Opioid Use Disorder (OUD) represents a significant public health issue, and there remains room for improvement in the understanding of the neurobiology underlying OUD. Among the tools used for studying OUD neurobiology are functional magnetic resonance imaging (fMRI) studies of brain neural functional connectivity. Functional connectivity measures the statistical dependence between brain regions of spontaneous fluctuations in the fMRI signal [1,2]. Resting state fMRI functional connectivity can provide information about how the brain is organized into functional networks and how those functional networks may differ in OUD. Zhang and Volkow (2019) have reviewed the addiction functional connectivity literature with focus on the Default Mode Network (DMN). That review reported differences in substance users’ functional connectivity within sub-systems of the DMN and between the DMN and other networks, such as the Salience Network (SN) and the Executive Control Network (ECN) [3]. The DMN, SN, and ECN are three networks possibly related to addiction and psychopathology in general [4,5]. It has been suggested that functional connectivity within and among the DMN, SN, and ECN is altered in substance use disorders, possibly reflecting
