The climax of mental integration would seem to be attention (Sherrington, 1940). We employed ANT (attention-networks test) that has been applied to fMRI brain imaging (Fan J. et al., 2005). The task was to request participants to report the direction of an arrow projected on a screen. Several activation areas have been detected (p<0.05, FWE corrected) in each of three attention-related processes, i.e. alerting caused by presenting a cue, orienting by presenting spatial cues, and conflict resolving by simultaneously presenting disturbing flanker arrows heading towards the other end. The activated areas are almost in accord with the dorsal frontoparietal network proposed by Corbetta et al. (2008), involving dorsal parietal and dorsal frontal cortices. Visual association areas were also activated possibly by the top-down signal. Overall left laterality was apparent. Moreover, in the conflict resolving, an area encompassing parts of the paracingulate, medial frontal eye field and supplementary motor area in the right hemisphere was also activated. These areas are known to be activated by interference and other tasks. In the right hemisphere, posterior middle frontal gyrus, which has been proposed to be involved in orienting attention to the left visual field, was activated. Right dorsal parietal cortex was only weakly activated.
Brain activities are "intermediate phenotypes" situated in between genes and human behavior. To assess the intermediate phenotypes, brain imaging by using fMRI is most suited. We are investigating several of attention-related and unrelated genetic variations (SNPs) to find the effect of genes on the activation pattern detected. In this way we may be able to investigate the relationship between genes and behavior, and the attention-related substrate and mechanism in human brain.