Basic neurophysiology of primate locomotion

To initiate and terminate bipedal and quadrupedal locomotor movements, a smooth transition to and from standing is necessary. For this, integration of postural and locomotor control systems is required. Recent studies in nonhuman primates and other quadrupedal animals such as cats have clearly shown that there exist significant analogies between the primate species investigated (Macaca mulatta, Macaca fascicularis, and marmosets) and the cats regarding the spinal stepping generator or central pattern generator (CPG), supraspinal descending pathways which activate CPG, and the midbrain and brain stem postural and locomotor control structures. Further studies aimed at elucidating the differences and similarities in the manner of locomotor control among different animal species will help us in understanding the control mechanisms involved in both bipedal and quadrupedal locomotor movements in nonhuman primates.