MUSCLE-SPINDLE ACTIVITY IN MAN DURING VOLUNTARY FAST ALTERNATING MOVEMENTS
MUSCLE-SPINDLE ACTIVITY IN MAN DURING VOLUNTARY FAST ALTERNATING MOVEMENTS
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DOI：
10.1136/jnnp.38.7.625
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发表时间：
1975-01-01
影响因子：
11
通讯作者：
LOFSTEDT, L
中科院分区：
文献类型：
--
作者：
HAGBARTH, KE;WALLIN, G;LOFSTEDT, L
在健康受试者正中神经和腓神经中插入钨微电极，记录手指和足屈肌初级纺锤形传入神经纤维的单位活动。在模拟帕金森震颤的手指和脚的随意快速交替运动中，在Ia传入纤维中观察到两种类型的放电：(1)发生在屈肌松弛阶段的拉伸反应；(2)发生在屈肌收缩阶段的放电。与牵拉反应相反，纺锤体收缩放电可被记录部位近端的肌神经部分利多卡因阻断，表明它们是由梭内纤维的纺锤运动激活引起的。根据单个肌电爆发的开始和结束、纺锤形收缩放电的开始时间和有关肌肉的牵拉反射潜伏期之间的时间关系，得出以下结论：这类运动中的复发性梭外收缩是由快速的直接α通路启动的，但个别收缩阶段通常持续足够长的时间，从而受到通过纺锤体环的共同激活的梭形马达环的影响。据推测，交替运动中的这种伽马环影响有助于保持屈肌和伸肌以规则的相互方式工作，收缩的强度根据外部负荷进行调整。
Single unit activity in primary spindle afferent nerve fibres from finger and foot flexors was recorded with tungsten microelectrodes inserted into the median and peroneal nerves of healthy subjects. During voluntary fast alternating finger and foot movements, simulating the tremor of Parkinsonism, two types of discharges were seen in the Ia afferent fibres: (1) stretch responses occurring during the flexor relaxation phases, and (2) discharges occurring during the flexor contraction phases. Contrary to the stretch responses the spindle contraction discharges could be eliminated by a partial lidocaine block of the muscle nerve proximal to the recording site, indicating that they resulted from fusimotor activation of intrafusal fibres. On the basis of the temporal relations between the beginning and end of individual EMG-bursts, the start of the spindle contraction discharges and the latency of the stretch reflex in the muscles concerned, the following conclusions were drawn: the recurrent extrafusal contractions in movements of this type are initiated by the fast direct alpha route, but individual contraction phases generally last long enough to be influenced subsequently by the coactivated fusimotor loop through the spindles. It is postulated that this gamma loop influence during alternating movements helps to keep flexor and extensor muscles working in a regular reciprocal fashion with contractions adjusted in strength to the external loads.