The study investigates the brain reorganization associated with the transition from sub-acute back pain (SBP) to chronic back pain (CBP). Over a one-year longitudinal study, patients with SBP were followed to determine if their pain persisted or recovered. Brain scans were conducted at four visits, and the results showed that only those with persisting pain (SBPp) exhibited decreases in gray matter density in specific regions, including the nucleus accumbens (NAc), insula, and sensorimotor cortex (S1/M1). Importantly, greater functional connectivity between the NAc and the medial prefrontal cortex (mPFC) at baseline predicted pain persistence. This suggests that the corticostriatal circuitry, particularly the mPFC-NAc connection, is causally involved in the transition from acute to chronic pain. The study provides a temporal profile of brain parameters during pain chronification and highlights the role of the mPFC-NAc circuit in pain persistence.The study investigates the brain reorganization associated with the transition from sub-acute back pain (SBP) to chronic back pain (CBP). Over a one-year longitudinal study, patients with SBP were followed to determine if their pain persisted or recovered. Brain scans were conducted at four visits, and the results showed that only those with persisting pain (SBPp) exhibited decreases in gray matter density in specific regions, including the nucleus accumbens (NAc), insula, and sensorimotor cortex (S1/M1). Importantly, greater functional connectivity between the NAc and the medial prefrontal cortex (mPFC) at baseline predicted pain persistence. This suggests that the corticostriatal circuitry, particularly the mPFC-NAc connection, is causally involved in the transition from acute to chronic pain. The study provides a temporal profile of brain parameters during pain chronification and highlights the role of the mPFC-NAc circuit in pain persistence.