TABLE 1.

Formation process of Internet addiction (IA) in the Availability, Controllability, Excitability (ACE) model (Kimberly S. Young).

Stage	Features	Performance
Indulgence and revelry	NAcc is unusually active, and the reward system is shifting from natural rewards to behavioral inducements.	Hard to resist the urge to use the Internet.
Indulgence and revelry	The dopaminergic system causes an imbalance in the reward system and a shift in motivation to use the Internet from pleasure seeking to alleviating negative emotions.	Severe weakening of inhibitory control and withdrawal syndrome.
Desire and seek	Increasing imbalance in the reward system and a dramatic increase in the thirst for the Internet.	Unstoppable urge to surf the Internet, which seriously affects daily life and impairs the brain function.