Rationale Synthetic opioids like fentanyl are contributing to unprecedented overdose rates, yet the neural circuitry underlying fentanyl-associated behaviors remains poorly understood. The ventral tegmental area (VTA) projects to both the nucleus accumbens (NAc) and prefrontal cortex (PFC), forming distinct pathways that are implicated in drug-cue associations, though their specific roles in fentanyl-context encoding are not w...