We screened for any channels involved in the oddball task for the control subjects. A significant increase was found in five channels on the right hemisphere (CH 5, 10, 15, 21, and 22). Among these channels, the right CH 10 in the right prefrontal and CH 22 in the right parietal cortices exhibited the most significant activation and were the only channels remaining after family-wise error correction (CH 10, mean 0.074, SD 0.080, , Bonferroni-corrected, Cohen’s and CH 22, mean 0.050, SD 0.077, , Bonferroni-corrected, Cohen’s ). Therefore, the right CH 10 and CH 22 were determined as the channels of interest in the main analyses. In ADHD subjects, significant ATX effects on the oxy-Hb increase were found in three channels on the right hemisphere (CH 10, 15, and 22). We found that no channels were activated in the pre-ATX condition, but that the right post- and precentral gyri (CH 7, , uncorrected) were activated in the preplacebo condition. In addition, the left middle and superior temporal gyri were significantly activated in the postplacebo condition (CH 17, , uncorrected), while significant activation was found in the right prefrontal and parietal regions in the post-ATX condition (CH 10, 15, and 22, , uncorrected). The marginal activations in the right inferior and middle temporal gyri in the pre-/postplacebo condition might reflect compensatory or placebo activations specific to ADHD children, but further studies are necessary to examine the reproducibility and underlying functional mechanisms of these results.