Placebo enhances reward learning in Parkinson’s disease (PD) by modulating brain activity related to reward processing. A study using fMRI and a reward learning task in PD patients found that expectations of dopamine release, induced by placebo, enhanced reward learning and modulated activity in the striatum and ventromedial prefrontal cortex (vmPFC). These effects were specific to reward learning, not to learning from punishment. Placebo effects on reward learning paralleled those of dopaminergic medication, suggesting a shared neurobiological mechanism. The study also showed that placebo increased value representation in the vmPFC and reduced striatal prediction error responses, consistent with dopamine's role in reward learning. These findings highlight the importance of expectations in shaping learning and behavior, and suggest that placebo effects in PD may be mediated by dopaminergic mechanisms. The results indicate that expectations about treatment can enhance learning and motor symptoms, with potential implications for treatment strategies in PD. The study used a within-subject design to compare placebo, medication, and off-drug conditions, and found that placebo effects were selective to reward learning, not punishment learning. The findings suggest that placebo effects in PD are not due to general treatment effects but are specifically related to reward processing. The study also found that placebo effects on learning were associated with reduced striatal BOLD responses to reward and prediction error, which may reflect increased integration of reward information across trials. Overall, the study demonstrates that expectations about treatment can enhance learning and behavior in PD, with potential implications for treatment strategies.Placebo enhances reward learning in Parkinson’s disease (PD) by modulating brain activity related to reward processing. A study using fMRI and a reward learning task in PD patients found that expectations of dopamine release, induced by placebo, enhanced reward learning and modulated activity in the striatum and ventromedial prefrontal cortex (vmPFC). These effects were specific to reward learning, not to learning from punishment. Placebo effects on reward learning paralleled those of dopaminergic medication, suggesting a shared neurobiological mechanism. The study also showed that placebo increased value representation in the vmPFC and reduced striatal prediction error responses, consistent with dopamine's role in reward learning. These findings highlight the importance of expectations in shaping learning and behavior, and suggest that placebo effects in PD may be mediated by dopaminergic mechanisms. The results indicate that expectations about treatment can enhance learning and motor symptoms, with potential implications for treatment strategies in PD. The study used a within-subject design to compare placebo, medication, and off-drug conditions, and found that placebo effects were selective to reward learning, not punishment learning. The findings suggest that placebo effects in PD are not due to general treatment effects but are specifically related to reward processing. The study also found that placebo effects on learning were associated with reduced striatal BOLD responses to reward and prediction error, which may reflect increased integration of reward information across trials. Overall, the study demonstrates that expectations about treatment can enhance learning and behavior in PD, with potential implications for treatment strategies.