報酬キューへの持続的誘引をエンコードする位相性ドーパミン

Reward-predictive cues can become attractive themselves due to incentive salience attribution. This manifests as persistent engagement with cues, known as sign-tracking. Cue-evoked phasic dopamine in the nucleus accumbens core (NAc) is critical for sign-tracking and cue-evoked reward craving, yet is also known to follow learning rules requiring outcome value updating. Would cue-evoked dopamine track incentive salience persistence, or change in accord with reward value alteration while failing to encode persistent behaviors? We assessed NAc dopamine activity using fiber photometry in sign-tracking rats during an omission task, in which physical cue interaction cancels reward. Animals adapted to reward loss while maintaining non-physical cue interaction reflective of persistent incentive salience. Cue-evoked dopamine remained unchanged during omission, mirroring robust incentive salience but not behavioral adaptations occurring with learning. In contrast, outcome-related dopamine reflected reward gain or loss. Therefore, cue-related dopamine encodes persistence of cue value, independent of outcome-related dopamine signals tracking reward occurrence.