Neuroimaging of standing and walking: Special emphasis on Parkinsonian gait

Quadruped animal studies indicate two major systems for locomotion, the basal ganglia–brainstem and basal ganglia–thalamo-cortical systems. Consistent with these studies, human neuroimaging studies have suggested gait-related activity in the brainstem locomotor centers, cerebellum, basal ganglia, and multiple motor cortices. As for pathophysiology of Parkinsonian gait, underactivity of the supplementary motor areas and cerebellar hemisphere, combined with overactivity of the vermis, have been shown. Overactivation of the lateral premotor cortex is observed during paradoxical improvement of Parkinsonian gait under visual guidance. The activation of visuomotor network including the lateral premotor cortex may bypass the basal ganglia–thalamo-cortical abnormality and directly drive brainstem locomotor centers.