Organization of motor output in slow finger movements in man.
Organization of motor output in slow finger movements in man.
复制标题
人体缓慢手指运动中运动输出的组织。
DOI：
10.1113/jphysiol.1993.sp019837
复制
发表时间：
1993
期刊：
影响因子：
--
通讯作者：
J. Wessberg
中科院分区：
文献类型：
--
作者：
Å. Vallbo;J. Wessberg
1.缓慢的手指运动进行了分析，在正常人受试者的运动学和肌电图活动的长手指肌肉。在单掌指关节的随意斜坡运动过程中，记录前臂上手指伸肌和屈肌的表面肌电图，沿着记录角位置和角速度。角加速度是从速度记录中计算出来的。2.结果发现，运动并不平滑，但具有台阶或不连续性，通常以100 - 125 ms的间隔重复出现，产生以8 - 10 Hz周期为主的速度和加速度曲线。这种不连续性在第一次试验中就很明显，因此不依赖于训练。它们的幅度和数量在受试者之间变化，但对个体受试者来说相对稳定。3.观察到8 - 10 Hz周期的自主斜坡运动速度变化很大，较高的速度与较大的步幅相关，重复频率与缓慢自主斜坡的小步相同。观察到的最大步幅幅度比生理震颤大一个数量级以上。4.单个8 - 10 Hz周期是不对称的，因为减速通常比前一个加速度达到更高的峰值，这表明拮抗剂有助于制动作用。此外，在非常缓慢的自主坡道中，运动周期通常被零速度周期间隔开，提供了高度非正弦的速度曲线。5.肌电的激动剂和拮抗剂的肌肉调制密切相关的加速度和减速的个别运动周期。这些调制都存在于伸肌和屈肌，虽然他们更一致，通常更突出，在前者。6.研究结果表明，缓慢手指运动的一个特征是向肌肉系统输出8 - 10 Hz的周期性输出，这表明缓慢手指运动是由一系列双相力脉冲实现的，不仅涉及缩短激动剂肌肉推动运动，而且还涉及拮抗剂肌肉，其活动在激动剂后不久增加，并导致单个运动步骤的急剧减速。7.有人提出，作为一个假设，这种双相电机输出可能反映了一个类似的组织的下降电机命令缓慢的手指运动。因此，该命令将包括一系列双相脉冲，以每秒8 - 10个的速率连接，以及能够设置脉冲大小并因此设置运动的总体速度的脉冲高度调节器。
1. Slow finger movements were analysed in normal human subjects with regard to kinematics and EMG activity of the long finger muscles. Surface EMG from the finger extensor and flexor muscles on the forearm was recorded along with angular position and angular velocity during voluntary ramp movements at single metacarpophalangeal joints. Angular acceleration was computed from the velocity record. 2. It was found that movements were not smooth but characterized by steps or discontinuities, often recurring at intervals of 100‐125 ms, yielding velocity and acceleration profiles dominated by 8‐10 Hz cycles. The discontinuities were manifest from the very first trial and thus not dependent on training. Their amplitude and amount varied between subjects but were relatively stable for the individual subject. 3. The 8‐10 Hz cycles were seen with voluntary ramp movements of widely varying velocities, higher velocities being associated with larger steps recurring with the same repetition rate as the small steps of slow voluntary ramps. Maximal step amplitude observed was more than one order of magnitude larger than physiological tremor. 4. The individual 8‐10 Hz cycle was asymmetrical in that decelerations usually reached higher peaks than the preceding acceleration, suggesting that the antagonist contributed with a braking action. Moreover, in very slow voluntary ramps, the movement cycles were often interspaced by periods of zero velocity, providing a highly non‐sinusoidal velocity profile. 5. The EMG of the agonist and the antagonist muscles was modulated in close relation to the accelerations and decelerations respectively of the individual movement cycle. These modulations were present in both extensor and flexor muscles, although they were more consistent and usually more prominent in the former. 6. The findings indicate that a feature of slow finger movements was an 8‐10 Hz periodic output to the muscular system, suggesting that slow finger movements are implemented by a series of biphasic force pulses, involving not only the shortening agonist muscle propelling the movement, but the antagonist muscle as well whose activity increased shortly after the agonist and contributed to a sharp deceleration of the individual step of movement. 7. It is proposed, as a hypothesis, that this biphasic motor output may reflect a similar organization of the descending motor command for slow finger movements. Hence, this command would include a series of biphasic pulses, concatenated at a rate of 8‐10 per second and a pulse‐height regulator capable of setting the size of the pulse and thus the overall speed of the movement.
影响因子：
14.5
作者：
ABEND, W;BIZZI, E;MORASSO, P
通讯作者：
MORASSO, P