Forssberg H, Grillner S, Halbertsma J, Rossignol S
Acta Physiol Scand. 1980 Mar;108(3):283-95. doi: 10.1111/j.1748-1716.1980.tb06534.x.
The interaction of the two hindlimbs were investigated by an analysis of the muscular activity and the movements in 14 chronic spinal kittens during treadmill locomotion (i.e. in kittens subjected to a transection of the spinal cord (Th10--12)) one or two weeks after birth). At low speed the limbs were alternating (walk or trot). At higher they were activated more simultaneous, as during gallop. The two limbs could walk at different velocities, as during walking in a circle, when the two belts of the treadmill were driven at different speeds. The duration of the support phases was mainly influenced by the speed of the belt on which the limb was walking. The limbs could still maintain a common rhythm up to a two or three fold speed difference, as the flexion or the first extension phase of the limb walking on the "fast" belt was prolonged and the flexion phase of "slow limb" was shortened. At extreme speed differences the limb on the "fast belt" performed 2, 3 and even 4 steps during one stepcycle of the "slow limb". The placement of the feet was found to maintain the most stable relationship during alternating gaits at different speed differences. It is concluded that all phases of the step cycle are modifiable and that there are several mechanisms coordinating the limbs within the spinal cord.
通过对14只出生后一两周接受脊髓横断术（胸10 - 12）的慢性脊髓小猫在跑步机上运动时的肌肉活动和运动情况进行分析，研究了其两条后肢之间的相互作用。在低速时，四肢交替运动（行走或小跑）。在较高速度时，它们更同时被激活，如在飞奔时。两条腿可以以不同速度行走，比如在跑步机的两条皮带以不同速度驱动时，就像在绕圈行走时那样。支撑期的持续时间主要受肢体所行走皮带速度影响。四肢在速度差达到两到三倍时仍能保持共同节奏，因为在“快速”皮带上行走的肢体的屈曲或首次伸展期会延长，而“慢速肢体”的屈曲期会缩短。在极端速度差时，“快速皮带”上的肢体在“慢速肢体”的一个步周期内会执行2步、3步甚至4步。研究发现，在不同速度差的交替步态中，足部位置能保持最稳定的关系。得出的结论是，步周期的所有阶段都是可调节的，并且脊髓内存在多种协调四肢的机制。
