The MPTP monkey models clearly represent most of the existing symptomatic/pathophysiologic models, which aim at recapitulating the motor manifestations of PD (whether or not they display signs of neurodegeneration), and are used to develop symptomatic therapies or to study circuit-related questions. Because we believe that only nonhuman primates accurately mimic the motor expression of PD, in our opinion, these are the only animals that are optimal for such studies. MPTP mouse models for instance fail to replicate symptomatic manifestation of PD.