0.13 (0.14) | 0.4557 |
| VMB → RPFC | −0.01 (0.09) | 0.7102 | 0.03 (0.11) | −0.005 (0.11) | 0.9294 | −0.05 (0.013) | 0.2795 | −0.07 (0.16) | 0.23 (0.16) | 0.1629 |
| LPFC → RPFC | 0.20 (0.04) | 0.0001 (0.015) | 0.04 (0.04) | 0.03 (0.04) | 0.6433 | 0.23 (0.05) | 0.0001 (0.015) | 0.08 (0.05) | 0.03 (0.05) | 0.2668 |
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.