The motor system and motor disorders.

The beneficial effects of placebos and the harmful effects of nocebos on motor functions concern not only sports performance but also pathological conditions and, in particular, movement disorders. In the pathological context, most studies have been conducted on Parkinson disease, where placebo and nocebo can influence motor and nonmotor symptoms, modulate the activity of subcortical and cortical brain regions, and, in the case of placebos, induce the dopaminergic release in the basal ganglia. In contrast, knowledge about placebo and nocebo effects in other movement disorders is still limited and derives mainly from randomized control studies in which the term "placebo response" is more appropriate than "placebo effect." As will be illustrated in this chapter, the study of placebo and nocebo effects in the motor domain has addressed different motor functions involving more focused body districts or the entire body and has allowed discovering the involvement of a set of cortical and subcortical brain structures belonging to the motor control network.