Pain-Related Nucleus Accumbens Function: Modulation by Reward and Sleep Disruption.

The nucleus accumbens (NAc) has been implicated in sleep, reward, and pain modulation, but the relationship between these functional roles is unclear. This study aimed to determine if NAc function at the onset and offset of a noxious thermal stimulus is enhanced by rewarding music, and if that effect is reversed by experimental sleep disruption. Twenty-one healthy subjects underwent functional MRI (fMRI) scans on two separate days following both uninterrupted sleep and experimental sleep disruption. During fMRI scans, participants experienced noxious stimulation while listening to individualized rewarding or neutral music. Behavioral results revealed that rewarding music significantly reduced pain intensity compared to neutral music and disrupted sleep was associated with decreased pain intensity in the context of listening to music. In whole-brain FWE cluster-corrected analysis, NAc was activated at pain onset, but not during tonic pain or at pain offset. Sleep disruption attenuated NAc activation at pain onset and during tonic pain. Rewarding music altered NAc connectivity with key nodes of the corticostriatal circuits during pain onset. Sleep disruption increased reward-related connectivity between the NAc and the anterior midcingulate cortex (aMCC) at pain onset. This study thus indicates that experimental sleep disruption modulates NAc function during the onset of pain in a manner that may be conditional on the presence of competing reward-related stimuli. These findings point to potential mechanisms for the interaction between sleep, reward, and pain, and suggest that sleep disruption affects both the detection and processing of aversive stimuli that may have important implications for chronic pain.