Role of basal ganglia-brainstem systems in the control of postural muscle tone and locomotion.

This chapter argues that a basal ganglia-brainstem system throughout the mesopontine tegmentum contributes to an automatic control of movement that operates in conjunction with voluntary control processes. Activity of a muscle tone inhibitory system and the locomotion executing system can be steadily balanced by a net excitatory cortical input and a net inhibitory basal ganglia input to these systems. We further propose that dysfunction of the basal ganglia-brainstem system, together with that of the cortico-basal ganglia loop, underlies the pathogenesis of motor disturbances expressed in basal ganglia diseases.