We hypothesized that OUD subjects would have lower within-network DMN and lower within-network SN functional connectivity relative to HC, based on previous findings in OUD individuals who were actively using illicit opioids and/or taking methadone or buprenorphine [19,20]. We hypothesized that OUD subjects would score higher in NU, similar to previous findings in opioid users and other substance users [18,21]. We also hypothesized that NU scores would negatively correlate with SN functional connectivity of both groups based on a previous study using tobacco users and the proposed associations of the SN with salience detection and evaluation [22,23]. We also performed exploratory analyses of associations between NU scores and the within-network functional connectivity of the DMN, LECN, and RECN. We also planned exploratory analyses to compare between groups the within-network functional connectivity of the LECN and RECN. All of these hypotheses were registered with the Open Science Framework (OSF) prior to any data analysis in this study [24]. The present study also compared post-hoc the functional connectivity of OUD subjects with different levels of OUD severity. To investigate the effects of
