Gait acts as a gate for reflexes from the foot
Gait acts as a gate for reflexes from the foot
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DOI：
10.1139/y04-071
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发表时间：
2004-08-01
影响因子：
2.1
通讯作者：
Dietz, V
中科院分区：
文献类型：
--
作者：
Duysens, J;Bastiaanse, CM;Dietz, V
在人类步态过程中，电刺激足在摆动相开始时在TA（胫骨前肌）中产生易化P2（中等潜伏期）反应，而相同的刺激在摆动相结束时引起抑制反应，沿着拮抗剂中的易化反应。这种现象被称为相位依赖反射反转。抑制反应可以从腿部的各种皮肤部位和刺激某些肌肉如股直肌（RF）诱发。本文回顾了反射逆转的数据，并增加了新的数据在这个话题上，使用分裂带范式。到目前为止，TA中的反射反转只能在步进周期的开始和结束阶段进行研究，这仅仅是因为只有在存在背景活动时才能证明抑制。通常，在步伐周期中只有2个TA爆发，而TA在大多数站立阶段通常是无声的。要想知道在站立阶段发生了什么，我们需要有一种方法来唤起站立阶段的一些背景活动。为此，进行了新的实验，其中要求受试者在带有分裂带的跑步机上行走。当受试者以不相等的腿速度行走时，行走模式适应于类似跛行的步态模式。然后，TA在缓慢移动腿的大部分站立阶段保持活跃，这被用作主要支撑。这种活动是支持腿中的激动性和拮抗性腿部肌肉共同激活的结果，并且代表了稳定身体的方法之一。电刺激给予皮肤神经（腓肠神经）在踝关节的两倍的感知阈值。12名受试者中有9名在站立阶段显示出TA活动增加，而在分裂带上行走，其中5名在缓慢侧给予刺激时，在站立的第一部分显示出明显的仰卧位。得出的结论是，在大多数受试者中，TA抑制通路在大部分站立阶段保持开放。有人建议，TA抑制增加负载的踝跖屈肌在负载阶段的立场。
During human gait, electrical stimulation of the foot elicits facilitatory P2 (medium latency) responses in TA (tibialis anterior) at the onset of the swing phase, while the same stimuli cause suppressive responses at the end of swing phase, along with facilitatory responses in antagonists. This phenomenon is called phase-dependent reflex reversal. The suppressive responses can be evoked from a variety of skin sites in the leg and from stimulation of some muscles such as rectus femoris (RF). This paper reviews the data on reflex reversal and adds new data on this topic, using a split-belt paradigm. So far, the reflex reversal in TA could only be studied for the onset and end phases of the step cycle, simply because suppression can only be demonstrated when there is background activity. Normally there are only 2 TA bursts in the step cycle, whereas TA is normally silent during most of the stance phase. To know what happens in the stance phase, one needs to have a means to evoke some background activity during the stance phase. For this purpose, new experiments were carried out in which subjects were asked to walk on a treadmill with a split-belt. When the subject was walking with unequal leg speeds, the walking pattern was adapted to a gait pattern resembling limping. The TA then remained active throughout most of the stance phase of the slow-moving leg, which was used as the primary support. This activity was a result of coactivation of agonistic and antagonistic leg muscles in the supporting leg, and represented one of the ways to stabilize the body. Electrical stimulation was given to a cutaneous nerve (sural) at the ankle at twice the perception threshold. Nine of the 12 subjects showed increased TA activity during stance phase while walking on split-belts, and 5 of them showed pronounced suppressions during the first part of stance when stimuli were given on the slow side. It was concluded that a TA suppressive pathway remains open throughout most of the stance phase in the majority of subjects. The suggestion was made that the TA suppression increases loading of the ankle plantar flexors during the loading phase of stance.