Effect of COMT genotype on fMRI activation during the two-back working
memory task. Regions showing a significant effect of genotype on fMRI
activation (voxelwise P < 0.005) are in red (shown
clockwise from upper left in right lateral, left lateral, right medial,
and left medial views, respectively). In dorsolateral prefrontal cortex
(e.g., Brodmann area 46; x = 58,
y = 32, z = 12; cluster
size = 47; Z = 2.55) and anterior cingulate
(e.g., Brodmann 32; x = 6, y =
60, z = 8; cluster size = 77;
Z = 2.36), Val/Val individuals showed a greater
fMRI response (and by inference, greater inefficiency, as performance
is similar) than Val/Met individuals who have greater activation than
Met/Met individuals. Post hoc analysis of genotype group contrasts
confirmed these significant relationships in dorsolateral prefrontal
and cingulate cortices across all groups.