Bipedal locomotion by the normally quadrupedal Japanese monkey, M. Fuscata: strategies for obstacle clearance and recovery from stumbling
Mori, F.; Tachibana, A.; Takasu, C.; Nakajima, K.; Mori, S.
Acta Physiologica et Pharmacologica Bulgarica 26(3): 147-150
2001
ISSN/ISBN: 0323-9950 PMID: 11695527 Document Number: 534130
This study explored how the normally quadrupedal Japanese monkey adjusts to treadmill perturbations, when trained to walk bipedally. The monkey was required to use the left hindlimb to clear an obstacle that was fixed on the left side of a treadmill belt. The monkey either cleared the obstacle (CL: cleared locomotion), or stumbled over it (SL: stumbled locomotion). For CL, it changed its left hind limb's kinematics according to the obstacle's height and position relative to the left foot. In SL, the monkey used a "defensive posture", which included a rapid lowering of the right foot and forelimb movements, to stabilize the perturbed posture and thereby prevent falling. Then, with powerful extensions of its lower limb joints, the monkey raised its center-of-mass to the appropriate level for continuation of normal bipedal walking. The results show that M. Fuscata recruited both anticipatory and reactive neural mechanisms to accommodate to the obstacle.