EVIDENCE FAVORING PRESYNAPTIC INHIBITION BETWEEN ANTAGONIST MUSCLE AFFERENTS IN THE HUMAN FOREARM
EVIDENCE FAVORING PRESYNAPTIC INHIBITION BETWEEN ANTAGONIST MUSCLE AFFERENTS IN THE HUMAN FOREARM
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DOI：
10.1113/jphysiol.1987.sp016726
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发表时间：
1987-10-01
影响因子：
5.5
通讯作者：
ROTHWELL, JC
中科院分区：
文献类型：
--
作者：
BERARDELLI, A;DAY, BL;ROTHWELL, JC
1.单一的运动阈值电刺激桡神经的螺旋沟产生三个阶段的抑制放松的手腕和手指屈肌的H反射。抑制的第一阶段发生的条件测试间隔为-1至3毫秒，并表示双突触Ia相互抑制屈肌运动神经元的传入输入从伸肌。第二阶段发生的条件试验间隔为5-40毫秒。在本研究中的第二抑制相的特性进行了研究。2.产生第二阶段抑制所需的桡神经刺激的阈值强度为0.7 × 104。运动阈值和所需的产生第一（双突触）阶段的抑制。3.桡神经刺激对肌电大小影响的时间过程。还研究了运动皮层对经颅电刺激的反应。结果与H反射测试结果进行了比较。第一阶段抑制的时程和深度与两种测试输入相同。然而，仅在H反射测试刺激下观察到抑制的第二阶段。在桡神经传入齐射后30 ms，皮质脊髓齐射到达颈髓时，屈肌反应被促进而不是被抑制。4.单一刺激（2-3 × 104），感觉阈值）对腕部桡神经的浅（皮）分支的刺激未能产生对屈肌H反射的抑制。相反，当正中神经Ia齐射（用于H反射）被定时为在桡神经皮肤传入齐射后30-40 ms之间到达颈髓时，H反射被促进。与在螺旋沟中使用混合神经刺激的结果相反，这种皮肤输入对皮质诱发的e.m.g.反应和H反射。5.我们的结论是，屈肌H反射抑制的第二阶段产生的活动在大直径（组I）伸肌传入的H反射通路在premotoneuronal网站的行为。我们建议，该网站是突触前的Ia传入神经末梢，这种抑制竞争与后来（可能是突触后）的屈肌H反射的促进产生部分活动在桡神经的皮肤传入纤维。
1. A single motor-threshold electrical stimulus to the radial nerve in the spiral groove produced three phases of inhibition in the H reflex of relaxed wrist and finger flexor muscles. The first phase of inhibition occurred with a conditioning-test interval of -1 to 3 ms and represents disynaptic Ia reciprocal inhibition of flexor motoneurones by afferent input from extensor muscles. The second phase occurred with a conditioning-test interval of 5-40 ms. The characteristics of the second inhibitory phase have been investigated in the present study. 2. The threshold intensity of radial nerve stimulation required to produce the second phase of inhibition was 0.7 .times. motor threshold and was the same as that required to produce the first (disynaptic) phase of inhibition. 3. The time course of the effect of a radial nerve stimulus on the size of e.m.g. response to transcranial electrical stimulation of the motor cortex also was studied. The results were compared to those obtained with H reflex testing. The time course and depth of the first phase of inhibition were identical with both test inputs. The second of phase of inhibition, however, was seen only with the H reflex test stimulus. When the corticospinal volley was timed to arrive at the cervical cord 30 ms after the radial nerve afferent volley, the flexor muscle response was facilitated rather than inhibited. 4. A single stimulus (2-3 .times. sensory threshold) to the superficial (cutaneous) branch of the radial nerve at the wrist failed to produce inhibition of the flexor H reflex. Instead, the H reflex was facilitated when the median nerve Ia volley (for the H reflex) was timed to arrive at the cervical cord between 30-40 ms after the radial nerve cutaneous afferent volley. In contrast to results using mixed nerve stimulation in the spiral groove, there was no difference between the effect of this cutaneous input on the cortically evoked e.m.g. response and the H reflex. 5. We conclude that the second phase of flexor H reflex inhibition is produced by activity in large-diameter (group I) extensor muscle afferents which acts on the H reflex pathway at a premotoneuronal site. We suggest that the site is presynaptic on the Ia afferent terminals and that this inhibition competes with a later (probably post-synaptic) facilitation of the flexor H reflex produced partly by activity in cutaneous afferent fibres of the radial nerve.