Twitch properties of human thenar motor units measured in response to intraneural motor-axon stimulation.
Twitch properties of human thenar motor units measured in response to intraneural motor-axon stimulation.
复制标题
测量人类鱼际运动单位对神经内运动轴突刺激的抽搐特性。
DOI：
10.1152/jn.1990.64.4.1339
复制
发表时间：
1990
影响因子：
2.5
通讯作者：
Bigland-Ritchie,B
中科院分区：
文献类型：
--
作者：
Thomas,CK;Johansson,RS;Westling,G;Bigland-Ritchie,B
1.研究了神经内运动轴突刺激对人大鱼际运动单位的抽搐特性的影响。在强直刺激前后测量拇指外展和屈曲的力分量。计算每个单元的合力的大小、方向和时间导数，以及轴突传导速度。2.测量收缩和舒张速率的各种指标，包括收缩时间（从力开始到峰值的时间）、二分之一舒张时间（从峰值力到该值的二分之一的时间）、归一化最大收缩和归一化最大舒张速率（归一化为抽搐力的力信号的峰值正和负时间导数）以及这些最大速率发生的时间。3.对于不同的单位，合力的方向大致均匀分布在拇指外展和屈曲。在实验开始时，初始抽搐力范围从3到34 mN，收缩时间从35到80毫秒，和一半的放松时间从25到108毫秒。结果抽搐力量呈正相关，归一化最大松弛率，但不其他率指数或传导速度。各种收缩率措施相互关联，但一般不放松率。5.在涉及强直刺激的第一次测试后，大多数单位的抽搐被增强和减慢，特别是它们的放松阶段。然而，这些变化的程度在各单位之间差异很大。一般来说，初始力较弱的单位增强最多，有些可达三倍。这些收缩特性的变化被称为强直后收缩增强。（250字处删节）
1. The twitch properties of human thenar motor units were examined in response to intraneural motor-axon stimulation. Force components of thumb abduction and flexion were measured before and after tetanic stimulation. The magnitude, direction, and time derivatives of resultant forces, together with axon conduction velocities, were calculated for each unit. 2. Various indexes of contraction and relaxation rate were measured including contraction time (time from force onset to peak), one-half relaxation time (time from peak force to one-half that value), normalized maximum contraction and normalized maximum relaxation rates (peak positive and negative time derivatives of the force signal normalized to twitch force), and the times at which these maximum rates occurred. 3. For different units, the directions of resultant forces were approximately evenly distributed between thumb abduction and flexion. At the onset of the experiment, initial twitch forces ranged from 3 to 34 mN, contraction times from 35 to 80 ms, and one-half relaxation times from 25 to 108 ms. 4. Resultant twitch forces were positively correlated to normalized maximum relaxation rates, but not to other rate indexes or to conduction velocity. The various contraction rate measures were correlated to each other, but generally not to relaxation rates. 5. After the first test involving tetanic stimulation, the twitches of most units were potentiated and slowed, especially their relaxation phase. However, the extent of these changes varied considerably between units. In general, units with weak initial forces potentiated most, some up to three-fold. These changes in twitch properties were denoted posttetanic twitch potentiation.(ABSTRACT TRUNCATED AT 250 WORDS)