Objective To explore the mechanisms underlying supraliminal and subliminal N-back task in the children with symptoms of attention-deficit/hyperactivity disorder (ADHD).Methods Thirty-five ADHD children and thirty-three matched normal controls were enrolled.Working memory was measured with the different reaction time of N-back task.Results The error number of the subliminal 2-back task in ADHD group ((4.49± 1.20) times) was worse than that of the healthy controls ((3.79±-1.14) times), and the difference was significant(t=-2.459, P=0.017).In ADHD group,the error number of 1-back task and reaction time of 2-back task in subliminal task ((4.77±1.09) times, (1 447.49±271.35) ms) were worse than those of supraliminal task ((3.09± 1.63) times, (1 315.48±229.63) ms), and the difference was significant between the two tasks (t=4.755, P=0.000;t=-2.281, P=0.029).But there were no significant findings in healthy controls(P＞0.05).Conclusion The present study suggests that the working memory is impaired in ADHD children.

Internet gaming disorder (IGD) refers to individuals who are extremely dependent on online games and can’t control the game time reasonably.Generally, individuals with IGD also display withdrawal symptoms when they do not play games.Combined with previous studies, this paper discussed the cognitive dysfunction and neural mechanisms of IGD individuals, including executive function, reward system and emotional regulation dysfunction.First of all, executive function is a high-level cognitive processing ability that involves cognitive and behavioral processes.Cognitive control is often associated with the individual's goal-directed behavior and the ability to flexibly apply the high-level cognitive function. Repeated and excessive game behaviors of IGD individuals may be associated with their abnormal cognitive control and decision-making functions. And the attention process as another important component of executive function. The persistent addictive behavior in individuals with IGD were associated with a bias toward attention to game-related cues.Also, IGD individuals show differences in executive function abnormalities such as decision-making and dominance response inhibition, suggesting that there is a separation between "cold" and "hot" executive function abnormalities, and this feature may also be associated with other cognitive dysfunctions. Secondly, reward incentives play an important role in individual motivational learning and goal-oriented behavior. The increased sensitivity of IGD individuals to reward stimuli in various types of reward and punishment stimuli suggests that their reward system is abnormal.Finally, emotional regulation is an important cognitive function that is closely related to executive function. The anxiety and depression manifested by IGD individuals are often associated with their inability to apply emotional regulation strategies flexibly. It is difficult for individuals with IGD applied emotional regulation strategies flexibly, and inappropriate emotional regulation strategies and emotional responses suggest abnormal mood regulation. To sum up, cognitive dysfunction was not only the basis of IGD addiction symptoms, but also one of the important factors of its symptom maintenance. In addition, the further research prospects included expanded sampling population, deepening neural mechanism research and physical intervention are proposed for the lack of previous research in the last part of the article.