Dynamique et Physiopathologie des Réseaux Neuronaux, Inserm U667, Collège de France; Université Pierre et Marie Curie, Paris
The examination of the neurobiological mechanisms of the locomotion highlighted the presence of spinal neural networks containing all elements that can endogenously organize periodic motor commands for locomotion. The activity of these networks, which are termed central pattern generators, is controlled by peripheral afferents adapting the gait pattern progress and by descending afferents arising from central generators that release and determine the rhythm networks activity. This article mainly discusses the functional organization of the mesencephalic locomotor region (composed by pedunculopontine and cuneiform nuclei) and the motor control in basal ganglia circuits. We present data that raise the question of the pedunculopontine nucleus specific role in the control of locomotion. In addition, we report observations favoring the implication of interconnections between basal ganglia and superior colliculus in the target-directed locomotion. These data are discussed in relation to gait disorders encountered in patients with Parkinson disease.