TASK-DEPENDENT CHANGES IN THE RESPONSES TO LOW-THRESHOLD CUTANEOUS AFFERENT VOLLEYS IN THE HUMAN LOWER-LIMB
TASK-DEPENDENT CHANGES IN THE RESPONSES TO LOW-THRESHOLD CUTANEOUS AFFERENT VOLLEYS IN THE HUMAN LOWER-LIMB
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DOI：
10.1113/jphysiol.1991.sp018393
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发表时间：
1991-01-01
影响因子：
5.5
通讯作者：
SKUSE, NF
中科院分区：
文献类型：
--
作者：
BURKE, D;DICKSON, HG;SKUSE, NF
1. 在没有支撑的情况下站立的七名人类受试者中，使用一系列无痛刺激（300 Hz 的五个脉冲）电刺激腓肠神经，旨在激活来自皮肤机械感受器的传入。 在校正肌电图的刺激后平均值中寻找刺激序列对同侧和对侧腿部不同肌肉的反射效应。 研究受试者保持不同姿势时反射影响模式的变化。 2． 在同侧胫骨前肌、比目鱼肌、股二头肌和股外侧肌中可以看到清晰的反射反应，但仅限于肌肉主动收缩时。 在每块肌肉中，抑制是前 100 毫秒内的主要反射反应。 在七名受试者中的四名中，在对侧胫骨前肌和比目鱼肌中可检测到反射变化，前 200 毫秒内的峰峰值调制是同源同侧肌肉的 25-50%。 3． 当受试者试图站在倾斜的平台、不稳定的平台上或单腿弯曲而另一条腿弯曲时，不同的肌肉组合会被激活，包括屈肌和伸肌，或者主要是屈肌，或者主要是伸肌。 在每种姿势中，反射效应仅在活跃的肌肉中可见。4． 对于同侧胫骨前肌，刺激后约 60 毫秒和 80 毫秒，EMG 响应的短潜伏期成分出现任务依赖性变化。 当坐着进行随意收缩时，这些部件很难定义，而当站在平台上，脚趾向上倾斜时，它们很小。 当同侧腿弯曲或站立在不稳定的底座上时，这些早期成分在每个受试者中都更加突出。 对于对侧胫骨前肌，主导反射模式是坐姿和自愿收缩时的抑制，以及双足站立倾斜脚趾向上时的促进。 这些反射模式的变化不能用不同程度的背景收缩来解释。5． 结论是，足部的皮肤机械感受器对双肢、特别是同侧肢体的肌肉具有广泛的反射作用。 并且不同肌肉和单个肌肉内的反射模式可能会根据受试者正在执行的任务而改变。 这些依赖于任务的变化表明皮肤反射活动表达的可塑性，影响短潜伏期脊髓通路和长潜伏期通路。
1. In seven human subjects who were standing without support the sural nerves were stimulated electrically using trains of non-painful stimuli (five pulses at 300 Hz), designed to activate afferents from cutaneous mechanoreceptors. The reflex effects of the stimulus train on different muscles of the ipsilateral and contralateral legs were sought in post-stimulus averages of rectified EMG. Changes in the pattern of reflex influence were investigated when the subjects maintained different postures.2. Clear reflex responses were seen in ipsilateral tibialis anterior, soleus, biceps femoris and vastus lateralis, but only when the muscles were actively contracting. In each muscle, inhibition was the dominant reflex response within the first 100 ms. In four of the seven subjects, reflex changes were detectable in the contralateral tibialis anterior and soleus, the peak-to-peak modulation within the first 200 ms being 25-50% of that for the homologous ipsilateral muscle.3. When subjects attempted to stand on a tilted platform, an unstable platform or on one leg with the other flexed, different combinations of muscles were active, involving both flexors and extensors or predominantly flexors or predominantly extensors. In each posture the reflex effects were demonstrable only in the active muscles.4. With ipsilateral tibialis anterior, there were task-dependent changes in the short-latency components of the EMG response, approximately 60 ms and 80 ms after the stimulus. When seated performing voluntary contractions these components were difficult to define, and when standing on a platform tilted toe-up they were small. When the ipsilateral leg was flexed or when standing on an unstable base, these early components were more prominent in each subject. With contralateral tibialis anterior, the dominant reflex pattern was inhibition when seated and contracting voluntarily, and facilitation during bipedal stance tilted toe-up. These changes in reflex pattern could not be explained by different levels of background contraction.5. It is concluded that cutaneous mechanoreceptors of the foot have widespread reflex actions on muscles throughout both limbs, particularly the ipsilateral limb. and that the reflex pattern in different muscles and within a single muscle may change dependent on the task that the subject is undertaking. These task-dependent changes indicate plasticity in the expression of cutaneous reflex activity, affecting both short-latency spinal as well as long-latency pathways.