ORGANIZING PRINCIPLES FOR SINGLE-JOINT MOVEMENTS .2. A SPEED-SENSITIVE STRATEGY
ORGANIZING PRINCIPLES FOR SINGLE-JOINT MOVEMENTS .2. A SPEED-SENSITIVE STRATEGY
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DOI：
10.1152/jn.1989.62.2.358
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发表时间：
1989-08-01
影响因子：
2.5
通讯作者：
AGARWAL, GC
中科院分区：
文献类型：
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作者：
CORCOS, DM;GOTTLIEB, GL;AGARWAL, GC
1.正常人受试者在水平面上从静止的初始位置到视觉上定义的目标的固定距离上进行手肘的离散屈曲。我们测量了关节角度，加速度和肌电图（EMG）从两个激动剂和两个拮抗剂肌肉。2.运动速度的变化引起的明确指示的主题或通过调整目标的宽度。指示总是要求准确地停在目标区域。3.峰值惯性扭矩和加速度，运动时间，综合肌电图都与速度高度相关。我们表明，惯性扭矩可以被用来作为一个链接变量，几乎足以解释所有的任务之间的相关性，肌电图，和运动学。4.当受试者执行需要控制运动速度的任务时，他们会调整肌肉产生扭矩的速率。这个速率是由肌肉被激活的方式来调节的。关节扭矩发展的速率与激动剂EMG上升的速率以及与积分EMG相关。5.拮抗剂EMG显示两个分量。第一个的潜伏期为30-50 ms，与运动动力学无关。第二分量的延迟与移动时间成比例。两个部件的上升速率和面积与扭矩成比例。6.我们提出了组织原则，控制单关节运动中的任务是由两个策略之一。这些策略被称为速度不敏感策略和速度敏感策略。7.提出了一个模型，其中的动作下的速度敏感的策略是通过控制的强度提供给运动神经元池的激励脉冲执行。其作用是调节关节扭矩的增加速率，从而调节加速度。8.可变的距离，速度，准确性和负载的运动被证明是由两个一致的肌肉激活规则集之一控制。这些规则适用于控制激动肌和拮抗肌。激活规则导致可区分的EMG和扭矩发展模式。所有可观察到的运动学变化被解释为这些影响的确定性后果。
1. Normal human subjects made discrete flexions of the elbow over a fixed distance in the horizontal plane from a stationary initial position to a visually defined target. We measured joint angle, acceleration, and electromyograms (EMGs) from two agonist and two antagonist muscles. 2. Changes in movement speed were elicited either by explicit instruction to the subject or by adjusting the target width. Instructions always required accurately stopping in the target zone. 3. Peak inertial torques and accelerations, movement times, and integrated EMGs were all highly correlated with speed. We show that inertial torque can be used as a linking variable that is almost sufficient to explain all correlations between the task, the EMG, and movement kinematics. 4. When subjects perform tasks that require control of movement speed, they adjust the rate at which torque is developed by the muscles. This rate is modulated by the way in which the muscles are activated. The rate at which joint torque develops is correlated with the rate at which the agonist EMG rises as well as with integrated EMG. 5. The antagonist EMG shows two components. The latency of the first is 30-50 ms and independent of movement dynamics. The latency of the second component is proportional to movement time. The rate of rise and area of both components scale with torque. 6. We propose organizing principles for the control of single-joint movements in which tasks are performed by one of two strategies. These are called speed-insensitive and speed-sensitive strategies. 7. A model is proposed in which movements made under a speed-sensitive strategy are executed by controlling the intensity of an excitation pulse delivered to the motoneuron pool. The effect is to regulate the rate at which joint torque, and consequently acceleration, increases. 8. Movements of variable distance, speed, accuracy, and load are shown to be controlled by one of two consistent sets of rules for muscle activation. These rules apply to the control of both the agonist and antagonist muscles. Rules of activation lead to distinguishable patterns of EMG and torque development. All observable changes in movement kinematics are explained as deterministic consequences of these effects.