OBSERVATIONS ON THE AUTOMATIC COMPENSATION OF REFLEX GAIN ON VARYING THE PREEXISTING LEVEL OF MOTOR DISCHARGE IN MAN
OBSERVATIONS ON THE AUTOMATIC COMPENSATION OF REFLEX GAIN ON VARYING THE PREEXISTING LEVEL OF MOTOR DISCHARGE IN MAN
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DOI：
10.1113/jphysiol.1986.sp016066
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发表时间：
1986-05-01
影响因子：
5.5
通讯作者：
MATTHEWS, PBC
中科院分区：
文献类型：
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作者：
MATTHEWS, PBC
众所周知，人类牵张反射显示自动增益补偿;换句话说，肌电（e.m.g.）由给定的干扰引起的反应随着预先存在的自主活动的水平而逐渐增加，并且因此保持背景的近似恒定比例。这种行为现在已经被观察到使用振动作为刺激Ia行动和记录反射发展的力量，除了电动势。通过振动拮抗剂和激动剂来研究抑制和兴奋，发现它们受到类似的调节。实验是在手肘肌在随意驱动下等长收缩时进行的。振动是以5 Hz调制的方波或以一到五个脉冲的脉冲串传递。e.g.m.由后者产生的响应足够短，以表明增益补偿是脊髓反射动作的特征。在讨论中，它的结论是，在原则上自动增益补偿可以很容易地归因于已知的组织的运动神经元池。随着背景力的增加，可被给定输入频率调制的活动运动神经元的数量也增加，并且处于募集或去募集边缘的那些运动单元将更大和更强。
The human stretch reflex is well known to show automatic gain compensation; in other words, the electromyographic (e.m.g.) response evoked by a given disturbance increases progressively with the level of pre-existing voluntary activity, and so remains an approximately constant proportion of the background. Such behaviour has now been observed using vibration as the stimulus to Ia action and recording the reflexly developed force, in addition to the e.m.g. Inhibition was studied as well as excitation by vibrating the antagonist as well as the agonist, and found to be similarly regulated. The experiments were performed on the elbow flexors while they were contracting isometrically under voluntary drive. The vibration was either square-wave modulated at 5 Hz or delivered in bursts of one to five pulses. The latency of the e.g.m. responses produced by the latter was sufficiently short to show that gain compensation was a feature of spinal reflex action. In the Discussion, it is concluded that in principle automatic gain comensation can be readily attributed to the known organization of the motoneurone pool. As the background force increases so does the number of active motoneurones a vailable to be frequency-modulated by a given input, and the larger and stronger will be those motor units which are on the verge of recruitment or de-recruitment.