Neural correlates for the suppression of habitual behavior: a functional MRI study.
OBJECTIVE Attention-deficit/hyperactivity disorder (AD/HD) is a common developmental disorder. Many reports have suggested that symptoms of AD/HD are related to frontal lobe dysfunctions, particularly disinhibition. However, measuring neurological findings with biomarkers during frontal functional tasks has sometimes been difficult in children with AD/HD. This study aimed to investigate frontal inhibitory function objectively in children with AD/HD during "rock, paper, scissors" (RPS) tasks, as a familiar game for Japanese children, using near-infrared spectroscopy (NIRS). SUBJECTS AND METHODS Eighteen children with AD/HD were compared with 27 typically developing children (TDC). Children from each group were divided into two age groups: younger, 6-10years; and older, 11-16years. Changes in oxygenated hemoglobin [oxy-Hb] were measured in the prefrontal region using NIRS during a 'to lose' RPS task, in which subjects were asked to present the RPS signal that would lose in response to one of the three signals displayed randomly on a computer screen every 2.0s. RESULTS The rate of correct performance with both TDC and AD/HD increased with age. Only in the older group, the rate of correct performance was significantly higher with TDC than with AD/HD. However, children with AD/HD in both age groups showed significantly lower [oxy-Hb] activity in the prefrontal region during the 'to lose' RPS task, particularly in the dorsolateral area. CONCLUSIONS Our results suggest that prefrontal region activation during the 'to lose' RPS task could offer a biomarker for diagnosing AD/HD, and may help in the early treatment of AD/HD.