FUNCTIONAL BRAIN NETWORK ANALYSIS S IN RELATION TO THE RISKY DECISION MAKING USING THE TRANSCRANIAL DIRECT-CURRENT STIMULATION (TDCS) ON LEFT DLPFC IN SUBSTANCE USERS: A QEEG AND GRAPH THEORY STUDY

Background and Aim : Recent neurobiological and neuropsychological studies have shown that the risky decision making behaviors and addictions share many structural and functional aspects. Moreover, brain stimulation studies using transcranial magnetic stimulation or transcranial direct current stimulation (tDCS) have obtained various results showing the causal relationship between brain regions and decision making. In this study, we used transcranial direct-current stimulation over the dorsolateral prefrontal cortex (DLPFC) of two samples of subjects (dependent substance users (according to the DSM-IV criteria) and control subjects) to investigate the effects of the left cortical stimulation on risky decision making task, the balloon analog risk task (BART).Methods : All subjects randomly received a left anodal/right cathodal stimulation (LAnC) and a sham (placebo) stimulation, each run a few minutes apart. Five minutes of Eye-Closed resting-state EEG was recorded before and after tDCS. Participants were asked to perform the BART immediately before and after each stimulation. For the EEGs, two graph parameters, the clustering coefficient and general efficiency for frequency bands of Delta, Theta, Alpha1, Alpha2, Beta1, Beta2, and Beta3 were computed. Two graph parameters, the clustering coefficient and the general efficiency for frequency these bands were computed.Results : Our results reveal that the activation of the left DLPFC results in a reduction of risky behaviors at the BART task both in control subjects and substance dependent users. Substance users decrease the risky decision making after left DLPFC anodal stimulation. Control subjects’ performance was not affected by the anodal stimulation of the left DLPFC. The result does not show any significant difference between the clustering coefficient and the general efficiency before and after tDCS.Conclusion : These results support the hypothesis that excessive risk propensity in dependent substance users might be due to a hypoactivation of the right DLPFC and an unbalance interhemispheric interaction. In conclusion, since risky decision-making seems to be, at least in part, responsible for maintenance and relapse of addiction, we argue that a neuromodulation-based approach could represent a valuable adjunct in the clinical treatment of addiction

کلیدواژه ها:

Substance users ، Graph Theory ، Complex Functional Brain Network