The use of neuroimaging assays is another means to obtain more refined phenotypes or endophenotypes in genetics studies. For example, in three independent investigations, variation in MAOA genotype has been found to relate to anterior cingulate cortex (ACC) activation during completion of tasks assessing impulsivity (42-44). Variation in MAOA activity has also been found to be associated with activation in more dorsal regions of ACC in functional neuroimaging paradigms that assess sensitivity to social rejection (45). The ACC is a central locus of information processing and regulation in the brain (46), and these preliminary studies suggest two possible mechanisms by which MAOA-L may confer risk for aggressive behavior.
