In conclusion, our results do not show an association between placebo EBR and striatal D1R or D2R availability but reveal such an association with the EBR measures obtained with MP indicating that modulation of eye blinks by DA emerges under condition when the dopamine system is stimulated, which might explain why associations are observed in patients with Parkinson disease or with schizophrenia. This evidence concerns the gene DRD2 and Parkinson disease.