FIGURE 1.

Schematics illustrating the general organization of supraspinal structures controlling locomotion in vertebrates. Reticulospinal cells constitute a large part of the locomotor-related descending inputs that activate the spinal locomotor CPGs. The MLR receives inputs from the basal ganglia and projects extensively to reticulospinal cells. The cortex projects down to the basal ganglia, the MLR and reticulospinal cells. The basal ganglia and the hypothalamus project down to the MLR as well as to reticulospinal neurons. There is another locomotor region, the DLR, that was identified in several species of vertebrates. Far less is known about this locomotor region that projects directly to reticulospinal neurons.