The risky decision-making deficits is the core feature of the methamphetamine (MA) dependence. Our previous research found that MA dependents have network abnormalities such as decision-making and rewarding. The feedback-related negativity amplitude in the prefrontal central area of MA users becomes smaller and blunted after a loss. Moreover, the neural modulation over the prefrontal cortex showed potent to decrease the craving, and the functional connectivity between frontal cortex and subparietal lobules increases. It suggests that there is a correlation between the decision-making network and the reward network of MA addicts, but there is no real-time observation of the dynamic changes of these brain network activities, so it is difficult to correct the interaction mechanism.

In order to clarify the dynamic brain network mechanism of the risky decision-making deficits among MA dependents, firstly, based on magneto-encephalography source information reconstruction methods, firstly, based on magneto-encephalography source information reconstruction methods, the investigators will observe the sequence and interaction among decision-making network, rewarding network, and emotion network. Besides, the investigators clarify that the trans-cranial current stimulation over prefrontal cortex could improve the speed and intensity of the key network interactions among MA dependents, which could improve risky decision-making and craving. The successful implementation of the study is expected to provide important clues for elucidating the pathological mechanism of risky decision-making deficits in MA dependents and providing a theoretical basis for the treatment of addiction.

Inclusion Criteria:

Clinical diagnosis of severe MA defined in the Diagnostic and Statistical Manual of Mental Disorders-Fifth edition (DSM-5); Normal hearing and vision, or within normal range after correction;

Exclusion Criteria:

Clinical diagnosis of substance use disorder other than an MA or nicotine use disorder defined in the Diagnostic and Statistical Manual of Mental Disorders-Fifth edition (DSM-5) in the past 5 years; Suffering from diseases that affect cognitive function (such as cerebrovascular diseases) ; Schizophrenia, bipolar disorder, depression or other Axis I disorder of DSM-V criteria; any contraindication for fMRI scanning.