Summary of Main Findings. NAcc gain anticipation response was not significantly different from healthy controls in either non-opioid fibromyalgia (FM) and opioid fibromyalgia groups (gain versus no-gain anticipation, GVNant contrast) (top row). NAcc no-loss outcome response (non-punishment) was not significantly different from healthy controls in either non-opioid fibromyalgia and opioid fibromyalgia groups (no-loss versus loss outcome, NVLout contrast; second row). MPFC gain anticipation response was significantly decreased (blue arrow) in the non-opioid fibromyalgia group compared to healthy controls, but this decrease was not significant in the opioid fibromyalgia group (GVNant contrast; third row). MPFC no-loss outcome response was significantly increased (red arrow) in the non-opioid fibromyalgia group compared to healthy controls, and non-significantly decreased in the opioid fibromyalgia group (NVLout contrast; fourth row). (Light blue arrows within green circles indicate non-significant direction of response relative to controls; these are shown to inform future replication studies with larger sample sizes.) Fibromyalgia, FM; nucleus accumbens, NAcc; medial prefrontal cortex, MPFC.