Dysregulated interactions within and between 3 core brain networks (ie, the ECN, DMN, and SN) may underlie neuropsychiatric and addictive disorders.15,22,39 A composite network association index (the RAI) integrating the SN-ECN and SN-DMN cross-network correlations was developed to assess our network interaction hypothesis. The RAI in smokers was significantly lower in the abstinence compared with the smoking state. Post hoc analyses revealed a significantly weaker (negative) SN-DMN correlation during abstinence, suggesting that weaker inhibition between the DMN and SN was the driving force for the lower RAI. Also, change in the RAI during the abstinence (compared with smoking) state was negatively correlated with changes in smoking urges, suggesting that weaker network connectivity contributes to urges to smoke. Consistently, lower RAI values in the abstinence (compared with smoking) state also predicted less BOLD suppression in task-negative (DMN) regions during WM task performance.
