Table 3.
Brain activation differences between twins scoring high and low on obsessive–compulsive symptoms from the discordant group
| Test | Cluster labela | Anatomical location | BA |
MNI coordinates (19 pairs) |
Z-score | P-value | No. of voxels |
MNI coordinates (8 pairs)b |
Z-score | No. of voxels | Euclidean distance (mm) | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| x | y | z | x | y | z | ||||||||||
| ‘Planning versus baseline’ | |||||||||||||||
| High < low | A | Left premotor cortex | 6 | −27 | 3 | 54 | 3.41 | <0.001 | 15 | −30 | 0 | 48 | 3.84 | 9 | 7.3 |
| B | Right premotor cortex | 6 | 12 | 6 | 69 | 3.33 | <0.001 | 9 | 12 | 9 | 60 | 2.98 | 1 | 9.5 | |
| C | Right medial frontal cortex | 8 | 15 | 27 | 48 | 3.20 | 0.001 | 8 | – | – | – | – | – | – | |
| D | Right dorsolateral prefrontal cortex | 9 | 39 | 18 | 27 | 2.85 | 0.002 | 5 | 33 | 21 | 21 | 2.82 | 1 | 9 | |
| E | Left inferior parietal cortex | 40 | −39 | −54 | 51 | 4.33 | <0.001 | 46 | −39 | −54 | 51 | 2.70 | 4 | 0 | |
| 40 | −57 | −36 | 45 | 3.18 | 0.001 | 9 | −57 | −42 | 45 | 2.66 | 1 | 6 | |||
| F | Left superior parietal cortex | 7 | −12 | −54 | 54 | 3.40 | <0.001 | 14 | – | – | – | – | – | – | |
| 7 | −18 | −69 | 42 | 2.87 | 0.002 | 6 | 0 | −69 | 51 | 2.86 | 5 | 20.1 | |||
| G | Right superior parietal cortex | 7 | 30 | −72 | 48 | 2.93 | 0.002 | 5 | – | – | – | – | – | – | |
| H | Right superior parietal cortex | 19 | 30 | −78 | 30 | 3.36 | <0.001 | 9 | 39 | −84 | 33 | 3.40 | 1 | 11.2 | |
| High > low | I | Right middle temporal cortex | 39 | 54 | −69 | 12 | 3.44 | <0.001 | 12 | 57 | −60 | 21 | 3.02 | 4 | 13.1 |
| ‘Task load’ | |||||||||||||||
| High < low | J | Left dorsolateral prefrontal cortex | 9 | −9 | 30 | 36 | 3.09 | 0.001 | 9 | −21 | 15 | 48 | 2.61 | 1 | 22.6 |
| K | Right lingual cortex | 30 | 21 | −42 | 0 | 3.21 | 0.001 | 8 | – | – | – | – | – | – | |
| High > low | L | Right cingulate cortex | 24 | 12 | 0 | 48 | 3.46 | <0.001 | 10 | 12 | 0 | 48 | 2.76 | 1 | 0 |
| M | Left cingulate cortex | 24 | −9 | 0 | 42 | 3.01 | 0.001 | 9 | −3 | 3 | 42 | 2.99 | 3 | 6.7 | |
a Clusters with regional brain activation differences between discordant-high and discordant-low twins for the ‘planning versus baseline’ and ‘task load’ contrasts.
Test = test for significant decreases (high < low) or increases (high > low) in twins with high relative to low obsessive–compulsive symptoms scores; cluster label = alphabetical cluster label as displayed in anatomical overlays of Fig. 4A (‘planning versus baseline’ contrast) and B (‘task load’ contrast); BA = Brodmann area; MNI coordinates (19 pairs) (mm) = location of voxel with largest effect size for the 19-pair comparison; Z-score = z-value of voxel with largest effect size; P-value = cluster P-value; no. of voxels = number of voxels in cluster.
b Montreal Neurological Institute coordinates (mm) of voxel with largest effect size for the post hoc within-pair comparison in the 8 pairs still extremely discordant at the time of scanning; Z-score = z-value of voxel with largest effect size for the post hoc 8 pair comparison; no. of voxels = number of voxels in cluster for the post hoc 8 pair comparison; Euclidean distance (mm) = distance between the coordinates derived from the original 19 pair comparison and the coordinates derived from the additional 8 pair comparison.